Patent Publication Number: US-9405221-B2

Title: Powder container and image forming apparatus incorporating same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application is based on and claims priority pursuant to 35 U.S.C. §119 to Japanese Patent Application Nos. 2012-131349, filed on Jun. 8, 2012, and 2012-131218, filed on Jun. 8, 2012, in the Japan Patent Office, the entire disclosure of each of which is hereby incorporated by reference herein. 
     BACKGROUND 
     1. Technical Field 
     The present invention generally relates to a powder container including a rotatable powder chamber for containing powder, and further to a powder replenishing device and an image forming apparatus incorporating the powder container. 
     2. Description of the Background Art 
     There are powder replenishing devices, such as toner replenishing devices for supplying toner to an image forming apparatus, that use a powder container including a bottle body, serving as a powder chamber, for containing toner, and a front end cover, serving as a holding portion, for rotatably holding a front end portion of the bottle body. 
     In such configurations, typically a container gear is formed on a circumference of the front end portion of the bottle body to mesh with a driving gear provided in a body of an image forming apparatus (i.e., an apparatus body). As the bottle body rotates with the container gear meshing with the driving gear, toner contained inside the bottle body moves from a rear side to a front side of the bottle body along a spiral protrusion formed on an inner circumferential surface of the bottle body. In the front end portion, toner enters a hopper formed in a front end portion of the front end cover covering the bottle body. A nozzle inserted into the hopper from outside the front end cover, sucks in toner and transports the toner to a developing device incorporated in the image forming apparatus. 
     In such a configuration, it is possible that toner coagulate inside the bottle body if the apparatus is not used for a long time. Various approaches have been tried to loosen coagulated toner in the bottle body. For example, JP-H11-327275-A proposes a toner replenishing device that includes a cylindrical bottle holder having a diameter greater than that of the bottle body, and a rear end portion of the bottle body is inserted into the cylindrical bottle holder. 
     At a predetermined circumferential position of the bottle holder, an internal projection projects from an inner circumferential surface of the bottle holder, and a protrusion is formed in the rear end portion of the bottle body, at a predetermined circumferential position. When the protrusion of the rear end portion of the bottle body moves in a predetermined rotational range as the bottle body rotates, the protrusion overstrides the internal projection of the bottle holder. An impact at that time can vibrate the bottle body to loosen the toner therein. 
     SUMMARY 
     In view of the foregoing, one embodiment of the present invention provides a powder container that includes a rotatable powder chamber for containing powder used for forming images, having an opening on a first side in an axial direction of the powder container, a conveyor disposed inside the powder chamber to transport powder contained in the powder chamber to the first side from a second side in the axial direction, a protrusion radially projecting from an outer circumferential surface of the powder chamber, disposed in a circumferential area of the powder chamber, and a first facing member disposed facing the outer circumferential surface of the powder chamber. The protrusion contacts the first facing member as the powder chamber rotates. 
     In another embodiment, an image forming apparatus includes an image forming unit to form images on recording media, and the above-described powder container. 
     In yet another embodiment, a powder container includes a powder chamber for containing powder for forming images, having an opening on a first side in a longitudinal direction of the powder container, a conveyor disposed inside the powder chamber to transport the powder contained in the powder chamber to the first side from a second side in an axial direction, an end cover to cover an end portion of the powder chamber in which the opening is formed, and a retainer to retain the powder container. A retaining hole is formed in the end cover, and the retainer penetrates the retaining hole of the end cover and contacts an outer circumferential surface of the powder chamber. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       A more complete appreciation of the disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: 
         FIG. 1  is a longitudinal sectional view of a toner replenishing device and a front end portion of a toner container to be attached thereto, according to a first embodiment; 
         FIG. 2  is a schematic diagram illustrating a configuration of an image forming apparatus according to the first embodiment; 
         FIG. 3  is a schematic end-on axial view of an image forming unit for yellow of the mage forming apparatus shown in  FIG. 2 ; 
         FIG. 4  is a schematic diagram illustrating the toner replenishing device and the toner container connected thereto, included in the image forming apparatus shown in  FIG. 2 ; 
         FIG. 5  is a perspective view of a container frame of the image forming apparatus shown in  FIG. 2 , together with the toner containers mounted therein; 
         FIG. 6  is a perspective view of the toner container according to the first embodiment; 
         FIG. 7  illustrates an enlarged perspective view of the toner replenishing device and the front end portion of the toner container to be attached thereto; 
         FIG. 8  is an enlarged perspective view of the toner replenishing device and the front end portion of the toner container being attached thereto; 
         FIG. 9  is a longitudinal sectional view of the toner replenishing device and the front end portion of the toner container being attached thereto; 
         FIG. 10  is a perspective view of a bottle body of the toner container according to the first embodiment; 
         FIG. 11  is an exploded perspective view of the bottle body shown in  FIG. 10 , from which a nozzle receiver is removed; 
         FIG. 12  is a longitudinal sectional view of the bottle body shown in  FIG. 11 , from which the nozzle receiver is removed; 
         FIG. 13  is a longitudinal sectional view of the bottle body shown in  FIG. 12 , into which the nozzle receiver is inserted; 
         FIG. 14  is a perspective view illustrating the nozzle receiver from a front side of the toner container; 
         FIG. 15  is a perspective view illustrating the nozzle receiver from a rear side of the toner container; 
         FIG. 16  is a longitudinal sectional view of the nozzle receiver being cut at the position of shutter side supports; 
         FIG. 17  is a longitudinal sectional view of the nozzle receiver being cut at the position of an opening between the shutter supporters; 
         FIG. 18  is an exploded perspective view of the nozzle receiver from which a container shutter is removed; 
         FIG. 19  is a cross sectional view illustrating a container socket of the toner replenishing device and a front end portion of a toner container held therein, according to a first configuration of the first embodiment; 
         FIG. 20  is a cross-sectional view of the container socket and the bottle body being at a rotational position at which a protrusion starts contacting a container lock; 
         FIG. 21  is a cross-sectional view of the container socket and the bottle body being at a rotational position at which the protrusion fully faces the container lock; 
         FIG. 22  is a cross-sectional view of the container socket and the bottle body being at a rotational position at which the protrusion is disengaged from the container lock; 
         FIG. 23  is a graph illustrating a relation between the rotational angle of the bottle body and the distance to a front end of the container lock from a center of rotation of the bottle body; 
         FIG. 24  is a cross sectional view illustrating a container socket of a toner replenishing device and a front end portion of a toner container held therein, according to a second configuration of the first embodiment; 
         FIG. 25  is a graph illustrating the relation between the rotational angle of the bottle body and the distance to a front end of the container lock from a center of rotation of the bottle body; 
         FIG. 26  is a cross sectional view of a first variation of the container lock and the front end portion of the toner container immediately before received in the container socket; 
         FIG. 27  is a cross sectional view of the container lock shown in  FIG. 26  and the front end portion of the toner container being received in the container socket; 
         FIG. 28  is a cross sectional view of a second variation of the container lock and the front end portion of the toner container immediately before received in the container socket; 
         FIG. 29  is a cross sectional view of the container lock shown in  FIG. 28  and the front end portion of the toner container being received in the container socket; 
         FIG. 30  is a cross sectional view of a container socket of a toner replenishing device and a front end portion of a toner container held therein, according to a second embodiment; 
         FIG. 31  is a cross-sectional view of the bottle body at a certain angle from the state shown in  FIG. 30 , received in the toner replenishing device; 
         FIG. 32  is a cross sectional view of a toner replenishing device and a front end portion of a toner container according to a first configuration of the second embodiment; 
         FIG. 33  is a cross sectional view of a toner replenishing device and a toner container according to a second configuration of the second embodiment; and 
         FIG. 34  is a cross sectional view of a toner container and the adjacent configuration according to a third embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     In describing preferred embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of this patent specification is not intended to be limited to the specific terminology so selected, and it is to be understood that each specific element includes all technical equivalents that operate in a similar manner and achieve a similar result. 
     Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views thereof, a toner container, a toner replenishing device, and an image forming apparatus according to a first embodiment of the present invention is described. 
     According to the embodiments of the present invention described below, coagulation of powder contained in the powder container can be loosened without causing a substantial eccentric movement of the powder chamber therein. 
     First Embodiment 
       FIG. 1  illustrates a front end portion of the toner container and the toner replenishing device according to the first embodiment, and  FIG. 2  is a schematic diagram illustrating a configuration of the image forming apparatus according to the first embodiment. 
     Referring to  FIG. 2 , an image forming apparatus  500  according to the first embodiment can be an electrophotographic multicolor copier, for example. The image forming apparatus  500  includes an apparatus body or printer unit  100 , a sheet-feeding table or sheet feeder  200 , and a scanner  400  provided above the apparatus body  100 . 
     The image forming apparatus  500  includes a container frame  70  provided in an upper section of the apparatus body  100 . Four toner containers  32 Y,  32 M,  32 C, and  32 K for containing yellow, magenta, cyan, and black toners, respectively, are removably installable in the container frame  70 . That is, the toner containers  32 Y,  32 M,  32 C, and  32 K are replaceable. An intermediate transfer unit  85  is provided beneath the container frame  70 . 
     It is to be noted that the suffixes Y, M, C, and K attached to each reference numeral indicate only that components indicated thereby are used for forming yellow, magenta, cyan, and black images, respectively, and hereinafter may be omitted when color discrimination is not necessary. 
     The intermediate transfer unit  85  includes an intermediate transfer belt  48 , four primary-transfer bias rollers  49 , a secondary-transfer backup roller  82 , multiple tension rollers, and a belt cleaning unit. The intermediate transfer belt  48  is supported by the multiple rollers including the secondary-transfer backup roller  82  and is rotated in the direction indicated by an arrow shown in  FIG. 2  as the secondary-transfer backup roller  82  rotates. 
     The apparatus body  100  includes four image forming units  46  parallel to each other, facing the intermediate transfer belt  48 . Additionally, toner replenishing devices  60  corresponding to the respective toner containers  32  are provided beneath the toner containers  32 . Each toner replenishing device  60  supplies toner from the corresponding toner container  32  to a developing device  50  (shown in  FIG. 3 ) of the corresponding image forming unit  46 . 
     As shown in  FIG. 2 , an exposing device  47  is provided beneath the four image forming units  46 . The exposing device  47  exposes a surface of a drum-shaped photoreceptor  41  according to image data read by the scanner  400  or that externally acquired by external devices such as computers, thereby forming an electrostatic latent image thereon. Although the exposing device  47  in the configuration shown in  FIG. 2  employs laser beam scanning using a laser diode, other configurations such as those using light-emitting diode (LED) arrays may be used. 
       FIG. 3  is a schematic end-on axial view of the image forming unit  46 Y for yellow. The image forming unit  46 Y includes the drum-shaped photoreceptor  41 Y serving as a latent image bearer. Around the photoreceptor  41 Y, a charging roller  44 Y serving as a charging member, the developing device  50 Y, a photoreceptor cleaning device  42 Y, and a discharger are provided. Image forming processes, namely, charging, exposure, image development, image transfer, and cleaning processes are performed on the photoreceptor  41 Y, and thus a yellow toner image is formed on the photoreceptor  41 Y. 
     It is to be noted that other image forming units  46  have a similar configuration to that of the yellow image forming unit  46 Y except the color of the toner used therein and form toner images of the respective colors. Thus, only the image forming unit  46 Y is described below and descriptions of other image forming units are omitted. 
     Referring to  FIG. 3 , the photoreceptor  41 Y is rotated clockwise in  FIG. 3  as indicated by arrow Y 1  by a driving motor. The surface of the photoreceptor  41 Y is charged uniformly at a position facing the charging roller  41 Y by the charging roller  41 Y (charging process). When the photoreceptor  41 Y reaches a position to receive a laser beam L emitted from the exposing device  47 , the photoreceptor  41 Y is scanned with the laser beam L, and thus an electrostatic latent image for yellow is formed thereon (exposure process). Then, the photoreceptor  41 Y reaches a position facing the developing device  50 Y, where the latent image is developed with toner into a yellow toner image (development process). 
     The four primary-transfer bias rollers  49  sandwich the intermediate transfer belt  48  with the corresponding photoreceptors  41 , respectively, forming primary-transfer nips therebetween. Each primary-transfer bias roller  49  receives a transfer bias whose polarity is opposite the charge polarity of the toner. 
     At the position facing the primary-transfer bias roller  49 Y via the intermediate transfer belt  48 , the toner image is transferred from the photoreceptor  41 Y onto the intermediate transfer belt  48  (primary-transfer process). After the primary-transfer process, a certain amount of toner tends to remain on the photoreceptor  41 Y. Then, a cleaning blade  42   a  mechanically collects toner remaining on the photoreceptor  41 Y (cleaning process) at the position facing the photoreceptor cleaning device  42 Y. Subsequently, the discharger removes potentials remaining on the surface of the photoreceptor  41 Y. Thus, a sequence of image forming processes performed on the photoreceptor  41 Y is completed. 
     The above-described image forming processes are performed also in the image forming units  46 M,  46 C, and  46 K similarly. That is, the exposing device  47  disposed above the image forming units  46  in  FIG. 2  directs the laser beams L according to image data onto the photoreceptors  41  in the respective image forming units  46 . Specifically, the exposing device  47  includes light sources to emit the laser beams L, multiple optical elements, and a polygon mirror that is rotated by a motor. The exposing device  47  directs the laser beams L to the respective photoreceptors  41  via the multiple optical elements while deflecting the laser beams L with the polygon mirror. 
     The intermediate transfer belt  48  rotates in the direction indicated by the arrow shown in  FIG. 2  and sequentially passes through the respective primary-transfer nips. While the intermediate transfer belt  48  thus rotates, the toner images formed on the respective photoreceptors  41  are transferred from the photoreceptors  41  and superimposed one on another on the intermediate transfer belt  48 , forming a multicolor toner image. 
     Then, the intermediate transfer belt  48  carrying the multicolor toner image reaches a position facing a secondary-transfer roller  89  disposed facing the secondary-transfer backup roller  82 . The secondary-transfer backup roller  82  and the secondary-transfer roller  89  press against each other via the intermediate transfer belt  48 , and the contact portion therebetween is hereinafter referred to as a secondary-transfer nip. The multicolor toner image on the intermediate transfer belt  48  is transferred onto the sheet P (recording medium) transported to the secondary-transfer nip. A certain amount of toner tends to remain on the intermediate transfer belt  48  after the secondary-transfer process. The belt cleaning unit collects untransferred toner remaining on the intermediate transfer belt  48 , and thus a sequence of transfer processes performed on the intermediate transfer belt  48  is completed. 
     Next, sheet conveyance is described below. 
     The sheet P is transported by a sheet tray  26  of the sheet feeder  200  positioned beneath the apparatus body  100  to the secondary-transfer nip via a feed roller  27  and a registration roller pair  28 . More specifically, the sheet tray  26  contains multiple sheets P piled one on another. The feed roller  27  rotates counterclockwise in  FIG. 2  to feed the sheet P on the top in the sheet tray  26  toward a nip formed by the registration roller pair  28 . 
     The registration roller pair  28  stops rotating temporarily, stopping the sheet P with a leading edge of the sheet P stuck in the nip. The registration roller pair  28  resumes rotation to transport the sheet P to the secondary-transfer nip, time to coincide with the arrival of the multicolor toner image formed on the intermediate transfer belt  48 . Thus, the multicolor toner image is recorded on the sheet P. 
     Subsequently, the sheet P is transported to a fixing device  86 . In the fixing device  86 , a fixing belt and a pressing roller apply heat and pressure to the sheet P to fix the multicolor toner image on the sheet P. Subsequently, the sheet P is discharged by a discharge roller pair  29  outside the image forming apparatus  500  and stacked as an output image in a stack section  30 . Thus, a sequence of image forming processes performed in the image forming apparatus  500  is completed. 
     Next, a configuration and operation of the developing device  50 Y in the image forming unit  46 Y are described in further detail below. The image forming units  46  for other colors and the developing devices  50  therein are configured similarly, and thus descriptions thereof are omitted. 
     The developing device  50 Y includes a developing roller  51 Y disposed facing the photoreceptor  41 Y, a doctor blade  52 Y disposed facing the developing roller  51 Y, two developer conveying screws  55 Y respectively disposed in first and second developer reservoirs  53 Y and  54 Y, and a toner density sensor  56 Y to detect the density of toner in the second developer reservoir  54 Y. A casing of the developing device  50 Y is divided, at least partially, into the first and second developer reservoirs  53 Y and  54 Y. The developing roller  51 Y includes a stationary magnet roller or multiple magnets and a sleeve that rotates around the magnet roller, and the like. The first and second developer reservoirs  53 Y and  54 Y contain two-component developer G consisting essentially of carrier (carrier particles) and toner (toner particles). Additionally, the second developer reservoir  54 Y communicates, via an opening formed on an upper side thereof, with a vertical toner tube  64 Y forming a toner conveyance channel through which toner is supplied from the toner container  32 Y as indicated by arrow D. 
     Inside the developing device  50 Y, the developer G is agitated by the two developer conveying screws  55 Y and circulated between the first and second developer reservoirs  53 Y and  54 Y. While being transported by the developer conveying screw  55 Y, the developer G in the first developer reservoir  53 Y is attracted by magnetic fields generated by the magnet roller inside the developing roller  51 Y and carried onto the sleeve surface of the developing roller  51 Y. The developer G carried on the developing roller  51 Y moves in the circumferential direction of the developing roller  51 Y as the sleeve of the developing roller  51 Y rotates counterclockwise in  FIG. 3  as indicated by arrow Y 2 . At that time, toner particles in developer G are charged through friction with carrier particles to have a potential in the polarity opposite the polarity of carrier particles. Then, the toner particles are adsorbed to the carrier particles and carried on the developing roller  51 Y together with the carrier particles by the magnetic field generated on the developing roller  51 Y. 
     The developer G carried on the developing roller  51 Y is transported as indicated by arrow Y 2  in  FIG. 3  to a position where the doctor blade  52 Y faces the developing roller  51 Y. Then, the amount of developer G on the developing roller  51 Y is adjusted to a suitable amount by the doctor blade  52 Y, after which the developer G is carried to a development range facing the photoreceptor  41 Y. In the development range, the toner in developer G adheres to the latent image formed on the photoreceptor  41 Y due to the effect of the magnetic field generated between the developing roller  51 Y and the photoreceptor  41 Y. As the sleeve rotates, the developer G remaining on the developing roller  51 Y reaches an upper part in the first developer reservoir  53 Y and then drops from the developing roller  51 Y. 
     The concentration of toner in developer G contained in the developing device  50 Y is adjusted within a predetermined range. More specifically, the toner replenishing device  60 Y (shown in  FIG. 4 ), described later, supplies toner from the toner container  32 Y to the second developer reservoir  54 Y according to the consumption of toner in the developing device  50 Y. Inside the developing device  50 Y, toner is mixed with the developer G is by the developer conveying screws  55 Y and circulated between the first and second developer reservoirs  53 Y and  54 Y. 
     Next, a configuration of the toner replenishing devices  60  is described below. 
       FIG. 4  illustrates the toner replenishing device  60 Y and the toner container  32 Y connected thereto, and  FIG. 5  is a perspective view illustrating the container frame  70  to which the toner containers  32  are mounted. 
     The respective color toners contained in the toner containers  32 Y,  32 M,  32 C, and  32 K in the container frame  70  are supplied to the developing devices  50 Y,  50 M,  50 C, and  50 K by the toner replenishing devices  60 Y,  60 M,  60 C, and  60 K according to the amount of the corresponding toner consumed. It is to be noted that the toner replenishing devices  60 Y,  60 M,  60 C, and  60 K have a similar structure, and the toner containers  32 Y,  32 M,  32 C, and  32 K have a similar structure except the color of toner used. Therefore, only the structure for yellow is shown in  FIG. 4 , omitting structures for other colors. 
     Each toner replenishing device  60  includes a conveying nozzle  611 , a conveying screw  614 , the vertical toner tube  64 , and a driving section  91 , and is connected to the toner container  32  installed in the container frame  70 . 
     In conjunction with insertion of the toner container  32  into the container frame  70  of the apparatus body  100  in the direction indicated by arrow Q shown in  FIG. 4  (hereinafter “installation direction Q”), the conveying nozzle  611  of the toner replenishing device  60  is inserted into the toner container  32  from the front side of the toner container  32 . Thus, the conveying nozzle  611  communicates with the interior of the toner container  32 . 
     The toner container  32  is cylindrical and constructed of a bottle body  33 , which can be monolithic with a container gear  301 , and a container front cover  34 . The container front cover  34  is fixed stationary to the container frame  70 , not to rotate. The container front cover  34  receives a front end portion of the bottle body  33  in its axial direction, meaning the direction in which the axis of rotation extends, and holds the front end portion rotationally. 
     The container frame  70  is constructed with a container cover section  73  to receive the container front covers  34  of the respective toner containers  32 , a container body section  72  that receives the bottle bodies  33  of the toner containers  32 , and an insertion section  71  having four insertion openings through which the toner containers  32  are inserted into and removed from the toner container frame  70 . It is to be noted that the container cover section  73  of the container frame  70  includes container sockets (or container fitting, container holder; container brackets)  608  ( 608 Y in  FIG. 4 ). The container sockets  608  are designed to receive the front end portions of the respective toner containers  32 . 
     Referring again to  FIG. 2 , when a front cover of the image forming apparatus  500  (on the front side of the paper on which  FIG. 2  is drawn) is opened, the insertion section  71  of the toner container frame  70  is exposed. The toner containers  32  are inserted and removed on the front side of the image forming apparatus  500  with the long axis of the toner containers  32  kept horizontal. 
     The longitudinal length of the container body section  72  of the container frame  70  is almost equal to the longitudinal length of the bottle body  33 . In addition, the container cover section  73  is positioned on one side in the longitudinal direction of the container body section  72  (on the leading side or downstream side in the direction of insertion), and the insertion section  71  is positioned on the other side (on the upstream side) of the container body section  72 . While the toner container  32  is being inserted into the container frame  70 , the container front cover  34  passes through the insertion section  71 , slides on the container body section  72  for a certain distance, and then is set in the container cover section  73 . 
     With the container front cover  34  held in the container cover section  73 , the bottle body  33  is rotated by the driving section  91  in the direction indicated by arrow A (hereinafter “direction A”) shown in  FIG. 4 . The driving section includes a driving motor, a driving gear, and the like transmits driving force to the container gear  301 . 
     A spiral protrusion  302  protrudes inward from an inner circumferential surface of the bottle body  33 . With this configuration, as the bottle body  33  rotates, toner inside the bottle body  33  is transported in the longitudinal direction thereof (from the left to the right in  FIG. 4 ) and is sent out from the container front cover  34  into the conveying nozzle  611 . 
     The conveying screw  614  is disposed inside the conveying nozzle  611 . When the driving section  91  inputs driving force to a screw gear  605 , the conveying screw  614  rotates, thus transporting toner inside the conveying nozzle  611 . The toner conveyed by the conveying screw  614  drops under its own weight through the vertical toner tube  64  (see  FIG. 4 ) and is supplied to the developing device  50 , in particular, to the second developer reservoir  54 . 
     It is to be noted that the toner container  32 Y,  32 M,  32 C, and  32 K are replaced when the respective service lives thereof have expired, that is, when almost all toner in the toner container  32  have been consumed. A handle  303  is provided at the end of the bottle body  33  on the side opposite the container front cover  34 , and users can grasp the handle  303  to remove the toner container  32  from the image forming apparatus  500  in replacement. 
     Toner is supplied to the developing device  50  from the toner container  32  when a controller  90  deems that toner supply is required from the toner consumption calculated according to image data used by the exposing device  47  or detection results generated by the toner density sensor  56 . Specifically, the controller  90  drives the driving section  91  to rotate the bottle body  33  and the conveying screw  614  for a predetermined time period, thereby supplying toner to the developing device  50 . 
     Since the conveying screw  614  inside the conveying nozzle  611  is rotated to supply toner, the amount of toner supplied from the toner container  32  can be calculated accurately by detecting the number of rotation of the conveying screw  614 . For example, the amount of supplied toner can be calculated accumulatively from when the toner container  32  is installed in the image forming apparatus  500 . When the accumulative amount of supplied toner reaches the amount of toner contained in the toner container  32  at the time of installation, the controller  90  deems that the toner container  32  is empty, which is a state referred to as “toner end”. Then, the controller  90  causes a display of the image forming apparatus  500  to instruct the user to replace the toner container  32 . Additionally, this message can be displayed also when the concentration of toner does not recover to a desired concentration even after toner supply is repeated, deeming that the toner container  32  is empty. 
     When the amount of supplied toner is controlled based on the number of rotation of the conveying screw  614 , the mount of toner is not adjusted after toner passes through the conveying nozzle  611 , and supplied as is to the developing device  50  through the vertical toner tube  64 . Even in the configuration in which the conveying nozzle  611  is inserted into the toner container  32 , a temporary toner reservoir such as a toner hopper may be provided, and the amount of toner supplied to the developing device  50  may be controlled by changing the amount of toner transported from the temporary toner reservoir to the developing device  50 . 
     Although the conveying screw  614  is used in the description above, toner in the conveying nozzle  611  may be transported using a different configuration. For example, negative pressure may be generated at the opening of the conveying nozzle  611  using a powder pump to give conveyance force to toner. 
     In configurations including the temporary toner reservoir, typically a toner end detector is provided to detect that the amount of toner remaining in the temporary toner reservoir falls below a threshold. According to the detection by the toner end detector, the bottle body  33  as well as the conveying screw  614  is rotated for a predetermined period to supply toner to the temporary toner reservoir. 
     If the toner end detector continues to report “toner end” even when this operation is repeated a predetermined number of times, the controller  90  causes the display of the image forming apparatus to instruct users to replace the toner container  32 , deeming that the toner container  32  is empty. Cumulative calculation of supplied toner from the installation of the toner container  32  is not required in the configuration in which whether any toner remains inside the toner container  32  is judged based on the detection by the toner end detector. However, the toner replenishing device  60  according to the present embodiment, which does not include the temporary toner reservoir, is advantageous in that the toner replenishing device  60  can be more compact, thereby reducing the size of the image forming apparatus  500 . 
     Next, the toner container  32  and the toner replenishing device  60  are described in further detail. As described above, the four toner containers  32  and the four toner replenishing devices  60  have similar configurations except the color of toner contained therein. 
       FIG. 1  is a longitudinal sectional view of the front end portion of the toner container  32  and the toner replenishing device  60  before the toner container  32  is attached thereto.  FIG. 6  is a perspective view of the toner container  32  according to the present embodiment.  FIG. 7  is an enlarged perspective view of the front end portion of the toner container  32  and the toner replenishing device  60  before the toner container  32  is mounted therein.  FIG. 8  is an enlarged perspective view of the toner replenishing device  60  and the front end portion of the toner container  32  attached thereto.  FIG. 9  illustrates a longitudinal section of the toner replenishing device  60  and the front end portion of the toner container  32  attached thereto. 
     The toner replenishing device  60  includes a nozzle shutter  612  in addition to the conveying nozzle  611  provided with the conveying screw  614 . The nozzle shutter  612  closes a nozzle opening  610  formed in the conveying nozzle  611  in the state shown in  FIGS. 7 and 9 , in which the toner container  32  is not connected to the conveying nozzle  611 . When the toner container  32  is connected to the conveying nozzle  611 , the nozzle shutter  612  opens the nozzle opening  610 . 
     In a center area of the front face of the toner container  32 , a nozzle connecting opening  331  for receiving the conveying nozzle  611  is formed, and a container shutter  332  is provided to close the nozzle connecting opening  331  when the conveying nozzle  611  is not connected thereto. The front end portion of the bottle body  33  includes a nozzle receiver  330  and the nozzle connecting opening  331 . In the first embodiment, as shown in, for example,  FIGS. 9, 12 and 13 , the container shutter  332  extends in the axial direction of the bottle body  33 , shaped like a plug, and slidable inside the nozzle receiver  330  in the axial direction. 
       FIG. 10  is a perspective view illustrating the bottle body  33  of the toner container  32 . It is to be noted that, in  FIG. 10 , the container front cover  34  is removed from the front end portion of the bottle body  33 .  FIG. 11  is an exploded perspective view of the bottle body  33  from which the nozzle receiver  330  is removed.  FIG. 12  is a longitudinal sectional view of the front end portion of the toner container  32  and the nozzle receiver  330  separated therefrom.  FIG. 13  is a longitudinal sectional view of the front end portion of the toner container  32  to which the nozzle receiver  330  is attached. 
     The bottle body  33  is substantially cylindrical and rotatable around a center axis (i.e., the axis of rotation). It is to be noted that, hereinafter the terms “front” and “anterior” mean the side on which the container front cover  34  is disposed, and the terms “rear” and “posterior” mean the side on which the bottle body  33  is disposed in the direction in which the axis of rotation of the bottle body  33  extends. The longitudinal direction of the toner container  32  parallels the axial direction thereof, and the axial direction is kept horizontal when the toner container  32  is connected to the toner replenishing device  60 . 
     Referring to  FIG. 10 , the portion of the bottle body  33  posterior to (upstream in the installation direction Q from) the container gear  301  have an external diameter greater than that of the front end portion thereof, and the spiral protrusion  302  is formed on the inner circumferential surface of that portion. As the bottle body  33  rotates in the direction A, toner therein receives conveyance force in the direction from one side to the other side in the axial direction (from the rear side to the front side). 
     Toner is transported to the front side along the spiral protrusion  302  as the bottle body  33  rotates in the direction A. The front end portion of the bottle body  33  includes a scooping portion  304  serving as a shovel or scoop to scoop up the toner using the rotation of the bottle body  33 . An inner surface of the scooping portion  304  projects or extends inward in the bottle body  33  serving as the powder chamber (as shown in  FIG. 30 ). 
     For example, a portion of the inner wall of the scooping portion  304 , on the upstream side in the direction of rotation, is shaped into a paddle blade against the direction of rotation and referred to as “scooping wall surface  304   f ”. The shape of the scooping portion  304  is not limited thereto. 
     When the space inside the scooping portion  304  is positioned on the lower side, using the rotation of the bottle body  33 , the scooping wall surface  304   f  scoops up the toner transported to the scooping portion  304  by the conveyance force exerted by the scooping portion  304 . Thus, the toner can be brought above the conveying nozzle  611 . 
     The container gear  301  is anterior to the scooping portion  304  in the bottle body  33 . The container front cover  34  is party cut away, forming a cutout  34   a  (i.e., a gear exposing cutout), to expose partly the container gear  301  (on the distal side in  FIG. 6 ) in a state in which the container front cover  34  is attached to the bottle body  33 . When the toner container  32  is connected to the toner replenishing device  60 , the container gear  301  exposed through the cutout  34   a  meshes with a container driving gear  601  (shown in  FIGS. 7 and 8 ) on the side of the toner replenishing device  60 . 
     A cylindrical front opening section  305  (i.e., a front opening forming section) is positioned anterior to the container gear  301  in the bottle body  33 . A fixing portion  337  of the nozzle receiver  330  is fitted in the front opening section  305  (press fit), and thus the nozzle receiver  330  can be fixed to the bottle body  33 . The fixing method is not limited to press fit. Alternatively, the nozzle receiver  330  may be glued or screwed to the bottle body  33 , for example. 
     After the bottle body  33  is filled with toner through the opening inside the front opening section  305 , the nozzle receiver  330  is fixed to the front opening section  305  of the bottle body  33 . 
     A cover catch  306  (shown in  FIGS. 9 through 12 ) projects from an outer circumferential surface at an end of the front opening section  305  on the side of the container gear  301 . To the toner container  32  (the bottle body  33  in particular) being in the state shown in  FIG. 10 , the container front cover  34  is attached from the front side (on the left in  FIG. 10 ). Then, the bottle body  33  penetrates the container front cover  34  in the axial direction. Then, a cover hook  341  provided in an upper portion of the container front cover  34  is hooked to the cover catch  306 . The cover catch  306  extends over the entire circumference of the front opening section  305 . With the cover hook  341  retained by the cover catch  306 , the bottle body  33  can rotate relative to the container front cover  34 . Although the cover catch  306  is continuous over the entire circumference in the configuration shown in the drawings, alternatively, the cover catch  306  may be divided and disposed at multiple positioned at intervals. For example, three cover catches  306  may be formed at 120 degrees apart. 
     The bottle body  33  can be formed by using biaxial stretch blow molding, for example. Typically, biaxial stretch blow molding includes two steps, namely, preform molding and stretch blow molding. In the preform molding step, resin is injected into a mold shaped like a test tube, thus forming a tube-shaped preform. During the step of injection molding, the front opening section  305 , the cover catch  306 , and the container gear  301  are formed at the opening of the tube-shaped preform. Subsequently, the preform is cooled, removed from the mold, and heated. Then, blow molding and stretch of the softened preform are executed as the step of stretch blow molding. 
     The portion of the bottle body  33  posterior to the container gear  301  can be formed in the step of stretch blow molding. That is, the handle  303  and the portion where the scooping portion  304  and the spiral protrusion  302  are positioned are formed by stretch blow molding. 
     The shapes of the elements, such as the container gear  301 , the front opening section  305 , and the cover catch  306 , positioned anterior to the container gear  301  are not changed from the preform. Accordingly, dimensional accuracy can be high. By contrast, elements produced by stretch blow molding, such the handle  303 , the scooping portion  304 , and the spiral protrusion  302 , may have a lower degree of dimensional accuracy than that of the front portions. 
     Next, the nozzle receiver  330  fixed to the bottle body  33  is described below. 
       FIG. 14  is a perspective view illustrating the nozzle receiver  330  from the front side.  FIG. 15  is a perspective view illustrating the nozzle receiver  330  from the rear side. 
     The nozzle receiver  330  includes the container shutter  332  and a shutter supporter  340 . The shutter supporter  340  includes a rear end support  335 , two shutter side supports  335   a , and the fixing portion  337 . The two shutter side supports  335   a  together from a part of a cylinder from which a large space between the shutter side supports  335   a  is cut away, thus forming an opening  335   b  between the shutter side supports  335   a . The opening  335   b  communicates with the nozzle opening  610 . With this configuration, the container shutter  332  can be guided to move inside a cylindrical space defined inside the shutter side supports  335   a  in the axial direction. The nozzle receiver  330  further includes a container seal  333  and a shutter spring  336  that can be a coil spring. 
       FIG. 16  is a longitudinal sectional view of the nozzle receiver  330  being cut at the position of the shutter side supports  335   a .  FIG. 17  is a longitudinal sectional view of the nozzle receiver  330  being cut at the position of the opening  335   b .  FIG. 18  is an exploded perspective view of the nozzle receiver  330  from which the container shutter  332  is pulled out. 
     As shown in  FIGS. 16 and 17 , a front end of the shutter spring  336  contacts a wall face of the container shutter  332 , and a rear end oaf the shutter spring  336  contacts a wall face of the rear end support  335 . At that time, since the shutter spring  336  is compressed, the container shutter  332  is urged away from the rear end support  335  (to the right in  FIGS. 16 and 17 ) downstream in the installation direction Q) to the front end. 
     A pair of hooks  332   a  is formed at the rear end of the container shutter  332  to be hooked on an outer wall of the rear end support  335 . With the hooks  332   a , the container shutter  332  can be prevented from moving further away from the rear end support  335  from the position shown in  FIGS. 16 and 17 . The position of the container shutter  332  can be determined relative to the container shutter  332  by the engagement between the hooks  332   a  and the rear end support  335  as well as the bias force exerted by the shutter spring  336 . 
     The fixing portion  337  is shaped like a stepped cylinder with its inner diameter decreasing to the rear end. As shown in  FIG. 16 , the container seal  333  that is toroidal is disposed in a portion where the diameter of the cylindrical space between the two shutter side supports  335   a  equals to the inner diameter of the fixing portion  337  (on which the outer face of the container shutter  332  slides) so that the container seal  333  contacts the step on the front side. The container seal  333  can be fixed to the step of the fixing portion  337  using glue or double-sided adhesive tape. 
     As shown in  FIGS. 16 and 17 , in the fixing portion  337  of the nozzle receiver  330 , a seal jam preventing space  337   b  is provided at an innermost position of the step that contacts the container seal  333 . The seal jam preventing space  337   b  is cylindrical and have a diameter smaller than the external diameter of the toroidal container seal  333  and greater than the diameter of the inner circumferential surface on which the outer circumferential surface of the container shutter  332  slides. 
     When the container shutter  332  moves to the rear side from the position (shown in  FIGS. 16 and 17 ) closing the nozzle connecting opening  331 , an inner circumferential portion of the toroidal container seal  333  slides on the container shutter  332 . Accordingly, the inner circumferential portion of the container seal  333  deforms elastically toward the rear side, being pulled by the container shutter  332 . If the stepped portion of the fixing portion  337 , with which the container seal  333  contacts, is continuous with the inner circumferential surface that slidingly contacts the outer circumferential surface of the container shutter  332 , there can be a risk that the deformed portion of the container seal  333  is sandwiched between the outer circumferential surface of the container shutter  332  and the inner circumferential surface of the fixing portion  337  that slidingly contacts the container shutter  332 . If the container seal  333  is entangled in the portion where the fixing portion  337  slidingly contacts with the container shutter  332 , the container shutter  332  is locked relative to the fixing portion  337 , and opening and closing of the nozzle connecting opening  331  are hindered. 
     In view of the foregoing, in the toner container  32  according to the present embodiment, the nozzle receiver  330  includes the seal jam preventing space  337   b  on the inner circumferential side thereof. Since the seal jam preventing space  337   b  has an external diameter smaller than the external diameter of the toroidal container seal  333 , the container seal  333  does not enter the seal jam preventing space  337   b  as a whole. Even if the portion of the container seal  333  pulled by the container shutter  332  and deformed elastically moves to the rear side and enters the seal jam preventing space  337   b , the container seal  333  can be prevented from being entangled in the portion where the fixing portion  337  slidingly contacts the container shutter  332  because the diameter of the seal jam preventing space  337   b  is greater than the inner circumferential surface that slidingly contacts the outer circumferential surface of the container shutter  332 . Accordingly, the container seal  333  can be prevented from being entangled in the portion where the fixing portion  337  slidingly contacts with the container shutter  332 , and the container shutter  332  can be prevented from being locked relative to the fixing portion  337 . Thus, opening and closing of the nozzle connecting opening  331  can be secured. 
     As shown in  FIGS. 16 through 18 , on the inner circumferential surface of the fixing portion  337 , multiple ribs  337   a  (i.e., nozzle shutter positioning ribs) are formed in the area where the container seal  333  is provided. Referring to  FIGS. 16 and 17 , when the container seal  333  is fixed to the fixing portion  337 , a front end face (on the right in  FIGS. 16 and 17 ) of the container seal  333  is projects beyond a front end of the rib  337   a  in the axial direction. As shown in  FIG. 9 , the nozzle shutter  612  of the toner replenishing device  60  includes a nozzle shutter flange  612   a , and a front face (left side in  FIG. 9 ) of the nozzle shutter flange  612   a  receives a nozzle shutter spring  613  (hereinafter “spring receiving surface  612   f ”). 
     Referring to  FIG. 9 , when the toner container  32  is connected to the toner replenishing device  60 , the nozzle shutter flange  612   a  of the nozzle shutter  612  comes into contact with the front ends of the ribs  337   a . Then, the nozzle shutter flange  612   a  contacts the front end portion of the container seal  333  projecting beyond the ribs  337   a , presses or squeezes the container seal  333 , and then contacts the ribs  337   a . Thus, at the time of installation, sealing around the conveying nozzle  611  in the nozzle connecting opening  331  can be secured, preventing toner leak, since the container seal  333  is squeezed by the nozzle shutter flange  612   a.    
     In the toner container  32 , the elastic container seal  333  forms a front end face of the nozzle receiver  330  in which the nozzle connecting opening  331  (to which the conveying nozzle  611  is inserted) is formed. Then, the nozzle shutter flange  612   a  (i.e., a contact portion) of the nozzle shutter  612  (i.e., powder inlet opening and closing member) presses against the front end face, compressing the container seal  333 . With this operation, the surface of the nozzle shutter flange  612   a  opposite the spring receiving surface  612   f  closely contacts the container seal  333 , thus enhancing toner leak prevention. 
     In the fixing portion  337  of the nozzle receiver  330 , when the container seal  333 , the elastic member, is squeezed, the nozzle shutter flange  612   a  (shown in  FIG. 9 ) comes into contact with the multiple ribs  337   a . As the rear side (opposite the spring receiving surface  6120  of the nozzle shutter flange  612   a  contacts the ribs  337   a , the nozzle shutter  612  is set in position relative to the toner container  32  in the axial direction. Thus, the relative positions between the front end face of the container seal  333 , the front end face of the front opening section  305 , and the nozzle shutter  612  in the axial direction are determined. 
     In installation of the toner container  32 , after the nozzle shutter flange  612   a  contacts the ribs  337   a  and determines the position of the nozzle shutter  612  relative to the toner container  32 , opening of the nozzle opening  610  is started. By contrast, in removal of the toner container  32  from the toner replenishing device  60 , the position of the nozzle shutter  612  relative to the toner container  32  does not change while the nozzle opening  610  is open, even if the conveying nozzle  611  is moved in the direction of removal from the toner container  32 . The nozzle shutter  612  is pulled out from the toner container  32  together with the conveying nozzle  611  after the nozzle shutter  612  closes the nozzle opening  610 . While the nozzle shutter flange  612   a  is in contact with the ribs  337   a , the portion of the conveying nozzle  611  in which the nozzle opening  610  is formed is positioned substantially inside the toner container  32  (upstream in the installation direction Q) from the entrance of the nozzle connecting opening  331 . Since opening or closing of the nozzle opening  610  is started when the nozzle opening  610  is inside the toner container  32 , toner leak from the nozzle opening  610  can be prevented. 
     The nozzle receiver  330  fixed to the bottle body  33  rotates as the bottle body  33  rotates. At that time, the shutter side supports  335   a  of the nozzle receiver  330  rotate around the conveying nozzle  611  of the toner replenishing device  60 . Accordingly, when the rotating shutter side support  335   a  is present above the nozzle opening  610  formed in the upper portion of the conveying nozzle  611 , the rotating shutter side support  335   a  hinders supply of toner from the bottle body  33  to the conveying nozzle  611 . By contrast, when the two shutter side supports  335   a  are positioned on the lateral sides of the conveying nozzle  611  and the nozzle opening  610  formed in the conveying nozzle  611  faces the opening  335   b  formed in the shutter supporter  340 , toner can be supplied from the bottle body  33  to the conveying nozzle  611  as indicated by arrow  13  shown in  FIG. 9 . 
     In the nozzle receiver  330  shown in  FIGS. 16 and 17 , a rear portion of the fixing portion  337  is reduced in external diameter from the front portion of the fixing portion  337 . Thus, a step is formed on the outer circumferential surface of the fixing portion  337  in midway in the axial length thereof. Additionally, as shown in  FIG. 13 , the front opening section  305  of the bottle body  33  has an inner circumferential surface conforming to the shape of the outer circumferential surface of the fixing portion  337 . Thus, a rear portion of the front opening section  305  is reduced in inner diameter, thus forming a step. This configuration can inhibit deviation of axis of the nozzle receiver  330  relative to the bottle body  33  as the step on the outer circumferential surface of the fixing portion  337  contacts the step on the inner circumferential surface of the front opening section  305  over the entire circumference. The term “deviation of axis” used here means that the center axis of the cylindrical fixing portion  337  is inclined from the center axis of the cylindrical front opening section  305 . 
     As shown in  FIG. 7 , the toner replenishing device  60  further includes the container socket  608  including container locks (lock levers)  609  serving as retainers, and container engagement portions  339  are formed in the container front cover  34 . The engagement portions  339  include holes for the container locks  609  to penetrate the container front cover  34  from outside. Additionally, an identification (ID) tag  700  is provided to the container front cover  34  for recording data relating to the toner container  32  such as usage conditions. Reference numeral  800  shown in  FIGS. 7 and 8  represents a connector for the ID tag  700 . The container front cover  34  further includes color discrimination ribs  34   b  to prevent the toner container  32  of the wrong color from being mounted to the container socket  608 . 
     Next, a configuration of the toner replenishing devices  60  is described below in further detail. 
     As shown in  FIGS. 7 and 8 , the toner replenishing device  60  includes a nozzle holder  607  to fix the conveying nozzle  611  to a frame  602  of the apparatus body  100  of the image forming apparatus  500 . The container socket  608  is fixed to the nozzle holder  607 . The vertical toner tube  64  is fixed to the nozzle holder  607  and communicates with the interior of the conveying nozzle  611  from below. 
     The driving section  91  is fixed to the frame  602 . The driving section  91  includes a driving motor  603 , the container driving gear  601 , and a worm gear  603   a  to transmit rotation of the driving motor  603  to a rotary shaft of the container driving gear  601 . A drive transmission gear  604  is fixed to the rotary shaft of the container driving gear  601  to engage the screw gear  605  fixed to the rotary shaft of the conveying screw  614 . In this configuration, rotation of the driving motor  603  is transmitted via the container driving gear  601  and the container gear  301  to the toner container  32 , thereby rotating the toner container  32 . The driving motor  603  further rotates the conveying screw  614  via the drive transmission gear  604  and the screw gear  605 . 
     Alternatively, a clutch may be provided in a drive transmission route from the driving motor  603  to the container gear  301  or a drive transmission route from the driving motor  603  to the screw gear  605 . When such a clutch is provided, only one of the toner container  32  and the conveying screw  614  can be driven as the driving motor  603  rotates. 
     Next, installation of the toner container  32  to the toner replenishing device  60  is described below. 
     Referring to  FIG. 1 , when the toner container  32  is moved toward the toner replenishing device  60  (in the installation direction Q shown in, for example,  FIGS. 1 and 7 ), an end  611   a  of the conveying nozzle  611  contacts a front end face of the container shutter  332 . It is to be noted that the end  611   a  is on the opening side, whereas the opposite side of the conveying nozzle  611  is referred to as “base side”. When the toner container  32  is moved further toward the toner replenishing device  60 , the conveying nozzle  611  presses against the front end face of the container shutter  332 . Then, as the shutter spring  336  is compressed, the container shutter  332  is pushed inside the toner container  32  (to the rear side of the toner container  32 , and the end  611   a  of the conveying nozzle  611  is inserted into the nozzle connecting opening  331 . At that time, a nozzle shutter tube  612   e  anterior to (upstream in the installation direction Q from) the nozzle shutter flange  612   a  is inserted into the nozzle connecting opening  331  together with the conveying nozzle  611 . 
     As the toner container  32  moves further to the toner replenishing device  60 , the rear side of the nozzle shutter flange  612   a , opposite the spring receiving surface  612   f , contacts and presses the front end face of the container seal  333 . Accordingly, the rear side of the nozzle shutter flange  612   a  contacts the ribs  337   a , and the nozzle shutter  612  is set in position relative to the toner container  32  in the axial direction. 
     As the toner container  32  moves further to the toner replenishing device  60 , the conveying nozzle  611  is inserted further into the toner container  32 . At that time, the nozzle shutter  612  being in contact with the ribs  337   a  is pushed back, relative to the conveying nozzle  611 , to the base side of the conveying nozzle  611  (downstream side in the installation direction Q). With this movement, the nozzle shutter spring  613  is compressed, and the nozzle shutter  612  moves to the base side of the conveying nozzle  611  relative to the conveying nozzle  611 . With this relative movement, the nozzle opening  610  is released from the nozzle shutter  612  and exposed inside the bottle body  33 . Thus, the conveying nozzle  611  communicates with the interior of the bottle body  33 . 
     When the conveying nozzle  611  is retained in the nozzle connecting opening  331 , the shutter spring  336  and the nozzle shutter spring  613 , which are compressed, exert force to push back the toner container  32  relative to the toner replenishing device  60  (in the direction reverse to the installation direction Q). However, when the toner container  32  is inserted to the toner replenishing device  60 , the toner container  32  is moved in the installation direction Q, against the force exerted by the shutter spring  336  and the nozzle shutter spring  613 , to the position where the container engagement portion  339  receives the container lock  609  of the container socket  608  of the toner replenishing device  60 . Then, the axial position of the toner container  32  relative to the toner replenishing device  60  is determined in the state shown in  FIGS. 8 and 9  by the force exerted by the shutter spring  336  and the nozzle shutter spring  613  as well as engagement between the container locks  609  and the container engagement portions  339 . 
     As shown in  FIG. 7 , the container engagement portions  339  are formed in both lateral side faces of the container front cover  34 . On a virtual plane perpendicular to the axial direction of the toner container  32 , the container shutter  332  is positioned at a center of a segment connecting together the two container engagement portions  339 . If the container shutter  332  is not positioned on the segment connecting the two container engagement portions  339 , rotation moment (torque) can be caused. That is, rotational moment to rotate the toner container  32  around the segment is caused by the force exerted at the position of the container shutter  332  by the shutter spring  336  and the nozzle shutter spring  613 . It is possible that the rotational moment can tilt the toner container  32  relative to the toner replenishing device  60 . Therefore, in the toner container  32  according to the present embodiment, the container shutter  332  is positioned on the segment connecting together the two container engagement portions  339 . This configuration can protect the toner container  32  from tilting relative to the toner replenishing device  60  due to the bias force exerted at the position of the container shutter  332  by the shutter spring  336  and the nozzle shutter spring  613 . 
     It is to be noted that, in a state in which the toner container  32  is connected to the toner replenishing device  60 , the end face of the cylindrical front opening section  305 , which is the end face of the toner container  32 , does not contact the end face of a container setting section  615 , which is a part of the container socket  608  and can be disposed, for example, on the bottom of the container socket  608 . The container socket  608  and the container setting section  615  are used for positioning the toner container  32 . 
     The toner container  32  is inhibited from moving further in the installation direction Q if the end face of the cylindrical front opening section  305  contacts the end face of the container setting section  615  before the container locks  609  enter the container engagement portions  339 . Accordingly, positioning of the toner container  32  in the axial direction is hindered. Therefore, in a state in which the toner container  32  is connected to the toner replenishing device  60 , clearance is secured between the end face of the cylindrical front opening section  305  and the end face of the container setting section  615 . 
     With the toner container  32  positioned in the axial direction, the outer circumferential surface of the front opening section  305  slidingly contacts an inner circumferential surface  615   a  of the container setting section  615 . Accordingly, the position of the toner container  32  relative to the toner replenishing device  60  can be determined in a direction along a plane perpendicular to the axial direction of the toner container  32 . Thus, installation of the toner container  32  to the toner replenishing device  60  is completed. 
     After the toner container  32  is installed, the driving motor  603  is rotated, thereby rotating the bottle body  33  and the conveying screw  614  in the conveying nozzle  611 . As the bottle body  33  rotates, toner therein is transported by the spiral protrusion  302  to the front side. When the toner reaches the scooping portion  304 , the scooping portion  304  lifts the toner above the nozzle opening  610  as the bottle body  33  rotates, and toner falls to the nozzle opening  610 . Then, the toner is supplied into the conveying nozzle  611 . The toner is transported inside the conveying nozzle  611  by the conveying screw  614  and supplied to the developing device  50  through the vertical toner tube  64 . It is to be noted the flow of toner from the bottle body  33  to the vertical toner tube  64  is indicated by arrow  13  shown in  FIG. 9 . 
     Reference character a shown in  FIG. 9  represents the position where the front opening section  305  slidingly contacts the inner circumferential surface  615   a  of the container setting section  615  and the position of the toner container  32  relative to the toner replenishing device  60  is determined. It is to be noted that, although this position have both capabilities of sliding contact and positioning, alternatively, this position can have either of them. 
     The nozzle receiver  330  of the toner container  32  includes the nozzle connecting opening  331 , the opening  335   b , and the container shutter  332 . The nozzle connecting opening  331  provided in the front end portion of the bottle body  33  receives the conveying nozzle  611  in which the nozzle opening  610 , serving as a powder inlet, is formed. The opening  335   b  positioned between the shutter side supports  335   a  serves as a supply inlet to supply toner contained in the bottle body  33  to the nozzle opening  610 . As the conveying nozzle  611  is inserted into and pulled out from the nozzle receiver  330 , the container shutter  332  supported by the nozzle receiver  330  slides in the axial direction and opens and closes the nozzle connecting opening  331 . With this configuration, in the toner container  32 , the nozzle connecting opening  331  is kept closed until the conveying nozzle  611  is inserted thereto. Thus, before the toner container  32  is connected to the toner replenishing device  60 , leak and scattering of toner can be prevented. 
     When the conveying nozzle  611  is inserted into the nozzle connecting opening  331 , the container shutter  332  slides to the rear side, pushed by the conveying nozzle  611 . Then, toner accumulating around the opening  335   b  is pushed away. Thus, space for the portion of the conveying nozzle  611  including the nozzle opening  610  can be secured around the opening  335   b , and toner can be supplied reliably from the opening  335   b  to the nozzle opening  610 . Thus, leak or scattering of toner from the toner container  32  being removed from the toner replenishing device  60  can be prevented, while discharge of toner from the toner container  32  (bottle body  33 ) being connected to the toner replenishing device  60  can be secured. 
     Referring to  FIGS. 1 and 9 , when the nozzle opening  610  or the nozzle connecting opening  331  is open, it is possible that toner scatters therefrom. Therefore, the front end of the container setting section  615  of the toner replenishing device  60  and the front end of the front opening section  305  of the toner container  32  are away from the those openings regardless of whether the toner container  32  is connected to the toner replenishing device  60  or separated therefrom. This configuration can inhibit leak of toner from the nozzle connecting opening  331  before the toner container  32  is connected to the toner replenishing device  60  and from the contact portion between the container seal  333  and the conveying nozzle  611  after the toner container  32  is connected to the toner replenishing device  60 . Additionally, during installation and removal of the toner container  32 , the container setting section  615  is away from the nozzle opening  610 . The front end of the front opening section  305  of the toner container  32  is away from the container shutter  332 . 
     The container shutter  332  to seal the nozzle connecting opening  331 , through which toner is discharged from the toner container  32 , is positioned posterior to the front end of the front opening section  305  of the bottle body  33 . Thus, a certain distance is secured from the container shutter  332  to the front end of the front opening section  305 . In this configuration, to go out the bottle body  33 , toner is to travel a distance from the nozzle connecting opening  331  posterior to the opening end (i.e., the front end of the front opening section  305 ) of the bottle body  33 . Thus, toner is inhibited from reaching the outer circumferential surface of the front opening section  305 , thereby inhibiting scattering of toner. 
     The position of the toner container  32  relative to the toner replenishing device  60  in the direction perpendicular to the axial direction can be determined by engagement between the outer circumferential surface of the front opening section  305  and the inner circumferential surface of the cylindrical container setting section  615 . That is, the outer circumferential surface of the front opening section  305  of the bottle body  33  (i.e., a powder chamber) serves as the positioning portion relative to the toner replenishing device  60  serving as a powder conveyance device. Therefore, toner adhering to the outer circumferential surface of the front opening section  305  can change contact state with the inner circumferential surface  615   a  of the container setting section  615 , thus degrading positioning accuracy. 
     In view of the foregoing, the toner container  32  according to the present embodiment is designed to inhibit toner from reaching and adhering to the outer circumferential surface of the front opening section  305 , thereby preventing fluctuations in the positioning accuracy of the toner container  32  relative to the toner replenishing device  60 . 
     When the toner container  32  rotates, the outer circumferential surface of the front opening section  305  and the inner circumferential surface  615   a  of the container setting section  615  slide on each other. Hereinafter the outer circumferential surface of the front opening section  305  of the bottle body  33  is referred to as a sliding portion that slidingly contacts with the toner replenishing device  60 , serving as the powder conveyance device. If toner enters the sliding portion, it is possible that sliding load increases, thus increasing rotation torque of the toner container  32 . 
     By contrast, the toner container  32  according to the present embodiment can inhibit toner from reaching the outer circumferential side of the front opening section  305  and inhibit toner from entering the sliding portion with the inner circumferential surface  615   a  of the container setting section  615 . Accordingly, increases in sliding load can be reduced, stabilizing sliding, and increases in rotation torque can be reduced. Additionally, with toner inhibited from entering the sliding portion, coagulation of toner in the sliding portion can be inhibited. 
     When the toner container  32  is connected to the toner replenishing device  60 , the nozzle shutter flange  612   a  squeezes the container seal  333  and coheres the container seal  333  with pressure, securing prevention of toner leak. Disposing the container shutter  332  posterior to (inner side in the longitudinal direction from) the opening position (front end) of the toner container  32  can form a cylindrical space between the front end of the toner container  32  and the front end faces of the container shutter  332  and the container seal  333 . 
     In a configuration in which the container gear to mesh with the driving gear of the apparatus body is disposed in the front end portion of the bottle body, and the rear end portion of the bottle body includes a protrusion that contacts an internal projection projecting from an inner face of a bottle holder holding the bottle body, the possibility of damage to the container gear or the driving gear of the apparatus body can be higher. 
     More specifically, the orbit of the front end portion of the bottle body, where the container gear is provided, is preferably a perfect or almost perfect circle so that the container gear can properly mesh with the driving gear or the apparatus body. By contrast, the orbit of the rear end portion provided with the protrusion is eccentric since the protrusion overstrides the internal projection of the bottle holder. The eccentric movement of the rear end portion of the bottle body causes stress on the engagement between the container gear of the front end portion and the driving gear of the apparatus body, resulting in damage to them. A similar inconvenience can arise also in powder containers for containing powder other than toner. 
     In view of the foregoing, according to the embodiments of the present invention, coagulation of powder contained in a powder container can be loosened without causing a substantial eccentric movement of the powder chamber therein. This can be attained by configurations described below. 
     [First Configuration] 
     In  FIG. 10 , the bottle body  33  serving as the powder chamber includes the cover catch  306 , the cover catch  306 , the container gear  301 , and the scooping portion  304 , which are positioned in one end portion (i.e., the front end portion) in the axial direction of the bottle body  33 . As shown in  FIG. 6 , the front end portion is rotationally held inside the container front cover  34 . 
       FIG. 19  is a cross sectional view of the container socket  608  of the toner replenishing device  60  and the front end portion of the toner container  32  (the bottle body  33  and the container front cover  34 ) held therein. In  FIG. 19 , reference character D 1  represents a distance to a front end of the container lock  609  from a center of rotation of the bottle body  33 . 
     Referring  FIG. 19 , in a circumferential range of the scooping portion  304 , a protrusion  304   g  projects from the outer circumferential surface of the scooping portion  304 . In the configuration shown in  FIG. 19 , two protrusions  304   g  are formed on the outer circumferential surface of the scooping portion  304 . The protrusion  304   g  revolves around the axial line of rotation of the bottle body  33 , and a radius R 1  of revolution of the protrusion  304   g  is greater than the radius of the container gear  301 . 
     The two protrusions  304   g  are symmetrical about a point, namely, axis of rotation of the bottle body  33 , with their phases shifted 180 degrees. 
     The amount by which the protrusion  304   g  projects from the outer circumferential surface of the scooping portion  304  is designed such that the radius R 1  of orbit of revolution of the outer end of the protrusion  304   g  (around the axis of rotation of the bottle body  33 ) is smaller than the radius of inner circumference of the container front cover  34 . A minute clearance is secured between the inner circumferential surface of the container front cover  34  and the outer end of the protrusion  304   g  of the scooping portion  304  being received inside the container front cover  34 . Accordingly, as the scooping portion  304  rotates, the protrusion  304   g  revolves around the axis of rotation inside the container front cover  34 . 
     Inside the container front cover  34 , if movement of the front end portion of the bottle body  33  becomes eccentric, one of the two protrusions  304   g  contacts the inner circumferential surface of the container front cover  34 , thereby stopping the eccentric movement. Therefore, the orbit of the front end portion of the bottle body  33  can be an almost perfect circle. 
     The two container engagement portions  339  are formed at predetermined circumferential positions in the container front cover  34 , in which the scooping portion  304  is received. The container engagement portions  339  are symmetrical about a point, namely, axis of rotation of the bottle body  33 . 
     The container socket  608  supports the two container locks  609  slidably. A torsion coil spring  616  urges each container lock  609  from outside the container socket  608 , along a guiding groove formed in the container socket  608 , to the axial line of the bottle body  33 . A rear end of the container lock  609  (i.e., an outer end in the direction of diameter of the toner bottle  33  in  FIG. 19 ) is thicker than its front end (i.e., an inner end in the direction of diameter) and blocked by a projection formed in the guiding groove although the container lock  609  is urged by the torsion coil spring  616  inward in the direction of diameter. Thus, the container lock  609  can be latched at a predetermined position in the urged direction. 
     With the front end portion of the toner container  32  received inside the container socket  608 , the front end of the container lock  609 , latched in the guiding groove, penetrates the container engagement portion  339  and enters the interior of the container front cover  34 . However, the front end of the container lock  609  does not reach the outer circumferential surface of the scooping portion  304  as shown in  FIG. 19 . In other words, the front end of the container lock  609  being latched is positioned in the clearance between the inner circumferential surface of the container front cover  34  and the outer circumferential surface of the scooping portion  304  of the bottle body  33 . 
     More specifically, in the radial direction centered on the axis of rotation of the bottle body  33 , the front end position of the container lock  609  being latched is positioned outside the outer circumferential surface of the scooping portion  304  and inside the orbit of the protrusion  304   g  of the scooping portion  304 . Accordingly, when the protrusion  304   g  of the scooping portion  304  approaches the position facing the container lock  609  as the bottle body  33  rotates, the protrusion  304   g  contacts the container lock  609  as shown in  FIG. 20 . 
     The two container locks  609  are symmetrical about the axis of rotation of the bottle body  33 . Accordingly, as one of the protrusions  304   g  starts contacting the container lock  609 , the other protrusion  304   g  also starts contacting the corresponding container lock  609 . Therefore, the bottle body  33  does not become eccentric but can keep the orbit shaped into a substantially perfect circle. 
     The container lock  609  in contact with the protrusion  304   g  is pushed by the protrusion  304   g  outward in the radial direction centered on the axis of rotation. Thus, the container lock  609  moves outward in the radial direction, against the bias force exerted by the torsion coil spring  616 . In other words, the container lock  609  changes its position away from the protrusion  304   g  on contact with the protrusion  304   g  and can serves as a movable contact member or a facing member. In this configuration, as the container lock  609  moves to the position to avoid the protrusion  304   g  as shown in  FIG. 21 , the bottle body  33  can keep revolving on the almost perfect circular orbit. 
     As shown in  FIG. 20 , when the revolving protrusion  304   g  contacts the container lock  609 , the protrusion  304   g  receives force that inhibits rotations of the bottle body  33 . At that time, vibration is given to the toner contained inside the bottle body  33 , and coagulated toner can be loosened. 
     The scooping portion  304  is reduced in width compared with the bottle body  33  (powder chamber), and scooping capability may be degraded if toner adheres to the inner surface thereof, reducing the amount of toner supplied. Therefore, disposing the protrusion  304   g  to the scooping portion  304  is advantageous in that adhering toner can be separated from the inner surface of the scooping portion  304  by vibrating the scooping portion  304  progressively, thereby stabilizing the amount of toner supplied. 
     Although driving torque is increased by sliding between the protrusion  304   g  and the container lock  609 , the driving torque returns to normal abruptly when the protrusion  304   g  is disengaged from the container lock  609 . Accordingly, the rotational velocity of the bottle body  33  increases sharply for a moment, and vibration is given to the toner inside the bottle body  33 . This vibration can loosen coagulation of toner similarly. 
       FIG. 23  is a graph illustrating the relation between the rotational angle of the bottle body  33  and the distance to the front end of the container lock  609  from the center of rotation of the bottle body  33 . In  FIG. 23 , “range of contact” means a rotational angle range of the bottle body  33  in which the container lock  609  contacts the protrusion  304   g . When the container lock  609  starts contacting the protrusion  304   g , the distance D 1  from the axis of rotation to the front end of the container lock  609  is increased in one stroke to the radius R 1  of revolution of the protrusion  304   g . Thus, the container lock  609  moves in one stroke to the position not to be blocked by the protrusion  304   g  and starts sliding on the protrusion  304   g . Additionally, when the front end of the container lock  609  starts moving away from the protrusion  304   g  as the bottle body  33  rotates, the distance D 1  is reduced to the original distance in one stroke. 
     As described above, in the toner replenishing device  60  according to the present embodiment, coagulation of toner can be loosened without a substantial eccentric movement of the bottle body  33 . 
     It is to be noted that, although the description above concerns the configuration in which the container engagement portion  339  is formed in the container front cover  34 , serving as the holder for holding the movable container lock  609  from outside, alternatively, for example, the container lock  609  may be supported movably relative to the container front cover  34 . 
     Yet alternatively, a protrusion facing the outer circumferential surface of the bottle body  33  may be formed on the inner circumferential surface of the container front cover  34 , and a movable contact member may be supported by the bottle body  33 . Specifically, the movable contact member is disposed to contact the protrusion of the container front cover  34  when the bottle body  33  reaches a predetermined rotational position, and, on contact with the protrusion, the movable member moves away from the protrusion in the radial direction. 
     The container lock  609  serves as a latch to retain the container front cover  34  when the container lock  609  is inside the container engagement portion  339 . Use of the container lock  609  as both the lock for the toner container  32  and the movable contact member is advantageous in that component layout can be simpler compared with a configuration using separate members for them. 
     [Second Configuration] 
       FIG. 24  is a cross sectional view of the container socket  608  of the toner replenishing device  60  and the front end portion of the toner container  32  (the bottle body  33  and the container front cover  34 ) according to a second configuration usable in the toner replenishing device and the toner container according to the present embodiment. Other than the differences described below, the toner replenishing device and the toner container shown in  FIGS. 24 and 25  are similar to those described with reference to  FIGS. 19 through 23 . 
     In the configuration shown in  FIG. 24 , a tapered protrusion  304   g   2  is formed on the outer circumferential surface of the scooping portion  304  of the bottle body  33 . Specifically, the outer end (in the radial direction) of the protrusion  304   g   2  is tapered to move away from the axis of rotation toward the rear side in the direction A in which the bottle body  33  rotates so that the distance D 1  (shown in  FIG. 19 ) from the axis of rotation to the container lock  609  in contact with the protrusion  304   g   2  increases as the bottle body  33  rotates. 
       FIG. 25  is a graph illustrating the relation between the rotational angle of the bottle body  33  and the distance to a front end of the container lock  609  from a center of rotation of the bottle body  33 . As shown in  FIG. 25 , when the container lock  609  starts contacting the tapered protrusion  304   g   2 , the distance D 1  from the axis of rotation to the front end of the container lock  609  is increases gradually. The distance D 1  becomes equal to the radius R 1  of revolution of the protrusion  304   g  immediately before the container lock  609  is disengaged from the protrusion  304   g   2 . Then, the distance D 1  decreases in one stroke to the original (shown in  FIG. 19 ) after the container lock  609  avoids the protrusion  304   g   2 . 
     This configuration can alleviate the impact to each of the protrusion  304   g   2  and the container lock  609  at the start of contact therebetween. Accordingly, damage to the protrusion  304   g   2  or the container lock  609  can be inhibited. 
     [Variation] 
     Variations of the container locks according to the first embodiment are described below. Other than the differences described below, the configurations shown in  FIGS. 26 through 29  are similar to those described with reference to  FIGS. 19 through 23 . 
       FIG. 26  is a cross sectional view of two container locks  609 A according to a first variation and the front end portion of the toner container  32  immediately before received in the container socket  608  (shown in  FIG. 8 ). The two container locks  609 A each extending in the axial direction of the bottle body  33  are cantilevered by supporting members. The cantilevered end of the container lock  609 A is on the front side of the bottle body  33 , whereas a free end of the lock  609 A is on the rear side of the bottle body  33 . 
     The free end of the container lock  609 A is bent at 90 degrees from the axial direction of the bottle body  33  toward the axial line. The bent portion is referred to as a lock claw  609 A 1 . When insertion of the front end portion of the toner container  32  into the container socket  608  is started, the lock claws  609 A 1  of the respective container locks  609 A contact the outer surface of the container front cover  34  as shown in  FIG. 26 . Then, each container lock  609 A deforms for the length of the lock claw  609 A in the direction away from the axial direction of the bottle body  33 . 
     When the toner container  32  is fully received in the container socket  608 , the lock claw  609 A 1  of the container lock  609 A enters the container engagement portion  339  formed in the container front cover  34  as shown in  FIG. 27 . At that time, the deformed container locks  609 A revert to the original positions, hitting the outer circumferential surface of the bottle body  33 . Thus, vibration is given to the toner contained inside the bottle body  33  and coagulated toner can be loosened. 
     [Second Variation] 
       FIG. 28  is a cross sectional view of container locks  609 B according to a second variation and the front end portion of the toner container  32  immediately before received in the container socket. The two container locks  609 B each extending in a direction perpendicular to the axial direction of the bottle body  33  are biased by coil springs  607  from outside toward the axial line of the bottle body  33 . 
     When insertion of the front end portion of the toner container  32  into the container socket  608  is started, as shown in  FIG. 28 , the two container locks  609 B contact the outer circumferential surface of the toner container  32 . When the toner container  32  is fully received in the container socket  608 , the container locks  609 B enter the respective container engagement portions  339  formed in the container front cover  34  as shown in  FIG. 29 . At that time, the front end of each container lock  609 B biased by the coil spring  617  hits the outer circumferential surface of the bottle body  33 . Thus, vibration is given to the toner contained inside the bottle body  33  and coagulated toner can be loosened. 
     The various configurations according to the first embodiment can attain specific effects as follows. 
     Configuration A: A powder container (such as the toner container  32 ) includes a rotatable powder chamber (such as the bottle body  33 ) for containing powder and a holder (such as the container front cover  34 ) to rotatably hold an end portion of the powder container on one side in the axial direction of the powder chamber and configured to transport powder from the other side to the end portion as the powder chamber rotates and discharge the powder from the powder chamber. In this powder container, a protrusion (such as the protrusion  304   g ) projects from an outer circumferential surface of the axial end portion of the powder chamber. The projecting amount is smaller than the gap between the inner circumferential surface of the holder and the outer circumferential surface of the powder chamber so that the radius (R 1 ) of orbit of revolution (around the axial line thereof) is smaller than the radius of inner circumference of the holder. When the powder chamber is at a predetermined rotational position, a movable contact member (such as the container lock  609 ) provided to the holder contacts the protrusion and moves away from the protrusion, avoiding the protrusion. Alternatively, an opening (such as the container engagement portion  339 ) is formed in the holder for receiving the movable contact member from the outside of the holder. 
     Configuration B: A powder replenishing device includes the powder container according to configuration A and a conveyance channel (such as the vertical toner tube  64 ) through which powder flows from the powder container to a destination. 
     Configuration C: In configuration B, an end of the protrusion is tapered such that the outer end (in the radial direction) thereof deviates from the axis of rotation as the powder chamber rotates downstream in the direction of rotation thereof. This configuration can alleviate the impact to each of the protrusion and the movable contact member at the start of contact therebetween. 
     Configuration D: In configuration B or C, the movable contact member is provided separately from the holder, the opening for receiving the movable contact member is formed in the holder, and the movable contact member being inserted into the opening serves as a retainer to retain the holder. The configuration in which the movable contact member is used also as the retainer is advantageous in that component layout can be simpler. 
     In the first embodiment, when the powder chamber of the powder container is at a predetermined rotational position, a protrusion formed on the outer circumferential surface of the powder chamber contacts a movable contact member disposed facing the protrusion. Alternatively, a movable contact member supported by the powder chamber contacts a facing member disposed facing the outer circumferential surface of the powder chamber. In either case, on contact between the movable contact member and the facing member facing it, force to inhibit rotation of the powder chamber is generated, giving the powder chamber an impact in the direction of rotation. The impact can loosen coagulation of toner inside the powder chamber. 
     Subsequently, as the powder chamber rotates further, the movable contact member in contact with the protrusion of the powder chamber, or the movable contact member retained by the powder chamber and in contact with the facing member, moves in the radial direction, away from the protrusion or the facing member to avoid the protrusion or the facing member. With this movement, while the powder chamber follows an almost perfect circle orbit, the protrusion of the powder chamber passes by the contact position with the movable contact member, or the movable contact member of the powder chamber passes by the facing member. 
     Thus, while the powder chamber rotating along an almost perfect circle orbit, the powder chamber can be vibrated in the direction of rotation by the movable contact member that periodically contacts the protrusion of the powder chamber, or the movable contact member of the powder chamber that periodically contacts the facing member. Thus, coagulated powder can be loosened without causing a substantial eccentric movement of the powder chamber. 
     Second Embodiment 
     A second embodiment is described below. Descriptions of features of the second embodiment similar to those of the above-described first embodiment are omitted. 
     In the toner replenishing device  60 , the toner container  32  is replaced when no or almost no toner remains in the bottle body  33  (toner end). Therefore, it is preferable that “toner end” is detected, and users are advised to replace the toner container  32 . 
     As described above, in the configuration including the temporary toner reservoir for temporarily storing toner discharged from a toner container to be supplied to the developing device, typically a toner end detector is provided to the temporary toner reservoir. When the toner container becomes empty, no toner is supplied to the temporary toner reservoir, and the level of toner therein falls under the lower limit. Then, the toner end detector does not detect the presence of toner. Thus, “toner end” in the toner container can be detected according to the detection made by the toner end detector in the temporary toner reservoir. 
     However, in this configuration, the temporary toner reservoir is required to detect “toner end” in the toner container. A similar inconvenience can arise also in powder containers for containing powder other than toner. 
     In view of the foregoing, the second embodiment is designed to detect the amount of toner remaining in the powder chamber (i.e., the bottle body  33 ) of the powder container (i.e., the toner container  32 ) without providing a temporary reservoir for temporarily storing powder discharged from the powder container. 
     It is to be noted that the toner container  32  according to the second embodiment includes the protrusion  304   g  for loosening toner coagulation similarly to the first embodiment with reference to  FIGS. 19 through 25 . 
     Next, a feature of the present embodiment is described in further detail below. 
     In  FIG. 10 , the bottle body  33  serving as a powder chamber includes the cover catch  306 , the container gear  301 , and the scooping portion  304 , which are positioned in one end portion (i.e., the front end portion) in the axial direction of the bottle body  33 . As shown in  FIG. 6 , the front end portion is rotationally held inside the container front cover  34 . In the second embodiment, an axial area of the bottle body  33  is transparent entirely in the circumferential direction. More specifically, a cylindrical wall of the scooping portion  304  is formed with a light transmissive material entirely in the circumferential direction. Thus, the scooping portion  304  serves as a window. It is to be noted that, in  FIG. 10 , a number of dots in the scooping portion  304  represent toner visible from outside the bottle body  33 . 
       FIG. 30  is a cross sectional view of the container socket  608  of the toner replenishing device  60  and the front end portion of the toner container  32  held therein.  FIG. 30  illustrates the portion of the toner replenishing device  60  where the scooping portion  304  is positioned in the axial direction. In the configuration shown in  FIG. 30 , the front end portion of the scooping portion  304  is not cylindrical but oblate or shaped like a low-profile box. The scooping portion  304  is formed with a transparent material entirely in the direction of rotation. Alternatively, the scooping portion  304  may be translucent. 
     First and second openings  337  and  338  are formed in a container front cover  34 - 2  according to the second embodiment, which receives the front end portion of the bottle body  33 . The first opening  337  is adjacent to and on the right of the scooping portion  304  in  FIG. 30 , and the second opening  338  is adjacent to and on the left of the scooping portion  304  in  FIG. 30 . 
     The toner replenishing device  60  includes a light-emitting element  620  and a light-receiving element  621 . A toner supply controller is constructed of a central processing unit (CPU) as well as data storage units such as a random access memory (RAM), and a read only memory (ROM). The light-emitting element  620 , the light-receiving element  621 , and the toner supply controller together form a toner amount detector for detecting the amount of toner remaining in the bottle body  33 . 
     The light-emitting element  620  and the light-receiving element  621  are arranged as follows in a direction along the surface of the paper on which  FIG. 30  is drawn, which is perpendicular to the axial direction of the bottle body  33 . That is, the light-emitting element  620  faces the light-receiving element  621  via the second opening  338  of the container front cover  34 - 2 , the scooping portion  304  of the bottle body  33 , and the first opening  337  of the container front cover  34 - 2 . As indicated by broken lines in  FIG. 30 , light emitted from the light-emitting element  620 , for example, a light-emitting diode (LED), enters the container front cover  34 - 2  through the second opening  338  and penetrates the wall of the scooping portion  304  serving as the transparent window. 
     Since the wall of the scooping portion  304  is transparent entirely in the direction of rotation, light entering the container front cover  34 - 2  through the second opening  338  can penetrate the scooping portion  304  regardless of the rotational position of the scooping portion  304 . When the amount of toner remaining in the scooping portion  304  is reduced a certain amount, a part of the light again penetrates the transparent scooping portion  304  to the outside of the scooping portion  304  after traveling inside the scooping portion  304 . The light further travels through the first opening  337  outside the container front cover  34 - 2  and is received by the light-receiving element  621 . 
     The amount of light received by the light-receiving element  621  correlates with the amount of toner remaining in the scooping portion  304 . Specifically, as the amount of toner remaining in the toner container  32  decreases, the amount of toner in the scooping portion  304  decreases, and the amount of light received by the light-receiving element  621  increases. Then, the voltage output from the light-receiving element  621  increases. Accordingly, an algorithm correlating the amount of light received by the light-receiving element  621  with the amount of remaining toner can be prestored in the toner supply controller so that the amount of remaining toner can be calculated using the algorithm and the voltage output from the light-receiving element  621 . When the amount of remaining toner falls below a threshold, “toner end” can be displayed on a display. 
     It is to be noted that, due to the scooping portion  304  shaped like a low-profile box ( FIG. 30  illustrates a cross section of the low-profile box shape), depending on the rotational angle of the bottle body  33 , the scooping portion  304  is not present in the light path between the light-emitting element  620  and the light-receiving element  621 , and light reaches directly from the light-emitting element  620  to the light-receiving element  621  as shown in  FIG. 31 . The amount of light received by the light-receiving element  621  at that time does not correlate with the amount of remaining toner. Therefore, the toner supply controller calculates a mean value of the amount of light received in a predetermined period and obtains the amount of remaining toner based on the mean value. The predetermined period is longer than the duration of time required for a complete turn of the bottle body  33 . Since the mean value of the amount of light received in such period can correlate with the amount of toner remaining in the front end portion shaped like a low-profile box, the amount of remaining toner can be ascertained. 
     This configuration enables detection of the amount of toner remaining in the bottle body  33  without providing the temporary toner reservoir for temporarily storing toner discharged from the toner container  32  since the amount of toner in the scooping portion  304 , not the amount of toner discharged from the toner container  32 , can be detected using transmitted light. 
     It is to be noted that, since the rear portion of the scooping portion  304  in the axial direction is cylindrical, the light-receiving element  621  may be disposed to receive light emitted from the light-emitting element  620  at the position of the cylindrical rear portion thereof. 
     The front end portion of the bottle body  33  in the axial direction thereof is received in the container front cover  34 - 2 , and the scooping portion  304  shown in  FIG. 30  is positioned in the front end portion received in the container front cover  34 - 2 . In other words, in the toner replenishing device  60  according to the present embodiment, the front end portion of the bottle body  33  includes the window. 
     Referring to  FIG. 30 , since the window (i.e., the scooping portion  304 ) is received inside the container front cover  34 - 2 , the first and second openings  337  and  338  are formed in the container front cover  34 - 2  so that light emitted from the light-emitting element  620  can pass through the container front cover  34 - 2  before and after penetrating the scooping portion  304 . 
     As toner is consumed, the level of toner inside the bottle body  33  is substantially reduced in the entire axial length thereof, which is a state referred to as “toner near end”. In this specification, reduction in the amount of remaining toner from this state is divided in three levels. In a first reduction level, a small amount of toner is still present in the entire axial length of the bottle body  33 . 
     As the amount of toner decreases further, no or almost not toner is present in the rear end portion of the bottle body  33 , but a certain amount of toner remains in the front end portion thereof, which is a state close to “toner end” and hereinafter referred to as “second reduction level”. That is, a small amount of toner remains in this state. 
     As the mount of toner decreases further, the level of toner in the front end portion of the bottle body  33  decreases substantially. The term “toner end” used in this specification means this state. If the window is disposed in the rear end portion of the bottle body  33 , the state in which almost no toner is present in the rear end portion is detected based on changes in the amount of light received by the light-receiving element  621 . This state, however, is the above-described second reduction level and is slightly earlier than the time when the bottle body  33  becomes empty (toner end). 
     By contrast, when the window is disposed in the front end portion of the bottle body  33  as in the present embodiment, based on changes in the amount of light received by the light-receiving element  621 , the state in which almost no toner is present in the front end portion can be detected. In other words, the state of “toner end” can be detected. Thus, disposing the window in the front end portion of the bottle body  33  can enable more accurate detection of the timing when the toner bottle becomes empty (toner end). 
     In  FIG. 30 , the axial line of the bottle body  33  is a circular center of the conveying screw  614 . As shown in  FIG. 30 , in the present embodiment, the first and second openings  337  and  338  face each other at a position lower (in the direction of gravity) than the axial line inside the scooping portion  304 . With this arrangement, it can be known that the level of toner in the scooping portion  304  is substantially lower than the axial line based on changes in the amount of light received by the light-receiving element  621 . Accordingly, detection of the timing when the toner bottle is empty (toner end) can be more accurate compared with a configuration in which these openings are positioned above the axial line. 
     It is to be noted that, although the two container engagement portions  339  and the first and second openings  337  and  338  are provided separately in the container front cover  34 - 2  in the configuration shown in  FIG. 30 , these openings may be configured otherwise. Alternatively, for example, the container engagement portion  339  on the left in  FIG. 30  may be continuous with the second opening  338 , forming a single opening, and the container engagement portion  339  on the right may be continuous with the first opening  337 , forming a single opening. 
     Next, configurations applicable to the toner replenishing device according to the second embodiment are described with reference to  FIGS. 32 and 33 . Other than the differences described below, the toner replenishing device and the toner container shown in  FIGS. 32 and 33  are similar to those described with reference to  FIGS. 30 and 31 . It is to be noted that, in  FIGS. 32 and 33 , hatching of the container locks  609  is omitted since they are formed with a transparent material. 
     [First Configuration] 
       FIG. 32  is a cross sectional view of the toner replenishing device  60  and the front end portion of the toner container  32  (the bottle body  33  and the container front cover  34 - 2 ) according to a first configuration. 
     In the configuration shown in  FIG. 32 , the toner replenishing device  60  includes two container locks  609 C formed with transparent plastic. A reflecting mirror  609   a  is provided in each container lock  609 C. The light-emitting element  620  is disposed facing the container engagement portion  339  on the left in  FIG. 32 , formed in the container front cover  34 - 2 . The light-receiving element  621  is disposed facing the container engagement portion  339  on the right in  FIG. 32 , formed in the container front cover  34 - 2 . 
     The light emitted from the light-emitting element  620  enters the container lock  609 C on the left in  FIG. 30  and then travels downward, being deflected 90 degrees by the reflecting mirror  609   a  of the container lock  609 C. A first optical cable  622  shaped like a letter “L” is provided beneath the container lock  609 C on the left, overlapping the container lock  609  in the vertical direction. The light deflected by the reflecting mirror  609   a  of the container lock  609 C on the left enters the first optical cable  622 . Along the L-shaped first optical cable  622 , the light descends and is deflected in a horizontal direction. Then, the light is directed to the second opening  338  formed in the container front cover  34 - 2 . 
     Subsequently, the light travels through the second opening  338 , the scooping portion  304  of the bottle body  33 , and the first opening  337  and enters an L-shaped second optical cable  623 . After deflected and guided upward along the L-shaped second optical cable  623 , the light exits the second optical cable  623  and enters the transparent container lock  609 C on the right. After the reflecting mirror  609   a  of the container lock  609  deflects the light, the light-receiving element  621  receives the light. 
     In this configuration, light can be transmitted between the light-emitting element  620  and the light-receiving element  621  using the space where the container locks  609 C are provided. 
     [Second Configuration] 
     A second configuration usable in the second embodiment is described below with reference to  FIG. 33 , which is a cross sectional view of the toner replenishing device  60  and the front end portion of the toner container  32  (the bottle body  33  and the container front cover  34 - 2 ). In the second configuration, two container locks  609 D formed with a transparent plastic are used. However, the container locks  609 D do not include reflecting mirrors differently from the configuration shown in  FIG. 32 . 
     In the configuration shown in  FIG. 33 , the container engagement portion  339  on the left in  FIG. 33  serves also as an opening for receiving light. The container engagement portion  339  on the right in  FIG. 33  serves also as an opening for discharging light. 
     The light emitted from the light-emitting element  620  penetrates the container lock  609 D inserted in the container engagement portion  339  on the left, enters the container front cover  34 - 2 , and then penetrates the scooping portion  304 . Subsequently, the light penetrates the container lock  609 D inserted in the container engagement portion  339  on the right, exits the container front cover  34 - 2 , and then reaches the light-receiving element  621 . 
     In this configuration, light can be transmitted between the light-emitting element  620  and the light-receiving element  621  using the space of the container engagement portions  339  and the container locks  609 D. 
     Third Embodiment 
     A toner container according to a third embodiment is described below. Other than the differences described below, the container shown in  FIG. 34  is similar to the above-described embodiments. 
       FIG. 34  is a cross sectional view of a toner container  900  and the adjacent configuration usable in the toner replenishing device  60 . 
     The toner container  900  shown in  FIG. 34  includes a toner bottle  901  and a toner conveying member  902  disposed at the center of circular profile of the toner bottle  901 , extending in the axial line of the toner bottle  901 . The toner conveying member  902  includes a rotary shaft  902   a  extending in the axial line and rotatably supported and multiple blades  902   b . The multiple blades  902   b  are arranged along the axial line (in the direction perpendicular to the surface of the paper on which  FIG. 34  is drawn) although only a single blade  902   b  is illustrated in  FIG. 34 . The multiple blades  902   b  arranged along the axial line are fixed to the rotary shaft  902   a.    
     The rotary shaft  902   a  is connected to a drive device outside the toner bottle  901 . As the drive device rotates the rotary shaft  902   a , the multiple blades  902   b  rotate, thereby transporting toner from the rear side to the front side inside the toner bottle  901 . 
     In a front end portion of the toner bottle  901 , a first window  903  for introducing light from outside the toner bottle  901  and a second window  904  for discharging the light outside the toner bottle  901  are formed. The first window  903  faces the second window  904  via an interior of the toner bottle  901  in the direction (on a cross section of the toner bottle  901 ) perpendicular to the axial line thereof. 
     Outside the toner bottle  901 , a light-emitting element  920  faces the first window  903  formed in the toner bottle  901 . Additionally, a light-receiving element  921  faces the second window  904  formed in the toner bottle  901 . The first and second windows  903  and  904  are formed with transparent plastic or transparent glass. 
     The light emitted from the light-emitting element  920  inters the toner bottle  901  through the first window  903 . The light travels inside the toner bottle  901  along the cross sectional plane shown in  FIG. 34 , exits the toner bottle  901  through the second window  904 , and then light-receiving element  921 . The toner supply controller can ascertain the amount of toner remaining in the toner bottle  901  based on the amount of received light. Also in this configuration, whether the toner bottle  901  is empty can be detected without providing the temporary toner reservoir. 
     As described above, the specification of the present invention also provides the following configurations. 
     Configuration 1: A powder container includes a rotatable powder chamber for containing powder and a holder to rotatably hold an end portion of the powder container on one side in the axial direction or longitudinal direction of the powder chamber and configured to transport powder from the other side to the end portion as the powder chamber rotates and discharge the powder from the powder chamber. In this powder container, a window is formed with a light transmissive material in at least a part of the powder chamber in the axial direction thereof to transmit light through the powder chamber in a direction perpendicular to the axial direction. 
     Configuration 2: In configuration 1, the window extends entirely in the direction of rotation of the powder chamber. 
     Configuration 3: In a powder replenishing device that includes the powder container according to configuration 1 or 2 and a conveyance member to transport powder from the powder container to a destination, further a light-emitting element, a light-receiving element, and a powder amount detector are provided. The light-emitting element and the light-receiving element are disposed facing each other via the window in the direction perpendicular to the axial direction. Light emitted from the light-emitting element enters an interior of the powder chamber through the window, travels inside the powder chamber, exits the powder chamber through the window, and is received by the light-receiving element. The powder amount detector is configured to detect the amount of powder remaining in the powder chamber based on the detection result generated by the light-receiving element. 
     Configuration 4: In configuration 3, the window is positioned in the axial end portion received in the holder, and first and second openings are formed in the holder to guide external light into the axial end portion of the powder chamber and guide the light from inside the powder chamber to the outside of the holder. 
     Configuration 5: In configuration 4, the first and second openings are disposed to face each other at a position lower (in the direction of gravity) than the axial line in the holder. 
     Configuration 6: In configuration 5, the powder replenishing device further includes at least two retaining holes formed in the holder and at least two retainers inserted into the respective retaining holes to retain the holder. The two retaining holes respectively serve as the first and second openings to guide light into and out of the holder. 
     Configuration 7: In configuration 6, the retainers are formed with a transparent material. 
     Configuration 8: In a powder container including a powder chamber for containing powder and a powder conveying member to transport by rotation powder inside the powder chamber, two light transmission windows are formed in the powder chamber to guide external light to an interior of the powder chamber and discharge the light from inside the powder chamber. 
     Configuration 9: In a powder replenishing device including the powder container according to configuration 8 and a conveyance member to transport powder from the powder container to a destination, further a light-emitting element, a light-receiving element, and a powder amount detector are provided. The light-emitting element is disposed outside the powder chamber to face one of the light transmission windows, and the light-receiving element is disposed outside the powder chamber to face the other light transmission window. Light emitted from the light-emitting element enters an interior of the powder chamber through the light transmission window, travels inside the powder chamber, exits the powder chamber through the other light transmission window, and is received by the light-receiving element. The powder amount detector is configured to detect the amount of powder remaining in the powder chamber based on the detection result generated by the light-receiving element. 
     Configuration 10: An image forming apparatus includes the toner replenishing device according to any of configurations 1 through 7, or the powder replenishing device according to configuration 9. 
     The above-described configurations 1 to 10 can attain the following effects. 
     According to configurations 1 through 7 and configuration 10, external light directed to the window formed in the powder chamber enters the powder chamber through the window. When the amount of powder in the powder chamber is reduced a certain amount, a part of the light travels inside the powder chamber in the direction perpendicular to the axial direction and exits through the winder outside the powder chamber. In this configuration, when the light-emitting element is disposed facing the light-receiving element via the window in the direction perpendicular to the axial direction, the light-receiving element can receive the light that has been emitted from the light-emitting element and passed through the window and the interior of the powder chamber. Accordingly, the amount of powder remaining in the powder chamber can be detected based on the amount of light received by the light-receiving element. Since the amount of toner remaining in the powder chamber of the powder container not the amount of powder discharged from the powder chamber is detected, the amount of powder remaining in the powder chamber can be detected without providing a temporary reservoir for temporarily storing powder discharged from the powder container. 
     According to configuration 8 and 9, when the light-emitting element and the light receiving-element are disposed facing the respective light transmission windows formed in the powder chamber, the amount of powder remaining in the powder chamber can be detected based on the amount of light received by the light-receiving element after the light emitted from the light-emitting element travels the interior of the powder chamber. Also in this configuration, since the amount of toner remaining in the powder chamber of the powder container is detected, the amount of powder remaining in the powder chamber can be detected without providing a temporary reservoir for temporarily storing powder discharged from the powder container. 
     Numerous additional modifications and variations are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the disclosure of this patent specification may be practiced otherwise than as specifically described herein.