Patent Publication Number: US-9429903-B2

Title: Image forming apparatus having cartridge

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority from Japanese Patent Application No. 2014-074636 filed Mar. 31, 2014. The entire content of this priority application is incorporated herein by reference. 
     TECHNICAL FIELD 
     The present disclosure relates to an image-forming apparatus employing an electrophotographic system. 
     BACKGROUND 
     An electrophotographic image-forming apparatus known in the art is provided with a main body, and a process cartridge mounted in and removed from the main body and including a photosensitive drum. 
     In one such image-forming apparatus that has been proposed, the process cartridge is provided with a handle, and the main body is further provided with an optical system for irradiating light toward the photosensitive drum based on image data. The optical system is positioned on the front side of the process cartridge when the process cartridge is mounted in the main body. With this image-forming apparatus, the user grips the handle of the process cartridge to remove the process cartridge from the main body. 
     SUMMARY 
     However, in the process cartridge described above, the handle is provided between the process cartridge and the optical system in a horizontal direction. Consequently, space must be allocated in the image-forming apparatus between the handle and the optical system in the front-rear direction to allow the user to grip the handle, which makes it difficult to attain the compact image-forming apparatus in the front-rear direction. 
     In view of the foregoing, it is an object of the present disclosure to provide an image-forming apparatus that can be made more compact in a horizontal direction orthogonal to the vertical direction. 
     In order to attain above and other objects, the disclosure provides an image forming apparatus. The image forming apparatus may include a casing, a process cartridge, and an exposure unit. The casing may define a first direction, a second direction orthogonal to the first direction, and a third direction orthogonal to the first direction and the second direction. The third direction may extend vertically. The process cartridge may be configured to be mounted in and removed from the casing. The process cartridge may include a photosensitive body extending in the first direction and a grip having a portion. The exposure unit may be configured to expose the photosensitive body. The exposure unit may have a part overlapped with the process cartridge as viewed in the second direction when the process cartridge is mounted in the casing. The portion of the grip may be overlapped with the exposure unit as viewed in the third direction and disposed above the exposure unit in the third direction when the process cartridge is mounted in the casing. 
     According to another aspect, the disclosure provides an image forming apparatus. The image forming apparatus may include a casing, a photosensitive body, a developing cartridge, and an exposure unit. The casing may define a first direction, a second direction orthogonal to the first direction, and a third direction orthogonal to the first direction and the second direction. The third direction may extend vertically. The photosensitive body may extend in the first direction. The photosensitive body may be fixedly provided in the casing. The developing cartridge may be configured to be mounted in and removed from the casing and accommodate therein developing agent. The developing cartridge may include a grip having a portion. The exposure unit may be configured to expose the photosensitive body. The exposure unit may have a part overlapped with the process cartridge as viewed in the second direction when the developing cartridge is mounted in the casing. The portion of the grip may be overlapped with the exposure unit as viewed in the third direction and disposed above the exposure unit in the third direction when the developing cartridge is mounted in the casing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The particular features and advantages of the embodiments as well as other objects will become apparent from the following description taken in connection with the accompanying drawings, in which: 
         FIG. 1  is a central cross-sectional view of a printer wherein a process cartridge is at an internal position according to a first embodiment; 
         FIG. 2  is a central cross-sectional view of the printer wherein a developing cartridge is being removed from a drum cartridge according to the first embodiment; 
         FIG. 3  is a central cross-sectional view of the printer wherein the process cartridge is at an external position according to the first embodiment; 
         FIG. 4  is a plan view of the process cartridge according to the first embodiment; 
         FIG. 5A  is a left side view of the drum cartridge according to the first embodiment; 
         FIG. 5B  is a cross-sectional view of the drum cartridge according to the first embodiment; 
         FIG. 6A  is a left side view of the developing cartridge according to the first embodiment; 
         FIG. 6B  is a cross-sectional view of the developing cartridge according to the first embodiment; 
         FIG. 7  is a plan view of a process cartridge according to a second embodiment; 
         FIG. 8  is a cross-sectional view of a printer according to a third embodiment; 
         FIG. 9  is a cross-sectional view of a printer according to a fourth embodiment; and 
         FIG. 10  is a cross-sectional view of a printer according to a fifth embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     1. Overall Structure of a Printer 
       FIG. 1  shows a printer  1  as an example of an image forming apparatus in a first embodiment. The printer  1  of the first embodiment is a monochromatic printer having an electrophotographic system. The printer  1  includes a main casing  2  as an example of a casing, a sheet-feeding unit  3 , an image-forming unit  4 , a discharging unit  5 , a conveyance guiding unit  6 , and a flatbed scanner  7  as an example of an image reading unit. 
     Directions used in the following description in relation to the printer  1  will reference the state of the printer  1  when the printer  1  is resting on a level surface, where the right side of the printer  1  in  FIG. 1  will be called the “front,” and the left side of the printer  1  will be called the “rear.” Left and right sides of the printer  1  will be defined based on the perspective of a user facing the front side of the printer  1 , so that the near side of the printer  1  in  FIG. 1  is the “left side,” and the far side is the “right side.” Further, front, rear, left, right, top, and bottom sides of a process cartridge  15  described later are defined based on the mounted state of the process cartridge  15  in the main casing  2 . Directional arrows have also been provided in the drawings for reference. 
     Note that the left-right direction is an example of a first direction. Similarly, the front-rear direction is an example of a second direction, where the front side is an example of a first side and an example of a third side, and the rear side is an example of a second side and an example of a fourth side. Further, the top-bottom direction is identical to the vertical direction and is an example of a third direction. 
     The main casing  2  has a box-like shape and includes an access opening  10 , and a top cover  11  as an example of a cover. 
     The access opening  10  penetrates the main casing  2  vertically and provides communication between the interior and the exterior of the main casing  2 . 
     The top cover  11  is pivotally movable between a closed position at which the top cover  11  covers the access opening  10  ( FIG. 1 ), and an open position at which the access opening  10  is exposed ( FIGS. 2 and 3 ). The top cover  11  also functions as a discharge tray  12  configured to support sheets P as an example of a recording medium. 
     The main casing  2  accommodates therein the sheet-feeding unit  3 , the image-forming unit  4 , the discharging unit  5 , and the conveyance guiding unit  6  and supports the flatbed scanner  7  from below. 
     The sheet-feeding unit  3  is configured to supply sheets P to the image-forming unit  4 . The sheet-feeding unit  3  is provided in the bottom section of the main casing  2 . The sheet-feeding unit  3  includes a sheet cassette  9 , and a feeding roller  8  as an example of a separating roller. 
     The sheet cassette  9  has a box-like shape that is open on the top for accommodating a plurality of sheets P. The sheet cassette  9  is provided in the bottom section of the main casing  2  and can be mounted in and removed from the main casing  2 . 
     The feeding roller  8  has a general columnar shape elongated in the left-right direction. The feeding roller  8  is disposed above the front end of the sheet cassette  9 . 
     The image-forming unit  4  is configured to form images on the sheets P. The image-forming unit  4  is disposed above the sheet-feeding unit  3  in the main casing  2 . The image-forming unit  4  includes the process cartridge  15 , a scanning unit  16  as an example of an exposure unit, and a fixing unit  17 . 
     The process cartridge  15  can be moved between an internal position at which the process cartridge  15  is mounted in the main casing  2  ( FIG. 1 ), and an external position at which the process cartridge  15  is removed from the main casing  2  through the access opening  10  ( FIG. 3 ). Hence, the process cartridge  15  is configured to be mounted in and removed from the main casing  2  through the access opening  10 . 
     As shown in  FIG. 1 , the process cartridge  15  is disposed in the approximate center of the main casing  2  in a side view, above the approximate front-rear center of the sheet cassette  9  and rearward of the feeding roller  8 . In other words, the sheet cassette  9  is disposed below the process cartridge  15 , and the feeding roller  8  is disposed forward of the process cartridge  15 . 
     The process cartridge  15  includes a drum cartridge  18  as an example of a photosensitive cartridge, and a developing cartridge  19 . 
     The drum cartridge  18  includes a photosensitive drum  20  as an example of a photosensitive body, a transfer roller  21 , and a scorotron charger  22  as an example of a charger. 
     The photosensitive drum  20  has a general cylindrical shape elongated in the left-right direction. The photosensitive drum  20  is disposed at the rear portion of the drum cartridge  18 . The transfer roller  21  is disposed diagonally downward and rearward of the photosensitive drum  20 . The upper-front surface of the transfer roller  21  contacts the lower-rear surface of the photosensitive drum  20  at a nipping point N. The scorotron charger  22  is disposed diagonally upward and frontward of the photosensitive drum  20  but is separated therefrom. 
     The developing cartridge  19  is configured to be mounted in and removed from the drum cartridge  18  at the front side of the photosensitive drum  20 . The developing cartridge  19  includes a developing roller  26 , a supply roller  27 , a thickness-regulating blade  28 , and an agitator  29 . The developing cartridge  19  also accommodates therein toner as an example of a developing agent. 
     The developing roller  26  is disposed at the rear portion of the developing cartridge  19 . The upper rear portion of the developing roller  26  is exposed outside the developing cartridge  19 . The upper-rear surface of the developing roller  26  contacts the lower-front surface of the photosensitive drum  20 . 
     The supply roller  27  is disposed diagonally downward and forward of the developing roller  26 . The upper-rear surface of the supply roller  27  contacts the lower-front surface of the developing roller  26 . 
     The thickness-regulating blade  28  has a plate-like structure that is generally rectangular in a rear view and elongated in the left-right direction. The thickness-regulating blade  28  is disposed diagonally upward and forward of the developing roller  26 . The lower edge of the thickness-regulating blade  28  contacts the front surface of the developing roller  26 . 
     The agitator  29  is disposed diagonally upward and forward of the supply roller  27 . 
     The scanning unit  16  is disposed forward of the photosensitive drum  20  with a gap therebetween and above the feeding roller  8  with a gap therebetween. More specifically, the scanning unit  16  overlaps the feeding roller  8  as viewed in top-bottom direction, and the scanning unit  16  also overlaps the fixing unit  17  and the process cartridge  15  as viewed in the front-rear direction, when the process cartridge  15  is at the internal position, as shown in  FIG. 1 . Specifically, at least part of the scanning unit  16  overlaps the process cartridge  15  as viewed in the front-rear direction when the process cartridge  15  is at the internal position. In other word, at least part of the scanning unit  16  overlaps the developing cartridge  19  as viewed in the front-rear direction when the developing cartridge  19  is mounted in the main casing  2 . 
     The scanning unit  16  is configured to expose the photosensitive drum  20 . That is, the scanning unit  16  emits a laser beam L toward the photosensitive drum  20  along an irradiating path based on image data, as indicated by a solid line in  FIG. 1 . 
     The fixing unit  17  is disposed rearward of the process cartridge  15  with a gap therebetween. The fixing unit  17  includes a heating roller  30 , and a pressure roller  31 . 
     The pressure roller  31  is disposed diagonally downward and rearward of the heating roller  30 . The upper-front surface of the pressure roller  31  is in pressure contact with the lower-rear surface of the heating roller  30 . 
     The discharging unit  5  is configured to discharge sheets P onto the discharge tray  12  after the image-forming unit  4  has formed an image thereon. The discharging unit  5  includes a pair of discharge rollers  34 . 
     The discharge rollers  34  are disposed diagonally upward and forward of the fixing unit  17  and are separated therefrom. The discharge rollers  34  contact each other in a direction extending from upper front to lower rear. 
     The conveyance guiding unit  6  is configured to guide conveyance of sheets P within the main casing  2 . The conveyance guiding unit  6  has a first conveyance guide  6 A, and a second conveyance guide  6 B. 
     After the feeding roller  8  feeds a sheet P from the sheet cassette  9 , the first conveyance guide  6 A guides the sheet P through the nipping point N between the photosensitive drum  20  and the transfer roller  21  to the pair of discharge rollers  34 . Thus, the first conveyance guide  6 A defines a conveying path T 1  that is general S-shaped in a side view. 
     The second conveyance guide  6 B guides the conveyed sheet P having an image formed on one side from the discharge rollers  34  to a portion of the first conveyance guide  6 A on the upstream side of the nipping point N. More specifically, the second conveyance guide  6 B is formed continuously with a portion of the first conveyance guide  6 A positioned between the fixing unit  17  and the discharge rollers  34 , follows a general L-shaped path in a side view that passes between the sheet cassette  9  and the process cartridge  15 , and then curves upward to connect to the first conveyance guide  6 A at a position between the feeding roller  8  and the nipping point N. Thus, the second conveyance guide  6 B defines a re-conveying path T 2  that has a general C-shape in a side view, with the opening of the “C” facing upward. 
     The flatbed scanner  7  is disposed above the main casing  2  and faces the top of the top cover  11  with a gap therebetween. The flatbed scanner  7  includes a shaft  44 , a restraining cover  41 , a glass surface  42 , and a CCD sensor  43 . 
     The shaft  44  is provided on the lower-rear portion of the flatbed scanner  7 . The shaft  44  has a general columnar shape and extends in the left-right direction. The shaft  44  is rotatably supported in the upper-rear portion of the main casing  2 , whereby the flatbed scanner  7  is pivotally movable relative to the main casing  2  about the shaft  44 . 
     The flatbed scanner  7  is configured to read image data from a document by the CCD sensor  43  after the document has been placed on the glass surface  42  and covered with the restraining cover  41 . 
     2. Detailed Description of the Main Casing 
     As shown in  FIG. 3 , the main casing  2  is integrally configured of a pair of side walls  46 , a rear wall  47 , a bottom wall  49 , a front wall  48 , and a top wall  50 . The main casing  2  also includes a motor (not shown), an apparatus-side coupling (not shown), and the top cover  11  described above. 
     The side walls  46  constitute the left and right sides of the main casing  2  and are away from each other in the left-right direction. The side walls  46  have a plate-like structure that is generally L-shaped in a side view. Specifically, each side wall  46  is configured of a rear portion  46 A that has a general rectangular shape in a side view and is elongated top-bottom direction, and a front portion  46 B that has a general rectangular shape in a side view and is elongated in the front-rear direction. The front portion  46 B extends forward from the lower front portion of the rear portion  46 A. Each side wall  46  is formed with a groove  53 . 
     The grooves  53  are formed on the inner left-right surfaces of the corresponding side walls  46  in the front portion  46 B and are aligned with each other in the left-right direction. That is, the grooves  53  are recessed outward in the left-right direction from the inner left-right surfaces of the corresponding front portions  46 B constituting the side walls  46 . The grooves  53  extend diagonally downward and rearward from the top edges of the rear end portions of the corresponding front portions  46 B. Each groove  53  has a wide section  57 , and a narrow section  58 . 
     The wide section  57  constitutes the upper portion of the groove  53  and is formed to gradually narrow toward the lower rear end thereof. The narrow section  58  constitutes the lower portion of the groove  53  and extends continuously downward and rearward from the lower rear end of the wide section  57 . The width of the narrow section  58  is uniform. The lower-rear end of the narrow section  58  has a general semicircular shape in a side view, with the concave of the narrow section  58  facing diagonally upward and forward. 
     An apparatus-side coupling is disposed at the bottom end of the narrow section  58  of the left-side groove  53 . The apparatus-side coupling is an interlocking mechanism well known in the art that is configured to move left and right in association with the opening and closing operation of the top cover  11 . When the top cover  11  is at the open position, the apparatus-side coupling is retracted further leftward from the right surface of the left side wall  46 . When the top cover  11  is at the closed position, the apparatus-side coupling is advanced to a position further rightward than the right surface of the left side wall  46 . The apparatus-side coupling is configured to transmit a drive force from the motor and rotates clockwise in a left side view when transmitting the drive force. 
     The rear wall  47  constitutes the rear portion of the main casing  2 . The rear wall  47  has a plate-like structure that is generally rectangular in a rear side view and is elongated in the left-right direction. The left and right edges of the rear wall  47  are formed continuously with the rear edges of the respective side walls  46 . 
     The bottom wall  49  constitutes the bottom portion of the main casing  2 . The bottom wall  49  has a plate-like structure and is generally rectangular in a bottom view. The left and right edges of the bottom wall  49  are formed continuously with the bottom edges of the corresponding side walls  46 , and the rear edge of the bottom wall  49  is formed continuously with the bottom edge of the rear wall  47 . 
     The front wall  48  constitutes the front portion of the main casing  2 . The front wall  48  has a plate-like structure that is generally rectangular in a front view and elongated in the left-right direction. The left and right edges of the front wall  48  are formed continuously with the front edges of the respective side walls  46 . 
     The top wall  50  constitutes the top portion of the main casing  2 . The top wall  50  includes a first wall section  65 , a second wall section  66 , and a third wall section  67 . 
     The first wall section  65  constitutes the front portion of the top wall  50  and is positioned above the scanning unit  16  so as to cover the same. The first wall section  65  extends continuously rearward from the top edge of the front wall  48  and is elongated in the left-right direction. The left and right edges of the first wall section  65  are formed continuously with the upper front portions of the respective side walls  46 . 
     More specifically, the first wall section  65  integrally possesses a curved wall  69 , and a sloped wall  70 . 
     The curved wall  69  constitutes the front portion of the first wall section  65 . The curved wall  69  extends continuously upward from the top edge of the front wall  48  so as to curve toward the rear. 
     The sloped wall  70  constitutes the rear portion of the first wall section  65 . The sloped wall  70  integrally possesses a first sloped section  70 A, and a second sloped section  70 B. 
     The first sloped section  70 A extends continuously rearward from the top edge of the curved wall  69  and slops downward. The second sloped section  70 B forms a bend from the rear edge of the first sloped section  70 A and slopes downward toward the rear. The second sloped section  70 B has a steeper downward slope than the first sloped section  70 A. 
     The second wall section  66  constitutes the rear portion of the top wall  50 . The second wall section  66  is disposed above the discharging unit  5  and is positioned higher than the first wall section  65 . The second wall section  66  extends continuously forward from the top edge of the rear wall  47  and is elongated in the left-right direction. The left and right edges of the second wall section  66  are formed continuously with the top edges of the respective rear portions  46 A of the side walls  46 . 
     As shown in  FIG. 1 , the second wall section  66  contacts the lower rear portion of the flatbed scanner  7  to support the flatbed scanner  7 . The shaft  44  of the flatbed scanner  7  is rotatably supported at the corner of the second wall section  66  and the rear wall  47 . 
     The third wall section  67  bends and extends downward from the front edge of the second wall section  66 . The third wall section  67  is elongated in the left-right direction. The left and right edges of the third wall section  67  are formed continuously with the upper front edges of the rear portions  46 A of the side walls  46 . The third wall section  67  is formed with a discharge opening  68 . 
     The discharge opening  68  is formed at the top region of the third wall section  67  in front of the discharge rollers  34 . The discharge opening  68  penetrates the top edge of the third wall section  67  in the front-rear direction and has a size and shape for allowing passage of sheets P. 
     The access opening  10  is defined by the rear edge of the sloped wall  70 , the bottom edge of the third wall section  67 , and the parts of the front portions  46 B of the side walls  46  that are positioned between the sloped wall  70  and the third wall section  67 . Hence, the access opening  10  is formed at the rear of the scanning unit  16  and above the process cartridge  15  when the process cartridge  15  is mounted in the main casing  2 . The access opening  10  has a general rectangular shape in a plan view and provides vertical communication between the interior and the exterior of the main casing  2 . 
     As described above, the top wall  50  supports the top cover  11  provided for opening and closing the access opening  10 . 
     The top cover  11  includes a rotational shaft  78  as an example of a pivot shaft, and a cover body  79 . 
     The rotational shaft  78  has a general columnar shape elongated in the left-right direction. The rotational shaft  78  is rotatably supported on the bottom end of the third wall section  67 , i.e., the rear peripheral edge of the access opening  10 . Accordingly, the rotational shaft  78  is disposed diagonally upward and rearward of the process cartridge  15  when the process cartridge  15  is at the internal position. More specifically, the rotational shaft  78  is disposed between the scorotron charger  22  and the fixing unit  17  in the front-rear direction. 
     The cover body  79  has a plate-like structure that is generally rectangular in a plan view. 
     The cover body  79  of the top cover  11  is pivotally movable about the rotational shaft  78  between the closed position shown in  FIG. 1  at which the top cover  11  covers the access opening  10 , and the open position shown in  FIG. 3  at which the access opening  10  is exposed. 
     When the top cover  11  is at the closed position shown in  FIG. 1 , the cover body  79  extends diagonally upward and forward from the rotational shaft  78 , and then curves and extends forward. The front end of the cover body  79  is positioned above the area at which the rear edge of the curved wall  69  connects with the first sloped section  70 A. In this way, the cover body  79  is positioned above the process cartridge  15  mounted in the main casing  2 . Further, the rotational shaft  78  is disposed at the lowest end of the top cover  11 . 
     However, when the top cover  11  is at the open position shown in  FIG. 3 , the cover body  79  extends diagonally upward and forward from the rotational shaft  78 , and then curves and continues extending diagonally upward and forward at a gentler upward slope. The front edge of the cover body  79  is disposed high enough above the sloped wall  70  to form space allowing the process cartridge  15  to pass therethrough. 
     3. Detailed Description of the Process Cartridge 
     As described above, the process cartridge  15  includes the drum cartridge  18  and the developing cartridge  19 . 
     (1) Drum Cartridge 
     As shown in  FIGS. 5A and 5B , the drum cartridge  18  includes a drum-cartridge frame  23 , and a drum-cartridge handle  86  as an example of a grip unit. 
     The drum-cartridge frame  23  has a box-like shape that is open on the top. The drum-cartridge frame  23  is integrally configured of a pair of side walls  87 , a bottom wall  88 , a front wall  93 , a transfer-roller accommodating section  89 , and a charger support wall  94 . 
     The side walls  87  constitute the left and right end portions of the drum-cartridge frame  23  and oppose but are separated from each other in the left-right direction. The side walls  87  have a plate-like structure that is generally rectangular in a side view and elongated in the front-rear direction. Each of the side walls  87  includes a receiving groove  90 , a through-hole  91 , and a collar  92 . 
     The receiving groove  90  is formed in the inner left-right surface of the corresponding side wall  87 . The receiving groove  90  is recessed outward in the left-right direction from the inner left-right surface of the corresponding side wall  87  and extends diagonally downward and rearward from the top edge of the side wall  87 . Specifically, the receiving groove  90  includes a guide part  90 A, an intermediate part  90 B, and an end part  90 C. 
     The guide part  90 A constitutes the upper portion of the receiving groove  90 . The guide part  90 A extends diagonally downward and rearward from the approximate front-rear center region of the top edge of the side wall  87 . The guide part  90 A becomes narrower toward the lower-rear end thereof. 
     The intermediate part  90 B extends continuously rearward from the bottom end of the guide part  90 A. 
     The end part  90 C curves continuously upward and rearward from the rear end of the intermediate part  90 B. The rear end of the end part  90 C has a general semicircular shape in a side view. The concave of the end part  90 C faces diagonally downward and forward. 
     As shown in  FIG. 5A , the through-hole  91  is formed at the rear portion of the corresponding side wall  87  at a position diagonally upward and rearward of the end part  90 C of the corresponding receiving groove  90  and separated therefrom. The through-hole  91  has a general circular shape in a side view and penetrates the side wall  87  in the left-right direction. 
     The collar  92  is disposed on the outer left-right surface of the corresponding side wall  87  and is configured to be inserted into the corresponding groove  53 . The collar  92  has a general cylindrical shape elongated in the left-right direction. The collar  92  protrudes outward in the left-right direction from the peripheral edge of the corresponding side wall  87  defining the corresponding through-hole  91 . The outer diameter of the collar  92  is approximately equal to the width of the narrow section  58 . 
     As shown in  FIG. 5B , the bottom wall  88  bridges the lower front edges of the side walls  87 . The bottom wall  88  has a plate-like structure with a general rectangular shape in a bottom view and is elongated in the left-right direction. The bottom wall  88  includes a pair of protruding parts  96 . 
     As shown in  FIGS. 4 and 5B , the protruding parts  96  are disposed on the top surface of the bottom wall  88  in the approximate front-rear center region thereof and are separated from each other in the left-right direction. As shown in  FIG. 5B , the protruding parts  96  have a general triangular shape in a side view and protrude upward from the bottom wall  88 . 
     The front wall  93  bridges the front end portions of the side walls  87 . The bottom edge of the front wall  93  is connected to the front edge of the bottom wall  88 . The front wall  93  has a plate-like structure that is generally rectangular in a front view and elongated in the left-right direction. The front wall  93  is formed with a through-hole  97  as an example of an opening. 
     The through-hole  97  is formed at the top portion of the front wall  93  and penetrates the front wall  93  in the front-rear direction. The through-hole  97  has a size and shape to allow passage of the laser beam L emitted from the scanning unit  16 . 
     The transfer-roller accommodating section  89  constitutes the lower rear end portion of the drum-cartridge frame  23  and is provided at the rear of the bottom wall  88  with a gap therebetween. The transfer-roller accommodating section  89  has a general U-shape in a side view, with the opening of the “U” facing upward and is elongated in the left-right direction. The left and right ends of the transfer-roller accommodating section  89  are formed continuously with the lower rear end portions of the side walls  87 . 
     The charger support wall  94  constitutes the upper-rear portion of the drum-cartridge frame  23  and is disposed above and separated from the transfer-roller accommodating section  89 . The charger support wall  94  is elongated in the left-right direction. The left and right ends of the charger support wall  94  are formed continuously with the upper-rear end portions of the corresponding side walls  87 . The charger support wall  94  is integrally configured of a body  94 A, and a cover part  94 B. 
     The body  94 A has a squared U-shape in a side view, with the opening of the “U” facing diagonally downward and rearward. The body  94 A is formed with an opening  95  at the top wall thereof. As shown in  FIG. 4 , the opening  95  has a general rectangular shape in a plan view and is elongated in the left-right direction. As shown in  FIG. 5B , the opening  95  penetrates the top wall of the body  94 A in a direction extending from upper front to lower rear. 
     The cover part  94 B has a plate-like structure with a general rectangular shape in a rear view and is elongated in the left-right direction. The cover part  94 B extends continuously downward and rearward from the lower-rear edge of the body  94 A, and then curves to follow the surface of the photosensitive drum  20 . 
     A cartridge-mounting opening  99  is defined by the top edges of the side walls  87 , the top edge of the front wall  93 , and the front edge of the charger support wall  94 . The cartridge-mounting opening  99  has a general rectangular shape in a plan view and has a size sufficient for allowing passage of the developing cartridge  19 . 
     The side walls  87 , the bottom wall  88 , and the front wall  93  further define an accommodating space S at the front side of the photosensitive drum  20  for accommodating therein the developing cartridge  19 . The accommodating space S is in vertical communication with the cartridge-mounting opening  99 . 
     The drum-cartridge frame  23  also supports the photosensitive drum  20 , the transfer roller  21 , and the scorotron charger  22 . 
     The photosensitive drum  20  is disposed at the rear end portions of the side walls  87  at a position diagonally upward and forward of the transfer-roller accommodating section  89  and downward and rearward of the charger support wall  94 . The photosensitive drum  20  includes a drum body  100 , and a pair of flange parts  101 . 
     The drum body  100  includes a metal tube having a general cylindrical shape that is elongated in the left-right direction, and a photosensitive layer that coats the circumferential surface of the metal tube. 
     The flange parts  101  are fitted into respective left and right ends of the drum body  100 . As shown in  FIGS. 5A and 5B , each flange part  101  is integrally configured of a fitting part  102 , and an insertion part  103 . 
     The fitting part  102  constitutes the inner portion of the flange part  101  in the left-right direction. The fitting part  102  has a general cylindrical shape elongated in the left-right direction. The outer endface of each fitting part  102  in the left-right direction is closed. The outer diameter of the fitting part  102  is approximately equal to the inner diameter of the drum body  100 . The fitting part  102  is nonrotatably fitted into the corresponding axial end portion of the drum body  100  in the left-right direction. 
     The insertion part  103  constitutes the outer portion of the flange part  101  in the left-right direction. The insertion part  103  has a general cylindrical shape that shares the central axis with the fitting part  102  and protrudes outward in the left-right direction from the outer end of the corresponding fitting part  102  in the left-right direction. The outer diameter of the insertion part  103  is smaller than the outer diameter of the fitting part  102  and approximately equal to the inner diameter of the through-hole  91 . 
     As shown in  FIG. 5A , the insertion part  103  of the left flange part  101  is configured to be connectable with insertion of the right end of the apparatus-side coupling. The insertion part  103  of the left flange part  101  is integrally provided with a pair of engaging protrusions  104 . The engaging protrusions  104  are provided on the inner circumferential surface of the insertion part  103  at an interval of 180 degrees in the circumferential direction of the insertion part  103 . The engaging protrusions  104  have a general rectangular shape in a side view and protrude radially inward from the inner circumferential surface of the insertion part  103 . 
     By inserting the insertion part  103  of each flange part  101  into the corresponding through-hole  91  and the collar  92 , the photosensitive drum  20  is rotatably supported in the drum-cartridge frame  23  about the rotational axis A of the drum body  100 . 
     As shown in  FIG. 5B , the transfer roller  21  is disposed inside the transfer-roller accommodating section  89 . The transfer roller  21  has a general columnar shape elongated in the left-right direction. The transfer roller  21  is rotatably supported in the drum-cartridge frame  23  with left and right ends supported in the corresponding side walls  87 . The upper-front surface of the transfer roller  21  contacts the lower-rear surface of the drum body  100  of the photosensitive drum  20 . 
     The scorotron charger  22  is supported in the charger support wall  94 . The scorotron charger  22  includes a discharge wire  22 A, and a grid electrode  22 B. 
     The discharge wire  22 A is disposed inside the body  94 A in the approximate center region thereof in a side view, and is stretched taut along the left-right direction. The discharge wire  22 A is disposed diagonally upward and forward of the photosensitive drum  20  with a gap therebetween. The grid electrode  22 B has a general squared U-shape in a side view, with the opening of the “U” facing diagonally upward and forward. The grid electrode  22 B is disposed inside the body  94 A so as to surround the discharge wire  22 A from the lower-rear side. With this construction, the lower-rear side of the grid electrode  22 B is positioned between the discharge wire  22 A and the drum body  100 . 
     The drum-cartridge handle  86  is provided at the front end portion of the drum cartridge  18 . The drum-cartridge handle  86  has a pair of pivoting shafts  115 , and a handle body  116 . 
     The pivoting shafts  115  are spaced apart from each other in the left-right direction. The pivoting shafts  115  have a general columnar shape elongated in the left-right direction. The inner portions of the pivoting shafts  115  in the left-right direction are supported on the upper-front corners of the corresponding side walls  87  so as to be incapable of rotating relative to the corresponding side walls  87 . The outer portions of the pivoting shafts  115  in the left-right direction protrude farther outward in the left-right direction than the corresponding side walls  87 . 
     As shown in  FIG. 4 , the handle body  116  has a general U-shape in a plan view, with the opening of the “U” facing rearward. The handle body  116  is integrally configured of a pair of cylindrical parts  118 , a pair of coupling parts  119 , and a grip part  120  as an example of a grip and an example of a first grip. 
     As shown in  FIGS. 4 and 5A , the cylindrical parts  118  are separated from each other in the left-right direction and positioned to correspond to the respective pivoting shafts  115 . The cylindrical parts  118  have a general cylindrical shape elongated in the left-right direction. The inner diameter of the cylindrical parts  118  is approximately equal to the outer diameter of the pivoting shafts  115 . 
     The coupling parts  119  have a rod-like structure extending in a direction from lower rear to upper front. The coupling parts  119  extend continuously upward and forward from the corresponding cylindrical parts  118 . 
     As shown in  FIG. 4 , the grip part  120  bridges the front end portions of the coupling parts  119 . The grip part  120  has a plate-like structure that is generally rectangular in a plan view and elongated in the left-right direction. 
     As shown in  FIGS. 4 and 5A , the outer portions of the pivoting shafts  115  in the left-right direction is rotatably inserted into the corresponding cylindrical parts  118 . Thus, the drum-cartridge handle  86  is supported on the drum-cartridge frame  23 . With this configuration, the grip part  120  is pivotally movable about the pivoting shafts  115  relative to the drum-cartridge frame  23 . 
     (2) Developing Cartridge 
     As shown in  FIGS. 6A and 6B , the developing cartridge  19  includes a developing-cartridge frame  25 , and a developing-cartridge handle  125  as an example of a grip unit. 
     The developing-cartridge frame  25  is integrally configured of a pair of side walls  126 , a toner accommodating section  127 , a blade support part  128 , and a bottom wall  129 . 
     The side walls  126  constitute the left and right portions of the developing-cartridge frame  25  and oppose each other in the left-right direction with a gap therebetween. As shown in  FIG. 6A , the side walls  126  have a plate-like structure with a general rectangular shape in a side view and are elongated in the front-rear direction. 
     As shown in  FIG. 6B , the toner accommodating section  127  is disposed between the front portions of the side walls  126 . The toner accommodating section  127  has a general angular cylindrical shape elongated in the left-right direction. The toner accommodating section  127  has a bottom wall  127 A that curves in a side view with the convex facing downward. The left and right ends of the toner accommodating section  127  are closed by the front portions of the side walls  126 . The toner accommodating section  127  accommodates toner therein. 
     The toner accommodating section  127  is formed with a through-hole  130 . The through-hole  130  is formed at the front wall of the toner accommodating section  127  near the bottom end thereof and penetrates the front wall in the front-rear direction. 
     The blade support part  128  is disposed at the upper portion on the front surface of the front wall of the toner accommodating section  127 . The blade support part  128  has a general rectangular shape in a side view and protrudes forward from the toner accommodating section  127 . 
     The bottom wall  129  extends rearward from the bottom peripheral edge of the through-hole  130  in the toner accommodating section  127 . The bottom wall  129  is elongated in the left-right direction. The left and right ends of the bottom wall  129  are connected to the bottom edges of the side walls  126  at the rear portions of the bottom wall  129 . 
     More specifically, the bottom wall  129  includes an arc-shaped part  129 A, and a lip part  129 B. 
     The arc-shaped part  129 A constitutes the front portion of the bottom wall  129 . The arc-shaped part  129 A has a general semicircular shape in a side view, and the concave portion of the arc-shaped part  129 A faces upward so as to follow the circumferential surface of the supply roller  27 . The front edge of the arc-shaped part  129 A is connected to the rear edge of the bottom wall  127 A of the toner accommodating section  127 . 
     The bottom surfaces of the arc-shaped part  129 A and the bottom wall  127 A of the toner accommodating section  127  define a recessed part  131  at the front portion of the arc-shaped part  129 A and at the rear portion of the bottom wall  127 A. The recessed part  131  has a general triangular shape in a side view and forms an upward recess from the bottom surface of the developing-cartridge frame  25 . 
     The lip part  129 B constitutes the rear portion of the bottom wall  129 . The lip part  129 B has a general arc shape in a side view, and the concave portion of the lip part  129 B faces diagonally upward and forward so as to follow the circumferential surface of the developing roller  26 . The front edge of the lip part  129 B is connected to the rear edge of the arc-shaped part  129 A. 
     The developing-cartridge frame  25  supports the developing roller  26 , the supply roller  27 , the thickness-regulating blade  28 , and the agitator  29 . 
     The developing roller  26  is disposed above the lip part  129 B with a gap therebetween. As shown in  FIGS. 6A and 6B , the developing roller  26  includes a roller shaft  134 , a roller body  133 , and a pair of cylinders  135 . 
     The roller shaft  134  has a general columnar shape elongated in the left-right direction. The left-right dimension of the roller shaft  134  is greater than the left-right dimension of the developing-cartridge frame  25 . The left and right ends of the roller shaft  134  are rotatably supported on the corresponding side walls  126 , thereby rotatably supporting the developing roller  26  in the developing-cartridge frame  25 . The left and right ends of the roller shaft  134  protrude outward in the left-right direction from the corresponding side walls  126 . 
     The roller body  133  has a general cylindrical shape elongated in the left-right direction. The left-right dimension of the roller body  133  is smaller than the left-right dimension of the roller shaft  134 . The roller body  133  covers the roller shaft  134  and is disposed at a position between the rear end portions of the side walls  126 . 
     One of the cylinders  135  is provided on each of the left and right ends of the roller shaft  134  and disposed at the outer side of the corresponding side wall  126  in the left-right direction. The cylinders  135  have a general cylindrical shape elongated in the left-right direction. The inner diameter of the cylinders  135  is approximately equal to the outer diameter of the roller shaft  134 , while the outer diameter of the cylinders  135  is approximately equal to the width of the intermediate parts  90 B and end parts  90 C of the receiving grooves  90 . The cylinders  135  are fitted over the left and right end portions of the roller shaft  134  in the outer sides of the side walls  126  in the left-right direction so as to be rotatable relative to the roller shaft  134 . 
     As shown in  FIG. 6B , the supply roller  27  is disposed inside the arc-shaped part  129 A at the lower-front side of the developing roller  26 . The supply roller  27  has a general columnar shape elongated in the left-right direction. The supply roller  27  is supported in the developing-cartridge frame  25  with its left and right ends rotatably supported in the corresponding side walls  126 . 
     The thickness-regulating blade  28  is fixed to the rear surface of the blade support part  128 . The bottom edge of the thickness-regulating blade  28  contacts the front surface of the roller body  133 . 
     The agitator  29  is disposed in the toner accommodating section  127 . The agitator  29  includes an agitator shaft  136 , and an agitating blade  137 . 
     The agitator shaft  136  has a general columnar shape elongated in the left-right direction. The agitating blade  137  is formed of a flexible film material and extends radially outward from the agitator shaft  136 . 
     The agitator  29  is supported on the developing-cartridge frame  25  with the left and right ends of the agitator shaft  136  rotatably supported in the corresponding side walls  126 . 
     As shown in  FIGS. 6A and 6B , the developing-cartridge handle  125  is provided at the front end portion of the developing cartridge  19 . The developing-cartridge handle  125  includes a pair of pivoting shafts  140 , and a handle body  141 . 
     The pivoting shafts  140  are separated from each other in the left-right direction. The pivoting shafts  140  have a general columnar shape elongated in the left-right direction. The inner portions of the pivoting shafts  140  in the left-right direction are non-rotatably supported on the upper-front corners of the corresponding side walls  126 . Thus, the outer portions of the pivoting shafts  140  in the left-right direction protrude outward in the left-right direction from the corresponding side walls  126 . 
     As shown in  FIG. 4 , the handle body  141  has a general U-shape in a plan view with the opening of the “U” facing rearward. The left-right dimension of the handle body  141  is smaller than the left-right distance between the pair of coupling parts  119  of the handle body  116 . As shown in  FIG. 6A , the handle body  141  includes a pair of cylindrical parts  142 , a pair of coupling parts  143 , and a grip part  144  as an example of a grip and an example of a second grip. Hence, the process cartridge  15  includes the grip part  120  and the grip part  144  as grips. 
     The cylindrical parts  142  are separated from each other in the left-right direction and disposed at positions corresponding to the pivoting shafts  140 . The cylindrical parts  142  have a general cylindrical shape elongated in the left-right direction. The inner diameter of the cylindrical parts  142  is approximately equal to the outer diameter of the pivoting shafts  140 . 
     The coupling parts  143  are rod-like members extending in a direction from lower rear to upper front. Specifically, the coupling parts  143  extend continuously upward and forward from the corresponding cylindrical parts  142 . 
     As shown in  FIG. 4 , the grip part  144  bridges the top ends of the coupling parts  143 . The grip part  144  has a plate-like structure that is generally rectangular in a plan view and elongated in the left-right direction. 
     As shown in  FIG. 6A , the developing-cartridge handle  125  is supported on the developing-cartridge frame  25  by rotatably inserting the outer portions of the pivoting shafts  140  in the left-right direction into the corresponding cylindrical parts  142 . With this arrangement, the developing-cartridge handle  125  is pivotally movable about the pivoting shafts  140  relative to the developing cartridge frame  25 . 
     The developing cartridge  19  having the above construction is configured to be mounted in and removed from the accommodating space S formed in the drum cartridge  18 , as shown in  FIG. 1 , thereby configuring the process cartridge  15 . When the developing cartridge  19  is mounted in the drum cartridge  18 , the cylinders  135  are inserted into the end parts  90 C of the corresponding receiving grooves  90 . Further, the recessed part  131  of the developing-cartridge frame  25  receives the pair of protruding parts  96  such that the bottom wall  127 A of the toner accommodating section  127  contacts the upper-front surfaces of the protruding parts  96 . 
     (3) Mounting the Process Cartridge in the Main Casing 
     When the process cartridge  15  is in the mounted state in the main casing  2 , i.e., is at the internal position, the grip part  120  of the drum-cartridge handle  86  is disposed at the front region of the top surface of the first sloped section  70 A, and the grip part  144  of the developing-cartridge handle  125  is disposed at the rear region of the top surface of the first sloped section  70 A. 
     Accordingly, at least part of the grip part  120  and at least part of the grip part  144  are disposed above the scanning unit  16  so as to overlap the scanning unit  16  vertically. Hence, the grip part  120  and the grip part  144  are positioned above the irradiating path of the laser beam L. The grip part  120  and the grip part  144  are disposed along the first sloped section  70 A, i.e., are rest on the first sloped section  70 A. 
     Further, the front portion of the cover body  79  of the top cover  11  covers the grip part  120  and the pivoting shafts  140  from above. 
     As shown in  FIG. 4 , the grip part  144  is arranged adjacent to the rear side of the grip part  120  and is surrounded by the handle body  116 . 
     In addition, the coupling parts  143  of the developing-cartridge handle  125  are positioned outside the irradiating path of the laser beam L in the left-right direction, and the coupling parts  119  of the drum-cartridge handle  86  are positioned outside the coupling parts  143  of the developing-cartridge handle  125  in the left-right direction. 
     Further, the developing cartridge  19  is disposed such that the developing-cartridge frame  25  is positioned below the irradiating path of the laser beam L, as shown in  FIG. 1 . The developing roller  26  is disposed below the irradiating path of the laser beam L. 
     While not shown in the drawings, the collars  92  of the drum cartridge  18  are inserted into the bottom ends of the corresponding narrow sections  58  of the grooves  53 . Further, the apparatus-side coupling is advanced rightward and inserted into the insertion part  103  of the left flange part  101  and engaged with the pair of engaging protrusions  104 . 
     4. Image-Forming Operation 
     (1) Developing Operation 
     When the printer  1  described above begins an image-forming operation under control of a control unit (not shown), the scorotron charger  22  applies a uniform charge to the surface of the photosensitive drum  20 . At this time, a drive force is inputted from the apparatus-side coupling through the left flange part  101  of the photosensitive drum  20  and rotates the photosensitive drum  20  clockwise in a left side view. 
     Next, the scanning unit  16  irradiates the laser beam L diagonally downward and rearward onto the surface of the photosensitive drum  20 . The laser beam L passes through the through-hole  97  formed in the drum cartridge  18 , between the coupling parts  143  of the developing-cartridge handle  125 , and over the developing-cartridge frame  25  to expose the front circumferential surface of the drum body  100  of the photosensitive drum  20 , thereby forming an electrostatic latent image on the surface based on image data. Here, the image data may be transmitted to the printer  1  from a personal computer (not shown) or the like connected to the printer  1  or be read by the flatbed scanner  7 , for example. 
     The agitator  29  agitates toner inside the toner accommodating section  127  and supplies the agitated toner through the through-hole  130  to the supply roller  27 . The supply roller  27  in turn supplies this toner to the developing roller  26 . At this time, the toner is positively tribocharged between the developing roller  26  and the supply roller  27 , so that the developing roller  26  carries charged toner on the surface thereof. The thickness-regulating blade  28  then regulates the toner carried on the developing roller  26  in a uniform thickness. 
     The developing roller  26  supplies this toner having uniform thickness to the electrostatic latent image formed on the circumferential surface of the drum body  100 . As a result, the drum body  100  carries a toner image thereon. 
     (2) Sheet-Feeding Operation 
     In the meantime, the feeding roller  8  rotates to separate and convey sheets P accommodated in the sheet cassette  9  one at a time along the first conveyance guide  6 A of the conveyance guiding unit  6 . Each sheet P is guided along the upstream portion of the first conveyance guide  6 A to follow a U-shaped path leading to a path sloping downward to the rear, and then is supplied to the nipping point N between the drum body  100  and the transfer roller  21 . 
     (3) Transferring and Fixing Operations 
     The toner image carried on the circumferential surface of the drum body  100  is transferred onto a sheet P as the sheet P passes through the nipping point N between the drum body  100  and the transfer roller  21  to transfer the toner image onto the sheet P. Subsequently, the sheet P passes between the heating roller  30  and the pressure roller  31  in the fixing unit  17 . At this time, the toner image is thermally fixed to the sheet P by heat and pressure applied by the heating roller  30  and the pressure roller  31 . 
     After the toner image is fixed to the sheet P, the sheet P is guided along the downstream portion of the first conveyance guide  6 A along a U-shaped path that leads to a path sloping downward and forward, and arrives at a position between the discharge rollers  34 . By rotating in a forward direction, the discharge rollers  34  discharge the sheet P through the discharge opening  68  onto the discharge tray  12 . Through this operation, a sheet P accommodated in the sheet cassette  9  is conveyed along the conveying path T 1  that is substantially S-shaped in a side view and defined by the first conveyance guide  6 A. 
     (4) Duplex Printing Operation 
     To form images on both surfaces of a sheet P, the discharge rollers  34  are rotated in reverse before a sheet P having a toner image fixed on one surface is discharged into the discharge tray  12 , reversing the conveying direction of the sheet P toward the second conveyance guide  6 B. The sheet P is guided along the second conveyance guide  6 B to follow a U-shaped path that leads to a forward path passing between the process cartridge  15  and the sheet cassette  9 . The sheet P is returned from the second conveyance guide  6 B to the first conveyance guide  6 A at a position upstream of the nipping point N between the photosensitive drum  20  and the transfer roller  21 . 
     Subsequently, the sheet P is once again conveyed through the nipping point N between the photosensitive drum  20  and the transfer roller  21  to transfer the toner image onto the other surface of the sheet P, and the toner image is thermally fixed to the sheet P as the sheet P passes between the heating roller  30  and the pressure roller  31 , as described above. Subsequently, the discharge rollers  34  rotating in the forward direction discharge the sheet P onto the discharge tray  12 . 
     (5) Inhibition of Gas Deposits on the Discharge Wire 
     Sometimes gas is produced in the fixing unit  17  during the fixing operation described above. This gas may contact and become deposited on the discharge wire  22 A of the scorotron charger  22 , potentially causing discharge problems of the discharge wire  22 A. 
     However, in the first embodiment described above, the cover part  94 B of the charger support wall  94  is provided between the scorotron charger  22  and the fixing unit  17  in the front-rear direction. The cover part  94 B prevents gas produced in the fixing unit  17  from reaching the discharge wire  22 A. 
     Further, the opening  95  faces in a direction diagonally upward and forward which is opposite to the fixing unit  17  in the front-rear direction. This configuration prevents gas produced in the fixing unit  17  from passing through the opening  95  and reaching the discharge wire  22 A, thereby reducing the occurrence of discharge problems in the discharge wire  22 A. 
     Further, since the lowest end of the discharge tray  12  is positioned between the scorotron charger  22  and the fixing unit  17  in the front-rear direction, the discharge tray  12  can further prevent gas produced in the fixing unit  17  from reaching the discharge wire  22 A. That is, the rotational shaft  78  is disposed between the discharge wire  22 A and the fixing unit  17  in the front-rear direction, thereby preventing the gas produced in the fixing unit  17  from reaching the discharging wire  22 A. 
     5. Operations for Mounting and Removing the Process Cartridge Relative to the Main Casing 
     Next, operations for removing the process cartridge  15  from the main casing  2  and for mounting the process cartridge  15  into the main casing  2  will be described. 
     (1) Removing the Process Cartridge from the Main Casing 
     The operations for removing the process cartridge  15  from the main casing  2 , i.e., for moving the process cartridge  15  from the internal position to the external position, will be described. 
     As shown in  FIG. 3 , the user standing on the front side of the printer  1 , i.e., the side of the scanning unit  16  opposite the process cartridge  15  when the process cartridge  15  is at the internal position, pivots the flatbed scanner  7  counterclockwise about the shaft  44  in a left side view and then pivots the top cover  11  about the rotational shaft  78  from the closed position to the open position. Note that the pivotal movement of the top cover  11  from the closed position to the open position may be in conjunction with the pivotal movement of the flatbed scanner  7  through a known interlocking mechanism. 
     Through this operation, space allowing the removal of the process cartridge  15  is formed between the front ends of the flatbed scanner  7  and the cover body  79 , and the first wall section  65 , and thus the grip part  120  and the grip part  144  are exposed. 
     Next, the user grips the grip part  120  and pulls the grip part  120  diagonally upward and forward. As the grip part  120  is pulled, the collars  92  are guided first in the narrow sections  58  of the corresponding grooves  53  and then along the bottom edges of the corresponding wide sections  57 , enabling the process cartridge  15  to be pulled diagonally upward and forward. 
     The process cartridge  15  subsequently passes diagonally upward and forward through the space formed between the front ends of the cover body  79  and flatbed scanner  7 , and the first wall section  65 . The process cartridge  15  is removed from the main casing  2 . In other words, the process cartridge  15  passes above the scanning unit  16  and between the flatbed scanner  7  and the scanning unit  16  and then is removed from the main casing  2 . 
     During this operation, the bottom portion of the process cartridge  15 , and specifically the bottom wall  88  and the transfer-roller accommodating section  89  slide sequentially on the second sloped section  70 B and the first sloped section  70 A of the first wall section  65  and are guided thereby. Once the process cartridge  15  has been moved from the internal position to the external position in this way, the operations for removing the process cartridge  15  from the main casing  2  are complete. 
     (2) Mounting the Process Cartridge in the Main Casing 
     To mount the process cartridge  15  in the main casing  2 , the above operations for removing the process cartridge  15  are performed in reverse. 
     More specifically, the user pivots the flatbed scanner  7  counterclockwise in a left side view and moves the top cover  11  to the open position, as shown in  FIG. 3 . Next, the user passes the process cartridge  15  through the space between the cover body  79  and the flatbed scanner  7 , and the first wall section  65 . The user inserts the process cartridge  15  into the main casing  2  through the access opening  10 . In other words, the process cartridge  15  passes over the scanning unit  16 , between the flatbed scanner  7  and the scanning unit  16  and then is inserted into the main casing  2 . At this time, the collars  92  are inserted into the wide sections  57  of the corresponding grooves  53 . 
     Next, the user pushes the process cartridge  15  diagonally downward and rearward into the main casing  2 . Through this operation, the collars  92  are guided along the bottom edges of the wide sections  57  of the grooves  53 , slide from the wide sections  57  into the narrow sections  58 , and then are guided to the bottom ends of the narrow sections  58 . In this way, the process cartridge  15  is moved from the external position to the internal position and is now mounted in the main casing  2 . 
     Next, the user moves the top cover  11  from the open position to the closed position, and pivots the flatbed scanner  7  clockwise in a left side view until the flatbed scanner  7  contacts the second wall section  66 , as shown in  FIG. 1 . This completes the operations for mounting the process cartridge  15  in the main casing  2 . 
     When the process cartridge  15  is at the internal position described above, the scorotron charger  22 , the developing roller  26 , the toner accommodating section  127 , the scanning unit  16 , and the feeding roller  8  are all positioned forward of a vertical plane I passing vertically through the rotational axis A of the photosensitive drum  20 , while the fixing unit  17  and the discharge rollers  34  are positioned rearward of the vertical plane I. The plane I is a plane orthogonal to the front-rear direction. The scorotron charger  22  is positioned on the scanning unit  16  side of the vertical plane I. 
     Further, the drum-cartridge frame  23  is disposed on the rear side of the scanning unit  16  and is arranged adjacent to the scanning unit  16  in the front-rear direction. That is, the drum-cartridge frame  23  partially overlaps the scanning unit  16  as viewed in the front-rear direction. The scanning unit  16 , the toner accommodating section  127 , the developing roller  26 , and the photosensitive drum  20  are sequentially arranged in the front-rear direction from the front side toward the rear side. 
     6. Operations for Mounting and Removal of the Developing Cartridge Relative to the Main Casing 
     Next, operations for removing the developing cartridge  19  from and mounting the developing cartridge  19  in the main casing  2  will be described. 
     To remove the developing cartridge  19  from the main casing  2 , as in the operations for removing the process cartridge  15  from the main casing  2  described above, the user pivots the flatbed scanner  7  counterclockwise in a left side view and moves the top cover  11  to the open position, as shown in  FIG. 2 . 
     This operation creates sufficient space allowing the developing cartridge  19  to pass therethrough between the front edges of the cover body  79  and the flatbed scanner  7 , and the first wall section  65 . Note that when the developing cartridge  19  is removed from the main casing  2 , the space between the cover body  79  and the flatbed scanner  7 , and the first wall section  65  may be narrower than the space required for removing the process cartridge  15  from the main casing  2  because the space need only allow passage of the developing cartridge  19 . 
     The user then grips the grip part  144  of the developing-cartridge handle  125  and pulls the developing cartridge  19  diagonally upward and forward. At this time, the cylinders  135  shown in  FIG. 6A  are guided by the end parts  90 C of the receiving grooves  90  to move diagonally downward and forward, while the bottom wall  127 A of the toner accommodating section  127  is guided on the upper front surface of the protruding parts  96  to move diagonally downward and forward, as shown in  FIGS. 1 and 2 . Consequently, the developing cartridge  19  moves forward so that the developing roller  26  separates from the photosensitive drum  20 . 
     As the user continues to pull the developing cartridge  19 , the cylinders  135  are sequentially guided from the end parts  90 C through the intermediate parts  90 B to guide parts  90 A to move upward and forward. Accordingly, the developing cartridge  19  moves diagonally upward and forward through the cartridge-mounting opening  99  and separates from the drum cartridge  18  of the process cartridge  15  in the internal position. 
     Subsequently, the developing cartridge  19  passes through the access opening  10  and is removed from the main casing  2  through the space formed between the cover body  79  and the flatbed scanner  7 , and the first wall section  65 . In other words, the developing cartridge  19  passes above the scanning unit  16  between the scanning unit  16  and the flatbed scanner  7  and then is removed from the main casing  2 . 
     To mount the developing cartridge  19  in the main casing  2 , the operations for removing the developing cartridge  19  described above are performed in reverse. 
     That is, the user pivots the flatbed scanner  7  and moves the top cover  11  to the open position, creating space allowing the developing cartridge  19  to pass between the front ends of the cover body  79  and the flatbed scanner  7 , and the first wall section  65 . 
     Next, the user passes the developing cartridge  19  through the space between the cover body  79  and the flatbed scanner  7 , and the first wall section  65 . The user inserts the developing cartridge  19  into the main casing  2  through the access opening  10 . Hence, the developing cartridge  19  passes over the scanning unit  16  between the scanning unit  16  and the flatbed scanner  7  and then is inserted into the main casing  2 . 
     Thereafter, the developing cartridge  19  is inserted downward and rearward through the cartridge-mounting opening  99  into the drum cartridge  18  of the process cartridge  15 , which has been at the internal position. At this time, the cylinders  135  are inserted into the guide parts  90 A of the corresponding receiving grooves  90 . 
     As the user continues to push the developing cartridge  19  downward and rearward, the cylinders  135  are sequentially guided from the guide parts  90 A through the intermediate parts  90 B to the end parts  90 C. Through this operation, the developing cartridge  19  moves diagonally downward and rearward and is accommodated in the accommodating space S formed in the drum cartridge  18 . Thus, the receiving grooves  90  guide the developing cartridge  19  being mounted in or removed from the drum cartridge  18 . 
     Subsequently, the user moves the top cover  11  from the open position to the closed position and pivots the flatbed scanner  7  clockwise in a left side view. The operation for mounting the developing cartridge  19  in the main casing  2  is complete. 
     7. Operational Advantages 
     (1) As shown in  FIG. 1 , at least part of the grip part  120  is arranged above the scanning unit  16  so as to overlap the scanning unit  16  vertically when the process cartridge  15  is at the internal position. That is, the grip part  120  has a portion overlapped with the scanning unit  16  vertically when the process cartridge  15  is at the internal position. Accordingly, the user can reliably grip the grip part  120  and can smoothly remove the process cartridge  15  from the main casing  2 , even when the front-rear space allocated between the process cartridge  15  and the scanning unit  16  is reduced. Thus, this arrangement allows the printer  1  to be made more compact in the front-rear dimension, while still enabling the process cartridge  15  to be removed smoothly from the main casing  2 . The grip part  120  and the grip part  144  may be entirely overlapped with the scanning unit  16  vertically. 
     (2) As shown in  FIG. 2 , the developing cartridge  19  that accommodates toner therein is configured to be mounted in and removed from the drum cartridge  18 . Therefore, the developing cartridge  19  that accommodates toner therein and the drum cartridge  18  that possesses the photosensitive drum  20  can be replaced separately, thereby reducing running costs. 
     Specifically, in case where the process cartridge integrally includes a photosensitive drum and accommodates therein toner, the process cartridge is removed from the casing and replaced with new one, when the toner accommodated in the process cartridge is consumed by the image forming operation and the amount of the toner drops below a prescribed amount. Here, when the process cartridge not only accommodates toner but also fixedly includes the photosensitive drum, the photosensitive drum needs to be replaced together with the process cartridge. 
     However, the photosensitive drum normally has a longer life than the period in which the toner accommodated in the process cartridge is dropped below the prescribed amount through the image-forming operations. Hence, if the photosensitive drum is integrally replaced together with the process cartridge, it is difficult to reduce running costs for the image-forming apparatus. 
     In the embodiment, the developing cartridge  19  accommodating toner therein is replaced separately from and independently of the drum cartridge  18  having the photosensitive drum  20 , thereby reducing running costs. 
     Further, the drum cartridge  18  is provided with the grip part  120 , as shown in  FIG. 1 . When the process cartridge  15  is mounted in the main casing  2 , at least part of the grip part  120  is positioned above the scanning unit  16  so as to overlap the scanning unit  16  vertically. Accordingly, the user can reliably grip the grip part  120  and can smoothly remove the developing cartridge  19  and the drum cartridge  18  from the main casing  2  as the integral process cartridge  15 . Hence, this arrangement enables the process cartridge  15  to be smoothly removed from the main casing  2  while achieving a reduction in running costs. 
     (3) As shown in  FIG. 1 , the developing cartridge  19  includes the grip part  144 . When the process cartridge  15  is at the internal position, at least part of the grip part  144  is arranged above the scanning unit  16  so as to overlap the scanning unit  16  vertically. That is, the grip part  144  has a portion overlapped with the scanning unit  16  vertically. Accordingly, the user can reliably grip the grip part  144  and can smoothly remove the developing cartridge  19  from the main casing  2 , as shown in  FIG. 2 . 
     (4) As shown in  FIG. 4 , the grip part  144  is disposed adjacent to the rear of the grip part  120 . That is, the grip part  144  and the grip part  120  are arrayed with each other in the front-rear direction. Hence, when removing the developing cartridge  19  or the process cartridge  15  from the main casing  2 , the user can clearly determine whether to grip the grip part  120  or the grip part  144 . Thus, the user can more easily remove the developing cartridge  19  and the process cartridge  15  from the main casing  2 . 
     (5) As shown in  FIG. 1 , the drum cartridge  18  has the through-hole  97  formed in the front wall  93  through which the laser beam L emitted from the scanning unit  16  passes to reach the photosensitive drum  20 . Accordingly, this construction restrains the drum cartridge  18  from interfering with the laser beam L, preventing interference with the exposure of the photosensitive drum  20 . 
     (6) As shown in  FIG. 1 , the grip part  120  is disposed above the irradiating path of the laser beam L. Therefore, the user can easily access the grip part  120 . Further, since the laser beam L passes beneath the grip part  120 , the grip part  120  is restrained from interfering with the exposure of the photosensitive drum  20 . 
     (7) As shown in  FIG. 1 , the developing cartridge  19  is provided in the main casing  2  such that the developing roller  26  in the developing cartridge  19  is disposed beneath the irradiating path of the laser beam L. Hence, space in the main casing  2  beneath the irradiating path of the laser beam L can be used for arranging the developing cartridge  19  and the developing-cartridge frame  25 , thereby ensuring an efficient arrangement of the developing cartridge  19 . 
     Further, since the grip part  120  is disposed above the irradiating path of the laser beam L, the user can easily grip the grip part  120  despite the developing cartridge  19  being positioned beneath the irradiating path of the laser beam L, as described above. Hence, this construction allows the user to smoothly remove the process cartridge  15  from the main casing  2 . 
     (8) As shown in  FIG. 3 , the main casing  2  is formed with the access opening  10 , and the process cartridge  15  is reliably mounted in and removed from the main casing  2  through the access opening  10 . Since the access opening  10  is disposed at the rear side of the scanning unit  16 , the scanning unit  16  is positioned between the user and the process cartridge  15  positioned at the internal position when the user accesses the process cartridge  15  from the front side of the scanning unit  16 . Thus, this arrangement increases the distance from the user to the process cartridge  15 , which may lead to bothersome operations for removing the process cartridge  15  from the main casing  2  due to the far distance between the front side of the main casing and the process cartridge  15 . 
     However, in the preferred embodiment, at least part of the grip part  120  is provided above the scanning unit  16  so as to overlap the scanning unit  16  vertically when the process cartridge  15  is at the internal position shown in  FIG. 1 . Accordingly, even though the access opening  10  is positioned to the rear of the scanning unit  16 , the user can easily access the grip part  120  and smoothly remove the process cartridge  15  from the main casing  2 . 
     (9) As shown in  FIGS. 1 through 3 , the top cover  11  moves between the closed position and the open position. Thus, when the top cover  11  is at the closed position, the top cover  11  can prevent the external light from penetrating the main casing  2  through the access opening  10 . This configuration reduces the amount of external light that reaches the photosensitive drum  20 , thereby suppressing degradation of the photosensitive drum  20  and the formation of erratic electrostatic latent images on the surface of the photosensitive drum  20 . 
     On the other hand, the access opening  10  is exposed when the top cover  11  is at the open position, enabling the user to reliably mount the process cartridge  15  in and remove the process cartridge  15  from the main casing  2  through the access opening  10 . 
     (10) As shown in  FIG. 1 , the rotational shaft  78  is disposed at the upper rear side of the process cartridge  15  when the process cartridge  15  is at the internal position. The cover body  79  of the top cover  11  is arranged above the process cartridge  15  when the process cartridge  15  is at the internal position. Hence, the front edge of the cover body  79  is positioned forward from the rotational shaft  78 . As a result, the user can easily access the front edge of the cover body  79  from the front side of the scanning unit  16 . By operating the front edge of the cover body  79 , the user can reliably move the top cover  11  between the closed position and the open position. 
     (11) As shown in  FIG. 1 , the rotational shaft  78  is disposed between the fixing unit  17  and the scorotron charger  22  in the front-rear direction. Accordingly, the rotational shaft  78  can restrain gas generated from the fixing unit  17  from reaching the scorotron charger  22 . 
     (12) As shown in  FIG. 1 , the printer  1  is provided with the flatbed scanner  7  for reading the document. Therefore, the printer  1  can form images on sheets P based on image data of the document read by the flatbed scanner  7 . 
     Further, when the process cartridge  15  is being mounted in or removed from the main casing  2 , as shown in  FIG. 3 , the process cartridge  15  passes between the scanning unit  16  and the flatbed scanner  7 . Thus, the flatbed scanner  7  can be arranged so as not to interfere with the mounting and removal of the process cartridge  15 . 
     (13) As shown in  FIG. 1 , the feeding roller  8  is disposed at the front side of the process cartridge  15  when the process cartridge  15  is at the internal position. The fixing unit  17  is disposed at the rear side of the process cartridge  15  when the process cartridge  15  is at the internal position. In other words, the feeding roller  8 , the process cartridge  15 , and the fixing unit  17  are aligned with each other in the front-rear direction, enabling the printer  1  to be compact in the vertical direction. 
     (14) As shown in  FIGS. 5A and 5B , the grip part  120  pivots about the pivoting shafts  115 , thereby improving the operation of the grip part  120 . 
     (15) As shown in  FIG. 1 , the scorotron charger  22  is disposed at the scanning unit  16  side of the vertical plane I. This layout ensures a more efficient arrangement of the scorotron charger  22 . 
     8. Second Through Fifth Embodiments 
     Next, second through fifth embodiments of the image-forming apparatus according to the present disclosure will be described with reference to  FIGS. 7 through 10 , wherein like parts and components are designated with the same reference numerals to avoid duplicating description. 
     (1) Second Embodiment 
     As shown in  FIG. 4 , the grip part  144  is disposed on the rear side of the grip part  120  in the first embodiment described above. However, in the second embodiment, the grip part  120  is disposed on the rear side of the grip part  144 , as shown in  FIG. 7 . In the following description, like parts and components have been designated with the same reference numerals as those used in the first embodiment to avoid duplicating description. 
     In this case, the drum-cartridge handle  86  is fixed to the front wall  93  of the drum-cartridge frame  23 . The left-right dimension of the drum-cartridge handle  86  is smaller than the left-right gap between the coupling parts  143  of the developing-cartridge handle  125 , while the front-rear dimension of the drum-cartridge handle  86  is smaller than the front-rear gap between the front wall  93  and the grip part  144 . 
     More specifically, the coupling parts  119  of the drum-cartridge handle  86  are separated from each other in the left-right direction. The coupling parts  119  have a plate-like structure that is generally rectangular in a plan view and elongated in the front-rear direction. The coupling parts  119  extend diagonally upward and forward from the left and right edges of the top edge of the front wall  93 . The grip part  120  has a plate-like structure that is generally rectangular in a plan view and elongated in the left-right direction. The grip part  120  bridges the front ends of the coupling parts  119 . 
     When the process cartridge  15  is at the internal position, the handle body  116  is disposed between the coupling parts  143  of the developing-cartridge handle  125  in the left-right direction, and the grip part  120  is disposed adjacent to the rear edge of the grip part  144  in the front-rear direction. 
     Further, the grip part  120  is disposed on the top surface of the rear region of the first sloped section  70 A, while the grip part  144  is disposed on the top surface of the front portion of the first sloped section  70 A. Accordingly, at least part of the grip part  120  and at least part of the grip part  144  are disposed above the scanning unit  16  so as to overlap the scanning unit  16  vertically. 
     Thus, the second embodiment can obtain the same operational advantages described above in the first embodiment. 
     (2) Third Embodiment 
     In the first embodiment described above, the developing cartridge  19  is removably mountable in the drum-cartridge frame  23 , as shown in  FIG. 1 . In the third embodiment shown in  FIG. 8 , the printer  1  includes a process cartridge  151  having a drum-cartridge frame  231 , a developing unit  191  integrally (i.e., non-removably) mounted in the drum-cartridge frame  231 , the drum-cartridge handle  86 . In the following description, like parts and components have been designated with the same reference numerals as those used in the first embodiment to avoid duplicating description. 
     The drum-cartridge frame  231  is integrally configured of the side walls  87 , the bottom wall  88 , the front wall  93 , the transfer-roller accommodating section  89 , the charger support wall  94 , and a top wall  98 . 
     The top wall  98  has a plate-like structure that is generally rectangular in a plan view. The front edge of the top wall  98  is connected to the top edge of the front wall  93 . The rear edge of the top wall  98  is connected to the upper-front edge of the charger support wall  94 . The left and right edges of the top wall  98  are respectively connected to the top edges of the corresponding side walls  87 . 
     The developing unit  191  is disposed inside the drum-cartridge frame  231  and fixed thereto. The developing unit  191  has a developing-unit frame  251  integrally configured of the side walls  126 , the toner accommodating section  127 , the blade support part  128 , and the bottom wall  129 . 
     Note that the developing-cartridge handle  125  of the first embodiment is not provided on the developing unit  191  in the third embodiment. Only the drum-cartridge handle  86  is provided on the process cartridge  151 . 
     The third embodiment having the above configuration can obtain the same operational advantages described above in the first embodiment. 
     (3) Fourth Embodiment 
     In the first embodiment described above, the process cartridge  15  is provided with the scorotron charger  22 , as shown in  FIG. 1 . In the fourth embodiment, the process cartridge  15  may be provided with a charging unit  202  instead of the scorotron charger  22  of the first embodiment. In the following description, like parts and components have been designated with the same reference numerals as those used in the first embodiment to avoid duplicating description. 
     The charging unit  202  is accommodated in the body  94 A of the charger support wall  94 . The charging unit  202  includes a charging roller  200 , and a cleaning roller  201 . 
     The charging roller  200  is disposed diagonally upward and forward of the drum body  100  of the photosensitive drum  20 . The charging roller  200  has a general columnar shape elongated in the left-right direction. The charging roller  200  is rotatably supported on the drum-cartridge frame  23 . The lower-rear surface of the charging roller  200  contacts the upper-front surface of the drum body  100 . During the image-forming operation described above, the charging roller  200  applies a uniform charge to the circumferential surface of the drum body  100 . 
     The cleaning roller  201  is disposed diagonally upward and forward of the charging roller  200 . The cleaning roller  201  has a general columnar shape elongated in the left-right direction. The cleaning roller  201  is rotatably supported on the drum-cartridge frame  23 . The lower-rear surface of the cleaning roller  201  contacts the upper-front surface of the cleaning roller  200 . The cleaning roller  201  is configured to collect toner particles, dust particles, or other matter deposited on the circumferential surface of the charging roller  200 . 
     The fourth embodiment having this configuration can obtain the same operational advantages described above in the first embodiment. 
     (4) Fifth Embodiment 
     In the first embodiment described above, the developing cartridge  19  is removably mountable in the drum cartridge  18  having the photosensitive drum  20 . However, in the fifth embodiment shown in  FIG. 10 , the photosensitive drum  20  is fixedly provided in the main casing  2 , and the developing cartridge  19  is removably mountable in the main casing  2 . In the following description, like parts and components have been designated with the same reference numerals as those used in the first embodiment to avoid duplicating description. 
     In this case, the main casing  2  includes the photosensitive drum  20 , the transfer roller  21 , and the scorotron charger  22 , which are not removably provided therein. 
     The photosensitive drum  20  is disposed in the approximate center region of the main casing  2  at a position rearward of the scanning unit  16  and on the lower-front side of the fixing unit  17  but spaced apart from both the scanning unit  16  and the fixing unit  17 . The left and right ends of the photosensitive drum  20  are rotatably supported on the rear ends of the front portions  46 B of the side walls  46 . 
     The transfer roller  21  is disposed diagonally downward and rearward of the photosensitive drum  20 . The left and right ends of the transfer roller  21  are rotatably supported on the lower-rear portion of the front portions  46 B of the side walls  46 . The scorotron charger  22  is disposed diagonally upward and forward of the photosensitive drum  20  with a gap therebetween. The left and right ends of the scorotron charger  22  are supported on the upper-rear portion of the front portions  46 B of the side walls  46 . 
     In the fifth embodiment, the receiving grooves  90  are formed at the inner left-right surfaces of the front portions  46 B of the side walls  46 . The receiving grooves  90  are recessed outward in the left-right direction from the inner left-right surfaces of the corresponding front portions  46 B of the side walls  46 . Each receiving groove  90  has the guide part  90 A, the intermediate part  90 B, and the end part  90 C. 
     The guide part  90 A extends diagonally downward and rearward from the approximate front-rear center region on the top edge of the front portion  46 B of the corresponding side wall  46 . The guide part  90 A becomes narrower toward the lower-rear end. The intermediate part  90 B extends continuously rearward from the bottom end of the guide part  90 A. The end part  90 C curves continuously upward and rearward from the rear end of the intermediate part  90 B. 
     In the printer  1  having the above structure, the developing cartridge  19  is mounted in the main casing  2  such that the developing-cartridge frame  25  is disposed between the photosensitive drum  20  and the scanning unit  16  in the front-rear direction, as depicted in  FIG. 10  in two-dot chain line. Thus, the scanning unit  16  is disposed in front of the developing-cartridge frame  25  of the developing cartridge  19  when the developing cartridge  19  is mounted in the main casing  2 . Further, the developing-cartridge frame  25  is positioned below the irradiating path of the laser beam L and the developing roller  26  is also disposed below the irradiating path of the laser beam L. 
     When the developing cartridge  19  is mounted in the main casing  2 , the cylinders  135  are inserted in the end parts  90 C of the corresponding receiving grooves  90 , and the upper-rear surface of the roller body  133  of the developing roller  26  contacts the lower-front surface of the drum body  100  of the photosensitive drum  20 . Further, the grip part  144  of the developing-cartridge handle  125  is disposed at the rear region of the top surface of the first sloped section  70 A. Thus, at least part of the grip part  144  is disposed above the scanning unit  16  so as to overlap the scanning unit  16  vertically and is positioned above the irradiating path of the laser beam L. 
     Further, when the top cover  11  is at the closed position, the cover body  79  of the top cover  11  is disposed above the developing cartridge  19  mounted in the main casing  2  with a space therebetween. At this time, the rotational shaft  78  is positioned at the upper-rear side of the developing cartridge  19 . 
     As described in the first embodiment, when the developing cartridge  19  is removed from the main casing  2 , the flatbed scanner  7  pivotally moves counterclockwise about the shaft  44  in a left side view and then the top cover  11  is at the open position. Next, the user grips the grip part  144  of the developing-cartridge handle  125  and pulls the developing cartridge  19  diagonally upward and forward. At this time, the cylinders  135  sequentially move from the end parts  90 C through the intermediate parts  90 B to the guide parts  90 A while being guided thereby. As a result, the developing cartridge  19  moves diagonally upward and forward, passing through the access opening  10  and subsequently passing through the space between the cover body  79  and flatbed scanner  7 , and the first wall section  65  before being extracted from the main casing  2 . 
     To mount the developing cartridge  19  in the main casing  2 , the above operations for removing the developing cartridge  19  are performed in reverse. 
     That is, the user passes the developing cartridge  19  through the space between the cover body  79  and flatbed scanner  7 , and the first wall section  65 . The user inserts the developing cartridge  19  into the main casing  2  through the access opening  10 . At this time, the cylinders  135  are inserted first into the corresponding guide parts  90 A, subsequently pass through the intermediate parts  90 B, and then arrive at the end parts  90 C. Through this operation, the developing cartridge  19  moves diagonally downward and rearward to be mounted in the main casing  2 . 
     According to the fifth embodiment described above, at least part of the grip part  144  is arranged above the scanning unit  16  so as to overlap the scanning unit  16  vertically when the developing cartridge  19  is mounted in the main casing  2 . Accordingly, the user can reliably grip the grip part  144  and smoothly remove the developing cartridge  19  from the main casing  2 , despite a reduction in space between the developing cartridge  19  and the scanning unit  16  in the front-rear direction. 
     Thus, the fifth embodiment described above can make the printer  1  more compact in the front-rear direction while still enabling the developing cartridge  19  to be smoothly removed from the main casing  2 . 
     Note that the first through fifth embodiments described above may be combined as appropriate. 
     While the description has been made in detail with reference to the embodiments thereof, it would be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the above described embodiments.