Patent Publication Number: US-9429895-B2

Title: Cleaning device and image forming apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority to and incorporates by reference the entire contents of Japanese Patent Application No. 2014-029510 filed in Japan on Feb. 19, 2014 and Japanese Patent Application No. 2014-134341 filed in Japan on Jun. 30, 2014. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a cleaning device and an image forming apparatus such as a copier, a printer, a facsimile, or a multifunction peripheral having two or more of the functions of the copier, the printer, and the facsimile and is provided with the cleaning device. 
     2. Description of the Related Art 
     In an image forming apparatus such as a copier, a printer, a facsimile, or a multifunction peripheral including two or more of the functions of the copier, the printer, and the facsimile, the toner is left behind on the surface of a photoconductor or an intermediate transfer belt that are examples of a member to be cleaned, after the toner is transferred onto a transfer sheet. 
     A cleaning device is provided in the image forming apparatus to remove such remaining substances from the surface of the member to be cleaned. Some cleaning devices include a cleaning member for removing the remaining substances from the surface of the member to be cleaned, and a conveying member for conveying the removed remaining substances outside of the cleaning device. 
     According to the disclosure in Japanese Patent Application Laid-open No. 2004-101816, once transfer is completed, a cleaning blade  201 , a cleaning brush  202 , and a brush roller  203  abutting against a cleaned body  200  scrape off the toner T remaining on the surface of the cleaned body  200 , as illustrated in  FIG. 15 . The scraped toner T is conveyed from the cleaning blade  201  to the brush roller  203 , and conveyed further to the cleaning brush  202 . 
     A flicker  204  abutting against the cleaning brush  202  flicks off the toner T remaining in the cleaning brush  202  from the cleaning brush  202  into a waste toner conveying coil  205 , and the waste toner conveying coil  205  conveys the toner outside of the cleaning device. 
     A partitioning member  206  is positioned between the cleaning brush  202  and the waste toner conveying coil  205 . When the flicker  204  flicks the toner T off from the cleaning brush  202 , the partitioning member  206  prevents the toner T having not reached the waste toner conveying coil  205  from flying away and being scattered again on the cleaned body  200  and the like. This structure allows the cleaning device to remove more toner from the cleaned body  200 . 
     With the invention disclosed in Japanese Patent Application Laid-open No. 2004-101816, however, the toner T flicked by the flicker  204  may fly away to directions other than the waste toner conveying coil  205 , and land on the surface of the cleaned body  200  again without reaching the partitioning member  206 , so that the toner T is not collected very efficiently. 
     In view of the above-mentioned problem, there is a need to provide a cleaning device capable of cleaning the toner and the like on the surface of the cleaned body more efficiently. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to at least partially solve the problems in the conventional technology. 
     According to the present invention, there is provided a cleaning device comprising: a member to be cleaned having a surface that moves; a cleaning member that cleans the surface of the member to be cleaned; a conveying member that conveys a substance removed from the surface of the member to be cleaned by the cleaning member to outside of the cleaning device; a collecting member that is rotatably configured, has a surface for carrying the substance, and conveys the substance toward the conveying member; and a partitioning member that guides the substance from the collecting member to the conveying member, the collecting member comprising: a conveying portion that carries and conveys the substance; a holding portion that holds the conveying portion; and a protrusion that protrudes toward an upstream side of the conveying portion in a rotating direction of the collecting member, wherein the partitioning member is placed in such a manner that one end of the partitioning member faces the rotating collecting member, and the other end faces the conveying member, and the conveying portion and the protrusion of the collecting member are brought into contact with the partitioning member by the rotation of the collecting member. 
     The present invention also provides an image forming apparatus comprising the above-mentioned cleaning device 
     The above and other objects, features, advantages and technical and industrial significance of this invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic illustrating a general structure of an image forming apparatus according to an embodiment of the present invention; 
         FIG. 2  is a cross-sectional view illustrating a general structure of a cleaning device according to a first embodiment of the present invention; 
         FIG. 3  is a schematic illustrating how the toner is collected in the cleaning device; 
         FIG. 4  is a schematic of a cleaning device according to a second embodiment of the present invention; 
         FIG. 5  is comparative schematic of a partitioning member according to the first embodiment and that according to the second embodiment; 
         FIG. 6  is a schematic of a cleaning device according to a third embodiment of the present invention; 
         FIG. 7  is a schematic illustrating an end of a collection vane according to the third embodiment; 
         FIG. 8  is a schematic of a cleaning device according to a fourth embodiment of the present invention; 
         FIG. 9  is a schematic diagram of the cleaning device according to the fourth embodiment; 
         FIG. 10  is a schematic of a cleaning device according to a fifth embodiment of the present invention; 
         FIG. 11  is a schematic illustrating a general structure of a cleaning device according to a sixth embodiment of the present invention; 
         FIGS. 12A and 12B  are schematics illustrating a general structure of a cleaning device according to a seventh embodiment of the present invention; 
         FIG. 13  is a schematic illustrating a general structure of a cleaning device according to an eighth embodiment of the present invention; 
         FIGS. 14A and 14B  are schematics illustrating a general structure of a cleaning device according to a ninth embodiment of the present invention; and 
         FIG. 15  is a schematic illustrating a general structure of a conventional cleaning device. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Some embodiments of the present invention will now be explained with reference to some drawings. In the drawings, the same or equivalent portions are assigned with the same reference numerals, and redundant explanations thereof are simplified or omitted as appropriate. 
     As illustrated in  FIG. 1 , an image forming apparatus  1  includes an image reading unit  2 , an image forming unit  3 , a transfer unit  4 , a sheet feeding unit  5 , a fixing unit  6 , and an ejecting unit  7 . 
     The image reading unit  2  includes a contact glass  21  on which an original is placed, a reading carriage  24  provided with a light source  22  and an optical path conversion reflecting mirror  23  for reading an image of the original G placed on the contact glass  21 , a reading optical system  25  including a lens transmitting reflected light from the original, the reflected light being formed by the reading carriage  24 , and an optical element  26  such as a charge-coupled device (CCD) on which the light transmitted through the reading optical system  25  becomes incident and that reads the incident light as an image signal. 
     The image forming unit  3  is positioned below the image reading unit  2 , and includes a process cartridge  31  that is removably mounted on the image forming apparatus  1 . The process cartridge  31  includes a photoconductor  32  being a member to be cleaned of which surface can carry toner, a charging roller  33  that charges the surface of the photoconductor  32  uniformly, a developing unit  34  that supplies toner to the surface of the photoconductor  32 , and a cleaning device  35  for cleaning the surface of the photoconductor  32 . 
     A writing unit  36  is positioned on the left side of the process cartridge  31  in  FIG. 1 , at a position enabled to irradiate the photoconductor  32  with a laser. 
     The transfer unit  4  is positioned adjacent to the process cartridge  31  in  FIG. 1 . The transfer unit  4  includes an endless belt  43  rotatably stretched across a driving roller  41  and a driven roller  42 , and a facing roller  44  positioned facing the photoconductor  32  with the belt  43  positioned therebetween. The facing roller  44  is pressed against the internal circumferential surface of the belt  43 , thereby forming a transfer nip with the photoconductor  32 , at a position where the pressed portion of the belt  43  is brought into contact with the photoconductor  32 . 
     The sheet feeding unit  5  is positioned at the bottom of the image forming apparatus  1 , and includes a sheet feeding cassette  51  storing therein recording sheets P serving as recording media, and a sheet feeding roller  52  for feeding the recording sheets P from the sheet feeding cassette  51 . 
     A conveying path Y for guiding a recording sheet P from the sheet feeding unit  5  to the ejecting unit  7  is provided with its most upstream end positioned at the sheet feeding unit  5 . In addition to a registration roller pair  53 , conveying roller pairs not illustrated are provided as appropriate along the conveying path Y leading to the ejecting unit  7 . 
     The fixing unit  6  includes a fixing roller  61  including an internal heat source, and a pressing roller  62  capable of pressing the fixing roller  61 . 
     The ejecting unit  7  is positioned on the most downstream side of the conveying path Y in the image forming apparatus  1 . Disposed in the ejecting unit  7  are a sheet ejection roller pair  71  for ejecting the recording sheet P to the outside, a sheet ejection sensor  72  for detecting passage of the recording sheet P, and a sheet ejection tray  73  for storing the ejected recording sheet P. 
     A basic operation of the image forming apparatus  1  will now be explained with reference to  FIG. 1 . 
     As the image reading unit  2  reads an original, the image information of the original read by the optical element  26  is output to a control unit (not illustrated) and digitized. 
     Based on the image information from the control unit, the writing unit  36  irradiates the photoconductor  32  with a laser L, and the photoconductor  32  is exposed thereby. 
     When the image forming operation is started, the photoconductor  32  is caused to rotate, to move the outer circumferential surface of the photoconductor  32  in the direction of the arrow X in  FIG. 1 . The surface of the photoconductor  32  is then uniformly charged with the charging roller  33 , and an electrostatic latent image is formed on the surface of the photoconductor  32  through the exposure. By allowing an electrostatic latent image to be formed on the photoconductor  32  and allowing the toner stored in the developing unit  34  to be supplied onto the photoconductor  32 , the electrostatic latent image is visualized as a toner image (developer image) that is a visible image. 
     When the image forming operation is started, the sheet feeding roller  52  in the sheet feeding unit  5  is driven in rotation, and feeds the top recording sheet P in the sheet feeding cassette  51  into the conveying path Y. The recording sheet P fed into the conveying path Y is sent onto the belt  43  by the registration rollers  53 . 
     Before conveying the recording sheet P, the surface of the belt  43  is charged by a charger (not illustrated). This allows the belt  43  to convey the recording sheet P stably, by electrostatically adsorbing the recording sheet P, onto the surface of the belt  43 . 
     The fed recording sheet P is conveyed by the belt  43  to a position at which the photoconductor  32  and the facing roller  44  face each other, and a toner image is transferred from the photoconductor  32  onto the recording sheet P. 
     At the time of transfer, a constant-voltage or constant-current controlled voltage, controlled to the opposite polarity of the polarity to which the toner is charged, is applied to the facing roller  44 . A transfer field is generated thereby in the transfer nip between the facing roller  44  and the photoconductor  32 , and the toner image on the photoconductor  32  is transferred onto the recording sheet P. 
     After the image transfer, some toner remain and are attached on the surface of the photoconductor  32 . The cleaning device  35  therefore removes the remaining toner from the surface of the photoconductor  32 , and the photoconductor  32  performs the image forming operation again. 
     The registration rollers  53  feed the recording sheet P onto the belt  43  at such timing that the leading end of the toner image on the surface of the photoconductor  32  overlaps with the leading end of the position where the image is to be formed on the fed recording sheet P. 
     The recording sheet P after the toner image is transferred is conveyed into the fixing unit  6 . The recording sheet P is then heated and pressed by the fixing roller  61  heated by the heat source and the pressing roller  62 , and the toner image is fixed onto the recording sheet P. The recording sheet P on which the toner image is fixed is then separated from the fixing roller  61 , and further conveyed by conveying roller pairs not illustrated. The recording sheet P is then ejected onto the sheet ejection tray  73  by the sheet ejection roller  71  in the ejecting unit  7 . 
     When the recording sheet P is ejected onto the sheet ejection tray  73 , the sheet ejection sensor  72  positioned upstream of the sheet ejection roller  71  detects the ejection of the sheet, and the timings for conveyance and ejection of the next recording sheet P, transfer of an image onto the recording sheet P, and the like are controlled. 
       FIG. 2  is a schematic illustrating a general structure of the cleaning device according to the first embodiment. The cleaning device collects toner, paper powder, and the like as substances to be removed from the surface of the photoconductor  32 . 
     The cleaning device  35  according to the present invention is positioned above the photoconductor  32 , and includes a cleaning blade  100  serving as a cleaning member for cleaning the photoconductor  32 , a collection vane  101  serving as a collecting member for collecting the substances to be removed such as toner from the cleaning blade  100 , a conveying coil  102  serving as conveying member for conveying the substances to be removed to the outside, and a partitioning member  103  positioned between the collection vane  101  and the conveying coil  102 . 
     The cleaning blade  100  is a member positioned extending along the axial direction of the photoconductor  32 , and is made of an elastic material such as rubber. An upstream end of the cleaning blade  100 , being upstream in the rotating direction X of the photoconductor  32 , abuts against the photoconductor  32 , and is placed in a manner held against the photoconductor  32 . By allowing the cleaning blade  100  to abut against the photoconductor  32 , the toner remaining on the surface of the photoconductor  32  after the transfer is scraped off, and is accumulated in the abutment part of the cleaning blade  100 . 
     On the upstream side of the cleaning blade  100 , being upstream in the rotating direction X, the collection vane  101  is provided. The collection vane  101  includes vanes  101   a  serving as conveying portions that collect and convey the toner removed by the cleaning blade  100 , a holding portion  101   b  for holding the vanes  101   a , and protrusions  101   c  protruding on the upstream side of the holding portion  101   b , being upstream in a rotating direction Z of the collection vane  101 . 
     In a structure in which the cleaning blade  100  is placed above the photoconductor  32 , such as that in the image forming apparatus  1  according to the present invention, it is difficult to collect the toner removed by the cleaning blade  100  by allowing the toner to fall into a waste toner container or the like by the force of gravity. The collection vane  101  is therefore provided. 
     The collection vane  101  is provided rotatably (movably along a surface) in the direction of the arrow Z, about a rotational axis  101   d  extending in parallel with the photoconductor  32 . The sheet-like vanes  101   a  are mounted on both surfaces of the holding portion  101   b . The holding portion  101   b  has protrusions  101   c  each of which protrudes from the corresponding end of the holding portion  101   b  toward the upstream side of the rotating direction Z of the collection vane  101 , and has an S-like shape, with its ends bent by 90 degrees. 
     The holding portion  101   b  may be made of a material such as metal or resin, and the vane  101   a  may be made of a material such as metal, resin, or elastic rubber. 
     The collection vane  101  is rotated in the direction of the arrow Z about the rotational axis  101   d , and the surface facing the photoconductor  32  is rotated (surface-moved) in the counter direction of the rotating direction X of the photoconductor  32 . When the toner at the end of the cleaning blade  100  piles up to a certain level or higher and enters the rotational area of the collection vane  101 , the accumulated toner is collected by the vane  101   a , and the rotational movement of the collection vane  101  conveys the toner in the direction of the arrow Z. 
     Because the collection vane  101  collecting the toner at the end of the cleaning blade  100  is rotated in the counter direction of the rotation of the photoconductor  32 , the collection vane  101  is prevented from pushing the toner accumulated at the end of the cleaning blade  100  deeper into the cleaning unit  35  (in the direction of the arrow X). 
       FIG. 3  is a schematic illustrating how the toner on surface of the photoconductor  32  accumulates at the cleaning blade  100 , is collected and conveyed by the collection vane  101 , and is guided by the partitioning member  103  to the conveying coil  102 . 
     The partitioning member  103  is formed of a flexible polyurethane sheet, and is arranged in such a manner that one end  103   a  of the partitioning member  103  is in contact with the rotating vane  101   a , and the other end  103   b  faces the conveying coil  102  and inclined toward the conveying coil  102 . The toner is therefore carried along the inclined surface of the partitioning member  103  toward the other end  103   b . The other end  103   b  is placed immediately below the conveying coil  102 . This configuration enables the conveying coil  102  to collect the toner carried to the other end  103   b  efficiently. By positioning the other end  103   b  immediately below the conveying coil  102 , the length of the partitioning member  103  can be reduced to the minimum length required to convey the toner, so that a certain level of strength or higher of the partitioning member  103  can be ensured. 
     The other end  103   b  of the partitioning member  103 , the other end  103   b  being positioned near the conveying coil  102 , is fixed to a support  104   a  of a housing  104  of the cleaning device  35 , and a part of the other end  103   b  of the partitioning member  103  is supported by the support  104   a . By allowing the support  104   a  to support the part, the direction at which the partitioning member  103  is placed can be stabilized. In this manner, the rotating collection vane  101  can come into contact with the partitioning member  103  at an appropriate angle, and the toner conveyed to the partitioning member  103  can be further conveyed toward the other end  103   b  appropriately. 
     The support  104   a  is inclined along the outer circumferential surface of the conveying coil  102 , and this inclination allows the conveying coil  102  to collect the toner more efficiently. 
     Explained now is the process how the toner collected by the collection vane  101  is carried to the conveying coil  102 . 
     The toner is conveyed by the rotating collection vane  101 , and lifted upwardly from the lower position at which the cleaning blade  100  is placed. Once the vane  101   a  passes through the apex A of the rotation, the vane  101   a  moves downwardly from that point on, and the toner carried on the surface of the vane  101   a  falls from the vane  101   a.    
     The toner then lands on the partitioning member  103  that is brought into contact with the collection vane  101 , and the fallen toner is guided along the inclined surface of the partitioning member  103 , and carried to the conveying coil  102 . 
     After carrying the toner on its surface and dropping the toner onto the partitioning member  103 , the collection vane  101  keeps rotating, and presses the partitioning member  103 . The pressing force of the collection vane  101  causes the partitioning member  103 , which is flexible, to warp. When the collection vane  101  is rotated further, the pressing force against the partitioning member  103  is released, and the partitioning member  103  bounces back to the original shape. At this time, with the force causing the partitioning member  103  to bounce back to the original shape, the toner remaining on the surface of the partitioning member  103  is flicked toward the conveying coil  102 . As the collection vane  101  is rotated further, the protrusion  101   c  protruding toward the upstream side of the rotating direction Z of the collection vane  101  abuts against the partitioning member  103 , with some delay from the vane  101   a , and presses the partitioning member  103 . This pressing force allows the toner on the partitioning member  103  to be conveyed into the conveying coil  102  again. In this manner, because the partitioning member  103  is pressed again by the protrusion  101   c , the toner can be collected more efficiently. 
     In the embodiment of the present invention, the collection vane  101  is provided with two vanes  101   a , so that the toner is conveyed twice as the collection vane  101  is rotated once. Alternatively, three or more vanes  101   a  may be provided by increasing the surfaces of the holding portion  101   b  on which the vane  101   a  is held. 
     In the embodiment of the present invention, the protrusion  101   c  is explained to protrude from the holding portion  101   b  toward the upstream side of the rotating direction Z, but the protrusion  101   c  may protrude from the vane  101   a . In such a configuration, the vane  101   a  may have an L shape with a protrusion protruding on the side of the holding portion  101   b , and the protrusion  101   c  may be allowed to press the partitioning member  103  continuously after the vane  101   a  presses the partitioning member  103 , and to push the toner toward the conveying coil  102 . 
     When the collection vane  101  is brought into contact with the partitioning member  103 , the collection vane  101  presses down the partitioning member  103  in such a direction that the partitioning member  103  is pressed against the housing of the cleaning device  35 . This pressing force of the collection vane  101  acts in a direction in which the partitioning member  103  is fixed against the cleaning device  35 . 
     The conveying coil  102  has a coil portion that conveys toner along the axial direction of the photoconductor  32  and the like, from the front side toward the rear side in  FIG. 3 . The toner carried into the conveying coil  102  is axially conveyed by the coil portion of the conveying coil  102  to the outside of the cleaning device  35 . 
     Through this process, the cleaning device  35  discharges the toner accumulated at the cleaning blade  100  to the outside via the conveying coil  102 . 
     The shape of the vane  101   a  is formed in a rectangle, viewing in the axial direction of the collection vane  101 . Alternatively, the vane  101   a  may be formed into an L shape or a shape bent twice, with a protrusion protruding in the opposite direction of the protrusion  101   c  and protruding toward the side abutting against the partitioning member  103  from the leading end where the toner is collected and that abuts against the partitioning member  103 . Such a structure allows the vane  101   a  to hold better thereon the toner collected from the photoconductor  32 . 
     According to the present invention, the photoconductor  32  is installed so as not to be in direct contact with the collection vane  101 , and the photoconductor  32  does not come into the area of rotation of the vanes  101   a . Although the toner can be collected more reliably by bringing the collection vane  101  into contact with the photoconductor  32 , such a contact might cause the photoconductor  32  to vibrate, and to result in defective image formation such as shock jitter. Thus, the photoconductor  32  is not brought into contact with the collection vane  101 , so that the photoconductor  32  is not caused to vibrate and result in defective image formation. 
     By using a flexible material such as rubber for the partitioning member  103 , the vibrations caused by contacting between the collection vane  101  and the partitioning member  103  is reduced, and the defective image formation is prevented. 
     The vibrations caused when the collection vane  101  is into contact with the partitioning member  103  can also be reduced by using a flexible material for the vanes  101   a  on the collection vane  101 . The vanes  101   a , however, are also required to have some rigidity because the vanes  101   a  need to collect the accumulated toner, to carry and to convey the toner on the surface thereof. 
     The partitioning member  103  flicks off the toner from its surface toward the conveying coil  102  by becoming warped as the partitioning member  103  is brought into contact with the vane  101   a , and by bouncing back to the original shape as the pressing force of the vane  101   a  is released. Thus, the partitioning member  103  is required to have some flexibility. 
     According to the present invention, the vane  101   a  is formed of a polyethylene terephthalate (PET) sheet so that higher rigidity of the vane  101   a  is ensured than that of the partitioning member  103 . The partitioning member  103  may be formed of a polyurethane sheet. 
     The toner may be collected with a brush-shaped roller instead of the collection vane  101 . While the toner accumulated at the cleaning blade  100  can be collected more efficiently with a brush, a brush also presents another challenge to overcome, e.g., the collected toner is less easily removed from the brush. The structure according to the embodiment is therefore more preferable. The toner collection efficiency can also be improved by providing a brush or a foamed material only to the leading end of the collection vane  101 . By providing a brush or a foamed material to the leading end of the collection vane  101 , shock jitter is less produced even when the leading end is brought into contact with the photoconductor  32 . 
       FIG. 4  illustrates a cleaning device according to a second embodiment of the present invention. 
     While the cleaning device according to the first embodiment is installed above the photoconductor  32 , the cleaning device according to the second embodiment is installed on the right or the left side of the photoconductor  32  (on the left side in  FIG. 4 ). 
     In the configuration according to the second embodiment, the conveying coil  102  can be positioned below the collection vane  101 . By positioning the conveying coil  102  below the collection vane  101 , the toner can be collected more easily from the collection vane  101  into the conveying coil  102  by allowing the toner to fall by the force of gravity. The toner can therefore be collected more efficiently. 
     Because the collection vane  101  is positioned above the partitioning member  103 , the partitioning member  103  receiving the falling toner can occupy a larger portion of the area in which the toner may fall from the collection vane  101 . 
     As illustrated in  FIG. 5 , an area D 0  in which the toner may fall occupies a left half of the circle representing an area D in which the collection vane  101  is rotated. Let us now compare the ratio occupied by the area in which the partitioning member E 2  according to the second embodiment can receive the fallen toner with respect to the entire area D 0  in which the toner may fall, with that with the partitioning member E 1  according to the first embodiment. While the partitioning member E 1  does not extend beyond the rotational axis  101   d  and has a gap in a length D 1  with respect to the rotational axis  101   d  in the right-and-left direction as illustrated in  FIG. 5 , the partitioning member E 2  extends beyond the rotational axis  101   d , and is positioned below the area D 0  in which the toner may fall. The partitioning member E 2  has therefore no gap. For these reasons, the partitioning member E 2  is capable of collecting the toner falling from the collection vane  101  more reliably. 
     In the configuration according to the first embodiment in which the collection vane  101  is placed directly beside the conveying coil  102  and the partitioning member  103  is brought into contact with the collection vane  101 , there is a limitation in the length by which the partitioning member  103  can be extended. The partitioning member  103  therefore cannot be extended toward the rotational axis  101   d , and the gap in the length D 1  is formed. 
     By contrast, in the configuration according to the second embodiment in which the collection vane  101  is placed above the conveying coil  102 , because there is no such a limitation, the partitioning member  103  can be extended to receive the fallen toner with a wider area. Therefore, the toner can be collected more reliably. 
     The conveying coil  102  may be placed below the collection vane  101  in the configuration of the cleaning device according to the first embodiment in which the cleaning device  35  is placed above the photoconductor  32 . There is, however, a requirement that the collection vane  101  needs to be placed near the photoconductor  32  because the collection vane  101  collects the toner from the surface of the photoconductor  32 . In order to achieve such a configuration, therefore, one of the following modifications is required. The size of the conveying coil  102  may be reduced so that the conveying coil  102  can be placed between the collection vane  101  and the photoconductor  32  according to the first embodiment; or the size of the collection vane  101  may be increased so that a sufficient space is ensured between the collection vane  101  and the photoconductor  32  to allow the conveying coil  102  to be placed between the collection vane  101  and the photoconductor  32  even when the collection vane  101  moves near the photoconductor  32 . The conveying coil  102  according to the former modification, however, lacks the conveying capacity, and the configuration according to the latter modification results in an increased size of the cleaning device  35 . It is therefore more preferable to position the conveying coil  102  below the collection vane  101  in the configuration in which the cleaning device  35  is placed on the right or the left side of the photoconductor  32 . 
     A blade holder  105  holds the cleaning blade  100  according to the second embodiment. The blade holder  105  may also hold the partitioning member  103 . In such a configuration, because the housing  104  does not need to have a structure for holding the partitioning member  103 , the layout of the components can be selected more freely, and the sizes of the unit can be reduced. 
     Another issue addressed by the present invention will now be explained. 
     In addition to the toner, paper powder from the recording sheets is another substance to be removed from the surface of the photoconductor  32  by the cleaning blade  100 . Because paper powder has extremely small particles in the order of nanometers, the paper powder alone can easily pass through the cleaning blade  100  and flow into the downstream side. When the toner accumulates at the leading end of the cleaning blade  100 , the toner can serve to stop the flow of the paper powder, advantageously. If the paper powder passes through the cleaning blade  100 , and a large amount becomes attached on the charging roller  33  positioned on the downstream side, defective charging might cause defective image formation. 
     Defective image formation resulting from the toner accumulated at leading end of the cleaning blade  100  can be prevented by providing the cleaning device  35  in the manner disclosed herein to remove the toner accumulated at leading end of the cleaning blade  100 . The paper powder, however, may cause some defects, as mentioned above. This trouble is particularly prominent at the axial ends of the photoconductor  32 , because the ends are almost unused in the image formation, and therefore toner is not directly carried on their surface. Explained now are some embodiments of the cleaning device  35  intended to address this issue. 
       FIG. 6  is a schematic of a collection vane according to a third embodiment of the present invention. 
     In the collection vane  101  according to the third embodiment, the axial ends of the vane  101   a  are extended longer than the holding portion  101   b , and are not supported by the holding portion  101   b.    
     Because the ends of the vane  101   a  are not supported by the holding portion  101   b , when the vane  101   a  scrapes off the toner accumulated at the leading end of the cleaning blade  100 , the toner pushes the ends of the vane  101   a  and causes the ends to warp. Because the ends of the vane  101   a  become warped, the toner is guided toward the axial ends of the vane  101   a  (that is, toward the axial ends of the photoconductor  32 ). 
     Because the toner is guided toward the axial ends, the toner is supplied to the axial ends of the photoconductor  32 , the ends being where the toner tends to be insufficient, so that the toner can prevent the paper powder from passing through the cleaning blade  100 . The width of the holding portion  101   b  is preferably shorter than that of the vane  101   a , and is the same or wider than the axial image formation area of the photoconductor  32 . 
     While illustrated in  FIG. 6  is an embodiment in which the both ends of the vane  101   a  are not supported by the holding portion  101   b , only one of the ends may be left unsupported. Because the conveying coil  102  conveys the conveyed toner axially, a sufficient amount of toner is supplied downstream in the conveying direction. On the downstream side of the conveying direction of the conveying coil  102 , therefore, the toner can become attached more easily to the collection vane  101  and the like indirectly. Because a certain amount of toner becomes attached to the photoconductor  32  and the cleaning blade  100 , the trouble of the paper powder passing through described above occurs less frequently. For this reason, only the end of the vane  101   a  on the upstream side of the conveying direction of the conveying coil  102  may be left unsupported by the holding portion  101   b.    
     A part of the unsupported end of the vane  101   a , being unsupported by the holding portion  101   b , may be configured thinner than the remaining part of the vane  101   a , or chamfered as illustrated in  FIG. 7 , so that the part is allowed to warp more easily. 
       FIG. 8  is a schematic illustrating a collection vane according to a fourth embodiment of the present invention. 
     In the collection vane  101  according to the fourth embodiment, a spiral-shaped vane  101   a  is mounted on the holding portion  101   b . The collection vane  101  according to the fourth embodiment conveys the toner scraped off from the cleaning blade  100  in the axial direction, as well as in the direction toward the conveying coil  102  (in the direction of the arrow Z in  FIG. 2 ), by the rotations of the spiral-shaped vane  101   a.    
     The vane  101   a  conveys the toner axially in the reverse direction of the direction in which the conveying coil  102  conveys the toner, and the toner is conveyed upstream in the conveying direction of the conveying coil  102 . The toner can therefore be supplied upstream in the conveying direction of the conveying coil  102  where the toner tends to be insufficient. In this manner, the trouble of the passing paper powder can be prevented. 
     The pitch of the spiral of the conveying coil  102  may be configured unequal in the axial direction, as illustrated in  FIG. 9 . By making the pitch smaller on the upstream side  102   a  in the conveying direction where the toner tends to be insufficient, the toner is allowed to stay more on the upstream side of the conveying coil  102  in the conveying direction. As an alternative to the configuration in which the conveying coil  102  has an axial spiral shape as described in the fourth embodiment, a paddle member may be provided on the upstream side  102   a . In this manner, the part of the conveying coil  102  with the paddle member can be provided with a conveying capability in the direction of the conveying coil  102  (in the direction of the arrow Z in  FIG. 2 ). 
       FIG. 10  is a schematic illustrating a collection vane according to a fifth embodiment of the present invention. 
     The collection vane  101  according to the fifth embodiment has a structure with a vane  101   a  one end of which is provided with an inclination. Only the end provided with the inclination has conveying capability for conveying the toner in the axial direction. In the embodiment, the inclination is provided only to one end of the vane  101   a , but the inclination may be provided to both ends. 
     In a sixth embodiment of the present invention illustrated in  FIG. 11 , the conveying coil  102  conveys the toner axially to both sides, with their border at the axial center. The toner conveyed to the axial ends is returned to the developing unit  34 , or collected into a collection container. The toner conveyed to the sides may be returned to the developing unit  34 , or collected into the collection container from the both sides. 
     With this structure for conveying the toner to the axial ends, the issue of insufficient toner at the axial ends can be addressed. The border at which the conveying direction is reversed is not limited to the axial center. For example, the border may be positioned at one third of the axial length of the conveying coil, the length being that from one end of the conveying coil  102  in the axial direction, and the direction in which the toner is conveyed may be reversed from this point on. Furthermore, in consideration of deterioration of toner caused by a high temperature environment, the border at which the conveying direction is reversed may be set in such a manner that the toner on a side that is more likely to be heated is conveyed to the collection container, and the toner on the side that is not affected by the heat is returned to the developing unit  34 . 
     In addition to the configuration explained above, the conveying coil  102  according to a seventh embodiment of the present invention may be rotated forwardly and reversely, while switching the directions, so that the directions in which the toner is conveyed are switched alternatingly. In such a configuration, the conveying coil  102  regularly performs the operation of supplying the toner to the end where the toner is insufficient by temporarily being rotated in the reverse direction, being reverse with respect to the ordinary rotating direction. 
     If the driving system of the conveying coil  102  is configured to operate in association with the photoconductor  32 , the photoconductor  32  cannot be rotated reversely during an image formation. The operation of reversely rotating the conveying coil  102  is therefore performed while image formation is not performed, to supply the toner to the side where there is insufficient toner. 
     In this example, if the photoconductor  32  is reversely rotated for a long time, the toner may become scattered around the photoconductor  32 . The photoconductor  32  cannot therefore be operated reversely for a long time. 
     To address this issue, the rotating direction of the photoconductor  32  may be changed using an idler gear  106 , an example of which is illustrated in  FIGS. 12A and 12B . To rotate the conveying coil  102  forwardly, as illustrated in  FIG. 12A , the photoconductor  32  is driven without the idler gear  106  between the conveying coil  102  and the photoconductor  32 . By driving the conveying coil  102  via the idler gear  106 , the conveying coil  102  can be rotated reversely, while keeping the photoconductor  32  being rotated forwardly, as illustrated in  FIG. 12B . 
     In other words, in a structure in which the conveying coil  102  has the driving source, the idler gear  106  prevents the photoconductor  32  from being rotated reversely by being driven by the reversely rotating conveying coil  102 , and can keep the photoconductor  32  rotated forwardly. In a structure in which the photoconductor  32  has the driving source, the forwardly rotating photoconductor  32  can cause the conveying coil  102  to rotate reversely by driving the conveying coil  102  via the idler gear  106 . 
     By using the idler gear  106 , the time for which the conveying coil  102  is rotated reversely can be extended, even in a structure in which the photoconductor  32  is driven in association with the conveying coil  102 . 
     As a way to engage the idler gear  106 , the engagement between the conveying coil  102  and the photoconductor  32  that are kept abutting against each other by a spring  107  may be separated once using a driving means such as an actuator. The idler gear  106  may then be inserted between the conveying coil  102  and the photoconductor  32 , and reengage the conveying coil  102  and the photoconductor  32 . If this separating and engaging operation is performed during the image forming operation, defects such as uneven image density may occur due to the variance in the load of the photoconductor  32 . Therefore, it is preferable for this operation to be performed while no image formation is performed, or between image forming operations. 
     A friction wheel may be used instead of the idler gear  106 . Furthermore, the idler gear  106  may also be moved inside of a space provided between the photoconductor  32  and the conveying coil  102  during the forward rotation. This configuration can omit the structure for separating the photoconductor  32  and the conveying coil  102 . 
     It is particularly effective to perform this reverse operation of the conveying coil  102  when the toner is not sufficiently attached to the cleaning blade  100 , e.g., when an image forming operation is performed for the first time after the image forming apparatus  1  is started, or when an image occupying a small area of the recording sheet on which the image is printed is output successively. This reverse operation is also particularly effective in an extreme environment causing more toner to pass through the cleaning blade, for example, in a highly humid high temperature environment, or in a low temperature environment. The reverse operation may also be performed regularly when a cumulative image formation time becomes equal to or more than a predetermined time. 
     Such conditions and the timing for causing the reverse operation of the conveying coil  102  may be determined by measuring the ambient temperature, or by detecting the ratio of an image with respect to the recording sheet on which the image is to be formed, or the cumulative image formation time. 
       FIG. 13  illustrates a configuration according to an eighth embodiment of the present invention. In the cleaning device according to the eighth embodiment, the partitioning member  103  is shorter in the axial direction of the photoconductor  32  and the like than the collection vane  101 , and the partitioning member  103  is absent at positions corresponding to the axial ends of the collection vane  101 . The other components are the same as those according to the first embodiment, so that explanations thereof are omitted herein. 
     Because the ends of the partitioning member  103  are shorter, part of toner conveyed from the collection vane  101  is not carried into the conveying coil  102 , and returned to the surface of the photoconductor  32  or the cleaning blade  100 . In this manner, the issue of toner shortage can be addressed. In  FIG. 13 , the lengths of both ends of the partitioning member  103  are represented shorter, but only the length of the upstream end in the toner conveying direction that is in the axial direction of the conveying coil  102  may be shorter. 
       FIGS. 14A and 14B  illustrate a configuration according to a ninth embodiment of the present invention. In the ninth embodiment, a wall  103   c  is provided to each axial end of the partitioning member  103 , as illustrated in  FIG. 14A . Because the walls  103   c  are provided, when the toner is moved from the collection vane  101  onto the partitioning member  103 , the walls  103   c  block the toner at the respective axial ends, and part of the toner is returned to the surface of the photoconductor  32  or the cleaning blade  100 . In this manner, the issue of toner shortage at the axial ends of the photoconductor  32  is addressed. If the axial ends are completely covered by the respective walls  103   c , the toner will not be collected at all at the axial ends. Therefore, the axial ends have some part without the walls  103   c , outside of the walls  103   c.    
     The height of the wall  103   c  can be changed as appropriate. The walls  103   c  may be provided only to one of the axial ends, without limitation to both ends, or may be provided to a position corresponding to a position of the photoconductor  32  where the paper powder tends to be generated more. 
     Some embodiments of the present invention are explained herein, but the present invention is not limited to the embodiments described above, and various modifications are still possible with the scope not deviating from the spirit of the present invention. 
     The image forming unit according to the present invention is not limited to the monochrome image forming unit illustrated in  FIG. 1 , and may be a color image forming unit, copier, printer, facsimile, or multifunction peripheral including two or more of the functions of the copier, the printer, and the facsimile. 
     The cleaning device according to the present invention is explained to clean the photoconductor  32 , but may also be used as a cleaning device for cleaning the intermediate transfer belt, for example. 
     Although the invention has been described with respect to specific embodiments for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art that fairly fall within the basic teaching herein set forth.