Patent Publication Number: US-7912401-B2

Title: Cleaning device and image forming apparatus including the same

Description:
This application is based upon and claims the benefit of priority from the corresponding Japanese Patent application No. 2008-276824, filed Oct. 28, 2008, the entire contents of which are incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention relates to cleaning devices configured to collect residual toner on image bearing members remaining after the transfer of toner images formed on the image bearing members onto sheets and/or an image forming apparatus that includes one or more such cleaning devices. 
     BACKGROUND OF THE INVENTION 
     Known image forming apparatuses, such as color printers, operate by forming toner images of colors on a plurality of image bearing members. The images are then transferred (i.e., primary transfer) onto another image bearing member so that a color toner image is formed. The color toner image is subsequently transferred (i.e., secondary transfer) onto a sheet. Such an image forming apparatus, generally, includes a cleaning device that collects or removes residual toner on the image bearing member after the transfer onto a sheet (secondary transfer). 
     An illustrative cleaning device includes a fur brush (an upstream fur brush) provided at a downstream position, with respect to a secondary transfer position, on a path along which the image bearing member moves, another fur brush (a downstream fur brush) provided at a more downstream position than the upstream fur brush, and a bias roller (a cleaning assist member) provided in contact with the image bearing member between the secondary transfer position and the upstream fur brush. 
     The bias roller is positively biased in an effort the charge of the residual toner on the image bearing member is both charged positively and uniformly. The positively charged residual toner is then removed by the upstream fur brush that is negatively biased. Residual toner failed to be removed by the upstream fur brush is removed by the downstream fur brush that is positively biased. In this manner, residual toner is removed from the image bearing member, whereby the image bearing member is cleaned. 
     In the foregoing cleaning device, toner adhered to the upstream and downstream fur brushes is rubbed off by cleaning members. However, the bias roller (cleaning assist member) is not cleaned. Therefore, if residual toner adheres to the bias roller, the bias roller is contaminated. Further, if the contamination on the bias roller adheres back to the image bearing member, image failure may occur on the sheet. Moreover, if such contamination scatters to the outside of the cleaning device, the internal components of the image forming apparatus may be contaminated. Particularly, when a sheet conveyance path is provided below the cleaning device, such contamination may adhere to a sheet that is being conveyed, leading to image failure. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a cleaning device configured to clean a cleaning assist member. Further, some embodiments may include an image forming apparatus including a cleaning device. In some embodiments, the cleaning device may suppress the occurrence of image failure and internal contamination. 
     According to an embodiment, a cleaning device may be provided that cleans an image bearing member bearing a toner image which is to be transferred at a transfer position onto a sheet. Some embodiments of the device may include, but are not limited to a cleaning member, a cleaning assist member, a cleaning mechanism, and/or a housing. In an embodiment, the cleaning member may be provided downstream of the transfer position with respect to movement of the image bearing member. In some embodiments, the cleaning member may be configured to collect residual toner from the image bearing member. An embodiment of the cleaning assist member may be provided on the upstream side and/or the downstream side in the direction of movement with respect to the cleaning member and may be configured to be pressed against the image bearing member so as to rub off the residual toner from the image bearing member. A cleaning mechanism may be configured to move the cleaning assist member away from the image bearing member according to a predetermined timing so as to remove the residual toner adhered to the cleaning assist member. In some embodiments, a housing may house the cleaning member, the cleaning assist member, and the cleaning mechanism. 
     In some embodiments, the predetermined timing may comprise variable timing which may depend on the occurrence of one or more events. In various embodiments, such events to establish predetermined timings may include, but are not limited to completion of image output jobs, during calibration, and/or in the event of sheet jamming. The above and other objects, features, and advantages of the present invention will be more apparent from the following detailed description of embodiments taken in conjunction with the accompanying drawings. 
     In this text, the terms “comprising”, “comprise”, “comprises” and other forms of “comprise” can have the meaning ascribed to these terms in U.S. Patent Law and can mean “including”, “include”, “includes” and other forms of “include”. 
     The various features of novelty which characterize the invention are pointed out in particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying descriptive matter in which embodiments of the invention are illustrated in the accompanying drawings in which corresponding components are identified by the same reference numerals. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following detailed description, given by way of example, but not intended to limit the invention solely to the specific embodiments described, may be understood in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a front cross-sectional view showing the overall configuration of an image forming apparatus including a cleaning device according to a general embodiment; 
         FIG. 2  schematically shows major elements of a cleaning device according to an embodiment, in a state where a cleaning assist member is in contact with an image bearing member; 
         FIG. 3  schematically shows the major elements of the cleaning device according to the embodiment depicted in  FIG. 2 , in a state where the cleaning assist member is away from the image bearing member; 
         FIG. 4  schematically shows major elements of a cleaning device according to an embodiment, in a state where a cleaning assist member is in contact with an image bearing member; 
         FIG. 5  schematically shows the major elements of the cleaning device according to the embodiment depicted in  FIG. 4 , in a state where the cleaning assist member is away from the image bearing member; 
         FIG. 6  schematically shows major elements of a cleaning device according to an embodiment, in a state where a cleaning assist member is in contact with an image bearing member; 
         FIG. 7  schematically shows the major elements of the cleaning device according to the embodiment depicted in  FIG. 6 , in a state where the cleaning assist member is away from the image bearing member; 
         FIG. 8  schematically shows major elements of a cleaning device according to an embodiment, in a state where a cleaning assist member is in contact with an image bearing member; and 
         FIG. 9  schematically shows the major elements of the cleaning device according to the embodiment depicted in  FIG. 8 , in a state where the cleaning assist member is away from the image bearing member. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Reference will now be made in detail to various embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. Each example is provided by way of explanation of the invention, and is by no way limiting. In fact, it will be apparent to those skilled in the art that various modifications, combinations, additions, deletions and variations can be made in the present invention without departing from the scope or spirit of the present invention. For instance, features illustrated or described as part of one embodiment can be used in another embodiment to yield a still further embodiment. It is intended that the present invention covers such modifications, combinations, additions, deletions, applications and variations that come within the scope of the appended claims and their equivalents. 
     Embodiments will now be described with reference to the drawings.  FIG. 1  is a front cross-sectional view showing the internal configuration of an image forming apparatus including a cleaning device according to a general embodiment. An image forming apparatus may be used as a copier for color printing. Image forming apparatus  10  includes a box-shaped apparatus body  11  and an image reading device  16  provided at the top of the apparatus body  11 . The image reading device  16  reads a document as an image. 
     As shown in  FIG. 1  apparatus body  11  houses image forming section  12 , fixing section  13 , and sheet storage section  14 . The image forming section may form an image in accordance with image information on a document read by the image reading device  16 . The fixing section  13  may fix the image formed and transferred onto a sheet P by the image forming section  12 . In some embodiments, sheet storage section  14  stores sheets onto which the image is to be transferred. Alternatively, sheets may be feed from an external tray. Sheets, as used herein, may include any material on which an image may be printed including, but not limited to paper, transparencies and any material known in the art. 
     Image reading device  16  includes document presser  161  provided at the top of apparatus body  11  in an openable/closable manner, and optical unit  162  provided in an upper portion of apparatus body  11  and facing document presser  161  with contact glass  163  interposed therebetween. Contact glass  163  has a flat surface with slightly smaller dimensions than document presser  161  so that the surface of the document placed thereon can be read. Document presser  161  opens and closes by being turned in one direction and the reverse direction about an axis defined along one side at the top face of apparatus body  11 , the one side being one of the constituents of image reading device  16 . 
     In some embodiments, an optical unit may include, but is not limited to one or more light sources, a plurality of mirrors, one or more lens units, a charge-coupled device (hereinafter “CCD”), and/or other devices known in the art.  FIG. 1  depicts optical unit  162  may include, although not shown, light sources, a plurality of mirrors, a lens unit, a charge-coupled device (CCD), and so forth. Light emitted from the light source may be reflected by the surface of the document. The reflected light may be further reflected by the mirrors, transmitted through the lens unit, and input as document information to the CCD. The document information that has been input as an analog quantity to the CCD may be converted into a digital signal, and is stored in a specific storage device. 
     The image forming section  12  forms a toner image on a sheet P fed from the sheet storage section  14 , and includes a magenta unit  12 M, a cyan unit  12 C, a yellow unit  12 Y, and a black unit  12 K arranged in that order from the upstream side (the left side in  FIG. 1 ) to the downstream side. In some embodiments, an order of the units may vary. For example, the units may be arranged in reverse or in any order known in the art. The units of the image forming section may include an image bearing member (e.g., photosensitive drum). For example, each of the units  12 M,  12 C,  12 Y, and  12 K may include photosensitive drum  121  and developer  122 . The photosensitive drums  121  receive toner applied thereto by the respective developers  122  while rotating counterclockwise as shown in  FIG. 1 . The toner is supplied to developers  122  from corresponding toner containers  20 . As shown in  FIG. 1 , in some embodiments toner containers  20  may be positioned on the front and right sides of the apparatus body  11 . 
     Toner containers  20  may be provided for each color used. For example,  FIG. 1  depicts magenta toner container  20 M, cyan toner container  20 C, yellow toner container  20 Y, and black toner container  20 K. Toner containers  20 M,  20 C,  20  Y,  20 K provide toner of the respective colors to the developers  122  (e.g., magenta developer  122 M, cyan developer  122 C, yellow developer  122 Y, and black developer  122 K). In some embodiments, developers included in the units  12 M,  12 C,  12 Y, and  12 K, may be positioned above image forming section  12 . Further, developers  122 M,  122 C,  122 Y,  122 K may be removed from apparatus body  11  in some embodiments. 
     As shown in  FIG. 1 , chargers  123  are provided above the respective photosensitive drums  121  (e.g., magenta drum  121 M, cyan drum  121 C, yellow drum  121 Y, and black drum  121 K). In some embodiments, exposure device  124  may be provided above each set of charger  123  and developer  122 . In some embodiments, the peripheral surfaces of photosensitive drums  121  are uniformly charged by respective chargers  123 . The charged peripheral surfaces of photosensitive drums  121  are irradiated with laser light from respective exposure devices  124  in accordance with pieces of data on images of the respective colors that are input from image reading device  16 , whereby individual electrostatic latent images are formed. Subsequently, developers  122  apply toner of the respective colors to the electrostatic latent images. Thus, toner images are formed on the peripheral surfaces of photosensitive drums  121 . 
     As shown in  FIG. 1 , a transfer belt (e.g., an image bearing member)  125  may be provided below photosensitive drums  121 . Transfer belt  125  is stretched between driving roller  125   a , following roller  125   b , secondary-transfer counter roller  125   c , and other rollers such that transfer belt  125  is in contact with the peripheral surfaces of photosensitive drums  121 . In some embodiments, transfer belt  125  rotates clockwise around driving roller  125   a  and following roller  125   b , synchronously with photosensitive drums  121 , while being pressed against the peripheral surfaces of photosensitive drums  121  by primary-transfer rollers  126  provided in correspondence with photosensitive drums  121 . 
     In parallel with the rotation of transfer belt  125 , a magenta toner image is first transferred from photosensitive drum  121  of magenta unit  12 M onto transfer belt  125 . Subsequently, a cyan toner image is transferred from photosensitive drum  121  of cyan unit  12 C so as to be overlaid onto the transferred magenta toner image on transfer belt  125 . Likewise, yellow and black toner images are transferred in that order from yellow and black units  12 Y and  12 K so as to be overlaid onto the previously transferred toner images. Thus, a color toner image is formed on transfer belt  125 . The color toner image on transfer belt  125  may be further transferred onto a sheet P conveyed from sheet storage section  14 . In alternate embodiments, an order of the colors may vary. Further, some embodiments may include the use of additional or fewer colors. 
     Referring to  FIG. 1 , cleaning devices  127  are shown to the right of the respective photosensitive drums  121 . Cleaning devices  127  remove residual toner from the peripheral surfaces of the respective photosensitive drums  121  so as to clean photosensitive drums  121 . The peripheral surfaces of photosensitive drums  121  cleaned by cleaning devices  127  face the respective chargers  123  again for next charging. Waste toner removed from the peripheral surfaces of the photosensitive drums  121  by the cleaning devices  127  may be collected through a specific path into a toner collecting bottle (not shown). In alternate embodiments, cleaning devices may be provided in any position proximate the photosensitive drums. 
     In an embodiment depicted in  FIG. 1 , sheet conveyance path  111  extends from an upper right position of sheet storage section  14  to a position below image forming section  12 . Pairs of conveyance rollers  112  are provided at appropriate positions on sheet conveyance path  111 . Conveyance rollers may convey each sheet P fed from sheet storage section  14  toward a position below transfer belt  125 . As shown in  FIG. 1 , secondary-transfer roller  113  is also provided on sheet conveyance path  111  at a position facing the secondary-transfer counter roller  125   c . In some embodiments, secondary-transfer roller  113  is in contact with transfer belt  125 . During conveyance, sheet P may be positioned between transfer belt  125  and secondary-transfer roller  113 . In some embodiments, sheet P may be compressed between the two surfaces of the transfer belt and the secondary transfer roller. For example, the toner image on transfer belt  125  may be transferred onto the sheet P when sheet P is nipped between transfer belt  125  and secondary transfer roller  113 . 
     Fixing section  13  fixes the toner image transferred onto sheet P by image forming section  12 . Fixing section  13  includes heating roller  131 , fixing roller  132  facing heating roller  131 , fixing belt  133  stretched between heating roller  131  and fixing roller  132 , and pressing roller  134  facing fixing roller  132  with fixing belt  133  interposed therebetween. The heating roller may include a heat source. Heat sources used may include, but are not limited to electrical heaters and/or radiant heaters, such as halogen lamps, or any heat sources known in the art. Sheet P on which the color image is fixed may be conveyed along sheet discharge path  114  extending from an upper position of fixing section  13  and is discharged toward discharge tray  115 . In some embodiments, the discharge tray may be provided on the left wall of the apparatus body. 
     Cleaning device  40  is provided between secondary-transfer roller  113  and following roller  125   b  along transfer belt  125 . In alternate embodiments, a cleaning device may be positioned at any point along the transfer belt. Cleaning device  40  may remove any residual toner on transfer belt  125 . Some embodiments may include multiple cleaning devices positioned along the transfer belt. Further, the cleaning device may collect the residual toner in some embodiments. For example, cleaning device  40  shown in  FIG. 1  collects, or removes, residual toner remaining on transfer belt  125  after the transfer of the toner image onto the sheet P performed by secondary-transfer roller  113 . Subsequently, the cleaned transfer belt may be compressed between photosensitive drums  121  and primary-transfer rollers  126  again to allow another toner image to be transferred via primary transfer to the transfer belt. 
     In some embodiments, sheet storage section  14  includes sheet trays  141  provided below image forming section  12  and fixing section  13 . Sheet trays  141  are removably attached to apparatus body  11  and each store a stack of sheets P.  FIG. 1  depicts two sheet trays  141 . Alternatively, three or more sheet trays  141  may be provided. Some embodiments may include only one sheet tray  141 . 
     Sheets P may be fed one by one from any of the sheet trays  141  when corresponding pickup rollers  142  are driven. Each sheet P fed in this manner is conveyed along sheet conveyance path  111  toward the nip between secondary-transfer roller  113  of image forming section  12  and transfer belt  125 , and the color toner image formed on transfer belt  125  is transferred onto the sheet P. The sheet P after being subjected to the transfer is conveyed as described above. 
     In some embodiments, as shown in  FIG. 1  cleaning device  40  collects residual toner on transfer belt  125  remaining after the secondary transfer of a toner image performed by secondary-transfer roller  113 . Secondary transfer occurs when an image is transferred from the transfer belt to a sheet being conveyed along the sheet conveyance path.  FIG. 2  schematically shows elements of cleaning device  40 , leaning device  40  includes fur brush roller  41 , sweep roller  42 , and cleaning assist member  43 . In some embodiments, the fur brush roller may be in contact with the transfer belt. Sweep roller  42  may be provided at an oblique lower position (at lower right in  FIG. 2 ) with respect to the fur brush roller  41  and in contact with the peripheral surface of the fur brush roller  41 . As shown in  FIG. 2 , cleaning assist member  43  is provided on the upstream side with respect to the fur brush roller  41  and on the downstream side with respect to the secondary-transfer roller  113  (shown in  FIG. 1 ) in the direction of transfer belt  125 . For example, transfer belt  125  moves between fur brush roller  41 , secondary-transfer roller  113 , and housing  44  which contains fur brush roller  41 , sweep roller  42 , and cleaning assist member  43 . 
     In some embodiments, the fur brush roller may be electrically conductive. Further, in some embodiments the fur brush roller may include a number of brush hairs evenly embedded in the peripheral surface thereof. In some embodiments, the polarity of the fur brush roller may be opposite to the polarity of the residual toner on the transfer belt  125  remaining after secondary transfer. For example, the toner used in forming toner images may be biased at a secondary transfer position with a positive polarity by the secondary-transfer roller  113  (shown in  FIG. 1 ). Accordingly, the residual toner on transfer belt  125  remaining after secondary transfer is positively charged. Therefore, by negatively biasing the fur brush roller, the residual toner can be electrically collected onto the fur brush roller. In some embodiments, as shown in  FIGS. 8 and 9  fur brush roller  41  faces a counter roller  125   d  with the transfer belt  125  interposed therebetween. Counter roller  125   d  is positioned proximate transfer belt  125 . In some embodiments, the counter roller may be in contact with the transfer belt. Additionally, some embodiments may include a counter roller which is grounded. 
     Sweep roller  42  is a shaft roller made of, for example, iron. Alternatively, sweep rollers may be made of a material including, but not limited to metals, composites, plastics and/or any materials known in the art. Sweep roller  42  has a rotating shaft  42   a  substantially parallel to rotating shaft  41   a  of fur brush roller  41 . Sweep roller  42  contacts the peripheral surface of fur brush roller  41 , thereby receiving the residual toner collected by fur brush roller  41 . Housing  44  has a portion of bottom member  44   a  thereof forming waste-toner chamber  45 . Waste-toner chamber  45  is positioned below sweep roller  42  and temporarily stores the residual toner received by the sweep roller  42 . In some embodiments, cleaning blade  46  may be included in housing  44  at an appropriate position. Cleaning blade  46  may be secured in contact with peripheral surface of sweep roller  42 . The residual toner on sweep roller  42  may be scraped off the peripheral surface of sweep roller  42  by cleaning blade  46  into the waste-toner chamber  45 . The residual toner may than be conveyed by waste-toner screw  47  provided in waste-toner chamber  45  to a waste-toner bottle (not shown). In some embodiments, the housing may include seal members at various positions. For example,  FIGS. 2-9  depict housing  44  contacting seal member  48 . Seal member  48  may contact the peripheral surface of sweep roller  42 . Thus, a seal member may inhibit scattering of the residual toner. For example, seal member  48  may inhibit the residual toner in waste-toner chamber  45  from scattering around fur brush roller  41  and sweep roller  42 . As in  FIGS. 8 and 9  referred to below, sweep roller  42  may be negatively biased, instead of fur brush roller  41 . In either case, residual toner on transfer belt  125  can be collected. 
     As shown in  FIG. 2  cleaning assist member  43  has contact surface  43   a  at which cleaning assist member  43  may contact transfer belt  125 . In some embodiments, the cleaning assist member may be pressed against the transfer belt, thereby assisting the collection of residual toner from the transfer belt. An embodiment of contact surface  43   a  may include a rubbing member. Contact surfaces may include, but are not limited to rough surfaces, a conductive flocked sheet, an insulated flocked sheet, a conductive plate, a brush roller in which a conductive pile sheet is wrapped around a roller, a brush roller in which an insulated pile sheet is wrapped around a roller or any other surface known in the art. For example, a contact surface may include a flocked sheet having a number of brush hairs embedded. In some embodiments, the contact surfaces may be bonded to the contact member, such as a flocked sheet may be bonded to the contact member. An example of the flocked sheet may include a layer having conductive pile thread woven into the layer to form the flocked sheet. When the flocked sheet is pressed against transfer belt  125 , residual toner on transfer belt  125  may be rubbed off and fall into housing  44 . Side member  44   b  of housing  44  is provided with seal member  49  on the upstream side with respect to the direction in which transfer belt  125  moves. Seal member  49  is in contact with transfer belt  125 , and may inhibit scattering of the residual toner outside of cleaning device  40 . 
     In cleaning device  40  configured as described above, if cleaning assist member  43  is contaminated with residual toner adhered thereto, the residual toner may adhere to the transfer belt. In particular, when cleaning assist member  43  is contaminated with a large amount of toner, the residual toner collected by cleaning assist member  43  may adhere to transfer belt  125 . This may occur during calibration or in the event of sheet jamming. If the primary transfer and/or the secondary transfer are performed with transfer belt  125  having residual toner adhered to it, image failure may occur on the sheet. To avoid image failure, an embodiment of the cleaning device may include a cleaning mechanism configured to clean the cleaning assist member by removing residual toner adhered to the cleaning assist member. This cleaning mechanism allows the cleaning assist member to be moved away from the transfer belt  125  at predetermined times (e.g., at fixed or irregular time intervals, and/or upon or after the occurrence of one or more events, such as the elapsing of a predetermined time period, output of a predetermined number of printed sheets, calibration, and/or sheeting jamming etc. Then, the cleaning assist member may be cleaned. Referring to  FIGS. 2 to 9 , embodiments of the cleaning mechanism will now be described. 
       FIGS. 2 and 3  show an embodiment of a cleaning mechanism. Specifically,  FIG. 2  depicts cleaning mechanism  60  where the cleaning assist member  43  is in contact with the transfer belt  125 . In contrast,  FIG. 3  depicts a cleaning mechanism where the cleaning assist member  43  is moved away from the transfer belt  125  by the cleaning mechanism  60 . As shown in  FIGS. 2 and 3 , cleaning mechanism  60  includes support member  61  that supports the cleaning assist member  43  such that the contact surface  43   a  (e.g., rubbing member, or flocked sheet) of cleaning assist member  43  is in contact with transfer belt  125 , and rotating shaft  62  extending through an opening provided in support member  61 . Support member  61  includes toner receiver  63  having a shape that allows residual toner rubbed off by the cleaning assist member  43  to lie thereon. The shape of the toner receiver may vary. Rotating shaft  62  may include a motor shaft rotated (clockwise in the drawings) by a motor (not shown). Motors used may include any motor known in art, such as a single-revolution-clutch motor. As shown in  FIG. 2 , the axis of rotating shaft  62  may extend substantially parallel to the rotating shafts  41   a  and  42   a  of the fur brush roller  41  and the sweep roller  42 . 
     In an embodiment of the cleaning mechanism, when rotating shaft  62  rotates according to a predetermined timing, the cleaning assist member  43  is moved away from the transfer belt  125  as is shown in  FIG. 3 . For example, the predetermined time may be after a predetermined time has passed. Alternatively or additionally, the rotating shaft may be configured to rotate at pre-determined time points. The rotation of the rotating shaft is configured to allow contact surface  43   a  of cleaning assist member  43  to be oriented to face downward, together with opening  63   a  of toner receiver  63 . Accordingly, residual toner adhered to contact surface  43   a  of cleaning assist member  43  and residual toner in toner receiver  63  may fall down under their own weight. The fallen residual toner may be inhibited from scattering from housing  44  to the outside of cleaning device  40 . Thus, cleaning mechanism  60  cleans cleaning assist member  43 . 
     An embodiment of cleaning mechanism  70  is depicted in  FIGS. 4 and 5 . Specifically,  FIG. 4  shows cleaning assist member  43  in contact with transfer belt  125 . In contrast,  FIG. 5  depicts cleaning assist member  43  moved away from transfer belt  125  by cleaning mechanism  70 . Cleaning mechanism  70  includes scraper  71 , support member  61  and rotating shaft. Scraper  71  may be a portion of side member  44   b  of housing  44 . In some embodiments, scraper  71  may include tip  72  extending from the upstream side with respect to and toward cleaning assist member  43 . An embodiment may include positioning tip  72  such that, when the cleaning assist member  43  rotates clockwise with the rotation of the rotating shaft  62 , contact surface  43   a  of cleaning assist member  43  is rubbed against tip  72  as is shown in  FIG. 5 . 
     Referring now to  FIG. 5 , when rotating shaft  62  rotates according to a predetermined timing, cleaning assist member  43  is moved away from transfer belt  125 . Contact surface  43   a  may then rub against tip  72  of scraper  71 . Accordingly, residual toner adhered to contact surface  43   a  falls into housing  44 . Thus, cleaning mechanism  70  cleans cleaning assist member  43 . An embodiment may include toner receiver  74  provided in housing  44 . Toner receiver  74  may be positioned to receive residual toner scraped off contact surface  43   a  by scraper  71 . Both scattering of residual toner inside the housing and adhesion of residual toner to the fur brush roller and the sweep roller can be suppressed using a toner receiver. Toner receiver  74  may also be included in the embodiment of the cleaning device shown in  FIGS. 2 and 3 . 
       FIGS. 6 and 7  depict an embodiment of a cleaning mechanism. Specifically,  FIG. 6  shows cleaning mechanism  80  where cleaning assist member  43  is in contact with transfer belt  125 . In contrast,  FIG. 7  shows a state where cleaning assist member  43  is moved away from transfer belt  125  by cleaning mechanism  80 . As shown in  FIGS. 6 and 7 , cleaning mechanism  80  includes link mechanism  87  that links cleaning assist member  43  and scraper  82  together in order to clean cleaning assist member  43 . In some embodiments, link mechanism  87  includes support member  81  and link member  83 . Support member  81  may support cleaning assist member  43  such that contact surface  43   a  of cleaning assist member  43  is in contact with transfer belt  125 . Link member  83  links end  81   a  of support member  81  and base  82   b  of scraper  82  together. As shown in  FIGS. 6 and 7 , an embodiment may include base  82   b  being positioned opposite tip  82   a  of scraper  82 . End  81   a  of support member  81  and end  83   a  of link member  83  are linked together with linking shaft  84 . Base  82   b  of scraper  82  and end  83   b  of the link member  83  are linked together with linking shaft  85 . First linking shaft  84  is movable in a substantially vertical direction along guide  86  (shown by the dashed line) provided at an appropriate position in housing  44 . In some embodiments, alternate configurations may be used. 
     Referring now to  FIG. 7 , cleaning mechanism  80  allows linking shaft  84  to move downward along guide  86  at a predetermined interval. As linking shaft  84  moves downward, cleaning assist member  43  moves away from transfer belt  125 . In addition, tip  82   a  of scraper  82  moves, in conjunction with the downward movement of first linking shaft  84 , such that tip  82   a  rubs against the contact surface  43   a  of cleaning assist member  43 . Accordingly, residual toner adhered to contact surface  43   a  falls into housing  44 . Thus, the cleaning mechanism may clean the cleaning assist member with the aid of the link mechanism. 
     Another embodiment of a cleaning mechanism is depicted in  FIGS. 8 and 9 .  FIG. 8  shows cleaning mechanism  90  where cleaning assist member  43  is in contact with transfer belt  125 . In contrast,  FIG. 9  depicts cleaning assist member  43  in a position such that it is moved away from transfer belt  125  by the cleaning mechanism  90 . As shown in  FIG. 9 , cleaning assist member may be brought into contact with sweep roller  42 . In addition, some embodiments may include cleaning mechanism  90  electrically cleaning assist member  43 . Cleaning mechanism  90  includes support member  91  that supports cleaning assist member  43  such that contact surface  43   a  of the cleaning assist member  43  is in contact with transfer belt  125 . Rotating shaft  92  may extend through an opening provided in support member  91 . Rotating shaft  92  may be a motor shaft rotated (counterclockwise in the drawings) by a motor (not shown). The axis of rotating shaft  92  may extend substantially parallel to rotating shafts  41   a  and  42   a  of fur brush roller  41  and sweep roller  42 , respectively. The angle of rotation of the rotating shaft is set to allow the cleaning assist member to be moved away from the transfer belt during rotation. Further, cleaning assist member  43  may comes into contact with the peripheral surface of sweep roller  42 . In some embodiments, sweep roller  42  may be negatively biased by bias source  95 . 
     Referring now to  FIG. 9 , rotating shaft  92  may be set to rotate according to a predetermined timing to allow cleaning assist member  43  to be moved away from transfer belt  125 . Further, rotation of rotating shaft  92  may allow contact surface  43   a  of cleaning assist member  43  to come into contact with the peripheral surface of sweep roller  42 . In some embodiments, toner image on transfer belt  125  is positively biased at the secondary transfer position by secondary-transfer roller  113 . Therefore, residual toner on transfer belt  125  remaining after the secondary transfer is positively charged. The positively charged residual toner may adhere to the rubbing member of cleaning assist member  43 . Hence, by bringing the rubbing member into contact with the negatively biased peripheral surface of sweep roller  42 , the residual toner adhered to the rubbing member can be electrically transferred to sweep roller  42 . Residual toner may be transferred from the rubbing member to sweep roller  42 . In some embodiments, the residual toner may be scraped off the peripheral surface of sweep roller  42  by cleaning blade  46 . The residual toner collected from the fur brush roller and the sweep roller may fall into waste-toner chamber  45 . Thus, in some embodiments, cleaning mechanism  90  may electrically clean cleaning assist member  43 . In some embodiments, cleaning mechanisms may clean a cleaning assist member using both electrical and mechanical means. For example, cleaning mechanism  90  may allow for both electrical and mechanical cleaning of cleaning assist member  43 . 
     In another embodiment, cleaning mechanism  90  may be configured such that bias source  96  is connected to support member  91  to allow support member  91  to be positively biased. In some embodiments, counter roller may be provided at a position facing cleaning assist member  43  with transfer belt  125  interposed therebetween. In some embodiments, such as embodiments providing for support member  91  to be electrically biased, counter roller  97  may be in contact with transfer belt  125  and may be grounded. Residual toner on transfer belt  125  may be charged at the secondary transfer position so as to have a positive polarity. In some embodiments, the polarity of the residual toner may be unstable. For example, residual toner may include negatively charged particles and neutral particles even after charging. In cleaning mechanism  90  where support member  91  has been positively biased, the residual toner on transfer belt  125  can be charged positively and uniformly. Uniformly charging the residual toner may allow an increase in the efficiency of residual toner collection. For example, fur brush roller  41  positioned downstream of cleaning assist member  43  may collect residual toner may efficiently collect residual toner. In an embodiment, when the rubbing member of cleaning assist member  43  is in contact with the sweep roller  42 , support member  91  is disconnected from bias source  96  and is grounded. 
     In an embodiment of the cleaning device, the cleaning assist member may be cleaned by any of cleaning mechanisms  60 ,  70 ,  80 , and  90  shown in  FIGS. 2-9 . Alternately, features of any of the cleaning mechanisms may be combined to clean a cleaning assist member. Cleaning the cleaning assist members may inhibit image failure caused by adhesion of residual toner on the cleaning assist member and/or the transfer belt. 
     In some embodiments, multiple cleaning devices may be positioned along transfer belt to remove residual toner. 
     As shown in  FIGS. 2-9 , sheet storage section  14  and the conveyance path of a sheet are positioned below the cleaning device  40 . Further, cleaning device  40  may include housing  44  which encloses cleaning assist member  43  and cleaning mechanisms  60 ,  70 ,  80 , or  90 . This may suppress scattering of residual toner outside of the cleaning device  40 . Thus, contamination of the sheet storage section and the conveyance path may be reduced. 
       FIGS. 2-9  depict cleaning device  40  having cleaning assist member  43  positioned upstream of fur brush roller  41 . Alternatively, in some embodiments cleaning assist member  43  may be provided on downstream of fur brush roller  41 . In the alternative case, any residual toner remaining can be collected by cleaning assist member  43  provided on downstream of the fur brush roller. 
     In the embodiments described above, illustrative predetermined timings according to which the cleaning assist member may be moved away from the transfer belt may correspond to one or more fixed or variable (e.g., irregular) times, time intervals, and/or events, etc. For example, the predetermined timing may correspond to a time at which and/or time period during which the cleaning assist member is and/or tends to be contaminated with toner. For example, during between image-output jobs, during calibration of the image forming apparatus  10 , and in the event of sheet jamming, large amount of toner may adhere to the transfer belt and thus be conveyed to the cleaning device  40 . Alternate embodiments may include configuring the cleaning assist member to be moved away from the transfer belt at predetermined times. 
     Those skilled in the art will understand that such predetermined timing may be implemented by one or more processors, (e.g., program-controlled processors), which may be included within image forming apparatus  10 . 
     Having thus described in detail embodiments of the present invention, it is to be understood that the invention defined by the foregoing paragraphs is not to be limited to particular details and/or embodiments set forth in the above description, as many apparent variations thereof are possible without departing from the spirit or scope of the present invention.