Patent Publication Number: US-7596340-B2

Title: Image forming apparatus having developer containing portion with slender end portion

Description:
This is a continuation of application Ser. No. 10/947,151 filed Sep. 23, 2004, which claims priority from JP Application No. 2004-038842 filed Feb. 16, 2004, the entire disclosure of each of which is incorporated herein by reference. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a developing cartridge capable of opening or closing a supply port and a recovery port at the same time. 
   2. Description of the Related Art 
   Conventionally, the image forming apparatuses of electrophotography such as a full-color copying machine, a printer, a facsimile apparatus and a composite apparatus thereof are based on a so-called tandem system is well known in which a plurality of image forming portions corresponding to each color of yellow, magenta, cyan and black are arranged in parallel, a toner image of each color of yellow, magenta, cyan and black formed by each image forming portion is directly transferred onto the recording sheet, or secondarily transferred via an intermediate transfer belt onto the recording sheet to form a full-color image. 
   Also, some image forming apparatuses such as the full-color copying machine, printer and so on are based on a so-called four cycle system in which a plurality of developing units corresponding to each color of yellow, magenta, cyan and black are arranged adjacent to a single photoconductive drum along the circumferential direction of a developing device main body, the developing device main body is rotationally driven to move a developing unit of each color to a developing position opposed to the photoconductive drum, a toner image of each color of yellow, magenta, cyan and black is formed on the photoconductive drum by rotating the photoconductive drum a predetermined number of times, and the toner image of each color of yellow, magenta, cyan and black formed on the photoconductive drum is directly transferred onto the recording sheet, or secondarily transferred via the intermediate transfer belt onto the recording sheet. 
   SUMMARY OF THE INVENTION 
   An object of the invention is to provide a developing cartridge capable of opening or closing a supply port and a recovery port at the same time. 
   In order to accomplish the above object, according to a first aspect of the invention, there is provided an image forming apparatus comprising a rotary developing device having a developing device main body rotatably disposed and a plurality of developing units arranged along a rotation direction of the developing device main body, a frame for supporting the rotary developing device in free rotation, and a drive source for rotationally driving the rotary developing device, wherein the drive source for rotationally driving the rotary developing device is disposed in an area to which the rotary developing device is projected in a direction orthogonal to a rotation axis. 
   Also, according to a second aspect of the invention, there is provided the image forming apparatus according to the first aspect wherein a driving force of the drive source is transmitted to a driving gear with external teeth disposed around the outer circumference at one end portion of the rotary developing device. 
   Also, according to a third aspect of the invention of the third aspect, there is provided the image forming apparatus according to the first or second aspect wherein the drive source is mounted on the same plane of the frame as the rotary developing device. 
   Also, according to a fourth aspect of the invention, there is provided the image forming apparatus according to any one of the first to third aspects, wherein the drive source and the rotary developing device are mutually connected via a reduction gear. 
   Further, according to a fifth aspect of the invention, there is provided an image forming apparatus comprising an image carrier disposed rotatably, a rotary developing device for developing sequentially an electrostatic latent image formed on the image carrier with a toner of different color, in which a developing device main body is rotatably disposed and a plurality of developing units are arranged along a rotation direction of the developing device main body, an intermediate transfer body on which a primary transfer of a toner image of different color developed sequentially on the image carrier is performed multiply, and secondary transfer means for performing a secondary transfer of the toner image of different color transferred onto the intermediate transfer body multiply onto a recording sheet, wherein the intermediate transfer body is overlapped on top of the rotary developing device, a primary transfer position and a secondary transfer position of the intermediate transfer body are closely placed, and the drive source for rotationally driving the rotary developing device is disposed at a position opposed at about 180° to the image carrier around the outer circumference of the rotary developing device in an area to which the rotary developing device is projected in a direction orthogonal to a rotation axis. 
   Also, according to a sixth aspect of the invention, there is provided the image forming apparatus according to the fifth aspect, wherein a control board of the image forming apparatus is disposed in the area to which the rotary developing device is projected in the direction orthogonal to the rotation axis. 
   Moreover, according to a seventh aspect of the invention, there is provided the image forming apparatus according to the fifth aspect, wherein a power source unit of the image forming apparatus is disposed in the area to which the rotary developing device is projected in the direction orthogonal to the rotation axis. 
   This invention provides the image forming apparatus of small size, which can be made as thin as possible in the direction of rotational axis of the rotary developing device. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects and advantages of this invention will become more fully apparent from the following detailed description taken with the accompanying drawings in which: 
       FIG. 1  is a perspective view showing the essence of a full-color printer as an image forming apparatus according to a first embodiment of this invention. 
       FIG. 2  is a schematic view showing the full-color printer as the image forming apparatus according to the first embodiment of this invention. 
       FIG. 3  is a front view showing a rotary developing device. 
       FIG. 4  is a perspective view showing the rotary developing device. 
       FIG. 5  is a cross-sectional view showing the rotary developing device. 
       FIGS. 6A and 6B  are cross-sectional views showing a developing unit. 
       FIG. 7  is a perspective view showing the developing unit. 
       FIG. 8  is a perspective view showing a developer cartridge. 
       FIGS. 9A to 9C  are transverse cross-sectional views showing the developer cartridge. 
       FIG. 10  is a longitudinal cross-sectional view showing the developer cartridge. 
       FIG. 11  is a schematic view showing the essence of the developer cartridge. 
       FIG. 12  is a plan view showing the essence of the full-color printer as the image forming apparatus according to the first embodiment of this invention. 
       FIGS. 13A to 13C  are schematic views showing a driving system of the rotary developing device. 
       FIG. 14  is a schematic view showing the conventional image forming apparatus. 
       FIG. 15  is a schematic view showing the conventional image forming apparatus. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. 
   First Embodiment 
     FIG. 2  shows a full-color printer of four cycle system as an image forming apparatus according to a first embodiment of the invention. 
   In  FIG. 2 , reference numeral denotes a full-color printer main body. A photoconductive drum  2  as an image carrier is disposed rotatably at a slightly right upper part of the center inside the full-color printer main body  1 . This photoconductive drum  2  is a conductive cylinder having a diameter of about 47 mm with a photoconductive layer made of OPC covered on the surface, for example, and driven rotationally at a process speed of about 150 mm/sec along the arrow direction by driving means, not shown. After the surface of the photoconductive drum  2  is charged at a predetermined potential by a charging roll  3  as charging means that is disposed almost directly under the photoconductive drum  2 , the image is exposed to a laser beam (LB) by an ROS4 (Raster Output Scanner) as exposure means that is disposed at a separated position directly under the photoconductive drum  2 , so that an electrostatic latent image is formed according to image information. The electrostatic latent image formed on the photoconductive drum  2  is developed by a rotary developing device including the developing units  5 Y,  5 M,  5 C and  5 K corresponding to each color of yellow (Y), magenta (M), cyan (C) and black (K) that are disposed along the circumferential direction to form a toner image of each color. 
   On the surface of the photoconductive drum  2 , each process of charging, exposure and developing is repeated by a predetermined number of times corresponding to the color of the image to be formed. In the rotary developing device  5 , the developing unit  5 Y,  5 M,  5 C or  5 K of corresponding color is moved to a developing position opposed to the photoconductive drum  2 . For example, when the full-color image is formed, each process of charging, exposure and developing is repeated four times on the surface of the photoconductive drum  2 , corresponding to each color of yellow (Y), magenta (M), cyan (C) and black (K), so that a toner image corresponding to each color of yellow (Y), magenta (M), cyan (C) and black (K) is sequentially formed on the surface of the photoconductive drum  2 . When the toner image is formed, the number of rotating the photoconductive drum  2  is different depending on the size of image. For example, for the A4 size, when the photoconductive drum  2  is rotated three times, one image is formed. That is, the toner image corresponding to each color of yellow (Y), magenta (M), cyan (C) and black (K) is sequentially formed on the surface of the photoconductive drum  2 , every time the photoconductive drum  2  is rotated three times. 
   The toner image corresponding to each color of yellow (Y), magenta (M), cyan (C) and black (K) sequentially formed on the surface of the photoconductive drum  2  is primarily transferred by a primary transfer roll  7  at a primary transfer position where an intermediate transfer belt  6  as an intermediate transfer body is wound around the outer circumference of the photoconductive drum  2 , and superimposed mutually on the intermediate transfer belt  6 . The toner image of each color of yellow (Y), magenta (M), cyan (C) and black (K) multiply transferred onto the intermediate transfer belt  6  is secondarily transferred collectively onto the recording sheet  9  supplied at a predetermined timing by a secondary transfer roll  8 . The recording sheet  9  is picked up by a pick-up roll  11  from a paper supply cassette  10  disposed on the bottom of the full-color printer main body  1 . One sheet is fed out by a feed roll  12  and a retard roll  13 , and conveyed to a secondary transfer position of the intermediate transfer belt  6  by a resist roll  14  to be synchronous with the toner image transferred onto the intermediate transfer belt  6 . 
   The intermediate transfer belt  6  is stretched around a plurality of rolls, and driven to be circularly moved at a predetermined process speed (about 150 mm/sec), along with the rotation of the photoconductive drum  2 . This intermediate transfer belt  6  is stretched under a preset tension by means of a lap-in roll  15  for designating the lap position of the intermediate transfer belt  6  on the upstream side of the photoconductive drum  2  in the rotational direction, a primary transfer roll  7  for transferring the toner image formed on the photoconductive drum  2  onto the intermediate transfer belt  6 , a lap-out roll  16  for designating the lap position of the intermediate transfer belt  6  on the downstream side of the lap position, a back-up roll  17  contacting with the secondary transfer roll  8  via the intermediate transfer belt  6 , a first cleaning back-up roll  19  opposed to a cleaning device  18  of the intermediate transfer belt  6 , and a second cleaning back-up roll  20 . 
   Also, the intermediate transfer belt  6  is stretched by a plurality of rolls  7 ,  15  to  17 ,  19  and  20 , as described above. In this embodiment, the intermediate transfer belt  6  is stretched in the shape of a flat, slender, and almost trapezoid in cross section to reduce the size of the full-color printer main body  1 . 
   By the way, in this embodiment, the image forming apparatus comprising the rotary developing device in which the developing device main body is disposed rotatably within the vertical plane, and the plurality of developing units and developer cartridges for supplying developer to the developing units are disposed along the circumferential direction of the developing device main body, and a replacement cover for allowing the developer cartridge of the rotary developing device to be replaced, a lever member being rotated along with an opening or closing operation of the replacement cover to regulate the rotational operation by interfering with a part of the developer cartridge not mounted at a proper mounting position of the developing device main body, and an abutment member, provided on the replacement cover, for making contact with the lever member for regulating the rotational operation to keep the replacement cover from being closed, when the developer cartridge is not mounted at a proper mounting position of the developing device main body. 
   That is, in this embodiment, the rotary developing device  5  occupies a large space in the full-color printer main body  1 , although the total size of the full-color printer is made as small as possible, as shown in  FIG. 2 . Therefore, the full-color printer main body  1  is designed to make the size of the apparatus smaller and improve the maintenance of the intermediate transfer belt  6  and the rotary developing device  5 . More specifically, the intermediate transfer belt  6  makes up an image forming unit  21  together with the photoconductive drum  2  and the charging roll  3 , and the image forming unit  21  as a whole is attached or detached on or from the full-color printer main body  1  by opening an upper cover  22  of the full-color printer main body  1 . A position sensor  23  including a reflection type photo-sensor for sensing a patch of toner formed on the intermediate transfer belt  6  is disposed on an upper part of the intermediate transfer belt  6 . 
   Also, the cleaning device  18  of the intermediate transfer belt  6  comprises a scraper  24  disposed in contact with the surface of the intermediate transfer belt  6  stretched by the first cleaning back-up roll  19 , and a cleaning brush  25  disposed in pressure contact with the surface of the intermediate transfer belt  6  stretched by the second cleaning back-up roll  20 , as shown in  FIG. 2 . The residual toner or paper powder removed by the scraper  24  and the cleaning brush  25  is withdrawn into the inside of the cleaning device  18 . The cleaning device  18 , which is swingable in a counterclockwise direction in the figure around a swing axis  26 , takes refuge to a position away from the surface of the intermediate transfer belt  6 , till the secondary transfer of the toner image of last color is ended, and makes contact with the surface of the intermediate transfer belt  6 , if the secondary transfer of the toner image of last color is ended. 
   Moreover, the recording sheet  9  onto which the toner image is transferred from the intermediate transfer belt  6  is conveyed to a fixing unit  27 , as shown in  FIG. 2 . In the fixing unit  27 , the toner image is fixed on the recording sheet  9  by heat and pressure. When printed on one side, the recording sheet  9  is directly exhausted onto a paper exhaust tray  29  provided on an upper part of the printer main body  1  by a paper exhaust roll  28 . 
   On the other hand, when printed on both sides, the recording sheet  9 , on which the toner image is fixed by the fixing unit  27 , is not directly exhausted on the paper exhaust tray  29  by the paper exhaust roll  28 , but the paper exhaust roll  28  is rotated reversely in a state where a trailing end part of the recording sheet  9  is carried by the paper exhaust roll  28 , and the conveyance passage of the recording sheet  9  is switched to a perfect printing paper conveyance passage  30 , whereby the recording sheet  9  is turned over by a conveying roll  31  disposed on the perfect printing paper conveyance passage  30  and conveyed to the secondary transfer position of the intermediate transfer belt  6  again to form the image on the back side of the recording sheet  9 . 
   Moreover, the full-color printer is able to mount an optional manual insertion tray  32  on the side face of the printer main body  1  in freely opening or closing manner, as shown in  FIG. 2 . The recording sheet  9  of any size and kind laid on this manual tray  32  is fed by a paper feed roll  33 , and conveyed via a conveying roll  31  and the resist roll  14  to the secondary transfer position of the intermediate transfer belt  6 , where the image is formed on the recording sheet  9  of any size and kind. 
   From the surface of the photoconductive drum  2  after the transfer process of the toner image is ended, the residual toner is removed by a cleaning blade  35  of a cleaning device  34  disposed obliquely under the photoconductive drum  2  at every rotation of the photoconductive drum  2 , thereby preparing for the next image forming process. 
     FIG. 3  is an appearance perspective view showing one specific example of the rotary developing device  5  which is applied to the image forming apparatus according to this embodiment. For convenience&#39;s sake, one developing unit  5 Y and one developer cartridge  45 Y mounted on the developing device main body are shown in  FIG. 3 . 
   This rotary developing device  5  comprises a developing device main body  40  disposed rotatably within the vertical plane, as shown in  FIGS. 3 and 4 . The developing device main body  40  comprises a cylindrical rotation shaft member  41  disposed in the central part along the longitudinal direction, a front flange member  42  disposed at a fore end in the longitudinal direction of the rotation shaft member  41 , a rear flange member  43  disposed at a rear end in the longitudinal direction of the rotation shaft member  41 , and a partition member  44  for partitioning a cylindrical space S formed by the rotation shaft member  41  and the front and rear flange members  42  and  43  into four at 90 degrees. 
   The developing device main body  40  is mounted on the printer main body  1  to be rotatable along the counterclockwise direction around the rotation shaft member  41 , as shown in  FIG. 2 . This developing device main body  40  has four developing units  5 Y,  5 M,  5 C and  5 K of yellow (Y), magenta (M), cyan (C) and black (K), arranged clockwise, which are packaged along the circumferential direction, and four developer cartridges  45 Y,  45 M,  45 C and  45 K of yellow (Y), magenta (M), cyan (C) and black (K) corresponding to the developing units  5 Y,  5 M,  5 C and  5 K, which are packaged along the circumferential direction, as shown in  FIG. 5 . 
   Since these developing units  5 Y,  5 M,  5 C and  5 K are constituted in the same way, a yellow (Y) developing unit  5 Y will be described below. This yellow (Y) developing unit  5 Y has a developing unit main body  46 , which is supplied with new developer from the corresponding developer cartridge  45 Y, as shown in  FIG. 5 . 
   Inside the developing unit main body  46 , there are disposed a developing roll  48  long in a direction perpendicular to the paper face, a part thereof being exposed to an opening portion  47  provided facing around the outer circumference of the developing unit main body  46 , and two spiral augers  49 ,  50  located on the rear side obliquely under the developing roll  48 , and extending in parallel to the developing roll  48 , as shown in  FIG. 6A . The developing roll  48  is disposed substantially over the total length of the developing unit main body  46 , as shown in  FIG. 7 . In the developing unit  5 Y, if the developing roll  48  is rotated, a spiral auger  49  on the deeper side conveys the developer  51  received within the developing unit main body  46  in one direction perpendicular to the paper face, while agitating it, as shown in  FIGS. 6A and 6B . On the other hand, a spiral auger  50  conveys the developer  51  in a direction opposite to the conveying direction of the spiral auger  49 , while agitating it, thereby supplying the developer  51  to the developing roll  48  uniformly. The developer  51  supplied on the surface of the developing roll  48  is regulated in layer thickness by a layer thickness regulating member  52 , and conveyed to a developing area opposed to the photoconductive drum  2 , along with the rotation of the developing roll  48 . In this embodiment, the developer  51  uses a two component developer containing the toner and carrier, but the developer  51  may use one component developer containing the toner alone, because it is only necessary to contain the toner. 
   The developing roll  48  adsorbs the carrier contained in the developer  51  due to a magnetic force by a magnet roll  48   a  disposed inside in fixed state, forms a magnetic brush of the developer  51  on the surface of the developing roll  48 , and conveys the toner adsorbed into the carrier to the developing area opposed to the photoconductive drum  2 , as shown in  FIGS. 6A and 6B . And the electrostatic latent image formed on the photoconductive drum  2  is visualized by the magnetic brush of the developer  51  containing the carrier and toner that is formed on the surface of the developing roll  48 . 
   Also, the developer cartridges according to this embodiment are provided corresponding to the plurality of developing units disposed along the circumferential direction of the developing device main body, which is disposed rotatably within the vertical plane, each developer cartridge supplying the developer at least containing the toner to the corresponding developing unit. The developer cartridge comprises a developer receiving portion for receiving the new developer, and a developer withdrawal portion, extending to one end of the developer receiving portion in the longitudinal direction, for withdrawing the used developer from the developing unit, in which the cross-sectional shape of the developer receiving portion is formed like non-circle to occupy almost all the space except for the developing unit among the space allocated to one developing unit of the developing device main body on which the developer cartridge is mounted, and the cross-sectional shape of the developer withdrawal portion is formed like circle to be substantially inscribed in the space except for the developing unit among the space allocated to one developing unit of the developing device main body on which the developer cartridge is mounted. 
   Also, in this embodiment, the cross-sectional shape of the developer receiving portion has two side faces making an acute angle to each other. 
   Moreover, in this embodiment, the cross-sectional shape of the developer receiving portion is formed roughly like tear-drop. 
   Also, in this embodiment, a supply port opened to the developer withdrawal portion in communication to the developer receiving portion, an opening/closing member for opening or closing the supply port, and a grip for gripping the developer cartridge that is mounted or dismounted on or from the developing device main body, the grip being formed integrally with the opening/closing member. 
   Moreover, in this embodiment, the opening/closing member is formed cylindrically to be inserted and fitted rotatably around the outer circumference of the developer receiving portion, the grip being protruded radially outwards in a part of the outer circumferential face of the opening/closing member. 
   Also, in this embodiment, the grip is received within the outer circumferential face of rotation of the developing device main body in a state where the developing device main body is rotatable. 
   Moreover, in this embodiment, a grip portion of the grip may be provided with non-slip means. 
   Also, in this embodiment, the developer cartridge may be provided with a lock mechanism for preventing the opening/closing member from being rotated in a direction to open the supply port in a state where the developer cartridge is removed from the developing device main body. 
   Moreover, in this embodiment, the developer cartridge may be provided with a stopper mechanism for preventing the developer cartridge from being removed from the developing device main body in a state where the opening/closing member opens the supply port. 
   Also, in this embodiment, the grip may be protruded out of the outer circumferential face of rotation of the developing device main body in a state where the developer cartridge is removable from the developing device main body. 
   That is, the developer cartridge  45  is a long and cylindrical container having a non-circular shape mostly in cross section, as shown in  FIG. 3  and  FIGS. 8 and 9 . The inside of this developer cartridge  45  is divided into a developer receiving portion  53  for receiving the new developer  52  and a developer withdrawal portion  55  for withdrawing the used developer  54  by a partition cap  56 , as shown in  FIG. 10 . In the illustrated embodiment, the developer receiving portion  53  occupies about four-fifths the total length of the developer cartridge  45 , and the developer withdrawal portion  55  occupies about one-fifth. However, the proportion of the length of the developer receiving portion  53  to the length of the developer withdrawal portion  55  may be different. 
   By the way, the developer receiving portion  53  of the developer cartridge  45  is formed like non-circle, but not circle, in cross section, as shown in  FIGS. 8 and 9 . The cross-sectional shape of the developer receiving portion  53  is triangular such that the angle of a corner portion  58  at the top is set to be slightly small, each of the corner portions  57 ,  58  and  59  being formed like a circular arc, or a tear-drop shaped like a falling tear, as shown in  FIGS. 9A to 9C . Particularly, the cross-sectional shape of the developer receiving portion  53  is such that a first corner portion  57  located at the lower end is formed like a circular arc having a relatively large radius, and the first and second side faces  60 ,  61  formed like plane are disposed like a V-character making an angle of about 60 degrees around the first corner portion  57 . Also, a second corner portion  58  and a third corner portion  59  located at the top of a first side face  60  and a second side face  61  are formed like circular arc to have a smaller radius than the first corner portion  57 , and the almost same radius. And a third side face  62  connecting the second corner portion  58  and the third corner portion  59  is formed like circular arc having as large a radius as that of the flange member  42  on the front side of the developing device  5 , as shown in  FIG. 4 . 
   Consequently, for the developer receiving portion  53  of the developer cartridge  45 , the cross-sectional shape of the developer receiving portion  53  is not circular and shaped like non-circle to occupy almost all the space S 2  except for the developing unit  5 Y among the space S 1  allocated to one developing unit  5 Y of the developing device main body  46  on which the developer cartridge  45  is mounted, as shown in  FIG. 9C . Therefore, even when the total size of the developing device  6  is reduced, and the diameter of the developing device  6  is set small, the developer receiving portion  53  can receive a large amount of developer  52 . 
   On the other hand, for the developer withdrawal portion  55  linked to one end of the developer receiving portion  53 , the cross-sectional shape of the developer withdrawal portion  55  is formed like circle to be substantially inscribed in the space S 2  except for the developing unit  5  among the space S 1  allocated to one developing unit  6  of the developing device main body  46  on which the developer cartridge  45  is mounted, with the diameter of circle being slightly smaller than that of the space S 2 , as shown in  FIGS. 9A and 9C . This developer withdrawal portion  55  is formed integrally like a cylinder having the shape of circular cross section at one end of the developer receiving portion  53  in the longitudinal direction, and the partition cap  56  is disposed at an end portion close to the developer receiving portion  53  of the developer withdrawal portion  55 , as shown in  FIG. 10 . 
   More particularly, the developer receiving portion  53  is formed slightly slender at an end portion close to the developer withdrawal portion  55 , and linked to the developer withdrawal portion  55  formed like cylinder, as shown in  FIG. 10 . Consequently, in the developer receiving portion  53 , an end portion  53   a  close to the developer withdrawal portion  55  is formed the same cylinder shape as the developer withdrawal portion  55 . In the cylindrical portion  53   a  of the developer receiving portion  53 , a supply port  65  for supplying the new developer  52  to the outside is opened like rectangle at a slightly inclined position at an end portion of the developer withdrawal portion  55 , as shown in  FIG. 10 . Also, a spiral agitator  66  for agitating the new developer  52  received inside the developer receiving portion  53  is disposed rotatably inside the developer receiving portion  53 . The developer  52  is conveyed through the supply port  65  to the outside by this agitator  66 . At an end portion on the rear side of the developer cartridge  45 , a gear  67  for rotationally driving the agitator  66  is provided such that a part thereof is exposed outside. This gear  67  is mated with a gear  67   a  provided on the developing device main body  46  to rotationally drive the agitator  66  in a state where the developer cartridge  45  is mounted in the developing device main body  46 , as shown in  FIG. 7 . 
   The developing unit  5 Y supplied with the developer  52  from the developer cartridge  45  has a shutter plate  68  on the side of the developing unit in contact with a portion corresponding to the supply port  65  of the developer cartridge  45 , in which the shutter plate  68  is curved like circular arc, as shown in  FIG. 7 . This shutter plate  68  is mounted to be freely slidable along the arrow direction on the developing unit main body  46 . Also, the shutter plate  68  has opened a refilling faucet  69  for receiving the new developer  52  supplied from the developer cartridge  45 , with a convex piece  69   a  projecting inwards at an end portion around the outer circumference of the refilling faucet  69 . The developing unit  5 Y refilled with the developer  52  through the refilling faucet  69  extends over a predetermined length in the upper part on the rear side of the developing device main body  46 , as shown in  FIGS. 6A ,  6 B and  7 . The developer is conveyed over a predetermined distance in the longitudinal direction of the developing unit main body  46  by a refilling auger  71  having a compensating port  71   a  of developer at the entrance, and then refilled into the inside of the developing unit main body  46  through a refilling opening portion, not shown, provided in the upper part on the rear side of the developing unit main body  46 . 
   Moreover, the developing unit  5 Y is provided with a withdrawal opening portion  95  in the upper part on the rear side of the developing unit main body  46  to withdraw the used developer among the developer  51  received inside the developing unit main body  46 , as shown in  FIG. 6B . When the developing unit  5 Y is rotated and moved to position C of  FIG. 4 , a flap  73  is opened to withdraw a part of the used developer  54 . The used developer  54  from the developing unit  5  is withdrawn through a withdrawal exhaust port  77  opened in the shutter plate  68 , as shown in  FIGS. 9A to 9C , and through a withdrawal port  74  opened in the developer cartridge  45 , as shown in  FIG. 10 , into the developer withdrawal portion  55  of the developer cartridge  45 , as shown in  FIG. 6B . A convex piece  70   a  is also protruded inwards in the withdrawal exhaust port  70  of the developing unit, as shown in  FIG. 7 . 
   Also, in this embodiment, a shutter member  75  as an opening/closing member for opening or closing the supply port  65  of the developer receiving portion  53  and the withdrawal port  74  (example of recovery port) of the developer withdrawal portion  55  (example of developer recovery portion) is inserted and fitted rotatably in the circumferential direction around the outer circumference of the developer receiving portion  53   a  (example of developer containing portion) and the developer withdrawal portion  55  that are formed like cylinder in the developer cartridge  45 , as shown in  FIGS. 8 and 9 . This shutter member  75  is formed like cylinder, like the developer receiving portion  53   a  and the developer withdrawal portion  55  of the developer cartridge  45 , as shown in  FIGS. 8 and 9 . The shutter member  75  has an inner diameter slightly larger than the outer diameter of the developer withdrawal portion  55 , and is formed like circle to be substantially inscribed in the space S 2  except for the developing unit  5 Y among the space S 1  allocated to one developing unit  5 Y of the developing device main body  46  on which the developer cartridge  45  is mounted, as shown in  FIG. 8 and 9C . 
   The shutter member  75  has opened a supply opening portion  76  and a withdrawal opening portion  77  at the positions corresponding to the supply port  65  and the withdrawal port  74  of the developer cartridge  45 , as shown in  FIGS. 6A ,  6 B,  10  and  11 . This shutter member  75  can be rotated along the outer circumference of the developer withdrawal portion  55  of the developer cartridge  45  to open or close the supply port  65  and the withdrawal port  74  of the developer cartridge  45  at the same time. The convex pieces  76   a  and  77   a  are protruded outwards at the edge of the supply opening portion  76  and the withdrawal opening portion  77  of the shutter member  75 . 
   Also, the shutter member  75  has a grip  78  for gripping the developer cartridge  45  to mount it on the developing device main body  46 , as well as rotating the shutter member  75  in a part along the circumferential direction of the developer cartridge, in which the grip  78  is protruded radially outwards, as shown in  FIG. 8 . For this grip  78 , the radius of curvature at the top end is set up to be coincident with the second corner portion  58  of the developer receiving portion  53  for the developer cartridge  45  in a state where the developer cartridge  45  is mounted on the developing unit main body  46  and the shutter member  75  is opened, as shown in  FIG. 9A . A non-slip portion  79  containing a plurality of convex pieces to facilitate the gripping is provided on the side face of the grip  78 . 
   Moreover, the grip  78  of the shutter member  75  extends out of the outer circumference of the developing device main body  46  in a state where the supply port  65  and the withdrawal port  74  of the developer cartridge  45  are closed by rotating the shutter member  75  in the clockwise direction, as shown in  FIG. 9A . 
   By the way, in this embodiment, an image forming apparatus comprises a rotary developing device in which a developing device main body is disposed rotatably within a vertical plane and a plurality of developing units and a plurality of developer cartridges for supplying developer to the developing units are arranged along a circumferential direction of the developing device main body, a frame for supporting the rotary developing device in free rotation, and a drive source for rotationally driving the rotary developing device, characterized in that the drive source for rotationally driving the rotary developing device is disposed in an area to which the rotary developing device is projected in a direction orthogonal to a rotation axis. 
   Also, in this embodiment, a driving force of the drive source is transmitted to a driving gear with external teeth disposed around the outer circumference at one end portion of the rotary developing device. 
   Moreover, in this embodiment, the drive source is mounted on the same plane of the frame as the rotary developing device. 
   Also, in this embodiment, the drive source and the rotary developing device are mutually connected via a reduction gear. 
   Moreover, in this embodiment, an image forming apparatus comprises an image carrier disposed rotatably, a rotary developing device for developing sequentially an electrostatic latent image formed on the image carrier with a toner of different color, in which a developing device main body is rotatably disposed within a vertical plane and a plurality of developing units and a plurality of developer cartridges for supplying developer to the developing units are arranged along a circumferential direction of the developing device main body, an intermediate transfer body on which a primary transfer of a toner image of different color developed sequentially on the image carrier is performed multiply, and secondary transfer means for performing a secondary transfer of the toner image of different color transferred onto the intermediate transfer body multiply onto a recording sheet, characterized in that the intermediate transfer body is overlapped on top of the rotary developing device, a primary transfer position and a secondary transfer position of the intermediate transfer body are closely placed, and the drive source for rotationally driving the rotary developing device is disposed at a position opposed at about 180° to the image carrier around the outer circumference of the rotary developing device in an area to which the rotary developing device is projected in a direction orthogonal to a rotation axis. 
   Also, in this embodiment, a control board and a power source unit of the image forming apparatus are disposed in the area to which the rotary developing device is projected in the direction orthogonal to the rotation axis. 
   That is, in this embodiment, a drive motor  90  including a pulse motor as a drive source for rotationally driving the rotary developing device  5  is disposed in an area  91  to which the rotary developing device  5  is projected in the direction orthogonal to a rotation axis member  41  as a rotation axis, as shown in  FIGS. 1 and 12 . This drive motor  90  is mounted via a reduction gear box  92  on the same plane of a frame  93  as the rotary developing device  5  in the printer main body  1 . The reduction gears  94  and  95  are contained within the reduction gear box  92  in a state where they are mated with a driving gear  96  of the drive motor  90 . Also, the reduction gear  94  is mated with a developing device gear  97  with external teeth having a larger diameter attached at an end portion of the developing device main body  40  in the rotary developing device  5 , as shown in  FIG. 13 . The reduction ratio of the developing device main body  40  to the rotating number of the drive motor  90  is set to 1/20, for example. 
   Though the rotary developing device  5  is reduced in size, the developing device main body  40  has four developing units  5 Y,  5 M,  5 C and  5 K of yellow (Y), magenta (M), cyan (C) and black (K), and four developer cartridges  45 Y,  45 M,  45 C and  45 K of yellow (Y), magenta (M), cyan (C) and black (K), which are packaged along the circumferential direction, as shown in  FIG. 4 . The diameter of the developing device main body  40  is the largest in the printer, and the mass and the rotational moment are large. Also, in the rotary developing device  5 , it is required to switch the developing units  5 Y,  5 M,  5 C and  5 K of yellow (Y), magenta (M), cyan (C) and black (K) within a limited period of time to increase the productivity of the printer. Consequently, the drive motor  90  is made as small as possible, but the largest as the motor within the printer. 
   In this case, the drive motor  90  rotationally drives the rotary developing device  5  at a reduction ratio as large as 1/20, and can be made as small as possible. 
   Moreover, in this embodiment, the intermediate transfer belt  6  is overlapped on top of the rotary developing device  5 , and a primary transfer position and a secondary transfer position of the intermediate transfer belt  6  are closely placed, as shown in  FIG. 2 . Also, the drive motor  90  is disposed at a position opposed at about 180° to the photoconductive drum  2  around the outer circumference of the rotary developing device  5  in an area  91  to which the rotary developing device  5  is projected in a direction orthogonal to a rotation axis. 
   Also, in this embodiment, a power source circuit  95  for supplying power to the drive motor  90  for rotationally driving and a control board  96  for controlling the printer are attached on the same plane as the drive motor  90  for the frame  93  with the drive motor  90  mounted. 
   With the above constitution, the full-color printer as the image forming apparatus according to this embodiment can be reduced in size and thickness in the following way. 
   That is, in the full-color printer, as shown in  FIG. 2 , in printing the full-color image, the rotary developing device  5  is switched sequentially to move the developing unit  5 Y,  5 M,  5 C and  5 K of desired color to the developing position opposed to the photoconductive drum  2  and develop the electrostatic latent image formed on the surface of the photoconductive drum  2  with the toner of predetermined color. 
   In this case, the rotary developing device  5  is rotationally driven by the drive motor  90  placed on the same side of the frame  93  as the rotary developing device  5  in switching each developing unit  5 Y,  5 M,  5 C and  5 K, as shown in  FIG. 1 . 
   In this way, in this embodiment, since the drive motor  90  for the rotary developing device  5  that is relatively large is disposed in a projected area  91  of the rotary developing device  5 , the drive motor  90  is restrained from extending to the back side as compared with where the drive motor  90  is disposed on the opposite face of the frame  93  to the rotary developing device  5  as shown in  FIGS. 1 and 12 , whereby the printer main body  1  can be made as thin as possible. 
   Also, in this embodiment, since the drive motor  90  for the rotary developing device  5  that is relatively large is disposed in a projected area  91  of the rotary developing device  5 , there is a large space for disposing the reduction gears, whereby the torque capacity of the drive motor  90  can be smaller by setting the reduction ratio at a large value, and the drive motor  90  itself is reduced in size. 
   Moreover, in this embodiment, since the drive motor  90  is fixed to the frame  93  for supporting the rotary developing device  5 , the relative positional relationship between the drive motor  90  and the rotary developing device  5  is fixed by the frame  93 , thereby stabilizing the driving. 
   Also, in this embodiment, since the torque capacity of the drive motor  90  is smaller, the drive motor  90  itself is reduced in size. 
   Moreover, in this embodiment, since the drive motor  90  is disposed sideways of the rotary developing device  5 , it is possible to make effective use of the space around the rotary developing device  5 , thereby reducing the size of the printer main body  1 . 
   Also, in this embodiment, the power source circuit  95  and the control board  96  are disposed sideways of the rotary developing device  5 , it is possible to make effective use of the space around the rotary developing device  5 , thereby reducing the size of the printer main body  1 . 
   The foregoing description of the preferred embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. The embodiments were chosen and described in order to explain the principles of the invention and its practical application to enable one skilled in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto, and their equivalents.