Patent Publication Number: US-9405223-B2

Title: Developing device, image forming apparatus, and process cartridge

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This patent application is based on and claims priority pursuant to 35 U.S.C. §119(a) to Japanese Patent Application No. 2014-121163, filed on Jun. 12, 2014, in the Japan Patent Office, the entire disclosure of which is hereby incorporated by reference herein. 
     BACKGROUND 
     1. Technical Field 
     Embodiments of the present disclosure generally relate to a developing device, a process cartridge, and an image forming apparatus, such as a copier, a printer, a facsimile machine, or a multifunction machine having at least two of coping, printing, facsimile transmission, plotting, and scanning capabilities, that includes a developing device. 
     2. Description of the Background Art 
     New developer stored in the developing device needs to be separate from the developing bearer in time to shipping or carrying. 
     If the new developer is kept contacting to a surface of the developing bearer for a long time, the new developer gets stuck on the developing bearer. 
     SUMMARY 
     So, the cover sheet to separate a developing storing part and the developing bearer is needed to be disposed between the developing storing part and the developing bearer. And after the cover sheet is disposed, the new developer is filled to the developer storing part. Then the developer will be shipped. 
     After a user or service-man receives the developing unit or image forming apparatus with developing device, they will remove the cover sheet and start to use the developing unit or image forming apparatus. 
     A developing device including a developing roller, development casing to store a developer, an opening communicating with a space in where the developing roller is disposed and a developer storing part, a cover sheet covering the opening, and a sheet collecting shaft collecting the cover sheet with rotating before using, is provided. 
     A transmitting mechanism to transmit a force for rotating to the sheet collecting shaft is also provided. 
     The transmitting mechanism does not transmit the force to the collecting shaft after the cover sheet is collected. 
    
    
     
       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. 1A  is a cross sectional view of a developing device before used.  FIG. 1B  is an enlarged perspective view of a developing device. 
         FIG. 2  is view of an image forming apparatus. 
         FIG. 3  is view of a developing part. 
         FIG. 4  is a cross sectional view of the developing device. 
         FIG. 5  is a perspective view of the developing device. 
         FIG. 6  is a developer movement in the developing device. 
         FIG. 7A  is an enlarged side view of one embodiment of the winding force input gear.  FIG. 7B  is an enlarged side view of another embodiment of the winding force input gear. 
         FIG. 8  is an enlarged perspective view of a protrusion of the casing. 
         FIG. 9  is view of a drive communication shutdown system. 
         FIG. 10  is view of a drive communication shutdown system with spring. 
         FIG. 11  is a view indicating a relation between a difference between a diameter of a thrust input gear and an rotating force input gear, and an amount of a bite of the case protrusion to the thrust input gear. 
         FIG. 12A  is a top view of the developing device without the development cover and without the cover sheet.  FIG. 12B  is a top view of the developing device without the development cover and with the cover sheet. 
         FIG. 13  is enlarged perspective view of near a rear side of the developing device. 
         FIG. 14A  is an enlarged perspective view of the developing device added a sheet set boss.  FIG. 14B  is an enlarged upper view of the developing device added a sheet set boss. 
     
    
    
     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. 
       FIG. 2  is a schematic diagram that illustrates a configuration of an image forming apparatus  500  according to the present embodiment, which can be a tandem-type multicolor copier, for example. 
     The image forming apparatus  500  includes a printer unit  100  that is an apparatus body, a document reading unit  4  and a document feeder  3 , both disposed above the printer unit  100 , and a sheet feeding unit  7  disposed beneath the printer unit  100 . The document feeder  3  feeds originals to the document reading unit  4 , and the document reading unit  4  reads image data of the originals. The sheet feeding unit  7  is a sheet container that contains sheets P (transfer sheets) of recording media and includes a sheet tray  26  in which the sheets P are stored and a feed roller  27  to feed the sheets P from the sheet tray  26  to the printer unit  100 . It is to be noted that broken lines shown in  FIG. 2  represent a conveyance path through which the sheet P is transported inside the image forming apparatus  500 . 
     A discharge tray  30  on which output images are stacked is provided on an upper side of the printer unit  100 . The printer unit  100  includes four image forming units  6 Y,  6 M,  6 C, and  6 K for forming yellow, magenta, cyan, and black toner images, respectively, and an intermediate transfer unit  10 . Each image forming unit  6  includes a drum-shaped photoreceptor  1  serving as an image bearer on which a toner image is formed, and a developing device  5  for developing an electrostatic latent image formed on the photoreceptor  1  into the toner image. 
     The intermediate transfer unit  10  includes four primary-transfer bias rollers  9 Y,  9 M,  9 C, and  9 K in addition to an intermediate transfer belt  8 . The intermediate transfer belt  8  serves as an intermediate transfer member onto which the toner images are transferred from the respective photoreceptors  1 , and the toner images are superimposed one on another thereon, thus forming a multicolor toner image. The primary-transfer bias rollers  9  serve as primary-transfer members to primarily transfer the toner images formed on the photoreceptors  1  onto the intermediate transfer belt  8 . 
     The printer unit  100  further includes a secondary-transfer bias roller  19  to transfer the multicolor toner image from the intermediate transfer belt  8  onto the sheet P. Further, a pair of registration rollers  28  is provided to suspend the transport of the sheet P and adjust the timing to transport the sheet P to a secondary-transfer nip between the intermediate transfer belt  8  and the secondary-transfer bias roller  19  pressed against it. The printer unit  100  further includes a fixing device  20  disposed above the secondary-transfer nip to fix the toner image on the sheet P. 
     Additionally, toner containers  11 Y,  11 M,  11 C, and  11 K for containing respective color toners supplied to the developing devices  5  are provided inside the printer unit  100 , beneath the discharge tray  30  and above the intermediate transfer unit  10 . 
       FIG. 3  is an enlarged view of one of the four image forming units  6 . The four image forming units  6  have a similar configuration except the color of toner used therein, and hereinafter the suffixes Y, M, C, and K may be omitted when color discrimination is not necessary. 
     As shown in  FIG. 3 , the image forming unit  6  includes a common unit casing to support the photoreceptor  1  and the developing device  5  and is configured as a modular unit (i.e., a process cartridge) removably installable in the apparatus body of the image forming apparatus  500 . This configuration can facilitate replacement of the developing device  5  in the apparatus body, thus facilitating maintenance work. 
     Additionally, the image forming unit  6  includes a cleaning unit  2 , a charging device  40 , and a lubrication device  41  positioned around the photoreceptor  1  in addition to the developing device  5 . In the image forming unit  6  according to the present embodiment, the cleaning unit  2  employs a cleaning blade  2   a , and the charging device  40  employs a charging roller  4   a.    
     Operations of the image forming apparatus  500  shown in  FIG. 2  to form multicolor images are described below. 
     When users press a start button with originals set on a document table of the document feeder  3 , conveyance rollers provided in the document feeder  3  transport the originals from the document table onto an exposure glass (contact glass) of the document reading unit  4 . Then, the document reading unit  4  reads image data of the original set on the exposure glass optically. 
     More specifically, the document reading unit  4  scans the image of the original with light emitted from an illumination lamp. The light reflected from the surface of the original is imaged on a color sensor via mirrors and lenses. The color sensor reads the multicolor image data of the original for each of decomposed colors of red, green, and blue (RGB), and converts the image data into electrical image signals. Further, the image signals are transmitted to an image processor that performs image processing (e.g., color conversion, color calibration, and spatial frequency adjustment) according to the image signals, and thus image data of yellow, magenta, cyan, and black are obtained. 
     Then, the image data of yellow, magenta, cyan, and black are transmitted to a writing unit (i.e., an exposure device). Then, the exposure device directs laser beams L to the respective photoreceptors  1  according to image data of respective colors. 
     Meanwhile, the four photoreceptors  1  rotate clockwise in  FIGS. 2 and 3 . The surface of the photoreceptor  1  is charged uniformly at a position facing the charging roller  4   a  of the charging device  40  (a charging process). Thus, charge potentials are given to the surface of each photoreceptor  1 . Subsequently, the surface of the photoreceptor  1  thus charged reaches a position to receive the laser beam L. 
     Then, the laser beams L according to the respective color image data are emitted from four light sources of the exposure device. The laser beams pass through different optical paths for yellow, magenta, cyan, and black and reach the surfaces of the respective photoreceptors  1  (an exposure process). 
     The laser beam L corresponding to the yellow component is directed to the photoreceptor  1 Y that is the first from the left in  FIG. 2  among the four photoreceptors  1 . A polygon mirror that rotates at high velocity deflects the laser beam L for yellow in a direction of a rotation axis of the photoreceptor  1 Y (main scanning direction) so that the laser beam L scans the surface of the photoreceptor drum  1 Y. With the scanning of the laser beam L, an electrostatic latent image for yellow is formed on the photoreceptor  1 Y charged by the charging device  40 . 
     Similarly, the laser beam L corresponding to the magenta component is directed to the surface of the photoreceptor  1 M that is the second from the left in  FIG. 2 , thus forming an electrostatic latent image for magenta thereon. The laser beam L corresponding to the cyan component is directed to the surface of the photoreceptor  1 C that is the third from the left in  FIG. 2 , thus forming an electrostatic latent image for cyan thereon. The laser beam L corresponding to the black component is directed to the surface of the photoreceptor  1 K that is the fourth from the left in  FIG. 2 , thus forming an electrostatic latent image for black thereon. 
     Subsequently, the surface of the photoreceptor  1  where the electrostatic latent image is formed is further transported to the position facing the developing device  5 . The developing device  5  contains developer including toner (toner particles) and carrier (carrier particles) and supplies toner to the surface of the photoreceptor  1 , developing the latent image thereon (a development process) into a single-color toner image. 
     Then, the surfaces of the respective photoreceptors  1  reach positions facing the intermediate transfer belt  8 , where the respective primary-transfer bias rollers  9  are provided in contact with an inner circumferential surface of the intermediate transfer belt  8  The primary-transfer bias rollers  9  face the respective photoreceptors  1  via the intermediate transfer belt  8 , thus forming primary-transfer nips, where the single-color toner images are transferred from the respective photoreceptors  1  and superimposed one on another on the intermediate transfer belt  8  (a transfer process). 
     Subsequently, the surface of the photoreceptor  1  reaches a position facing the cleaning unit  2 , where the cleaning blade  2   a  scrapes off toner remaining on the photoreceptor  1  (a cleaning process). 
     Additionally, the surface of each photoreceptor  1  passes through a discharge section facing a discharger, and electrical potentials remaining on the surface of the photoreceptor  1  are removed. Thus, a sequence of image forming processes performed on each photoreceptor  1  is completed, and the photoreceptor  1  is prepared for subsequent image formation. 
     Meanwhile, the intermediate transfer belt  8  carrying the superimposed single-color toner images (a multicolor toner image) transferred from the four photoreceptors  1  rotates counterclockwise in  FIG. 2  and reaches a position facing the secondary-transfer bias roller  19 . 
     Additionally, the feed roller  27  sends out the sheet P from the sheet tray  26 , and the sheet P is then guided by a sheet guide to the registration rollers  28 . The sheet P is caught in the nip between the registration rollers  28  and stopped. Then, the registration rollers  28  forward the sheet P to the secondary-transfer nip, timed to coincide with the multicolor toner on the intermediate transfer belt  8 . 
     In the secondary-transfer nip, the multicolor toner image is transferred from the intermediate transfer belt  8  onto the sheet P (a secondary-transfer process). 
     Subsequently, the intermediate transfer belt  8  reaches a position facing the belt cleaning unit including a belt cleaning blade, where toner remaining on the intermediate transfer belt  8  is collected by the belt cleaning unit. Thus, a sequence of transfer processes performed on the intermediate transfer belt  8  is completed. 
     The sheet P carrying the multicolor toner image is sent to the fixing device  20 . In the fixing device  20 , a fixing belt and a pressing roller are pressed against each other, forming a fixing nip, where the toner image is fixed on the sheet P with heat and pressure (i.e., a fixing process). 
     Then, the sheet P is transported by a pair of discharge rollers  25  and discharged outside the printer unit  100  as an output image onto the discharge tray  30 . Thus, a sequence of image forming processes is completed. 
       FIG. 4  is a cross-sectional view of the developing device  5  according to the present embodiment. The developing device  5  includes a casing  58  to contain developer. The casing  58  includes a lower case  58   a , an upper case  58   b , and a development cover  58   c.    
     The developing device  5  includes a developing roller  50  serving as a developer bearer disposed facing the photoreceptor  1 , multiple developer conveyance members, namely, a supply screw  53  and a collecting screw  54 , a doctor blade  52  serving as a developer regulator, and a partition  57 . The supply screw  53  and the collecting screw  54  may be screw members each including a rotary shaft and a spiral blade winding around the rotary shaft and transport developer in an axial direction by rotating. 
     The partition  57  divides, at least partly, an interior of the casing  58  into a supply channel  53   a  in which the supply screw  53  is provided and a collecting channel  54   a  in which the collecting screw  54  is provided. Additionally, on the cross section (shown in  FIG. 4 ) perpendicular to the axial direction, an end face of the partition  57  faces the developing roller  50  and positioned adjacent to the developing roller  50 . Thus, the partition  57  can also serve as a separator to facilitate separation of developer from the surface of the developing roller  50 . The partition  57  having the separating capability can inhibit the developer that has passed through the development range, carried on the developing roller  50 , from reaching the supply channel  53   a . Thus, the developer is not retained but can move to the collecting channel  54   a.    
     The developing roller  50  includes a magnet roller  55  including multiple stationary magnets and a developing sleeve  51  that rotates around the magnet roller  55 . The developing sleeve  51  is a rotatable, cylindrical member constructed of a nonmagnetic material. The magnet roller  55  is housed inside the developing sleeve  51 . The magnet roller  55  generates, for example, five magnetic poles, first through fifth poles P 1  through P 5 . The first and third poles P 1  and P 3  are south (S) poles, and the second, fourth, and fifth poles P 2 , P 4 , and P 5  are north (N) poles, for example. It is to be noted that bold petal-like lines with reference characters P 1  through P 5  in  FIG. 4  represent density distribution (absolute value) of magnetic flux generated by the respective magnetic poles on the developing sleeve  51  in a direction normal to the surface of the developing sleeve  51 . 
     The developing device  5  contains two-component developer consisting essentially of toner and carrier (one or more additives may be included). The supply screw  53  and the collecting screw  54  transport developer in the longitudinal direction (axial direction of the developing sleeve  51 ), and thus a developer circulation path is established inside the developing device  5 . Additionally, the supply screw  53  and the collecting screw  54  are arranged vertically, and the supply channel  53   a  and the collecting channel  54   a  are divided from each other with the partition  57  disposed between the two developer conveyance members. 
     Additionally, the doctor blade  52  is provided beneath the developing roller  50  in  FIG. 4  and upstream in the direction of rotation of the developing sleeve  51  from the development range where the developing roller  50  faces the photoreceptor  1 . The doctor blade  52  adjusts the amount of developer conveyed to the development range, carried on the developing sleeve  51 . 
     Further, a toner supply inlet  59  is in the developing device  5  to supply toner to the developing device  5  in response to consumption of toner because two-component developer is used in the present embodiment. While being transported, the supplied toner is agitated and mixed with the developer exiting in the developing device  5  by the collecting screw  54  and the supply screw  53 . 
     While being transported, the supplied toner is agitated and mixed with the developer exiting in the developing device  5  by the collecting screw  54  and the supply screw  53 . The developer thus agitated is partly supplied to the surface of the developing sleeve  51  serving as the developer bearer and carried thereon. After the doctor blade  52  disposed beneath the developing sleeve  51  adjusts the amount of the developer, the developer is transported to the development range. In the development range, toner in the developer on the developing sleeve  51  adheres to the latent image formed on the surface of the photoreceptor  1 . 
     The magnet roller  55  provided with the multiple stationary magnets is inside the developing sleeve  51 , and the magnet roller  55  has the multiple magnetic poles P 1  through P 5  for generating magnetic fields around the developing sleeve  51 . 
     For example, the developing device  5  according to the present embodiment is filled with 300 g of developer in which toner particles, including polyester resin as a main ingredient, and magnetic carrier particles are mixed uniformly so that the concentration of toner in developer is about 7% by weight. The toner has an average particle diameter of about 5.8 μm, and the magnetic carrier has an average particle diameter of about 35 μm. The supply screw  53  and the collecting screw  54  arranged in parallel are rotated at a velocity of about 600 revolutions per minute (rpm), thereby transporting the developer while mixing toner and carrier and charging the toner. 
     Additionally, toner supplied through the toner supply inlet  59  is agitated in the developer by rotating the supply screw  53  and the collecting screw  54  to make the content of toner in the developer uniform. 
     While being transported in the longitudinal direction by the supply screw  53  positioned adjacent to and parallel to the developing sleeve  51 , the developer in which toner and carrier are mixed uniformly is attracted by the fifth pole P 5  of the magnet roller  55  inside the developing sleeve  51  and carried on the outer circumferential surface of the developing sleeve  51 . The developer carried on the developing sleeve  51  is transported to the development range as the developing sleeve  51  rotates counterclockwise as indicated by an arrow shown in  FIG. 4 . 
     The developing sleeve  51  receives voltage from a high-voltage power source, and thus a development field (electrical field) is generated between the developing sleeve  51  and the photoreceptor  1  in the development range. With the development field, toner in developer carried on the surface of the developing sleeve  51  is supplied to the latent image formed on the surface of the photoreceptor  1 , developing it. 
     The developer on the developing sleeve  51  that has passed through the development range is collected in the collecting channel  54   a  as the developing sleeve  51  rotates. Specifically, the developer falls from the developing sleeve  51  to an upper face of the partition  57 , slides down the partition  57 , and then is collected by the collecting screw  54 . 
       FIG. 6  is a schematic diagram illustrating movement of developer in the longitudinal direction (axial direction) inside the developing device  5 . In  FIG. 6 , outlined arrows indicate the flow of developer in the developing device  5 . Although the partition  57  is not shown in  FIG. 6  for simplicity, openings (a developer-falling opening  71  and a developer-lifting opening  72 ) are in end portions of the partition  57  in the longitudinal direction of the developing device  5 , thus forming communication portions between the supply channel  53   a  and the collecting channel  54   a.    
     As shown in  FIG. 6 , at the downstream end of the supply channel  53   a  in the direction in which the developer is transported (hereinafter “developer conveyance direction”) by the supply screw  53 , developer is transported up through the developer-lifting opening  72  in the partition  57  to the upstream end the collecting channel  54   a  in the developer conveyance direction therein. By contrast, at the downstream end of the collecting channel  54   a  in the developer conveyance direction by the collecting screw  54 , developer is transported through the developer-falling opening  71  in the partition  57  to the upstream end of the supply channel  53   a  in the developer conveyance direction therein. 
     It is to be noted that, although the supply channel  53   a  and the collecting channel  54   a  are illustrated as if they are away from each other in  FIG. 6 , it is intended for ease of understanding of supply and collection of developer from the developing sleeve  51 . The supply channel  53   a  and the collecting channel  54   a  are separated by the planar partition  57  as shown in  FIG. 4 , and the developer-falling opening  71  and the developer-lifting opening  72  are through holes in the partition  57 . 
     As shown in  FIG. 6 , developer inside the supply channel  53   a  beneath the collecting channel  54   a  is scooped by the surface of the supply screw  53  while being transported in the longitudinal direction by the supply screw  53 . At that time, developer can be scooped by the surface of the developing sleeve  51  by the rotation of the supply screw  53  as well as the magnetic force exerted by the fifth pole P 5  (shown in  FIG. 4 ), serving as a developer scooping pole. Then, the developer carried on the developing sleeve  51  passes through the development range, is separated from the developing sleeve  51 , and transported to the collecting channel  54   a . At that time, developer is separated from the surface of the developing sleeve  51  by the magnetic force exerted by a developer release pole constructed of the fourth and fifth magnetic poles P 4  and P 5  having the same polarity (N) and being adjacent to each other and the separating capability of the partition  57 . 
     In the developing device  5 , the fourth and fifth poles P 4  and P 5  (i.e., the developer release pole) generate a repulsive magnetic force. The developer transported to the area in which the repulsive magnetic force is generated (i.e., a developer release area) is released by the developer release pole in a direction of composite of a normal direction and a direction tangential to the rotation of the developing sleeve  51 . Then, the developer falls under the gravity to the partition  57  and is collected by the collecting screw  54 . 
     The collecting screw  54  in the collecting channel  54   a , which is above the supply channel  53   a , transports the developer separated from the developing sleeve  51  in the developer release area axially in the direction opposite the direction in which the supply screw  53  transports the developer. 
     Through the developer-lifting opening  72 , the downstream end of the supply channel  53   a  in which the supply screw  53  is provided communicates with the upstream end of the collecting channel  54   a  in which the collecting screw  54  is provided. The developer at the downstream end of the supply channel  53  accumulates there and pushed up by the developer transported from behind. Then, the developer moves through the developer-lifting opening  72  to the upstream end of the collecting channel  54   a.    
     The toner supply inlet  59  is in the upstream end portion of the collecting channel  54   a , and fresh toner is supplied as required by a toner replenishing device from the toner container  11  (shown in  FIG. 2 ) to the developing device  5  through the toner supply inlet  59 . The upstream end of the supply channel  53   a  communicates with the downstream end of the collecting channel  54   a  via the developer-falling opening  71 . The developer transported to the downstream end of the collecting channel  54   a  falls under its own weight through the developer-falling opening  71  to the upstream end portion of the supply channel  53   a.    
     The developer is supplied to the developing roller from the supply channel and the developer passed developing area is collected to the collecting channel in the developing device  5  divided the supply channel  53   a  and the collecting channel  54   a.    
     In this system, the developer supplied to the developing roller does not return to the supply channel, and the developer is collected to the collecting channel. The developing device having this system is called ‘one way circulation developing device’. 
     As described above, the supply screw  53  and the collecting screw  54  rotate in the directions shown in  FIG. 4 , and developer is attracted to the developing sleeve  51  by the magnetic attraction exerted by the magnet roller  55  contained in the developing sleeve  51 . Additionally, the developing sleeve  51  is rotated at a predetermined velocity ratio to the velocity of the photoreceptor  1  to scoop up the developer to the development range consecutively. 
       FIGS. 1A and 1B  show the developing device before used by user served as new-developing device.  FIG. 1A  is a cross-sectional view of the developing device  5 , and  FIG. 1B  is an enlarged perspective view of the developing device of the end side of axis direction. The developer is stored in the supply channel  53   a  and the collecting channel  54   a  of the new-developing device. 
     The developing device includes a supply opening linking the developing roller  50  and inner of the supply channel  53   a , a collecting opening linking the developing roller and inner of the collecting channel  54   b , and a cover sheet  70  covering the supply channel  53   a  and the collecting channel  54   b.    
     The developing device includes a sheet collecting shaft  703  to which an end of the cover sheet is fixed, and a cover sheet storing part  705  that include the sheet collecting shaft inside. Before image forming process, the sheet collecting shaft  703  wind the cover sheet  70  with rotating. Then the cover sheet  70  is removed from the supply opening  53   b  and the collecting channel  54   b , and is collected to the cover sheet storing part  705 . After the cover sheet is collected, the developer stored the supply channel  53   b  and the collecting channel  54   b  is released to the developing roller to ready to develop. 
     Referring to  FIG. 1A , a sponge seal member  706  is disposed at the boundary part between the collecting channel  54   a  and the cover sheet storing part  705 . The cover sheet  70  through the boundary. The sponge is sealing the gap of the boundary part. The developer in the collecting channel  54   a  is prevented to enter to the cover sheet storing part  705 , by the sponge seal member  706   
     Referring to  FIG. 1B , a winding drive force input gear  710  is disposed at the end part of the sheet collecting shaft  703 . A shaft holder  704  prevent the sheet collecting shaft  703  from moving away from correct position. 
     When the developing device drive, a driving power is input to a developing driving member. The sheet collecting shaft is rotated by the driving power from the collecting screw gear serving as the developing driving member. Then the sheet collecting shaft  703  collect the cover sheet  70  to the cover sheet storing part. 
     The arrows A through D in  FIG. 1  describe rotating direction of the developing sleeve  51 , the supply screw  53 , collecting screw, and the sheet collecting shaft  703 , when the driving power is inputted to the developing device  51 . 
       FIG. 7A  is expansion side view of the winding force input gear  710 . The winding force input gear  710  is two-stage gear. A first stage of the winding force input gear  710  is an rotation force input gear  701  includes a spur gear inputted the force from the gear of the collecting screw  54 . 
     A second stage of the winding force input gear  710  is thrust input gear  702  includes worm. And the thrust input gear is rotating with the input gear  710 . It is possible to use a helical gear as the rotation force input gear  701  (see  FIG. 7B ). The worm used for the thrust input gear  702  is a screw gear which can be composed the worm gear by combing with a worm wheel. The winding force input gear  710  is fixed to direction of the perpendicular to the axis of the sheet collecting shaft  703 . However the winding force input gear  710  can move to direction of parallel to the axis of the sheet collecting shaft  703  (thrust direction). 
     Referring  FIG. 5 , the near side end of the supply screw  53   f  protrudes from the near side end face of the casing  58  of the developing device  5 . 
     A supply screw output gear  53   c  is at the near side end of a supply screw shaft  53   f.    
     A near side end of a collecting screw shaft  54   f  which is shaft of the collecting screw  54  protrudes from the near ide end face of the casing  58 . A collecting screw input gear  54   c  at the near side end of a collecting screw shaft  54   f . The collecting screw input gear  54   c  and the supply screw output gear  53   c  is meshing. 
     Referring to  FIG. 1B , a collecting screw output gear  54   d  is on the collecting screw shaft. A diameter of the collecting screw output gear is larger than the collecting screw input gear  54   c . In this embodiment, the collecting screw input gear  54   c  and the collecting screw output gear  54   d  is integrally formed two-stage gear. Before the cover sheet is wound up, the collecting output gear  54   d  and the rotation force input gear  701  is meshing. 
     When the developing device  5  is installed to image forming apparatus  500 , the force to rotate is inputted there into. The force to rotate is communicated to the developing sleeve  51  and the supply screw  53 . Then the developing sleeve  51  and the supply screw  53  rotate to a counterclockwise direction as an arrow B in  FIG. 1A . When the supply screw rotates, the supply screw output gear  53   c  fixed at the supply screw shaft rotates, and the collecting screw input gear meshed the supply screw output gear rotates. Since the collecting screw input gear  54   c  rotates, the collecting screw rotates to a clockwise direction as arrow C in  FIG. 1A , and the collecting screw output gear  54   d  rotates. When the collecting screw output gear  54   d  rotates, a winding force input gear  710  with the input gear  700  which is meshed with the collecting screw output gear  54   d , and the sheet collecting shaft  703 , fixed to direction of the perpendicular to the axis of the sheet collecting shaft  703 , rotates. 
     As shown in  FIG. 1B , the casing of the developing device has a case protrusion  709  protruding from the surface of the casing  58 , so that the case protrusion  709  meshes with a groove of the thrust input gear  702 .  FIG. 8  is an enlarged perspective view around the case protrusion  709 .  FIG. 9  is a side view of a drive communication shutdown system  700 , and describe a positional relation of the thrust input gear  702  and the case protrusion  709 . 
     Referring to  FIG. 9 , before the developing device  5  is used, the case protrusion  709  meshes with the groove of the thrust input gear  702  at a position which has a distance (Ls; described in  FIG. 9 ) from the near side end of the thrust input gear  702 . The winding force input gear is not fixed to the sheet collecting shaft  703 . However the winding force input gear is not able to move to thrust direction, because the case protrusion  709  contacts a thread of the thrust input gear  702 . The winding force input gear  710  is prevented from moving to the thrust direction before the force to rotate is inputted. 
     When the driving force is inputted from the image forming apparatus  500  to the developing device  5 , the sheet collecting shaft  703  rotates to the direction of arrow D in  FIG. 9 , with the winding force input gear  710 . The case protrusion  709  is engaged with the groove of the thrust input gear  702 . When the thrust input gear  702  rotates to direction of arrow E in  FIG. 9 , a force toward the thrust direction as arrow E in  FIG. 9 , is acting to the thrust input gear  702 . And then the winding force input gear  710  including the thrust input gear  702 , moves to the direction of arrow D in  FIG. 9 . 
     When the winding force input gear  710  moves to the thrust direction, a position of the rotation force input gear  701  relative to axis direction of the collecting screw output gear changes, and the rotation force input gear  701  is released from the collecting input gear  54   d . When the each gear is released, the communication of rotating force is cut and winding operation by the sheet collecting shaft is stopped. Thus in the developing device  5  of the embodiment, the drive communication shutdown system  700  is compounded by the winding force input gear  710  includes rotation force input gear  701  and the thrust input gear  702 , and the case protrusion  709 . 
     In the embodiment described in  FIG. 9 , thrust movement distance (LS) is longer than a length of a thrust direction length of the input gear (Lr). The thrust movement distance (LS) is a length from a contact point (engage point), where the case protrusion  709  contacts the thrust input gear  702  before the force is inputted, to an end part of the opposite side (right hand side in  FIG. 9 ) of the movement direction by rotating of the thrust input gear. A length of a thrust direction length of the input gear (Lr) is a length from a contact point, where an end part of the movement direction (left hand side in  FIG. 9 ) of the collecting screw output gear contacts the rotation force input gear  701 , to an end part of the movement direction by rotating of the collecting output gear. 
     Since the thrust movement distance (LS) is longer than a length of a thrust direction length of the input gear (Lr), the winding force input gear  710  moves to thrust direction (left hand side in  FIG. 9 ) by rotational inertia of the itself, after the rotation force input gear  701  is released from the collecting screw output gear  54   d . After the rotation by the inertia is stopped, the winding force input gear  710  is not able to move to thrust direction (right hand side in  FIG. 9 ), because the case protrusion  709  contacts the thread of the thrust input gear  702 . Therefore, the re-contacting of the collecting screw output gear  54   d  and rotation force input gear  701  is prevented. 
     A real loft angle is 15 degrees or more, and at the time of defining a club length as L (inches), head volume as W (cc) and the real loft angle as R (degrees), the following expression (A) is satisfied 
     At that time of defining the moving distance to the thrust direction of the thrust input gear  702  per one rotation as ‘lead Pi’, it is prefer to satisfy the following expression (1).
 
thrust movement distance ( LS )−a length of a thrust direction length of the input gear ( Lr )&lt;‘rotation number of the winding force input gear 710 by rotational inertia’ multiply ‘lead  Pi’   (1)
 
     When the expression (1) is satisfied, the thrust input gear is released from the case protrusion after winding process, and the case protrusion acts as a stopper which prevent the winding force input gear  710  from moving to the thrust direction (right hand direction in  FIG. 9 ). Therefore the re-contacting of the collecting screw output gear  54   d  and rotation force input gear  701  by the driving vibration of the image forming apparatus  500  is prevented more certainly. 
       FIG. 10  is side view of the other embodiment that the spring member  708  pulling the winding force input gear  710  toward the side of the moving thrust direction by a rotation, is added to the drive communication shutdown system  700 . In  FIG. 10 , the winding force input gear  710  is pulled by the spring member  708  toward the left hand side of  FIG. 10  even before the force is inputted. However the case protrusion  709  contacts with the thread of the thrust input gear  702  and the winding force input gear  710  does not move to the thrust direction. 
     When the driving force is inputted and the winding force input gear  710  moves to thrust direction (left hand side of  FIG. 10 ), the thrust direction end part of the thrust input gear pass through the case protrusion  709 . Then the winding force input gear  710  does not contact the case protrusion  709  and the winding force input gear  710  moves to the thrust direction (left side of  FIG. 10 ) by pulling force of the spring member. 
     As shown in  FIG. 10 , the thrust movement distance (LS) may be shorter than a length of a thrust direction length of the input gear (Lr), if a support of the moving of the thrust direction by the spring member  708  is added as shown in  FIG. 10 . 
     In this embodiment, after the thrust input gear  702  is released from the case protrusion, the rotation force input gear  701  is released from the collecting screw output gear, and the winding operation of the cover sheet is stopped. 
     If the force of the thrust direction by the spring member is added, the malfunction caused by the supporting of the spring member  708  is not occurred because of characteristics of the worm of the thrust input gear. 
     At that time of defining the winding amount needed to remove the cover sheet as winding amount (M), a diameter of the winding point of the sheet collecting shaft  703  as winding diameter (D) and the circular constant as ‘π’. It is preferable to satisfy the following expression (2).
 
thrust movement distance ( LS )/‘lead  Pi ’≧winding amount ( M )/(winding diameter ( D )×π)  (2)
 
     When the expression (2) is satisfied, the winding operation of the cover sheet  70  is stopped, after the cover sheet  70  is completely winded. 
       FIG. 11  is a view indicating a relation between the difference between the diameter of the thrust input gear  702  and the rotation force input gear  701 , and an amount of the bite of the case protrusion  709  to the thrust input gear  702 . 
     As shown in  FIG. 9  and  FIG. 10 , a moving direction of the thrust input gear by rotating itself is direction where rotation force input gear  701  faces thrust input gear  702  side. In this embodiment, at that time of defining a radius of a tooth tip circle of the thrust gear  702  as thrust input gear radius (Rs), the amount of the bite of the case protrusion  709  to the thrust input gear  702  as protruding biting amount (T) and a tooth tip circle of the rotation force input gear  701  as input gear radius (Rr). It is prefer to satisfy the following expression (3).
 
thrust input gear radius ( Rs )−protruding biting amount ( T )&gt;input gear radius ( Rr )  (3)
 
     When the expression (3) is satisfied, it is prevented that the rotation force input gear  701  moved to thrust direction contacts the case protrusion  709 . And the winding operation of the cover sheet  70  is stopped certainly. 
       FIGS. 12A and 12B  are top views of the developing device  5  without the development cover  58   c  as upper cover. It is a view indicating relation between the length of the axis direction of the cover sheet  70  and the casing  58  of the developing device  5 .  FIG. 12A  is view of the developing device without the cover sheet  70 .  FIG. 12B  is view of the developing device  5  with the cover sheet. 
     As shown in  FIGS. 12A and 12B , among the two side plates that form short side part of the both sides of the casing  58 , the one that is disposed at right side of the  FIG. 12  (the front side of the  FIG. 1A ) is a front side plate  58   f , and another side one that is disposed at left side of the  FIG. 12  (the rear side of the  FIG. 1B ) is a rear side plate  58   r.    
     A length of a place where the cover sheet cover the supply opening  53   b  and the collecting opening  54   b , in other words, between an inner wall of the front side plate  58   f  and rear side plate  58   r  that is disposed along the surface of the developing roller  50 , of an axis direction is defined a first casing distance Cs. 
       FIG. 13  is enlarged perspective view of near the rear side plate  58   r  of the developing device shown  FIG. 12B . In  FIG. 13 , a part hidden by the cover sheet  70  is described by a broken line.  FIG. 13  describes the part where the axial distance between inner wall of the front side plate  58   f  and the rear side part  58   r  is the first casing distance Cs is being illustrated. 
     The cover sheet is inserted at the part where the axial distance between inner wall of the front side plate  58   f  and the rear side part  58   r  is a first casing distance Cs. Therefore a developer leaking to the developing roller  50  from the supply channel  53   a  and the collecting channel  54   a  is prevented. In such a case, preferably, the cover sheet  70  covers the whole the developing roller  50  surface that faces the supply channel  53   a  and the collecting channel  54   a  as shown in  FIG. 1A . 
     The axis direction distance between the inner wall of the front side plate  58   f  and the rear side plate  58   r  at the cover sheet storing part  705  in where the sheet collecting shaft  703  is disposed, is defined as a second casing distance Cl. A width of the cover sheet  70  of a part that covers the supply opening  53   b  and collecting opening  54   b  (including lower end  70   a ) before the winding operation starts, is defined as a cover sheet width Ss. 
     A width of the cover sheet of a part including a part fixed to the sheet collecting shaft before the winding operation starts, is defined as a sheet root width Sl. 
     And the developing device  5  is set to be satisfied a following expression.
 
 Cl≧Sl&gt;Cs≧Ss   (4)
 
     Since the cover sheet width Ss is set so as to be shorter than the first casing distance Cs, the cover sheet can be disposed along the surface of the developing roller  50 . The sheet root width Sl is set so as to be larger than the first casing distance Cs, and the end part of the axis direction of the cover sheet  70  is sandwiched by the upper surfaces of the front side plate  58   f  and the rear side plate  58   r , and lower surface of the development cover  58   c.    
     At the upper surfaces of the front side plate  58   f  and the rear side plate  58   r , a step part is disposed between the inner surfaces forming the first casing distance Cs and an inner surface forming the second casing distance Cl. 
     As shown in  FIG. 12B  and  FIG. 13 , a broad end part of the sheet  70   b  where the more outside part than the cover sheet width Ss in the axis direction at the sheet root width Sl of the cover sheet  70 , is disposed at the step part. 
     The broad end part of the sheet  70   b  is sandwiched between the step parts at the front side plate  58   f  and rear side plate  58   f , and an end part of an axial direction of the development cover  58   c  reserved as axis direction casing that forms a part of the wall of the collecting channel  54   a  and elongated to the axis direction. 
     In the above embodiment, the broad end part of the sheet  70   b  is sandwiched between the upper surfaces of the front side plate  58   f  and rear side plate  58   r , and the lower surface of the development cover  58   c . The cover sheet is kept in a state as shown in  FIG. 1A . 
     The cover sheet can be disposed along the lower part of the development cover  58   c  that is a ceiling of the collecting channel  54   a , and the surface of the developing roller  50 . 
     As the cover sheet  70  is disposed along the lower surface of the development cover  58   c  by near the developing roller  50 , forming a gap between the lower surface of the developing cover  58   c  and the upper surface of the cover sheet  70  is prevented. 
     In this embodiment forming a gap between the lower surface of the developing cover  58   c  and the upper surface of the cover sheet  70  is prevented. And the developer passed through the gap of the end part of the axis direction of the cover sheet prevented from moving to the next gap. 
     Therefore, if the developer enters the gap of the end part of the axis direction of the cover sheet, it is clogged at the gap. The new developer is prevented from entering the gap. Remaining the developer at the gap between the cover sheet  70  and the development cover  58   c  is prevented. And forming the agglomerate and an abnormal image caused by the agglomerate is prevented. 
     The second casing distance Cl is set so as to be wider than the sheet root width Sl and the first casing direction Cs as shown the expression (4). Since the setting, a part of the cover sheet where it is wider than the first casing distance Cs, is collecting easily. 
       FIGS. 14A and 14B  are views of the developing device  5  added a sheet set boss  80  at the upper surfaces of the front side plate  58   f  and the rear side plate  58   r .  FIG. 14A  is an enlarged perspective view of the near the rear side plate with a sheet set boss  80 .  FIG. 14B  is an enlarged upper view of the near the rear side plate with the sheet set boss  80 . The sheet set boss  80  is a protrusion. 
     In the developing device shown in the  FIG. 14B , a boss opening  70   c  (a protrusion opening) penetrated by the sheet set boss  80  is disposed at the broad end part of the sheet  70   b.    
     In the developing device  5  shown in  FIGS. 14A and 14B , since the sheet set boss disposed at the casing  58  is penetrated the boss opening  70   c , the cover sheet is positioned and an assembling efficiency can be improved. 
     Even if a vibration is transmitted to the developing device  5  when it is transported, the cover sheet can keep the position as shown  FIG. 1A . 
     In this embodiment, the sheet set boss  80  is disposed at the upper surface of the front side plate  58   f  and rear side plate  58   r . However, a protrusion like the sheet set boss may be disposed at the lower surface of the development cover  58   c.    
     In  FIG. 14B , the cover sheet moves toward the under direction of  FIG. 14B , when the cover sheet is winded. An angle of an acute angle is disposed at an upper stream (upper direction of  FIG. 14B ) of the moving direction of the coversheet moved to the under direction of  FIG. 14B , of the sheet set boss  80 . 
     This angle cuts the cover sheet  70 . When the cover sheet  70  is winded, an upstream of the boss opening  70   c  part of the moving direction of the broad end part of the sheet  70   b , is prevented from remaining and is cut easily. 
     Therefore, a shape to hook the part of the cover sheet  70  to the sheet set boss, does not prevent the winding operation. 
     The upstream of the boss opening  70   c  part (upper side of  FIG. 14A ) of the moving direction of the cover sheet  70 , may have a slit or an assisting part to assist cutting. 
     In the above embodiment, when the cover sheet moves to the direction of the winded by the sheet collecting shaft  703 , the edge of the boss opening  70   c  contacted to the sheet set boss  80  is cut easily. 
     And, when the cover sheet  70  is winded, a frictional resistance between the cover sheet  70  and the sheet set boss  80  is restrained. A malfunction (i.e., the developing device is broken by shock) is prevented, when the cover sheet is stocked. 
     For example, assist processing to assist cutting is MAGIC CUT (Trade Mark). 
     As shown in  FIG. 14B , in a moving direction of the cover sheet, a shape of a downstream part (below side of  FIG. 14B ) of the sheet set boss  80  is formed as curved shape. In this case, the cover sheet part that contacts the curved part, is prevented from cutting. And the cover sheet  70  is prevented from passing through to opposite side (upper side of  FIG. 14B ) 
     As shown in  FIG. 1A , the developing device  5  has a vent opening  580  that communicates the outside and collecting channel  54   a  and air can pass through the vent opening  580 . Furthermore the developing device  5  has a cover filter  523  preventing from passing the developer through the vent opening  580 . In this embodiment, the vent opening prevents an increasing pressure of the developing device  5 . The cover filter  523  prevents toner leaking from developing device  5  through the vent opening  580 . 
     The cover sheet  70  shuts between the developer in the collecting channel  54   a  and the cover filter  523 , before the winding operation starts as shown in  FIG. 1A . Therefore before the developing device  5  is used, the developer is prevented to contact the cover filter  523 . A clogging of the cover filter  523  is prevented, and the service life of the cover filter  523  will be prolonged. 
     The winding operation is proceeded, before starting an initial process when the developing device is mounted to the image forming apparatus. Therefore a process that the serviceman or user pulls the cover sheet  70  is not needed, and a time of initial install process will be short. 
     Since the winding operation is automatic, malfunction by forgetting to remove the cover sheet is prevented, and usability is improved. 
     The sheet collecting shaft  703  winds the cover sheet  70  and moves the cover sheet  70  to a perpendicular direction of the rotation axis of the developing roller. 
     In this embodiment, the developing device is able to shut the developer to developing roller  50 , and to wind the cover sheet  70  automatically. To dispose the cover sheet  70  is simple, so the cover sheet is prevented from breaking. 
     The system, that after the cover sheet  70  is removed, in which transmitting force to the sheet collecting shaft is stopped, can be applied to a system that the cover sheet moves to a direction of parallel to the rotation axis by the winding operate. 
     In this embodiment, the developing device  5  is a one way circulation developing device, and a plurality of developer convey channels are connected via openings, the openings are covered by a cover sheet  70 . 
     The system winding the cover sheet automatically and stopping transmit of the rotation force to the sheet collecting shaft  703  after the cover sheet is removed, is not limited to the system from which a plurality of openings are covered by a cover sheet. 
     For example, the system described in patent of JP 4341957 can use the system winding the cover sheet automatically and stopping transmit of the rotation force to the sheet collecting shaft after the cover sheet is removed. 
     The system winding the cover sheet automatically and stopping transmit of the rotation force to the sheet collecting shaft after the cover sheet is removed can be used for the system the cover sheet is fixed to the casing, for example a system described in patent JP 4341957.