Patent Publication Number: US-7218866-B2

Title: Developer container and image forming apparatus

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a toner container for containing toner for use in electrophotographic system-based image formation, and to an image forming apparatus in which the toner container is detachably and attachably mounted. 
   2. Description of the Related Art 
   When a plurality of photoconductive drums for transferring a toner image to a recording sheet is mounted in an image forming apparatus in such a fashion as to correspond to a duplication speed, a plurality of kinds of toners are used to correspond to the photoconductive drums. Therefore, containers having various capacities and various systems must be prepared as developer containers for containing the toners. In the case of a full-color image forming apparatus, for example, four kinds or four colors of toners are necessary and four developer containers for containing the each toner are mounted. It is therefore necessary to identify which developer container contains which toner. 
   According to a first related art disclosed in, for example, Japanese Unexamined Patent Publication JP-A 1-232360 (1989) (page 3, FIGS. 3 and 4), for identifying the toners contained, a reflecting seal is applied onto a cartridge for containing a specific toner, but the reflecting seal is not applied onto a cartridge for containing an ordinary toner. A cartridge sensor mounted to a main body of a copying machine irradiates the cartridge mounted with rays of light, judges that the cartridge contains the specific toner on detecting that the rays of light are reflected, and thus identifies the toners. 
   According to a second related art disclosed in, for example, Japanese Unexamined Patent Publication JP-A 2-72381 (1990) (pages 2 and 3, FIG. 1), a memory device for storing information of a toner contained and electrodes connected to the memory device are attached to a container for containing the toner. A main body of an apparatus to which the container is mounted, is provided with reading means connected to the electrodes in the state where the container is mounted, for reading the information stored in the memory device. 
   According to a third related art disclosed in, for example, Japanese Unexamined Patent Publication JP-A 10-142913 (1998) (page 3, FIGS. 2 and 3), a cylindrical cartridge driven for rotation about an axis is provided with a semiconductor memory member for storing information of toners contained. An apparatus main body to which the cartridge is mounted is provided with detection means for detecting the information stored in the semiconductor memory member of the cartridge mounted. 
   According to a fourth related art disclosed in, for example, Japanese Unexamined Patent Publication JP-A 10-207209 (1998) (page 3, FIGS. 3 to 5), a cylindrical cartridge driven for rotation about an axis is provided with a semiconductor memory member for storing information of toners contained and conductive terminals connected to the semiconductor memory member and wound throughout the full outer periphery of the cartridge. An apparatus main body to which the cartridge is mounted is provided with conductive terminals coming into contact with the conductive terminals of the cartridge mounted and driven for rotation and a CPU communicating with the semiconductor memory member through both conductive terminals. 
   According to a fifth related art disclosed in, for example, Japanese Unexamined Patent Publication JP-A 2000-137417 (pages 4 to 5, FIG. 1), a bar code representing information of toners contained onto an outer peripheral surface of a cylindrical toner bottle driven for rotation about an axis, is recorded. A printer main body to which the toner bottle is mounted is provided with an optical sensor for optically reading the bar code of the rotating toner bottle. 
   When the toner cartridge and the container for containing the toner is still as in the first and second related arts, it is easy to detect reflected light from the reflecting seal bonded to the toner cartridge or to connect the electrodes and the reading means. 
   In the toner cartridge according to the third related art, however, the semiconductor memory member rotates with the toner cartridge and the construction of the image forming apparatus for connecting such a semiconductor member to the detection means is presumably complicated. However, this reference does not at all describe or suggest the construction. When the construction gets complicated like that, the production cost of the image forming apparatus becomes high. 
   In the fourth related art, the cartridge rotates while the conductive terminal of the apparatus main body keeps contact with the conductive terminal wound on the entire outer peripheral portion of the cartridge. Therefore, contact defect is likely to develop between these conductive terminals. When such a contact defect occurs between the conductive terminals, communication cannot be conducted smoothly between the semiconductor memory member of the cartridge and the CPU of the apparatus main body. Because the conductive terminal of the terminal is completely exposed, static electricity flows through the conductive terminal, for example, when a user touches it by hand and the information stored in the semiconductor memory member is likely to be destroyed. The user is also likely to strongly grip the conductive terminal of the cartridge by mistake and to break it. 
   The fifth related art involves the possibility that when the toner and dust adhere to the bar code recorded on the outer peripheral surface of the toner bottle, the optical sensor fails to correctly read the bar code. 
   SUMMARY OF THE INVENTION 
   An object of the invention is to provide a developer container in which information reading means of an image forming apparatus main body can correctly read out information of a developer contained in a container main body even when the container main body rotates, and an image forming apparatus in which the developer container can be detachably and attachably mounted. 
   The invention provides a developer container detachably and attachably mounted in an image forming apparatus, comprising: 
   a container main body formed in a cylindrical shape, for containing therein a developer for use in image formation; 
   a supporting member for supporting the container main body rotatably about its axis; and 
   storage means fixed to the supporting member, for storing developer associated information about the developer contained in the container main body, the storage means being connected to information reading means provided in an image forming apparatus in such a manner that the information reading means can read out the developer associated information in a state where the developer container is mounted in the image forming apparatus. 
   According to the invention, the container main body is shaped into the cylindrical shape and contains the developer for use in image formation. The supporting member supports the container main body and allows it to rotate about the axis. The storage means for storing the developer associated information about the developer contained in the container main body is fixed to the supporting member and in the state where the developer container is mounted in the image forming apparatus, the storage means is connected to the information reading means provided in the image forming apparatus in such a manner as to be capable of reading out the developer associated information. Even when the container main body rotates about the axis in the state where the developer container is mounted to the image forming apparatus, the supporting member does not rotate with the container main body, so that the storage means fixed to the supporting member does not rotate, either. A mechanism for connecting the storage means of the developer container and the information reading means of the image forming apparatus may well have a simple construction and connection can be made easily and reliably. Accordingly, even when the container main body rotates, the information reading means of the image forming apparatus main body can correctly read out the information of the developer contained in the container main body. 
   Further, in the invention, an accommodation recess opening in an attachment direction to an image forming apparatus main body is formed in the supporting member, and 
   the storage means is arranged in such a manner that a connection portion connected to at least the information reading means fits into the accommodation recess. 
   According to the invention, the accommodation recess opening in the attachment direction to the image forming apparatus main body is formed in the supporting member and the storage means is arranged in such a manner that the connection portion connected to at least the information reading means fits into the accommodation recess. Since the connection portion of the storage means is not exposed from the accommodation recess in this way, it becomes possible to prevent as much as possible the developer and dust from adhering to the connection portion, for example. Therefore, the information reading means of the image forming apparatus main body can correctly read out the information of the developer contained in the container main body. 
   Further, in the invention, the storage means is fitted as a whole into the accommodation recess. 
   According to the invention, since the storage means is fitted as a whole into the accommodation recess, the storage means is not exposed from the accommodation recess. Therefore, it becomes possible to prevent as much as possible the user from erroneously touching the storage means and the storage means from being damaged. 
   Still further, in the invention, the supporting member is further provided with guide means for restricting displacement of the supporting member in a direction intersecting the attachment direction and guiding the supporting member in such a manner as to undergo displacement in the attachment direction when the developer container is attached to the image forming apparatus main body. 
   According to the invention, the guide means restricts displacement of the supporting member in the direction intersecting the attachment direction and guides the supporting member in such a manner as to undergo displacement in the attachment direction when the developer container is attached to the image forming apparatus main body. Because the displacement of the supporting member in the direction intersecting the attachment direction is restricted when the developer container is mounted in the image forming apparatus main body, it becomes possible to prevent as much as possible the failure of connection between the storage means and the information reading means due to displacement of the supporting member in the direction intersecting the attachment direction. 
   Still further, in the invention, the supporting member is guided by the guide means and undergoes displacement in the attachment direction when the developer container is attached to the image forming apparatus, and the storage means is thereby connected to the information reading means. 
   According to the invention, the supporting member is guided by the guide means and undergoes displacement in the attachment direction when the developer container is attached to the image forming apparatus, and connection between the storage means and the information reading means can be made reliable. 
   Still further, the invention provides an image forming apparatus in which the developer container described above is detachably and attachably mounted. 
   According to the invention, the image forming apparatus can detachably and attachably mount the developer container accomplishing the operations described above. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other and further objects, features, and advantages of the invention will be more explicit from the following detailed description taken with reference to the drawings wherein: 
       FIG. 1  is a perspective view showing a developer container according to one embodiment of the invention; 
       FIG. 2  is a front view showing the developer container; 
       FIG. 3  is a left-hand side view showing the developer container; 
       FIG. 4  is a front view showing a container main body; 
       FIG. 5  is a left-hand side view showing the container main body; 
       FIG. 6  is a right-hand side view showing the container main body; 
       FIG. 7  is a perspective view showing a third container segment; 
       FIG. 8  is an enlarged front view showing the third container segment and other components in the vicinity; 
       FIG. 9A  is a sectional view taken along the line S 91 —S 91  of  FIG. 8 ; 
       FIG. 9B  is a sectional view taken along the line S 92 —S 92  of  FIG. 4 ; 
       FIG. 10  is a front view showing a supporting member; 
       FIG. 11  is a right-hand side view showing the supporting member; 
       FIG. 12  is an exploded right-hand side view showing the supporting member; 
       FIG. 13  is a sectional view taken along the line S 13 —S 13  of  FIG. 11 ; 
       FIG. 14A  is a front view showing a sealing material; 
       FIG. 14B  is a view showing a cross section perpendicular to a circumferential direction of the sealing material; 
       FIG. 15  is a front view showing how the developer container is assembled; 
       FIG. 16  is a sectional view taken along the line S 16 —S 16  of  FIG. 15 ; 
       FIG. 17  is a sectional view taken along the line S 17 —S 17  of  FIG. 3 ; 
       FIG. 18  is a sectional view taken along the line S 18 —S 18  of  FIG. 2 ; 
       FIGS. 19A and 19B  are enlarged views each showing Section IXX depicted in  FIG. 18 ; 
       FIGS. 20A and 20B  are views of assistance in explaining operations for guiding the developer contained in the third container segment of the container main body to a leading through hole of the supporting member, while the container main body is being rotated about a rotation axis L 31  in a rotation direction R; 
       FIGS. 21A and 21B  are views of assistance in explaining operations for guiding the developer contained in the third container segment of the container main body to the leading through hole of the supporting member, while the container main body is being rotated about the rotation axis L 31  in the rotation direction R; 
       FIG. 22  is a front view showing an information storage portion; 
       FIG. 23  is a left-hand side view showing the information storage portion; 
       FIG. 24  is a plan view showing the information storage portion; 
       FIG. 25  is a perspective view showing the information storage portion and an accommodation recess; 
       FIG. 26  is a graph showing the relationship between the time and the quantity of developer which is discharged from the developer container; 
       FIG. 27  is a sectional view showing an image forming apparatus according to another embodiment of the invention; 
       FIG. 28  is an enlarged sectional view showing a toner hopper and other components in the vicinity; 
       FIG. 29  is an enlarged plan view showing the toner hopper and other components in the vicinity; 
       FIG. 30  is a perspective view showing an information reading portion and an information storage portion; 
       FIG. 31  is a front view showing a state where the information storage portion is connected to the information reading portion; 
       FIG. 32  is a block diagram showing an electrical construction of the information storage portion and the information reading portion; and 
       FIG. 33  is an enlarged perspective view showing a main body-side coupling section. 
   

   DETAILED DESCRIPTION 
   Now referring to the drawings, preferred embodiments of the invention are described below. 
     FIG. 1  is a perspective view showing a developer container  30  according to one embodiment of the invention.  FIG. 2  is a front view showing the developer container  30 .  FIG. 3  is a left-hand side view showing the developer container  30 . The developer container  30  includes a container main body  31  and a supporting member  32 . The container main body  31 , which has substantially a cylindrical shape, is designed to contain developer such as coloring toner for use in electrophotographic system-based image formation. The supporting member  32  supports the container main body  31  in such a way that the container main body  31  is rotatable about its axis L 31 . The developer container  30  is capable of containing, for example,  1400  grams of developer. Hereinafter, the axis L 31  of the container main body  31  is also referred to as the “rotation axis L 31 ”. 
     FIG. 4  is a front view showing the container main body  31 .  FIG. 5  is a left-hand side view showing the container main body  31 .  FIG. 6  is a right-hand side view showing the container main body  31 . The container main body  31  includes a first container segment  33 , a second container segment  34 , and a third container segment  35 . In the container main body  31 , its length measurement A 31  in a direction of the axis L 31  may be arbitrarily determined, for example, it is preferably set at 458 mm. 
   The first container segment  33  is given the shape of a bottomed cylinder. In the first container segment  33 , its axial length measurement A 33  may be arbitrarily determined, for example, it is preferably set at 160 mm. The first container segment  33  has, in its inner periphery, feeding means for feeding developer in the axial direction when driven to rotate about the axis L 31 . As shown in  FIG. 4 , the feeding means has a plurality of first projection pieces  36  serving as feeding portions. The first projection piece  36  is so formed as to extend along a first extending direction transversely across the circumferential direction, and to protrude inward in a radial direction. The first projection pieces  36  are spaced apart in the circumferential and axial directions. Specifically, each of the first projection piece  36  extends inclinedly in a circular arc shape, with its downstream side end in a rotation direction placed in a position on a bottom portion  33   a  side as compared to its upstream side end in the rotation direction. 
   As shown in  FIGS. 4 and 5 , on the bottom portion  33   a  of the first container segment  33  are formed a convex fit  37  and a replenishment port  45 . The convex fit  37 , acting as a coupling portion, protrudes from an opening end  33   b  to the bottom portion  33   a . The convex fit  37  is formed in plural, in this embodiment, in a total number of two. The replenishment port  45  is formed at the center of the bottom portion  33   a  of the first container segment  33  so as to penetrate in the direction of the rotation axis L 31 , and to open in the shape of a circle which is coaxial with the axis L 33  of the first container segment  33 . Detachably attached to the replenishment port  45  is a replenishment lid  46  which is configured in accordance with the shape of the replenishment port  45 . The replenishment lid  46  is so designed that, while being kept attached to the replenishment port  45  to provide a seal therebetween, it is prevented from falling off because of the rotation of the container main body  31 . By detaching the replenishment lid  46  from the replenishment port  45 , the inner space of the container main body  31  communicates with the outside space, whereby making it possible to replenish the container main body  31  with developer. 
   Specifically, the convex fits  37  are located outward in the radial direction in contrast to the replenishment port  45 , and arranged at a roughly mutually symmetrical position with respect to the axis L 33  of the first container segment  33 . More specifically, as shown in  FIG. 5 , the convex fit  37  is so configured that its portion  37   a  on the upstream side in the rotation direction R has a plane extending vertically in the circumferential direction. Here, the rotation direction R refers to the direction in which rotation is made clockwise about the rotation axis L 31 , when viewed from the bottom portion  33   a  of the first container segment  33 . Moreover, the convex fit  37  is so configured that its portion on the downstream side in the rotation direction R is gradually inclined toward the other axial end from the upstream side to the downstream side in the rotation direction R. Here, a jutting amount A 37  by which the convex fit  37  juts in the direction of the axis L 33  from the rest part of the bottom portion  33   a  may be arbitrarily determined. For example, it is preferably set at 8 mm. The convex fit  37  such as shown herein is made attachable to and detachable from a main body-side coupling section  83  provided in an image forming apparatus  70 , which will be described later (refer to  FIG. 33 ). 
   Moreover, in the first container segment  33 , the bottom portion  33   a  has a face  33   c  which is defined by the juncture of the outer peripheral surface with the end face thereof. As shown in  FIG. 4 , the face  33   c  is shaped as a curved plane gradually inclined inward in the radial direction from the opening end  33   a  side to the bottom portion  33   a  side. 
   The second container segment  34  is given the shape of a bottomed cylinder. In the second container segment  34 , its axial length measurement A 34  may be arbitrarily determined, for example, it is preferably set at 210 mm. The second container segment  34  has, in its inner periphery, feeding means for feeding developer in the axial direction when driven to rotate about the axis L 31 . As shown in  FIG. 4 , the feeding means has a plurality of second projection pieces  39  serving as feeding portions. The second projection piece  39  is so formed as to extend along a second extending direction which differs from the first extending direction transversely across the circumferential direction, and to protrude inward in the radial direction. Each of the second projection pieces  39  are spaced apart in the circumferential and axial directions. Specifically, each of the second projection piece  39  extends inclinedly in a circular arc shape, with its downstream side end in the rotation direction placed in a position on a bottom portion  34   a  side as compared to its upstream side end in the rotation direction. 
   In the second container segment  34 , its axial length measurement A 34  is adjusted to be longer than the axial length measurement A 33  of the first container segment  33 . For example, the axial length measurement A 34  is preferably set to be 30 mm or more longer than the axial length measurement A 33 . As described previously, the axial length measurement A 33  of the first container segment  33  may be arbitrarily determined, for example, it is preferably set at 150 mm. Likewise, the axial length measurement A 34  of the second container segment  34  may be arbitrarily determined, for example, it is preferably set at 215 mm. Moreover, an internal diameter D 33  of the inner periphery part of the first container segment  33  excluding the first projection pieces  36 , as well as an internal diameter D 34  of the inner periphery part of the second container segment  34  excluding the second projection pieces  39 , may be arbitrarily determined, for example, it is preferably set at 105 mm. Further, an interval A 1  between a pair of the first projection pieces  36  (a pair of second projection pieces  39 ) which are adjacent to each other in the axial direction may be arbitrarily determined, for example, it is preferably set at 15 mm. 
   A length measurement A 36  of the first projection piece  36  in the first extending direction (a length measurement A 39  of the second projection piece  39  in the second extending direction) should preferably fall in a range approximately from 1/16 to ⅜ of the inner periphery length of the first container segment  33  (the inner periphery length of the second container segment  34 ). In case where the length measurement A 36  of the first projection piece  36  in the first extending direction (the length measurement A 39  of the second projection piece  39  in the second extending direction) is shorter than 1/16 of the inner periphery length of the first container segment  33  (the inner periphery length of the second container segment  34 ), the developer feeding capability is decreased. By contrast, in case where the length measurement A 36  of the first projection piece  36  in the first extending direction (the length measurement A 39  of the second projection piece  39  in the second extending direction) is longer than ⅜ of the inner periphery length of the first container segment  33  (the inner periphery length of the second container segment  34 ), the mechanical strength of the container main body  31  is undesirably decreased. Moreover, in case where the feeding capability of the first and second projection pieces  36  and  39  is unduly high, the possibility arises that developer will be coagulated in the vicinity of the discharge hole. In this embodiment, the length measurement A 36  of the first projection piece  36  in the first extending direction, as well as the length measurement A 39  of the second projection piece  39  in the second extending direction, may be arbitrarily determined, for example, it is preferably set at 60 mm. Further, the interval between the two first projection pieces  36  which are adjacent to each other in the circumferential direction, as well as the interval between the two second projection pieces  39  which are adjacent to each other in the circumferential direction, may be arbitrarily determined, for example, it is preferably set at 50 mm. 
   Moreover, a jutting amount A 2  by which the first projection piece  36  (the second projection piece  39 ) juts radially inward from the rest inner periphery part of the first container segment  33  (the second container segment  34 ) should preferably fall in a range approximately from 1 mm to 10 mm. In case where the jutting amount A 2  is greater than 10 mm, the developer feeding capability of the first and second projection pieces  36  and  39  can be enhanced, but excessive enhancement of the feeding capability may possibly lead to occurrence of developer coagulation in the vicinity of the discharge hole. In addition, the jutting amount A 2  exceeding 10 mm gives rise to a problem of forming the first and second projection pieces  36  and  39  by blow molding being difficult. By contrast, in case where the jutting amount A 2  is less than 1 mm, the developer feeding capability is so low that it is impossible to feed a sufficient quantity of developer into the discharge hole. In this embodiment, for example, the jutting amount A 2  by which the first projection piece  36  (the second projection piece  39 ) juts inward in the radial direction from the rest inner periphery part of the container segment is preferably set at 6 mm. Note that, the larger the number of the first and second projection pieces  36  and  39 , the higher the feeding capability. Thus, in this embodiment, the first projection piece  36  is preferably formed in a total number of twenty six, whereas the second projection piece  39  is preferably formed in a total number of thirty eight. 
   Further, an angle α which is formed between a tangential line of the first projection piece  36  (the second projection piece  39 ) and a circumferentially tangential line of the first container segment  33  (the second container segment  34 ), should preferably fall in a range from 2 to 45 degrees, more preferably, 5 to 30 degrees. In this embodiment, for example, the angle α is preferably set at approximately 9 degrees. The developer feeding capability of the container main body  31  is determined, in accordance with the above stated geometrical conditions of the first and second projection pieces  36  and  39 , so that developer can be constantly discharged in an appropriate quantity from a discharge hole  43 , from the time the container main body  31  is full of developer until the developer reaches the verge of running out. 
   In the second container segment  34 , its bottom portion  34   a  has a face which is defined by the juncture of the outer peripheral surface with the end face thereof. At least this face is shaped as a curved plane gradually inclined inward in the radial direction from the opening end  34   b  side to the bottom portion  34   a  side. Specifically, the end face  34   c  of the bottom portion  34   a  of the second container segment  34  is shaped into a partly spherical plane whose center protrudes from the opening end  34   b  side to the bottom portion  34   a  side. Moreover, the second container segment  34  has, in its outer periphery, a guide projection piece  40  formed at a distance from the end face of the opening end  34   b , toward the bottom portion  34   a  side, so as to protrude outward in the radial direction. The guide projection piece  40  is formed in plural (two pieces, in this embodiment), and they are spaced apart in the circumferential direction. The axial dimension of the guide projection piece  40  may be arbitrarily determined, for example, it is preferably set at 2.5 mm. 
     FIG. 7  is a perspective view showing the third container segment  35 .  FIG. 8  is an enlarged front view showing the third container segment  35  and other components in the vicinity.  FIG. 9A  is a sectional view taken along the line S 91 —S 91  of  FIG. 8 .  FIG. 9B  is a sectional view taken along the line S 92 —S 92  of  FIG. 4 . Reference is now made also to  FIG. 4 . The third container segment  35  is given substantially a cylindrical shape. Specifically, the third container segment  35  has, in axially middle positions about its outer periphery, a first concavity  41  and a second concavity  42  formed so as to be sunk inward in the radial direction. The third container segment  35  has also the discharge hole  43  formed in the first concavity  41  for discharging developer. An axial length measurement A 35  of the third container segment  35  is preferably set at 80 mm, for example. An internal diameter D 35  of the third container segment  35  excluding the first and second concavities  41  and  42  is made longer than the internal diameter D 33 , D 34  of the rest first, second container segment  33 ,  34 . The internal diameter D 35  of the third container segment  35  excluding the first and second concavities  41  and  42  may be arbitrarily determined, for example, it is preferably set at 110 mm. 
   The first concavity  41  is so formed as to extend along the rotation direction R, with its axial dimension W 41  made smaller than its dimension A 41  in the rotation direction R. The first concavity  41  has, at its downstream side end in the rotation direction R, an end wall portion  41   a  extending transversely across the rotation direction R. The discharge hole  43  is formed in part of the end wall portion  41   a  on the downstream side in the rotation direction of the first concavity  41 . The second concavity  42  is so formed as to extend along the rotation direction R, with its axial dimension W 42  made smaller than its dimension A 42  in the rotation direction R. The second concavity  42  is formed at a distance from the first concavity  41  in the circumferential direction of the third container segment  35 . The dimension A 41  in the rotation direction R of the first concavity  41  should preferably fall in a range from ¼ to half of the outer periphery length of the third container segment  35  excluding the first and second concavities  41  and  42 . In the first concavity  41 , for example, the dimension A 41  in the rotation direction R is preferably set at 120 mm, whereas the axial dimension W 41  is preferably set at 30 mm. Meanwhile, in the second concavity  42 , both the dimension A 42  in the rotation direction R and the axial dimension W 42  may be arbitrarily determined, for example, the former is preferably set at 120 mm, and the latter is preferably set at 30 mm. 
   Specifically, the first concavity  41  further includes a bottom wall portion  41   b , a first side wall portion  41   c , and a second side wall portion  41   d . The bottom wall portion  41   b  of the first concavity  41  extends along the rotation direction R, with its downstream side end in the rotation direction R made continuous with a radially-inner part of the end wall portion  41   a , and with its upstream side end in the rotation direction R made smoothly continuous with part of the outer periphery of the third container segment  35  excluding the first and second concavities  41  and  42 , existing between the first and second concavities  41  and  42 . In the bottom wall portion  41   b  of the first concavity  41 , its midsection in the rotation direction R, lying between the downstream side end in the rotation direction R and the upstream side end in the rotation direction R, is placed inward in the radial direction as compared to the third container segment  35  excluding the first and second concavities  41  and  42 . The midsection in the rotation direction R has substantially a part-cylindrical shape whose axis is defined by the axis L 35  of the third container segment  35 . In the bottom wall portion  41   b  of the first concavity  41 , the radius of curvature of the outer periphery of the midsection in the rotation direction R may be arbitrarily determined, for example, it is preferably set at 49 mm. 
   In the first concavity  41 , the first side wall portion  41   c  is arranged on one axial end side of the first concavity  41 . The first side wall portion  41   c  extends along the rotation direction R, with its downstream side end in the rotation direction R made continuous with one axial end of the end wall portion  41   a ; with its radially-inner part made continuous with one axial end of the bottom wall portion  41   b ; and with its radially-outer part made continuous with the outer periphery of one axial end of the third container segment  35  excluding the first and second concavities  41  and  42 . Moreover, in the first concavity  41 , the second side wall portion  41   d  is arranged on the other axial end side of the first concavity  41 . The second side wall portion  41   d  extends along the rotation direction R, with its downstream side end in the rotation direction R made continuous with the other axial end of the end wall portion  41   a ; with its radially-inner part made continuous with the other axial end of the bottom wall portion  41   b ; and with its radially-outer part made continuous with the outer periphery of the other axial end of the third container segment  35  excluding the first and second concavities  41  and  42 . The first and second side wall portions  41   c  and  41   d  of the first concavity  41  are each so formed as to upstand outward in the radial direction from the bottom wall portion  41   b . The first and second side wall portions  41   c  and  41   d  are each substantially perpendicular to the bottom wall portion  41   b.    
   The discharge hole  43  is formed in the axially middle position of the end wall portion  41   a  of the first concavity  41  so as to be located outward in the radial direction. Moreover, the discharge hole  43  is shaped as a rectangular opening, the lengthwise direction of which is aligned with the axial direction. Thus, in the end wall portion  41   a  of the first concavity  41 , the discharge hole  43  is so formed as to open radially outward as compared to the downstream side end in the rotation direction R of the bottom wall portion  41   b  of the first concavity  41 ; to open in the other axial end-ward position as compared to the downstream side end in the rotation direction R of the first side wall portion  41   c ; and to open in the one axial end-ward position as compared to the downstream side end in the rotation direction R of the second side wall portion  41   d . More specifically, the discharge hole  43  has its radially-outer surface made smoothly continuous with a part of the inner peripheral surface of the third container segment  35  excluding the first and second concavities  41  and  42  which is located on the downstream side in the rotation direction R of the first concavity  41 . 
   Specifically, the second concavity  42  further includes a bottom wall portion  42   b , a first side wall portion  42   c , and a second side wall portion  42   d . The bottom wall portion  42   b  of the second concavity  42  extends along the rotation direction R, with its ends on the upstream and downstream sides in the rotation direction R made smoothly continuous with part of the outer periphery of the third container segment  35  excluding the first and second concavities  41  and  42 , existing between the first and second concavities  41  and  42 . In the bottom wall portion  42   b  of the second concavity  42 , its midsection in the rotation direction R, lying between the downstream side end in the rotation direction R and the upstream side end in the rotation direction R, is placed inward in the radial direction as compared to the third container segment  35  excluding the first and second concavities  41  and  42 . The midsection in the rotation direction R has substantially a part-cylindrical shape whose axis is defined by the axis L 35  of the third container segment  35 . In the bottom wall portion  42   b  of the second concavity  42 , the radius of curvature of the outer periphery of the midsection in the rotation direction R may be arbitrarily determined, for example, it is preferably set at 49 mm. 
   In the second concavity  42 , the first side wall portion  42   c  is arranged on one axial end side of the second concavity  42 . The first side wall portion  42   c  extends along the rotation direction R, with its radially-inner part made continuous with one axial end of the bottom wall portion  42   b , and with its radially-outer part made continuous with the outer periphery of one axial end of the third container segment  35  excluding the first and second concavities  41  and  42 . Moreover, in the second concavity  42 , the second side wall portion  42   d  is arranged on the other axial end side of the second concavity  42 . The second side wall portion  42   d  has its radially-inner part made continuous with the other axial end of the bottom wall portion  42   b , and its radially-outer part made continuous with the outer periphery of the other axial end of the third container segment  35  excluding the first and second concavities  41  and  42 . The first and second side wall portions  42   c  and  42   d  of the second concavity  42  are each so formed as to upstand outward in the radial direction from the bottom wall portion  42   b . The first and second side wall portions  42   c  and  42   d  are each substantially perpendicular to the bottom wall portion  42   b.    
   As shown in  FIG. 8 , disposed about the outer periphery of each of one and the other axial ends of the third container segment  35  excluding the first and second concavities  41  and  42  are a plurality of discharge guide pieces  44  protruding outward in the radial direction. The discharge guide pieces  44  are evenly spaced in the circumferential direction. Specifically, the discharge guide piece  44  disposed at one axial end of the third container segment  35  is gradually inclined in the rotation direction R from the other axial end side to one axial end side. On the other hand, specifically, the discharge guide piece  44  disposed at the other axial end of the third container segment  35  is gradually inclined in the rotation direction R from one axial end side to the other axial end side. The jutting amount by which the discharge guide piece  44  juts radially outward from the outer periphery of the third container segment  35  excluding the first and second concavities  41  and  42  is preferably set at 1 mm, for example. A dimension in a longitudinal direction of the discharge guide piece  44  is preferably set at 24 mm. An angle ψ which is formed between the longitudinal direction of the discharge guide piece  44  and a width direction of the third container segment  35  is preferably set at 30 degrees. 
   The container main body  31  is a combination of the first, second, and third container segments  33 ,  34 , and  35  in one. That is, one axial end of the third container segment  35  is coupled to the opening end  33   b  of the first container segment  33 , whereas the other axial end of the third container segment  35  is coupled to the opening end  34   b  of the second container segment  34 . The container main body  31  such as shown herein is preferably produced by subjecting a synthetic resin material such as polyethylene to blow molding. In this way, the container main body  31  can be produced with ease. Another advantageous feature is that the number of the components constituting the developer container  30  can be reduced. 
   The bottom portion  33   a  of the first container segment  33  coincides with one axial end  33   a  of the container main body  31 , and the bottom portion  34   a  of the second container segment  34  coincides with the other axial end  34   a  of the container main body  31 . Thus, the first, second, and third container segments  33 ,  34 , and  35  are coaxially coupled to one another, with their axes L 33 , L 34 , and L 35  coinciding with one another, thereby constituting the container main body  31 . Moreover, in this state, the third container segment  35  is arranged in the axially middle position of the container main body  31  excluding the axial ends  33   a  and  34   a . Correspondingly, the first and second container concavities  41  and  42  and the discharge hole  43  of the third container segment  35  are arranged in the axially middle position of the container main body  31  excluding the axial ends  33   a  and  34   a . The axis L 31  of the container main body  31  is composed of the axes L 33 , L 34 , and L 35  of the first, second, and third container segments  33 ,  34 , and  35 . 
     FIG. 10  is a front view showing the supporting member  32 .  FIG. 11  is a right-hand side view showing the supporting member  32 . The supporting member  32 , which is given substantially a cylindrical shape, has an inner periphery  48  for supporting the part of the container main body  31  of the above structure which includes at least the third container segment  35 , from its outer side in the radial direction over its entire circumference. The inner periphery  48  has a cylindrical inner peripheral surface, the center of which coincides with the axis L 32 . The supporting member  32  includes a supporting base  49  having at least three or more abutment portions  49   a  on a virtual plane parallel to the axis L 32 . For example, the abutment portion  49   a  of the supporting base  49  is preferably formed as two rectangular planes, a longitudinal direction of which is aligned with a direction parallel to the axis L 32 . By bringing the abutment portion  49   a  of the supporting base  49  in contact with a horizontal surface, the supporting member  32  can be placed, with the axis L 48  of its inner periphery  48  arranged in parallel with the horizontal surface. An axial length measurement A 32  of the supporting member  32  is made longer than the axial length measurement A 35  of the third container segment  35 . The axial length measurement A 32  of the supporting member  32  may be arbitrarily determined, for example, it is preferably set at 100 mm. 
   In the state where the supporting base  49  is placed horizontally, on the upper part of the supporting member  32  is formed a discharge section  50  protruding in one horizontal direction defined as “one first horizontal direction F 1 ”. In terms of the discharge section  50 , in the axially middle position of the supporting member  32  is formed a leading through hole  51  so as to penetrate along one first horizontal direction F 1  and to open in the shape of an ellipse extending in a direction parallel to the axis L 32  of the supporting member. An internal diameter in the longitudinal direction of the leading through hole  51  is adjusted to be equal to or greater than the axial dimension W 41  of the first concavity  41  and the axial dimension W 42  of the second concavity  42  of the container main body  31 . 
   In the discharge section  50  of the supporting member  32  is disposed a shutter portion  65  for switching a downstream side opening in one first horizontal direction F 1  of the leading through hole  51  between an opened state and a closed state. The shutter portion  65  includes a shutter  65   a  and a shutter guide  65   b . The shutter guide  65   b  extends along a second horizontal direction which is perpendicular to the first horizontal direction. Beside its upstream side end in one second horizontal direction B 1  is opened the leading through hole  51 . The shutter  65   a  is supported by the shutter guide  65   b  so as to be slidable either in one second horizontal direction B 1  or in the direction opposite thereto, namely, another second horizontal direction B 2 . 
   The shutter  65   a  is slidingly displaced along the shutter guide  65   b , and is thereby arranged either in a closing position P 1  as indicated by a chain double dashed line in  FIG. 10  or in an opening position P 2 , at which the downstream side opening in the one first horizontal direction F 1  of the leading through hole  51  is closed and opened. Moreover, the shutter  65   a  is restrained from further sliding displacement in the downstream side in the other second horizontal direction B 2  beyond the closing position P 1 , and is also restrained from further sliding displacement in one second horizontal direction B 1  beyond the downstream side end in one second horizontal direction B 1  of the shutter guide  65   b . That is, the opening position P 2  is located in a position on the downstream side in one second horizontal direction B 1  as compared to the closing position P 1 , and is simultaneously located in a position on the upstream side in one second horizontal direction B 1  as compared to the downstream side end in the one second horizontal direction B 1  of the shutter guide  65   b . In this way, the shutter  65   a , on the one hand, is shifted from the closing position P 1  to the opening position P 2  by being slidingly displaced in one second horizontal direction B 1 , and, on the other hand, is shifted from the opening position P 2  to the closing position P 1  by being slidingly displaced in the other second horizontal direction B 2 . 
   A leading-out member  38  serving as leading-out means and a sealing sheet  66  serving as sealing means are provided in the supporting member  32 . The leading-out member  38  is formed of a polymer resin such as polyethylene terephthalate (abbreviated as “PET”), is shaped into a sheet form having flexibility and resilience and a proximal end thereof is arranged, more concretely, at a portion of the supporting member  32  facing the upstream end of the leading through hole  51  in the one first horizontal direction F 1 , in other words, on the inner periphery of the supporting member  32 . The sealing sheet  66  is formed of polyethylene, for example, into a sheet form having flexibility and a proximal end thereof is arranged at a portion of the supporting member  32  facing the upstream end of the leading through hole  51  in the one first horizontal direction F 1 . The proximal end of the leading-out member  38  is stacked on the upper face of the proximal end of the sealing sheet  66 . The leading-out member  38  and the sealing sheet  66  will be explained later in further detail. 
   Moreover, the supporting member  32  has two pieces of coupling projections  52  protruding outward in the radial direction. In the state where the supporting base  49  is placed horizontally, one of the coupling projections  52  is arranged above the discharge section  50 , and the other coupling projection  52  is arranged symmetrically with the above one with respect to the axis L 32 . Further, the supporting member  32  has a first guide piece  53  which is arranged below the discharge section  50  in the state where the supporting base  49  is placed horizontally. The first guide piece  53  is so formed as to protrude in one first horizontal direction F 1 , and to extend in parallel with the axis L 32 . Still further, the supporting member  32  has a second guide piece  54  which is arranged above the discharge section  50  in the state where the supporting base  49  is placed horizontally. The second guide piece  54  is so formed as to protrude in another first horizontal direction F 2  opposite to one first horizontal direction F 1 , and to extend in parallel with the axis L 32 . 
     FIG. 12  is an exploded right-hand side view showing the supporting member  32 . In the horizontally-placed state, the supporting member  32  can be divided into two parts with respect to a virtual plane which passes along the axis L 32  and is gradually inclined upwardly with increasing proximity to one first horizontal direction F 1 . Specifically, the supporting member  32  can be divided into a first supporting portion  55  and a second supporting portion  56 . The first supporting portion  55  is located below the virtual plane, whereas the second supporting portion  56  is located above the virtual plane. In terms of the supporting member  32 , the first supporting portion  55  includes the first guide piece  53 ; the discharge section  50 ; one part  52   a  of each of the coupling projection  52 ; the supporting base  49 ; and a part  48   a  on the first guide piece  53  side of the inner periphery  48 . On the other hand, the second supporting portion  56  includes the second guide piece  54 ; the other part  52   b  of each of the coupling projection  52 ; and a part  48   b  on the supporting base  49  side of the inner periphery  48 . 
   The first and second supporting portions  55  and  56  are attachably/detachably coupled to each other by a screw member  57 . Specifically, one part  52   a  of each of the coupling projection  52  of the first supporting portion  55  is coupled to the other part  52   b  of each of the coupling projection  52  of the second supporting portion  56  by the screw member  57 . The supporting member  32  is divided before it receives the container main body  31 . Then, the divided supporting member  32  portions are assembled to support the part of the container main body  31  which includes the first and second concavities  41  and  42  and the discharge hole  43 , from the radially outer side. Thereby, the container main body  31  can be supported over its entire circumference. The dividable configuration of the supporting member  32  helps facilitate the assembly operation. 
     FIG. 13  is a sectional view taken along the line S 13 —S 13  of  FIG. 11 . Reference is now made also to  FIG. 11 . The supporting member  32  has, at one axial end of its inner periphery  48 , a first supporting convexity  58  formed so as to protrude inward in the radial direction and to extend over an entire circumference in the circumferential direction, and also has, at the other axial end of its inner periphery  48 , a second supporting convexity  59  formed so as to protrude inward in the radial direction and to extend over an entire circumference in the circumferential direction. The supporting member  32  additionally has, at the other axial end of its inner periphery  48 , a third supporting convexity  60  formed so as to protrude inward in the radial direction and to extend an entire circumference in the circumferential direction. The third supporting convexity  60  is disposed in a position on the other axial end side as compared to the second supporting convexity  59 , with a spacing secured therebetween. The axial spacing between the second and third supporting convexities  59  and  60  is made slightly larger than the axial dimension of the guide projection piece  40  of the second container segment  34  of the container main body  31 . For example, it is preferably set at 3 mm. 
   The first and second supporting convexities  58  and  59  each have a plurality (four pieces, in this embodiment) of supporting projection pieces  61  protruding inward in the radial direction that are evenly spaced in the circumferential direction. In the supporting projection piece  61 , its radially-inner front end has a supporting surface curved as a cylindrical outer peripheral surface. The supporting projection pieces  61  provided in the first and second supporting convexities  58  and  59  are each so configured that a diameter of a virtual circle passing along the front end of each of the guide projection pieces  40  about the axis L 32  is made slightly longer than the outer diameter of the outer periphery of the first container segment  33  and the outer diameter of the outer periphery of the second container segment  34  excluding the guide projection piece  40 . For example, the diameter is preferably set at 107 mm. The internal diameter of the third supporting convexity  60  is made slightly longer than the outer diameter of the outer periphery of the second container segment  34  excluding the guide projection piece  40 . For example, the internal diameter is preferably set at 107 mm. 
   In adjacency to the other axial end of the first supporting convexity  58  formed at one axial end of the inner periphery  48  of the supporting member  32 , a first supporting concavity  67  is formed so as to be sunk outward in the radial direction and to extend over an entire circumference in the circumferential direction. In adjacency to one axial end of the second supporting convexity  59  formed at the other axial end of the inner periphery  48  of the supporting member  32 , a second supporting concavity  68  is formed so as to be sunk outward in the radial direction and to extend over an entire circumference in the circumferential direction. Moreover, between the second and third supporting convexities  59  and  60  formed at the other axial end of the inner periphery  48  of the supporting member  32  is formed a third supporting concavity  69  so as to be sunk outward in the radial direction and to extend over an entire circumference in the circumferential direction. For example, the axial dimension of the first, second supporting concavity  67 ,  68  is preferably set at 7 mm. The axial dimension of the third supporting concavity  69  is made slightly larger than the axial dimension of the guide projection piece  40  of the second container segment  34  of the container main body  31 . For example, it is preferably set at 3 mm. 
     FIG. 14A  is a front view showing a sealing material  47 .  FIG. 14B  is a view showing a cross section perpendicular to the circumferential direction of the sealing material  47 . The sealing material  47 , acting as sealing means, is made of a material possessing pliability and resilience, for example, a synthetic resin material such as silicon rubber. As shown in  FIG. 14A , the sealing material  47  is given substantially an annular shape. As shown in  FIG. 14B , the sealing material  47  includes a base portion  47   a  and an abutment portion  47   b . In the sealing material  47 , the base portion  47   a  is so configured that its cross section perpendicular to the circumferential direction around the axis L 35  has a rectangular shape. The abutment portion  47   b  protrudes from one radially-inner axial end of the base portion  47   a  so as to be gradually inclined outward in the radial direction from the other axial end side to one axial end side. 
   The diameter of the inner periphery of the base portion  47   a  of the sealing material  47  is made shorter than the outer diameter of the outer periphery of the first container segment  33  and the outer diameter of the outer periphery of the second container segment  34  excluding the guide projection piece  40 . For example, the diameter is preferably set at 99 mm. Moreover, the diameter of the outer periphery of the base portion  47   a  and the abutment portion  47   b  of the sealing material  47  is made equal to or greater than a diameter of a virtual circle passing along the outer periphery of each of the discharge guide pieces  44  of the third container segment  35  of the container main body  31  about the rotation axis L 31 . For example, the diameter is preferably set at 115 mm. Further, the axial dimension of the sealing material  47  is made equal to or less than the axial dimension of the first, second supporting concavity  67 ,  68  of the supporting member  32 . For example, the axial dimension is preferably set at 6 mm. 
     FIG. 15  is a front view showing how the developer container  30  is assembled.  FIG. 16  is a sectional view taken along the line S 16 —S 16  of  FIG. 15 . Prior to the assembly of the developer container  30 , the supporting member  32  is divided into the first and second supporting portions  55  and  56 . At the same time, one of the two sealing materials  47  is attached to the first container segment  33  of the container main body  31  as follows: the sealing material  47  is wound tightly on the opening end  33   b  of the first container segment  33 , with its base portion  47   a  brought into intimate contact with the end face of one axial end of the third container segment  35 . Meanwhile, the other sealing material  47  is attached to the second container segment  34  of the container main body  31  as follows: the sealing material  47  is wound tightly on the opening end  34   b  of the second container segment  34  in a position on one axial end side as compared to the guide projection piece  40 , with its base portion  47   a  brought into intimate contact with the end face of the other axial end of the third container segment  35 . 
   The part of the container main body  31  which includes the third container segment  35  is grippingly held, from the outer side in the radial direction, by the first and second supporting portions  55  and  56 . In this state, the first and second supporting portions  55  and  56  are coupled to each other by the screw member  57 . 
     FIG. 17  is a sectional view taken along the line S 17 —S 17  of  FIG. 3 . In the state where the container main body  31  is supported by the supporting member  32 , the axis L 31  of the container main body  31  coincides perfectly or substantially with the axis L 32  of the inner periphery  48  of the supporting member  32 . Thus, the container main body  31  is rotatable about the axis L 31  with respect to the supporting member  32 . In the case where the supporting base  49  of the supporting member  32  is placed on a horizontal surface, with the container main body  31  kept supported thereby, the first and second container segments  33  and  34  of the container main body  31  are located away from the horizontal surface, and the horizontal surface and the rotation axis L 31  are arranged parallel to each other. 
   In the supporting member  32 , specifically, the supporting projection pieces  61  provided in the first supporting convexity  58  each abut against the outer periphery of the first container segment  33 , whereas the supporting projection pieces  61  provided in the second supporting convexity  59  each abut against the outer periphery of the second container segment  34  excluding the guide projection piece  40 . It follows from this that the outer periphery of the first container segment  33  is supported, at approximately four equi-spaced points in the circumferential direction, by each of the supporting projection pieces  61  of the first supporting convexity  58 , and is simultaneously supported, at approximately four equi-spaced points in the circumferential direction, by each of the supporting projection pieces  61  of the second supporting convexity  59 . This arrangement makes it possible to minimize the frictional force generated between the outer periphery of the first container segment  33  and the first supporting convexity  58 , as well as the one generated between the outer periphery of the second container segment  34  and the second supporting convexity  59 , against the rotation of the container main body  31 . 
   The sealing material  47  of the first container segment  33  is fitted into the first supporting concavity  67  of the supporting member  32 . The abutment portion  47   b  of the sealing material  47  abuts resiliently against the other axial end face of the first supporting convexity  58  over its entire circumference. The sealing material  47  of the second container segment  34  is fitted into the second supporting concavity  68  of the supporting member  32 . The abutment portion  47   b  of the sealing material  47  abuts resiliently against one axial end face of the second supporting convexity  59  over its entire circumference. By the use of two sealing materials  47  such as shown herein, sealing can be achieved between the container main body  31  and the supporting member  32 , over an entire circumference in the circumferential direction. That is, sealing can be achieved with respect to the first and second concavities  41  and  42  and the discharge hole  43  of the container main body  31 , and part of the supporting member  32  closer to one and the other axial ends of the container main body  31  relatively to the leading through hole  51 . 
   The guide projection piece  40  of the second container segment  34  of the container main body  31  is fitted into the third supporting concavity  69  of the supporting member  32 , while being restrained from axial sliding displacement with respect to the supporting member  32 . Resultantly, the container main body  31  is restrained from axial sliding displacement with respect to the supporting member  32 . The outer periphery of each of the discharge guide pieces  44  of the third container segment  35  of the container main body  31  abuts against the inner periphery  48  of the supporting member  32 . In this way, the supporting member  32  supports the part of the container main body  31  which includes at least the first concavity  41 , from the outer side in the radial direction over the entire circumference, in such a way that the container main body  31  is rotatable about the rotation axis L 31 . 
     FIG. 18  is a sectional view taken along the line S 18 —S 18  of  FIG. 2 .  FIGS. 19A and 19B  are enlarged views each showing Section IXX depicted in  FIG. 18 . These  FIGS. 18 and 19A  are views when the container main body  31  exists in an initial state to the supporting member  32 . The proximal end  38   a  of the leading-out member  38  is disposed at the position of the supporting member  32  facing the upstream end of the leading through hole  51  in the one first horizontal direction F 1  and extends towards the upstream side in the rotation direction R. The free end  38   b  of the leading-out member  38  can come into resilient contact with at least the outer circumferential surface of the bottom wall portion  41   b  of the first concavity  41  and the outer circumferential surface of the bottom wall portion  42   b  of the second concavity  42  of the third container segment  35  of the container main body  31 . The free end  38   b  of the leading-out member  38  comes into contact with the at least the outer circumferential surfaces of the bottom wall portion  41   b  of the first concavity  41  and the bottom wall portion  42   b  of the second concavity  42  of the first concavity  41  of the third container segment  35  of the container main body  31  at an angle θ exceeding 90 degrees. More concretely, the angle θ is the angle between the surface of the free end  38   b  of the leading-out member  38  facing upward and the outer circumferential surface of the bottom wall portion  41   b ,  42   b  of each concavity  41 ,  42 . 
   The proximal end  66   a  of the sealing sheet  66  is disposed at the potion of the supporting member  32  facing the upstream end portion of the leading through hole  51  in the one first horizontal direction F 1 . A portion  66   b  of the sealing sheet  66  exclusive of the proximal end  66   a  is detachably and attachably disposed by, for example, fusion in such a manner as to cover at least the end wall portion  41   a  of the first concavity  41  when the container main body  31  is in the initial state to the supporting member  32 . In this initial state, the discharge hole  43  is closed by the portion  66   b  of the sealing sheet  66  exclusive of the proximal end  66   a . Accordingly, even when the user erroneously sets the shutter  65   a  of the shutter portion  65  to the open position P 2  in an initial state, it is possible to prevent the developer contained in the container main body  31  from being undesirably discharged from the leading through hole  51 . 
   When the container main body  31  is rotated in the rotation direction R from the initial state about the rotation axis L 31 , the portion  66   b  of the sealing sheet  66  exclusive of the proximal end  66   a  leaves the end wall portion  41   a  of the first concavity  41  and the discharge hole  43  is opened. The portion  66   b  of the sealing sheet  66  exclusive of the proximal end  66   a  that leaves the end wall portion  41   a  of the first concavity  41  is brought to a position between the third container segment  35  of the container main body  31  and the inner periphery  48  of the supporting member  32  on the downstream side in the rotation direction R of the leading through hole  51  of the supporting member  32  as shown in  FIG. 19B . In consequence, the discharge hole  43  can be easily opened by rotating the container main body  31  without directly removing the sealing sheet  66  by the user. 
   While the container main body  31  is kept in a developer-containing state with the supporting base  49  of the supporting member  32  placed horizontally, the internal space of the container main body  31  is composed of two layers: a developer layer made up by developer; and a pneumatic layer made up by gas present above the developer layer. The container main body  31  is rotated clockwise about the rotation axis L 31 , looking from the first container segment  33  to the second container segment  34 . At this time, the developer constituting the developer layer in the first container segment  33  is conveyed, along the rotation axis L 31 , from the first container segment  33  toward the third container segment  35 , or equivalently, conveyed in a first conveying direction C 1  (refer to  FIG. 2 ) by each of the first projection pieces  36 . At the same time, the developer constituting the developer layer in the second container segment  34  is conveyed, along the rotation axis L 31 , from the second container segment  34  toward the third container segment  35 , or equivalently, conveyed in a second conveying direction C 2  (refer to  FIG. 2 ) by each of the second projection pieces  39 . In this way, by rotating the container main body  31  about the rotation axis L 31 , the developer contained therein can be conveyed toward the discharge hole  43 . Moreover, in the third container segment  35 , the developer traveling in the first conveying direction C 1  and the developer traveling in the second conveying direction C 2  come into collision with each other, thereby achieving agitation of the developer. 
   The developer is under a force when conveyed to travel from the inner periphery of the first container segment  33  (the second container segment  34 ) including the first projection piece  36  (the second projection piece  39 ) toward the third container segment  35 . When the developer contained in the container main body  31  is larger in quantity, part of the developer located within the jutting amount A 2  by which the first projection piece  36  (the second projection piece  39 ) juts radially inward from the inner periphery of the first container segment  33  (second container segment  34 ) is agitated mainly by the rotation of the container main body  31 , thereby striking a proper developer balance in the container main body  31 . 
     FIGS. 20A ,  20 B,  21 A, and  21 B are views of assistance in explaining operations for guiding the developer contained in the third container segment  35  of the container main body  31  to the leading through hole  51  of the supporting member  32 , while the container main body  31  is being rotated about the rotation axis L 31  in the rotation direction R. Reference is now made also to  FIGS. 7 ,  9 A,  9 B, and  17 . In the state where the container main body  31  is supported by the supporting member  32  so as to be rotatable about the rotation axis L 31 , a first retaining space  62   a  is created facing the first concavity  41  of the third container segment  35  and the inner periphery  48  of the supporting member  32 . The first retaining space  62   a  is kept in substantially an enclosed state (apart from the discharge hole  43 ). The first retaining space  62   a  is arranged on the upstream side in the rotation direction R of the discharge hole  43 , and is continuous with the space within the container main body  31  via the discharge hole  43 . At the same time, a second retaining space  62   b  is created facing the second concavity  42  of the third container segment  35  and the inner periphery  48  of the supporting member  32 . The second retaining space  62   b  is kept in substantially an enclosed state. 
   Upon the rotation of the container main body  31  in the rotation direction R, the condition is changed from the state as shown in  FIG. 20A  in which the discharge hole  43  and the first retaining space  62   a  are located above an upper face  63   a  of the developer layer  63  existing within the container main body  31 , to the state as shown in  FIG. 20B  in which the discharge hole  43  and a downstream side part in the rotation direction R of the first retaining space  62   a  are located below the upper face  63   a  of the developer layer  63  existing within the container main body  31 . Then, as indicated by the arrow G 1 , the developer constituting the developer layer  63  contained within the container main body  31  starts to flow through the discharge hole  43  into the downstream side part in the rotation direction R of the first retaining space  62   a.    
   As described previously, the discharge hole  43  is formed in the axially middle position of the end wall portion  41   a  of the first concavity  41  so as to be located outward in the radial direction. Moreover, the discharge hole  43  is shaped as a rectangular opening, the lengthwise direction of which is aligned with the axial direction. Thus, in the end wall portion  41   a  of the first concavity  41 , the discharge hole  43  is opened outward in the radial direction as compared to the downstream side end in the rotation direction R of the bottom wall portion  41   b  of the first concavity  41 ; opened in a position on the the other axial end side as compared to the downstream side end in the rotation direction R of the first side wall portion  41   c ; and opened in a position on the one axial end as compared to the downstream side end in the rotation direction R of the second side wall portion  41   d.    
   For example, assuming that the discharge hole  43  is so formed as to open all over the area of the end wall portion  41   a . In this case, upon the rotation of the container main body  31  in the rotation direction R, the developer is squeezingly moved along the first concavity  41  of the container main body  31  and the inner periphery  48  of the supporting member  32 , so that it may be discharged from the discharge hole  43  into the first retaining space  62   a . Then, upon further rotation of the container main body  31  in the rotation direction R, the developer retained in the first retaining space  62   a  is pressed by the first concavity  41  of the container main body  31  and the inner periphery  48  of the supporting member  32 , which may lead to coagulation of the developer. In view of the foregoing, in this embodiment, as described above, the discharge hole  43  is formed in part of the end wall portion  41   a  of the first concavity  41 , in other words, the opening area of the discharge hole  43  is made narrower than the area of the end wall portion  41   a . This allows, in the vicinity of the discharge hole  43 , the developer to be diffusely discharged into the first retaining space  62   a . As a result, the developer discharged into the first retaining space  62   a  can be pulverized into fine particles, and the possibility of the above stated developer coagulation caused by the rotation of the container main body  31  can be minimized. 
   Moreover, the radially-outer surface of the discharge hole  43  is made smoothly continuous with a part of the inner peripheral surface of the third container segment  35  excluding the first and second concavities  41  and  42  which is located on the downstream side in the rotation direction R of the first concavity  41 . This allows, even if the developer contained in the container main body  31  is very small in quantity, the developer to flow smoothly into the downstream side part in the rotation direction R of the first retaining space  62   a  through the discharge hole  43 . 
   In the state as shown in  FIG. 20B , the developer constituting the developer layer  63  contained within the container main body  31  flows through the discharge hole  43  into the downstream side part in the rotation direction R of the first retaining space  62   a . Then, upon further rotation of the container main body  31  in the rotation direction R, the condition is changed from the state as shown in  FIG. 20B  to the state as shown in  FIG. 21A  in which the discharge hole  43  is located above the upper face  63   a  of the developer layer  63  existing within the container main body  31 , whereas the first retaining space  62   a  is located below the upper face  63   a  of the developer layer  63  existing within the container main body  31 . In the state as shown in  FIG. 21A , a predetermined quantity of developer is retained in the first retaining space  62   a . For example, the quantity of developer to be retained in the first retaining space  62   a  is preferably set at 6 gram. 
   Upon still further rotation of the container main body  31  in the rotation direction R, the condition is changed from the state as shown in  FIG. 21A  to the state as shown in  FIG. 21B  in which the free end  38   b  of the leading-out member  38  of the supporting member  32  enters the first retaining space  62   a , so that it juts out on the upstream side in the rotation direction R, and abuts resiliently against the outer peripheral surface of the bottom wall portion  41   b  of the first concavity  41  slidingly at an angle θ of greater than 90 degrees. At this time, the developer, retained in the first retaining space  62   a  located in a position on the upstream side in the rotation direction R as compared to the leading-out member  38 , finds its way toward the supporting member  32  in accompaniment with the rotation of the container main body  31  in the rotation direction R. 
   As indicated by the arrow G 2 , the leading-out member  38  guides the developer that thus flowed in, in other words, the developer having been discharged from the discharge hole  43  of the container main body  31 , along its upper surface, to lead it to the leading through hole  51 . The leading-out member  38  slides over the outer peripheral surface of the bottom wall portion  41   b  of the first concavity  41  in such a way that the developer is scraped off the outer peripheral surface. Therefore, the developer retained in the first retaining space  62   a  can be directed to the leading through hole  51  as wholly as possible. The developer that thus reached the leading through hole  51  is then discharged out of the developer container  30 . In this way, every time the container main body  31  makes one rotation about the rotation axis L 31  in the rotation direction R, the above-stated predetermined quantity of developer is discharged to the outside. 
   As described previously, in order to reduce the frictional force that hinders the rotation of the container main body  31  about the rotation axis L 31 , the inner periphery  48  of the supporting member  32  and the third container segment  35  excluding the first and second concavities  41  and  42  are designed so as not to abut against each other over the entire circumference in the circumferential direction. Such a structure is not without the potential of the leakage of the developer retained in the first retaining space  62   a  as described above. Hence, as described previously, the discharge guide pieces  44  are disposed about the outer periphery of each of one and the other axial ends of the third container segment  35  excluding the first and second concavities  41  and  42 . The discharge guide piece  44  disposed at one axial end of the third container segment  35  is gradually inclined in the rotation direction R from the other axial end side to one axial end side. On the other hand, the discharge guide piece  44  disposed at the other axial end of the third container segment  35  is gradually inclined in the rotation direction R from one axial end side to the other axial end side. As a result, in the event that the developer retained in the first retaining space  62   a  leaks therefrom toward one and the other sides as viewed in the direction of the rotation axis L 32 , during the rotation of the container main body  31  in the rotation direction R, each of the discharge guide pieces  44  gather the developer particles around the axially middle position of the third container segment  35  and the supporting member  32 . 
   Another advantageous feature is that, as described above, the second retaining space  62   b  is additionally provided. In the event that the developer retained in the first retaining space  62   a  leaks from its upstream side part in the rotation direction R, the leakage developer, as well as the developer gathered around the axially middle position by each of the discharge guide pieces  44 , is retained in the second retaining space  62   b . Upon the rotation of the container main body  31  in the rotation direction R, as shown in  FIG. 24A , the free end  38   b  of the leading-out member  38  of the supporting member  32  enters the second retaining space  62   b , so that it juts out on the upstream side in the rotation direction R, and abuts resiliently against the outer peripheral surface of the bottom wall portion  42   b  of the second concavity  42  slidingly at an angle θ of greater than 90 degrees. At this time, the developer, retained in the second retaining space  62   b  located in the a position on the upstream side in the rotation direction R as compared to the leading-out member  38 , finds its way toward the supporting member  32  in accompaniment with the rotation of the container main body  31  in the rotation direction R. Then, the developer is directed to the leading through hole  51  to be discharged out of the developer container  30 . In this way, in the event of the developer leaking from the first retaining space  62   a , every time the container main body  31  makes one rotation about the rotation axis L 31  in the rotation direction R, the leakage developer can be retained in the second retaining space  62   b . As a result, the above-stated predetermined quantity of developer can be discharged to the outside as reliably as possible. 
   Further advantageous feature is that, as described previously, in the state where the supporting base  49  is placed horizontally, on the upper part of the supporting member  32  is disposed the discharge section  50  protruding in one of the horizontal directions, namely, one first horizontal direction F 1 . In terms of the discharge section  50 , in the axially middle position of the supporting member  32  is disposed the leading through hole  51  so as to penetrate along one first horizontal direction F 1  and to open in the shape of an ellipse extending in a direction parallel to the axis L 32  of the supporting member. With this arrangement, even if the container main body  31  is full of developer, the upper face  63   a  of the developer layer  63  is kept located at or below the level of the leading through hole  51 . As a result, the developer can be prevented from inappropriately flowing from the container main body  31  into the leading through hole  51  without fail. 
     FIG. 22  is a front view showing an information storage portion  100 .  FIG. 23  is a left-hand side view showing the information storage portion  100 .  FIG. 24  is a plan view showing the information storage portion  100 . The developer container  30  further includes the information storage portion  100 . The information storage portion  100  serving as storage means is fixed to the supporting member  32  and stores developer associated information of the developer contained in the container main body  32 . In a state where the information storage portion  100  is mounted in the image forming apparatus main body  71  (refer to  FIGS. 27 to 29 ), the information storage portion  100  is connected to an information reading portion  207  (see  FIG. 30 ) provided in the image forming apparatus main body  71  in such a manner that the information reading portion  207  can read out the developer associated information. The information storage portion  100  includes a circuit board  101  and a casing  102 . The circuit board  101  has a semiconductor memory portion that will be described later and is not shown in the drawing, for storing the developer associated information. 
   Table 1 is a table representing the developer associated information stored in the information storage portion  100 . The semiconductor memory portion of the information storage portion  100  stores the developer associated information such as an apparatus name, information inherent to the developer such as a toner lot number which is a lot number of a developer and a color of the developer, information necessary for an image information process control such as a bias voltage, charge characteristics, a fixing temperature, and so forth suitable for the use of developer as shown in Table 1. The developer associated information is stored in the semiconductor memory portion when the developer is filled into the container main body  31  of the developer container  30 . 
   
     
       
         
             
             
             
           
             
                 
               TABLE 1 
             
             
                 
                 
             
             
                 
               Information content 
               address 
             
             
                 
                 
             
           
          
             
                 
               Apparatus name 
               0001 
             
             
                 
               Toner lot number 
               0002 
             
             
                 
               Color 
               0003 
             
             
                 
               Bias current 
               0004 
             
             
                 
               Charge characteristics 
               0005 
             
             
                 
               Melting point 
               0006 
             
             
                 
                 
             
          
         
       
     
   
   A connection supporting piece  103  protruding in a thickness direction of the circuit board  101  and having a substantially T-shaped form in a section perpendicular to the thickness direction is formed on the casing  102 . Four connection terminals  104 ,  105 ,  106  and  107  having electric conductivity and electrically connected to the semiconductor memory portion through the circuit board  101  are provided on the connection supporting piece  103 . When positive and negative electrodes of a DC power source are connected to the first connection terminal  104  and the fourth connection terminal  107 , electric signals containing the developer associated information stored in the semiconductor memory portion are outputted from the second connection terminal  105  and the third connection terminal  106 . Two insertion pieces  108  each protruding in the thickness direction of the circuit board  101  beyond the connection supporting piece  103 , having a circular form in a section perpendicular to the thickness direction and having a reduced diameter at its free end are formed in the casing  102 . Two connection holes  109  penetrating through the circuit board  101  in the thickness direction are formed in the circuit substrate  101  and the casing  102 . 
     FIG. 25  is a perspective view showing the information storage portion  100  and an accommodation recess  110 . An accommodation recess  110  opening in an attachment direction E 1  to the image forming apparatus main body  71  is formed in the supporting member  32 . The information storage portion  100  is arranged in such a manner that the first to fourth connection terminals  104  to  107  serving as a connection portion to be connected to at least the information reading portion  207  of the image forming apparatus main body  71  can be fitted into the accommodation recess  110 . More specifically, the information storage portion  100  is fitted as a whole into the accommodation recess  110 . In further detail, the accommodation recess  110  is formed in the supporting base  49  of the supporting member  31 . Because such an accommodation recess  110  is formed, the position of the accommodation recess  110  can be much more stabilized and the size of the supporting member  32  can be made smaller in comparison with a case where the accommodation recess  110  is disposed at other portion, when the developer container  30  is mounted in an image forming apparatus main body  71  described later. The open portion of the accommodation recess  110  is arranged on one end side in the axial direction with respect to the conductor port  51 . Accordingly, even when the developer discharged from the leading through hole  51  leaks to an undesirable position, it is possible to prevent as much as possible the developer from entering the accommodation recess  110  and adhering to each connection terminal  104  to  107 . 
   Guide holes  111  serving as guide means are formed in the supporting member  32 , more specifically in the first supporting portion  55  of the supporting member  32 . The guide holes  111  restrict displacement of the supporting member  32  in a direction intersecting the attachment direction E 1  of the supporting member  32  and guide the supporting member  32  in such a manner as to undergo displacement in the attachment direction E 1  when the developer container  30  is attached to the image forming apparatus main body  71 . The guide holes  111  are arranged in the proximity of the accommodation recess  110  and are so formed as to extend in the direction of the axis L 31 . Therefore, the guide holes  111  can stably guide the supporting member  32 . A guide projection  97  (refer to  FIGS. 1 and 31 ) serving as guide means is provided in the supporting member  32 , more specifically to the second supporting member  56  of the supporting member  32 . The guide protrusion  97  restricts displacement of the supporting member  32  in a direction intersecting its attachment direction E 1  and so guiding the supporting member  32  as to undergo displacement in the attachment direction E 1  when the developer container  30  is attached to the image forming apparatus main body  71 . The guide projection  97  is disposed on the supporting member  32  in the state where the supporting member  32  is put on the horizontal surface as shown in  FIG. 1  and protrudes towards one end of the supporting member  32  in the axial direction. Therefore, the guide projection  97  can stably guide the supporting member  32 . 
   When the information storage portion  100  is fixed to the supporting member  32 , the wall portion  112  facing the accommodation recess  110  of the supporting member  32  from the upstream side in the attachment direction E 1  and the circuit board  101  of the information storage portion  100  are arranged in such a manner as to face each other and the information storage portion  100  is then fitted as a whole into the accommodation recess  110 . A screw member is inserted into the connection hole  109  in this state to detachably and attachably fasten the information storage portion  100  and the supporting member  32 . At this time, the connection supporting piece  103  of the casing  102  of the information storage portion  100  and the insertion piece  108  are so arranged as to protrude in the attachment direction E 1 . The free end of the insertion piece  108  of the casing  102  of the information storage portion  100  is arranged on an imaginary plane passing through the open portion of the accommodation recess  110  or on the upstream side of the attachment direction E 1  relative to the imaginary plane. 
     FIG. 26  is a graph showing the relationship between the time and the quantity of developer which is discharged from the developer container  30 . In  FIG. 26 , the curve H 1  indicates the relationship between the time and the quantity of developer which is discharged from the developer container  30 , as observed when the internal diameter D 35  of the third container segment  35  of the container main body  31  is made equal to or shorter than the internal diameter D 33 , D 34  of the first, second container segment  33 ,  34 . On the other hand, the curve H 2  indicates the relationship between the time and the quantity of developer which is discharged from the developer container  30 , as observed when the internal diameter D 35  of the third container segment  35  of the container main body  31  is made longer than the internal diameter D 33 , D 34  of the first, second container segment  33 ,  34 . 
   Here, attention is paid to the property of developer. For example, even if fine powdery developer particles are heaped up into a sharp-pointed mound on a horizontal surface, it immediately begins to lose its sharpness. In this connection, in the case where the internal diameter D 35  of the third container segment  35  of the container main body  31  is made equal to or shorter than the internal diameter D 33 , D 34  of the first, second container segment  33 ,  34 , the developer being conveyed toward the discharge hole  43  in accompaniment with the rotation of the container main body  31  starts to move away from the discharge hole  43  immediately after the rotation of the container main body  31  comes to a halt. In such a case, during the container main body  31  contains only a very small quantity of developer left, it becomes difficult to convey a sufficient quantity of developer toward the discharge hole  43  immediately after the resumption of the rotation of the container main body  31 . 
   In this embodiment, as described previously with reference to  FIG. 8 , the internal diameter of the third container segment  35  of the container main body  31  is made longer than the internal diameter D 33 , D 34  of the rest first, second container segment  33 ,  34 . Therefore, while the container main body  31  contains only a very small quantity of developer left, the developer that has once reached the third container segment  35  can be prevented from leaving the third container segment  35  as reliably as possible. As a result, even when the container main body  31  contains only a very small quantity of developer left, a sufficient quantity of developer can be conveyed toward the discharge hole  43  as reliably as possible immediately after the resumption of the rotation of the container main body  31 . Besides, the developer contained in the container main body  31  can be discharged to the outside as wholly as possible. 
   As indicated by the curve H 1 , in the case where the internal diameter D 35  of the third container segment  35  of the container main body  31  is made equal to or shorter than the internal diameter D 33 , D 34  of the first, second container segment  33 ,  34 , as the quantity of the developer contained in the container main body  31  is decreased, the quantity of developer discharge is decreased correspondingly sharply. On the other hand, as indicated by the curve H 2 , in the case where the internal diameter D 35  of the third container segment  35  of the container main body  31  is made longer than the internal diameter D 33 , D 34  of the first, second container segment  33 ,  34 , in contrast to the case as indicated by the curve H 1 , even if the quantity of the developer contained in the container main body  31  is decreased, the quantity of developer discharge remains substantially invariant until the quantity of the developer becomes nearly zero. It follows from this that the developer container  30  in accordance with the embodiment is capable of performing developer discharge with stability for a longer period of time. 
   In the developer container  30  according to this embodiment, the information storage portion  100  for storing the developer associated information about the developer contained in the container main body  31  is fixed to the supporting member  32 . The information storage portion  100  is connected to the information reading portion  207  provided in the image forming apparatus main body  71  in such a manner that the information reading portion  207  can read out the developer associated information when the developer container  30  is mounted in the image forming apparatus main body  71 . Even when the container main body  31  rotates about the rotation axis L 31  in the state where the developer container  30  is mounted in the image forming apparatus main body  71 , the information storage portion  100  fixed to the supporting member  32  does not rotate because the supporting member  32  does not rotate with the container main body  31 . The mechanism for connecting the information storage portion  100  of the developer container  30  and the information reading portion  207  of the image forming apparatus main body  71  may well be a simple mechanism and can connect them easily and reliably. Therefore, even when the container main body  31  rotates, the information reading portion  207  of the image forming apparatus main body  71  can correctly read out the information of the developer contained in the container main body  31 . 
   According to the developer container  30  of this embodiment, the accommodation recess  110  opening in the attachment direction E 1  to the image forming apparatus main body  71  is formed in the supporting member  32  and the information storage portion  100  is arranged in such a manner that the connection terminals  104  to  107  connected to at least the information reading portion  207  fit into the accommodation recess  110 . Because the connection terminals  104  to  107  of the information storage portion  100  are not exposed in this way from the accommodation recess  110 , it is possible to prevent as much as possible the developer and the dust from adhering to the connection terminals  104  to  107 . In consequence, the information reading portion  207  of the image forming apparatus main body  71  can correctly read the information of the developer contained in the container main body  31 . 
   According to the developer container  30  of this embodiment, the information storage portion  100  is fitted as a whole into the accommodation recess  110  and is not exposed from the accommodation recess  110 . It is thus possible to prevent as much as possible the user from accidentally touching the information storage portion  100  and to prevent the information storage portion  100  from being broken and the developer associated information stored in the information storage portion  100  from being broken. 
   According to the developer container  30  of this embodiment, displacement of the supporting member  32  in the direction intersecting its attachment direction E 1  is restricted by the guide holes  111  when the developer container is attached to the image forming apparatus main body  71  but is guided in such a manner as to undergo displacement in the attachment direction E 1 . Because displacement of the supporting member  32  in the direction intersecting its attachment direction E 1  is restricted when the developer container is attached to the image forming apparatus main body  71 , it becomes possible to prevent as much as possible the failure of connection between the information storage portion  100  and the information reading portion  207  due to the displacement of the supporting member  32  in the direction intersecting its attachment direction E 1 . 
     FIG. 27  is a sectional view showing an image forming apparatus  70  according to another embodiment of the invention.  FIG. 28  is an enlarged sectional view showing a toner hopper  72  and other components in the vicinity.  FIG. 29  is an enlarged plan view showing the toner hopper  72  and other components in the vicinity.  FIG. 27  is a sectional view showing the image forming apparatus  70 , as seen from its front-side exterior portion  71   a . In the figure, the thickness of the construction is omitted in the interest of understanding of the invention. The front-side exterior portion  71   a  refers to one part of the image forming apparatus  70  with which the user normally faces during its use. On the other hand, a back-side exterior portion  71   b  refers to another part of the image forming apparatus  70  reverse to the front-side exterior portion  71   a  by which the user is present. Here, the image forming apparatus  70  is assumed to be placed on a horizontal surface, and a direction from the front-side exterior portion  71   a  to the back-side exterior portion  71   b , which is defined as a “front-to-back direction E”, is arranged parallel to the horizontal surface. 
   The electrophotographic image forming apparatus  70 , built as a printer, a copier, or the like, includes the developer container  30  explained hereinabove and an image forming apparatus main body (hereafter also referred to simply as an “apparatus main body”)  71 . The developer container  30  is detachably and attachably mounted in a toner hopper  72  disposed in the apparatus main body  71  through a container attachment port (not shown) disposed openably and closably in the front-side exterior portion  71   a  of the apparatus main body  71 . Moreover, in the image forming apparatus main body  71  are provided a cabinet front portion  93  which is disposed in a position on the backside exterior portion  71   b  side as compared to the front-side exterior portion  71   a , and an opening which is pierced along a thickness direction and can insert developer container  30 . Further, the image forming apparatus main body  71  has a cabinet back portion  94  which is disposed in a position on the front-side exterior portion  71   a  side as compared to the back-side exterior portion  71   b . The cabinet body (its entirety is not shown) including the cabinet front portion  93  and the cabinet back portion  94  holds the constituent components of the image forming apparatus main body  71 . 
   The toner hopper  72  includes a housing  73 , a developer supply section  74 , an agitation member  75 , and a supply roller  76 . The space inside the housing  73  is separated by the developer supply section  74  into at least a container housing space  77  and an agitation space  78 . The container housing space  77  is opened so as to face the front-side exterior portion  71   a  of the apparatus main body  71 . The agitation space  78  is kept in substantially a closed state. The developer container  30  is arranged within the container housing space  77 . 
   On an upper wall portion  73   a  of the housing  73  facing the container housing space  77  is formed a first guide concavity  79  extending along the front-to-back direction E of the apparatus main body  71 , in which the first guide piece  53  of the supporting member  32  of the developer container  30  is receivable. The first guide concavity  79  is so designed that the first guide piece  53  of the supporting member  32  of the developer container  30  is fitted therein so as to be slidable in its lengthwise direction, namely, either in an attachment direction E 1  (direction from the front-side exterior portion  71   a  to the back-side exterior portion  71   b ) or in a detachment direction E 2  opposite thereto, both of which are parallel to the front-to-back direction E of the apparatus main body  71 . Moreover, on a lower wall portion  73   b  of the housing  73  opposed to the upper wall portion  73   a  facing the container housing space  77  is formed a second guide concavity  80  extending along the front-to-back direction E of the apparatus main body  71 , in which the second guide piece  54  of the supporting member  32  of the developer container  30  is receivable. The second guide concavity  80  is so designed that the second guide piece  54  of the supporting member  32  of the developer container  30  is fitted therein so as to be slidable in its longitudinal direction, namely, either in the attachment direction E 1  or in the detachment direction E 2  of the apparatus main body  71 . 
   The developer supply section  74  is constituted by a platy member to separate the space inside the housing  73  into the container housing space  77  and the agitation space  78 . The developer supply section  74  has a communication hole  81  pierced all the way through its thickness direction, for providing communication between the container housing space  77  and the agitation space  78 . Below the communication hole  81  of the developer supply section  74  is disposed a guide member  82  protruding into the container housing space  77 . 
     FIG. 30  is a perspective view showing the information reading portion  207  and the information storage portion  100 .  FIG. 31  is a front view showing the state where the information storage portion  100  is connected to the information reading portion  207 . The apparatus main body  71  is further provided with the information reading portion  207 , serving as information reading means, for reading the developer associated information stored in the information storage portion  100  in the state where the information storage portion  100  is connected. A connection recess  208  into which the connection supporting piece  103  and the insertion piece  108  of the information storage portion  100  of the developer container  30  can be fitted, is formed in the information reading portion  207 . Electrically conductive reading-side connection terminals  209 ,  210 ,  211  and  212  to be electrically connected to the connection terminals  104  to  107 , respectively, of the information storage portion  100  while the connection supporting piece  103  and the insertion piece  108  of the information storage portion  100  are fitted into the connection recess  208 , are provided in the information reading portion  207  in such a manner as to face the connection recess  208 . 
   When the developer container  30  is attached to the image forming apparatus main body  71 , the guide piece, not shown, provided in the image forming apparatus main body  71  and extending in the attachment direction E 1  is inserted into the guide hole  111  of the supporting member  32 , thereby the supporting member  32  undergoes displacement in the attachment direction E 1  while being guided. Therefore, the information storage portion  100  is connected to the information reading portion  207  and connection between them can be made reliable. When the information storage portion  100  and the information reading portion  207  are connected to each other, the insertion piece  108  protruding in the attachment direction E 1  much more than the connection supporting piece  103  is fitted into the connection recess  208  earlier than the connection supporting piece  103 . The insertion piece  108  guides the connection supporting piece  103  in the attachment direction E 1  and the connection piece  103  is then fitted into the connection recess  208 . 
     FIG. 32  is a block diagram showing an electric construction of the information storage portion  100  and the information reading portion  207 . The information storage portion  100  includes a semiconductor memory portion  112 , a control circuit  113 , a transmission-reception circuit  114 , a power source circuit  115  and the connection terminals  104  to  107 . The semiconductor memory portion  112  is realized by a non-volatile memory capable of rewriting information such as a backup memory and a flash memory and stores the developer associated information. The control circuit  113  collectively controls the information storage portion  100  so as to read out the developer associated information stored in the semiconductor memory portion  112  and store the developer associated information in the semiconductor memory portion  112 . The transmission-reception circuit  114  controls communication with the information reading portion  207  connected to the information storage portion  100 . The power source circuit  115  supplies power supplied from the apparatus main body  71  through the connected information reading portion  207  to the semiconductor memory portion  112 , the control circuit  113  and the transmission-reception circuit  114 . The semiconductor memory portion  112 , the control circuit  113 , the transmission reception circuit  114 , the power source circuit  115  and the connection terminals  104  to  107  are arranged on the circuit board  101 . The semiconductor memory portion  112 , the control circuit  113 , the transmission-reception circuit  114  and the power source circuit  115  may be realized by a single IC. 
   The information reading portion  207  includes the reading-side connection terminals  209  to  212 , a transmission-reception circuit  213 , a control circuit  214 , an interface circuit  215  and a power source circuit  216 . The transmission-reception circuit  213  controls the communication with the information storage portion  100  connected to the information reading portion  207 . The control circuit  214  collectively controls the information reading portion  207 . The interface circuit  215  is connected to an apparatus main body control circuit  217  that is provided in the apparatus main body  71  and collectively controls the apparatus main body  71 , and communicates with the apparatus main body control circuit  217 . The power source circuit  216  supplies power to the transmission-reception circuit  213 , the control circuit  214 , the interface circuit  215  and the information storage potion  100 . 
   When the developer container  30  is attached to the apparatus main body  71 , power is supplied from the power source circuit  216  of the information reading portion  207  of the apparatus main body  71  to the power source circuit  115  of the information storage portion  100  of the developer container  30 . Subsequently, the apparatus main body control circuit  217  of the apparatus main body  71  transmits a request having a content to the effect that the developer associated information stored in the semiconductor memory portion  112  may as well be given to the information reading portion  207 , through the information reading portion  207  to the control circuit  113  of the information storage portion  100 . In response to this request, the control circuit  113  of the information storage portion  100  controls the transmission-reception circuit  114  so that the developer associated information stored in the semiconductor memory portion  112  is read out and given to the information reading portion  207 . The developer associated information given to the control circuit through the transmission-reception circuit  213  of the information reading portion  207  is given to the apparatus main body control circuit  217  through the interface circuit  215 . The apparatus main body control circuit  217  controls the apparatus main body  71  on the basis of the developer associated information obtained in this way. 
   When the developer container  30  is attached to the apparatus main body  71 , the apparatus main body control circuit  217  first confirms the name of the apparatus to which the developer container  30  contained in the developer associated information can be adapted. When the apparatus name contained in the developer associated information does not coincide with the apparatus name of the image forming apparatus  70 , the apparatus main body control circuit  217  judges that the developer container  30  that is not suitable is attached to the apparatus main body  71  and gives warning to the user through report means such as a display provided in the apparatus main body. In this state, even when the amount of the developer contained in the toner hopper  72  becomes small and a replenishment instruction of the developer to the toner hopper  72  is given to the developer container  30 , the container main body  31  of the developer container  30  is not rotated. When the user releases the developer container  30  from the apparatus main body  71  and attaches another developer container  30  to the apparatus main body  71 , the apparatus main body control circuit  217  again conducts confirmation of the apparatus name described above. 
   When the apparatus name contained in the developer associated information coincides with the apparatus name of the image forming apparatus  70 , the apparatus main body control circuit  217  judges that the developer container  30  suitable for the apparatus main body  71  is attached and permits the replenishment of the developer from the developer container  30  to the toner hopper  72 . When a replenishment signal representative of the replenishment of the developer is generated at this time, the replenishment of the developer from the developer container  30  to the toner hopper  72  is performed. 
   The apparatus main body control circuit  217  then transmits to the information storage portion  100  a request having the content to the effect that the information contained in the developer associated information and necessary for the image formation process control such as a bias voltage, charge characteristics, a fixing temperature, and so forth, that are suitable for using the developer contained in the developer container  30 . Consequently, the information is given to the apparatus main body control circuit  217  and the apparatus main body control circuit  217  sets process conditions of charging, exposure, development, transfer and fixing on the basis of the information. 
   Since the semiconductor memory portion  112  of the information storage portion  100  can rewrite the information, the information about the developer container  30  that changes with time, e.g. the remaining amount of the developer and the rotation time of the container main body  31  of the developer container  30 , may be stored in the semiconductor memory portion  112 . The remaining amount of the developer in the developer container  30  can be detected by use of a piezoelectric sensor and an integrated number of revolutions of the container main body  31 , and the remaining amount of the developer so detected is stored in the semiconductor memory portion  112 . 
   Conventionally, the timing at which the developer is used up has been detected. In the invention, however, the remaining amount of the developer is detected on the real time basis and is stored in the information storage portion  100 . When the remaining amount of the developer is displayed on display means of the apparatus main body  71 , the user can easily judge whether or not the developer container  30  may better be replaced with new one before the formation of the images on the basis of the remaining amount of the developer displayed on the display means when the images are formed on large amounts of recording sheets and it is possible to prevent the problem that the developer is used up during the formation of the images and the developer container  30  has to be replaced. The information storage portion  100  of the developer container  30  once released from the apparatus main body  71  during the operation, for the reason of the formation of large amounts of images, or the like, stores the remaining amount of the developer of the developer container  30 . It is therefore possible to confirm in advance that the developer container  30  is not the new one when the developer container is again attached to the apparatus main body  71 . 
   When the rotation time and the non-rotation time of the container main body  31  of the developer container  30  are stored in the information storage portion  100 , the condition of the developer contained in the developer container  30  can be grasped. When the developer is left standing without flowing, its fluidity drops and the developer is likely to aggregate depending on the environment in which it is left standing. Therefore, when the non-rotation time of the container main body  31  of the developer container  30  is stored in the information storage portion  100  as described above, the replenishment amount of the developer to the toner hopper  72  can be kept constant by changing the number of revolutions of the container main body  31 . Since the information storage portion  100  is included in the developer container  30 , it is possible to detect the non-rotation time of the container main body  31  contained in the developer associated information stored in the information storage portion  100  by separately preparing reading means for reading the developer associated information stored in the information storage portion  100  even when the developer container  30  is released from the apparatus main body  71 . 
   When the developer is fully discharged and the developer container  30  becomes empty, toner end information representing that the developer does not at all exist in the developer container  30  is stored in the information storage portion  100 . Consequently, even when the empty developer container  30  is again attached erroneously to the apparatus main body  71 , it is possible to notify the user quickly that the developer container  30  is empty. When the developer container  30  is recycled, it is possible to prevent the developer container  30  from being recycled erroneously the number of times exceeding its life by storing the number of times of utilization of the developer container  30  in the information storage portion  100 . To recycle the developer container  30 , information has been applied to the developer container by a bar code in the related art. In this case, it is necessary to create a bar code of the utilization history information to each developer container, to apply it to the developer container, to peel it at the time of recycling and to again apply a new bar code. This operation is considerably troublesome. In the invention, since the information storage portion  100  has the semiconductor memory portion  112  capable of rewriting the information, the developer container  30  can be recycled as such by merely rewriting the information and moreover, the complicated operation is not necessary, either. Therefore, the recycling cost can be reduced, too. Furthermore, since the information storage portion  100  exchanges data with the apparatus main body control circuit  217  of the apparatus main body  71  through the electrically conductive connection terminals  104  to  107  and  209  to  212 , the information storage portion  100  is stronger against contamination than conventional identification means such as a light reflection type sensor and wrong detection is less. 
     FIG. 33  is an enlarged perspective view showing the main body-side coupling section  83 . A driving force for rotating the container main body  31  of the developer container  30  is produced from a driving source  84 , such as a motor, of the apparatus main body  71 . The driving force is transmitted through a reduction device  85 , such as a reduction gear, to the main body-side coupling section  83 . The main body-side coupling section  83 , the driving source  84 , and the reduction device  85  constitute driving means. The main body-side coupling section  83  includes a rotation shaft  86 , a coupling support  87 , and a spring member  88 . The rotation shaft  86  is mounted rotatably in a bearing  89 , with its axis L 86  arranged parallel to the front-to-back direction E of the apparatus main body  71  and with its free end placed within the container housing space  77 . The bearing  89  is pierced through the cabinet back portion  94  back to back with part of the housing  73  on the side of the back-side exterior portion  71   b  of the apparatus main body  71 . 
   The coupling support  87 , which is formed in substantially a disc shape, is arranged so as to face the container housing space  77 . The coupling support  87  is made rotatable about the axis L 86  integrally with the rotation shaft  86 , and is coupled to the free end of the rotation shaft  86 . The coupling support  87  has, at the center of its surface  87   a  reverse to another surface facing with the cabinet back portion  94 , an auxiliary concavity  96  formed so as to be sunk toward the cabinet back portion  94 , the axis of which coincides with the axis L 86  of the rotation shaft  86 . In the auxiliary concavity  96  is receivable the replenishment port  45  to which the replenishment lid  46  is attached in the developer container  30 . The coupling support  87  also has, at the outer side in the radial direction of the auxiliary concavity  96  on its surface  87   a , a plurality (two pieces, in this embodiment) of concave fits  90  formed so as to be sunk toward the cabinet back portion  94 . The concave fits  90  are arranged symmetrically with each other with respect to the axis L 86  of the rotation shaft  86 . Each of the concave fits  90  is configured in accordance with the shape of its corresponding convex fit  37  of the container main body  31 . The convex fit  37  of the container main body  31  is fitted into the concave fit  90 , thus achieving engagement therebetween. 
   Moreover, the coupling support  87  is made displaceable about the axis of the rotation shaft  86  without falling off from the free end of the rotation shaft  86 . The spring member  88 , realized by the use of a coil compression spring or the like, is arranged between the cabinet back portion  94  and the coupling support  87 . The spring member  88  loads the coupling support  87  with a resilient force that tends to pull it away from the cabinet back portion  94  without hindering the rotation of the rotation shaft  86  and the coupling support  87 . A combination of one axial end  33   a  including the convex fit  37  of the container main body  31  of the developer container  30  and the coupling support  87  of the main body-side coupling section  83  constitutes a coupling structure. Thus, the convex fit  37  of the container main body  31  is detachably and attachably coupled to the coupling support  87  of the main body-side coupling section  83 . 
   The developer container  30  is attached to the apparatus main body  71  in the following manner. At first, the developer container  30  is inserted, from the front-side exterior portion  71   a  of the apparatus main body  71 , into the container housing space  77  of the toner hopper  72 , with its rotation axis L 31  arranged parallel to the attachment direction E 1 . At this time, the first guide piece  53  of the supporting member  32  of the developer container  30  is fitted into the first guide concavity  79  of the housing  73 , and concurrently the second guide piece  54  of the supporting member  32  is fitted into the second guide concavity  80  of the housing  73 . This helps prevent displacement of the supporting member  32  in any other direction than the attachment and detachment directions E 1  and E 2 . In this state, the developer container  30  is displaced in the attachment direction E 1  until it reaches an attachment position at which the leading through hole  51  of the discharge section  50  of the supporting member  32  communicates with the communication hole  81  of the developer supply section  74 . At this time, the coupling support  87  of the main body-side coupling section  83  is pressed by the convex fit  37  of the container main body  31  to recede contractedly in the attachment direction E 1 , and the spring member  88  is accordingly compressed. 
   The toner hopper  72  is provided with a regulatory member (not shown) for, while the developer container  30  is being kept at the attachment position, restraining displacement of the supporting member  32  in the attachment and detachment directions E 1  and E 2 , and releasing the restraint. When the developer contained in the developer container  30  is discharged completely, the user is able to release the restraint put on the supporting member  32  by the regulatory member so as for the developer container  30  to be displaced in the detachment direction E 2 . In this way, the developer container  30  is detached from the apparatus main body  71 . 
   Moreover, shutter displacement means (not shown) is additionally disposed around the communication hole  81 , facing with the container housing space  77 , of the developer supply section  74  of the toner hopper  72 , for slidingly displacing the shutter  65   a  of the shutter portion  65  of the developer container  30 . In order for the developer container  30  to be attached, the developer container  30  is inserted, from the front-side exterior portion  71   a  of the apparatus main body  71 , into the container housing space  77  of the toner hopper  72 , with its rotation axis L 31  arranged parallel to the attachment direction E 1 . At this time, the shutter  65   a  is slidingly displaced from the closing position P 1  in one second horizontal direction B 1  by the shutter displacement means. Upon the developer container  30  reaching the attachment position, the shutter  65   a  is arranged at the opening position P 2 . On the other hand, in order for the developer container  30  to be detached from the apparatus main body  71 , the developer container  30  is displaced from the attachment position in the detachment direction E 2 . At this time, the shutter  65   a  is slidingly displaced from the opening position P 2  in the other second horizontal direction B 2  by the shutter displacement means to the closing position P 1 . 
   Further, a sealing material (not shown) is additionally disposed at least either around the leading through hole  51  of the discharge section  50  of the supporting member  32  of the developer container  30 , or around the communication hole  81 , facing the container housing space  77 , of the developer supply section  74  of the toner hopper  72 . By dint of the sealing material, the developer flowing down from the leading through hole  51  to the communication hole  81  can be prevented from finding its way toward any area other than the agitation space  78 . 
   The apparatus main body  71  includes a development section  200  and a photoconductive drum  202 . As shown in  FIG. 29 , the development section  200  is arranged in the middle of the apparatus main body  71  as seen in the front-to-back direction E. This is because the photoconductive drum  202  is arranged in the middle of the apparatus main body  71  as seen in the front-to-back direction E. Moreover, the main body-side coupling section  83 , as well as the driving section including the driving source  84  and the reduction device  85  for rotating the agitation member  75  and the supply roller  76 , is arranged between the cabinet back portion  94  and the back-side exterior portion  71   b  in the apparatus main body  71 . Accordingly, in the state where the developer container  30  is arranged at the attachment position, the supporting member  32  of the developer container  30  is arranged in the middle of the apparatus main body  71  as seen in the front-to-back direction E. As described previously, in the developer container  30 , the container main body  31  is so designed that its one length measurement from the supporting member  32  to the end face of one axial end  33   a  having the convex fit  37  is made shorter than the other length measurement from the supporting member  32  to the end face of the other axial end  34   a.    
   According to the image forming apparatus  70  in accordance with the embodiment, in the developer container  30 , the supporting member  32  is arranged in the axially middle position of the container main body  31 . Accordingly, in the state where the developer container  30  is arranged at the attachment position in the image forming apparatus main body  71 , the supporting member  32  is arranged in the middle of the apparatus main body  71  as seen in the front-to-back direction E. With this arrangement, in the apparatus main body  71 , the container main body  31  can be elongated from a middle position in the front-to-back direction E to the front side, and concurrently elongated from the middle position in the front-to-back direction E to the back side, resulting in an advantage in increasing the capacity significantly. In this embodiment, as shown in  FIG. 29 , the other axial end  34   a  of the developer container  30  juts out closer to the front-side exterior portion  71   a  than the cabinet front portion  93 . 
   Moreover, in the container main body  31 , by making one length measurement from the supporting member  32  to the end face of one axial end  33   a  shorter than the other length measurement from the supporting member  32  to the end face of the other axial end  34   a , it is possible to secure, in the back side of the apparatus main body  71 , a certain region for disposing the driving section including the driving source  84  and the reduction device  85  to be coupled to the convex fit  37  of one axial end  33   a  of the container main body  31 . It follows, therefore, that the developer container  30  has succeeded in offering two unique effects: the space inside the apparatus main body  71  is utilized effectively while increasing the developer-containing capacity as much as possible. 
   With the developer container  30  kept arranged at the attachment position, the driving source  84  is activated to rotate the coupling support  87 . At this time, when the concave fit  90  of the coupling support  87  is kept in engagement with the convex fit  37  of the developer container  30 , the container main body  31  is allowed to rotate about the rotation axis L 31 . By contrast, when the concave fit  90  of the coupling support  87  is kept out of engagement with the convex fit  37  of the developer container  30 , only the coupling support  87  is subjected to angular displacement, for a while, until the engagement between the concave fit  90  of the coupling support  87  and the convex fit  37  of the developer container  30  is completed. Upon completion of the engagement between the concave fit  90  of the coupling support  87  and the convex fit  37  of the developer container  30 , the spring member  88  exerts a resilient force to make the engagement therebetween tighter. Then, the container main body  31  is allowed to rotate about the rotation axis L 31 . As the container main body  31  of the developer container  30  is rotated about the rotation axis L 31 , the developer contained in the developer container  30  is supplied, through the leading through hole  51  of the discharge section  50  of the supporting member  32  and the communication hole  81  of the developer supply section  74  of the toner hopper  72 , into the agitation space  78  and is stored therein. 
   The agitation member  75  and the supply roller  76 , each extending in the front-to-back direction E of the apparatus main body  71 , are arranged within the agitation space  78 , with a certain interval secured therebetween. The agitation member  75  is made rotatable about an agitation axis L 75  parallel to the front-to-back direction E, and has a flexible scraper member  91  extending in the direction of the agitation axis L 75 . Moreover, the agitation member  75  is rotated about the agitation axis L 75  in a clockwise direction J 1 , looking from the front of the apparatus main body  71 , under the driving force exerted by the driving source  84  disposed in the apparatus main body  71 . The supply roller  76  is made rotatable about a supply axis L 76  parallel to the front-to-back direction E. The outer peripheral surface of the supply roller  76  is made of a porous resin material such as a sponge. Moreover, the supply roller  76  is rotated about the supply axis L 76  in a counterclockwise direction J 2 , looking from the front of the apparatus main body  71 , under the driving force exerted by the driving source  84  disposed in the apparatus main body  71 . 
   The toner hopper  72  is additionally provided with an agitation wall portion  92  arranged so as to face the agitation space  78 . The agitation wall portion  92  is so formed as to communicate with the developer supply section  74 , and to extend in the front-to-back direction E of the apparatus main body  71 . The agitation wall portion  92  has a cross section formed in a U-like shape, as seen in a direction perpendicular to the agitation axis L 75  of the agitation member  75 . The agitation wall portion  92  is opened upwardly and thus has a part-cylindrical inner peripheral surface. Although the developer is supplied through a single communication hole  81  alone into the agitation space  78 , as described previously, since the developer discharged from the developer container  30  is excellent in flowability because of not only the agitation effect but also the mixing of gas into its fine particles, the developer passing through the communication hole  81  can be diffused satisfactorily in the direction of the agitation axis L 75  within the agitation space  78 . The developer supplied to the agitation space  78  is further diffused in the direction of the agitation axis L 75  in the agitation space  78  through agitation carried out by the agitation member  75 . 
   As the agitation member  75  is rotated, the developer having been supplied through the communication hole  81 , now contained in the agitation space  78 , is agitated thereby. Simultaneously, the scraper member  91  scrapes up the developer contained in the agitation space  78 , with its free end kept in abutment with the agitation wall portion  92 , to apply fine powdery developer particles substantially evenly to the surface of the supply roller  76  in the direction of its axis L 76 . Even when the agitation space  78  has only a small quantity of developer left, the residual developer is scraped up by the scraper member  91  and is then fed to the supply roller  76  properly, resulting in an advantage in minimizing the quantity of the developer that remains in the agitation space  78  unsupplied to the supply roller  76 . The developer given to the supply roller  76  is then fed to the development section  200 , in good condition, in accompaniment with its rotation. 
   The apparatus main body  71  further includes, in addition to the development section  200  and the photoconductive drum  202 , a recording sheet cassette  201 , a charging section  203 , a laser exposure section  204 , and a fixating section  205 . In the development section  200 , the toner, i.e., the developer supplied from the toner hopper  72  and magnetic carrier particles prepared beforehand are agitated together to produce dual-component developer. 
   The recording sheet cassette  201  accommodates recording sheets for use in image formation. The photoconductive drum  202 , which is composed of a cylindrical drum having a photosensitive element formed about its outer periphery, is rotated about its axis under the driving force exerted by the driving section. The charging section  203  applies electric charge to the photosensitive element of the photoconductive drum  202  to achieve photosensitization. In the laser exposure section  204 , the photosensitive element of the photoconductive drum  202  bearing electrical charge is exposed to laser light to form an electrostatic latent image on the photosensitive element. 
   In the development section  200 , the dual-component developer is agitated and is then fed to the photosensitive element of the photoconductive drum  202  on which an electrostatic latent image is formed, so that the electrostatic latent image is developed as a toner image. The photoconductive drum  202  transfers the toner image carried on the photoconductive drum  202  onto a recording sheet provided from the recording sheet cassette  201 . In the fixating section  205 , the toner image transferred onto the recording sheet is fixated. The recording sheet carrying the toner image fixated thereon is discharged onto a discharge tray  206 . In order to keep the toner concentration of the dual-component developer constant in the development section  200 , the supply roller  76  has its outer periphery made of a sponge, and its rotation is controlled properly. In this way, the supply roller  76  supplies a proper quantity of toner in fine powder form to the development section  200 . 
   Hereinafter, a brief explanation will be given as to the control of the container main body  31  of the developer container  30 , and the agitation member  75  and the supply roller  76  of the toner hopper  72 . A toner remaining quantity detector  95  is disposed in the agitation wall portion  92 . When the toner remaining quantity detector  95  detects a reduction in the quantity of the developer (hereafter also referred to as the “toner”) contained in the agitation space  78  of the toner hopper  72 , a non-illustrated control section controls the driving source  84  to rotate the container main body  31  of the developer container  30 . Thereby, the toner is fed into the agitation space  78 . When it is detected by the toner remaining quantity detector  95  that the agitation space  78  is not full of the toner in spite that the container main body  31  has been rotated for a predetermined period of time, the control section brings the rotation of the container main body  31  to a halt, and concurrently displays a message on a non-illustrated display section to notify the user to replace the developer container  30 . As of this point in time, in fact, some quantity of the developer is contained in the agitation space  78  of the toner hopper  72 . While the developer is still present in the agitation space  78  of the toner hopper  72 , the user is able to detach the empty developer container  30  from the apparatus main body  71 , and then attach a new developer container  30  containing developer to the apparatus main body  71 . Thus, even while the image forming apparatus  70  is in the midst of forming an image on a recording sheet, since the developer required for completing the image formation is still contained in the agitation space  78  of the toner hopper  72 , it is possible to replenish the apparatus main body  71  with developer without interrupting the image forming operations. 
   In this embodiment, developer replenishment can be effected simply by replacing the developer container  30  with a new one. For example, all that needs to be done by the user is simply to grasp the supporting member  32  and the second container segment  34  of the developer container  30 , and then insert the developer container  30 , the first container segment  33  having the convex fit  37  first, through the cabinet front portion  93  of the apparatus main body  71 , into the container housing space  77  of the toner hopper  72  in the attachment direction E 1 . On the other hand, to detach the developer container  30  from the apparatus main body  71 , what remains to be done by the user is simply to grasp the second container segment  34  of the developer container  30 , and then pull it out in the detachment direction E 2 . Quite understandably, this is very user-friendly. 
   In order to prevent coagulation of contained developer through agitation, users have hitherto had to shake a large-size, heavy toner cartridge upward, downward, rightward, and leftward. However, in the developer container  30  in accordance with the embodiment, developer coagulation can be prevented simply by rotating the container main body  31  about the rotation axis L 31 . This is very user-friendly. Moreover, in the developer container  30  in accordance with the embodiment, the mechanism for agitating the developer contained therein is quite simple. Further, in the developer container  30 , sealing is achieved between the container main body  31  and the supporting member  32 . While the developer container  30  is kept at the attachment position in the apparatus main body  71 , sealing is effected at least either around the leading through hole  51  of the discharge section  50 , or around the communication hole  81  of the developer supply section  74 , the leading through hole  51  and the communication hole  81  communicating with each other. With this sealing effect, developer leakage can be prevented in the container housing space  77  of the toner hopper  72  as reliably as possible. This helps keep the user&#39;s hands free of a developer smear as reliably as possible during the replacement of the developer container  30 . In addition, being substantially cylindrical-shaped, the developer container  30  can be housed in a slim, rectangular-parallelepiped package. This helps facilitate transportation and interpolation. 
   Another advantageous feature is that, as described previously, the developer container  30  requires less force to rotate the container main body  31  while keeping the quantity of developer discharge per one rotation of the container main body  31  as constant as possible. This does away with the need to increase the rotational speed of the container main body  31 . That is, developer can properly be fed into the agitation space  78  of the toner hopper  72  at a lower rotational speed. As a result, it is possible to feed developer into the agitation space  78  while keeping the quantity of developer discharge per one rotation of the container main body  31  as constant as possible. This leads to a reduction in torque in the driving source  84 , whereby making it possible to realize the driving source  84  by the use of a compact motor. 
   Note that, although the above description deals with the case where the developer container  30  and the image forming apparatus  70  in accordance with the embodiment is applied to a development system employing dual-component developer, the invention is applicable also to a development system employing toner alone. 
   The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description and all changes which come within the meaning and the range of equivalency of the claims are therefore intended to be embraced therein.