Patent Publication Number: US-9904235-B2

Title: Cleaning device and image forming apparatus

Description:
INCORPORATION BY REFERENCE 
     This application claims priority to Japanese Patent Application No. 2016-148956 filed on 28 Jul., 2016, the entire contents of which are incorporated by reference herein. 
     BACKGROUND 
     The present disclosure relates to cleaning devices for removing remaining toner, and image forming apparatuses provided with the cleaning device. 
     Image forming apparatuses based on an electrophotographic method are widely known. The method includes five processes, namely, uniformly charging an uncharged photoconductor (charging process), irradiating the surface of the charged photoconductor with a laser beam according to a document to be copied thereby forming a latent image of the document on the surface of the photoconductor (exposure process), visualizing the latent image with toner (developing process), transferring the visualized toner image onto a recording medium such as a sheet placed on an intermediate transfer belt (transfer process), and fixing the transferred toner image onto the recording medium (fixing process). 
     Toner remains on the intermediate transfer belt on which the toner image has been transferred onto the recording medium, so that the remaining toner must be removed prior to the next image formation. Accordingly, for image forming apparatuses, various types of cleaning devices for removing the remaining toner have been suggested and been put into practice. 
     One example of the cleaning devices includes: a fur brush roller that cleans a surface of an intermediate transfer belt; a collecting roller that collects toner attached to the fur brush roller; a cleaning blade that abuts on a circumferential surface of the collecting roller and scrapes the toner collected by the collecting roller; and a toner storing container that temporally stores the toner scraped off by the cleaning blade. 
     The toner scraped off by the cleaning blade is moved to the toner storing container, and the toner moved to the toner storing container is conveyed by a conveyance screw to outside of the cleaning device. There is another example of the cleaning devices in which a seal member with flexibility is provided so as to make contact with a surface of the collecting roller, to thereby suppress the toner scraped off by the cleaning blade from flowing back to a fur brush roller side. 
     SUMMARY 
     A technique improved over the above technique is proposed herein as an aspect of the present disclosure. 
     A cleaning device according to an aspect of the present disclosure includes a removing roller, a collecting roller, a cleaning blade, a toner storing container, a conveyance screw, and a toner crushing member. The removing roller removes toner remaining on an image carrier while rotating in contact with the image carrier around a first rotation axis extending in a width direction of the image carrier. The collecting roller collects toner attached on the removing roller from the removing roller while making contact with the removing roller and rotating around a second rotation axis that is parallel with an extending direction of the first rotation axis. The cleaning blade extends in parallel with an extending direction of the second rotation axis, makes contact with the collecting roller, and scrapes off toner attached on the collecting roller. The toner storing container stores the toner having been collected by the collecting roller and scraped off by the cleaning blade, and is partitioned from the removing roller and the collecting roller by a seal member extending in parallel with the first rotation axis and the second rotation axis. The conveyance screw is disposed in the toner storing container, and, by rotating around a third rotation axis extending in parallel with the extending direction of the first rotation axis, conveys toner to an extending direction of the third rotation axis with a spirally formed fin provided on the conveyance screw around the third rotation axis. The toner crushing member crushes the toner accumulated in the toner storing container. Additionally, the toner crushing member includes a supporting portion and a plurality of elastic pieces. The supporting portion extends in parallel with the extending direction of the third rotation axis and is attached above the conveyance screw. The plurality of elastic pieces extends from the supporting portion toward the conveyance screw and is swung by making contact with the fin that rotates in association with the rotation of the conveyance screw. Each of the elastic pieces is formed with a base end portion at a side of the supporting portion. The base end portion is formed narrower than a pitch of adjacent two fin parts of the fin and formed so as to be fitted between intervals of the adjacent two fin parts in the extending direction of the third rotation axis. Also, each of the elastic pieces is formed with a raised portion rising toward the seal member, and as the raised portion is swung by making contact with the fin, the elastic pieces vibrate the seal member. 
     An image forming apparatus according to another aspect of the present disclosure includes an image forming section including an image carrier and the above described cleaning device. The cleaning device removes toner remaining on the image carrier. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic partial front sectional view showing structure of an image forming apparatus according a first embodiment of the present disclosure. 
         FIG. 2  is a sectional view showing a transfer unit and its peripheral configuration. 
         FIG. 3  is a sectional view showing a cleaning device and its peripheral configuration. 
         FIG. 4  is a perspective view showing a configuration of the cleaning device. 
         FIG. 5  is a partial perspective sectional view showing the configuration of the cleaning device. 
         FIG. 6  is a view showing the cleaning device from which a fur brush roller and a collecting roller are removed. 
         FIG. 7A  is a view showing a conveyance screw and  FIG. 7B  is a view showing a toner crushing member. 
         FIG. 8A  is a perspective view showing the toner crushing member and a swing support shaft adjustment sheet when they are unattached to one another, and  FIG. 8B  is a view showing the toner crushing member to which the swing support shaft adjustment sheet is attached. 
         FIG. 9A  is a view showing a state in which elastic pieces are fitted between intervals of adjacent two fin parts of a fin provided on the conveyance screw, and  FIG. 9B  is a view showing a state in which the elastic pieces ride over the fin provided on the conveyance screw. 
         FIG. 10A  is a view schematically showing a state in which paper powder is bitten between the collecting roller and a seal member, and  FIG. 10B  is a view schematically showing a state in which the paper powder is falling off. 
         FIG. 11  is a perspective view showing elastic pieces according to a second embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, a description will be given of a cleaning device according to the present disclosure and an image forming apparatus including the cleaning device, with reference to the drawings.  FIG. 1  is a schematic partial front sectional view showing structure of the image forming apparatus according a first embodiment of the present disclosure. The image forming apparatus  1  is a multifunction peripheral having a plurality of functions, such as copying, printing, scanning, and facsimile transmission, and includes an apparatus body  11  having an operation section  47 , a document feeder  6 , a document reading section  5 , an image forming section  12 , a fixing section  13 , and a paper feed tray  14 . 
     The operation section  47  receives, from an operator, instructions such as an image forming operation execution instruction and a document reading operation execution instruction for various kinds of operation and processing executable by the image forming apparatus  1 . The operation section  47  includes a display section  473  for displaying operation guides for the operator. 
     A description will be given in performing the image forming operation by the image forming apparatus  1 . Based on, for example, the image data generated through the document reading operation, the image data stored in the built-in HDD, or the image data received from the network-connected computer, the image forming section  12  forms a toner image on recording paper P as a recording paper sheet (recording medium) fed from the paper feed tray  14 . 
     The image forming section  12  includes an image forming unit  12 Bk for black (Bk), an image forming unit  12 Y for yellow (Y), an image forming unit  12 C for cyan (C), and an image forming unit  12 M for magenta (M). Each of the image forming units  12 Bk,  12 Y,  12 C, and  12 M includes: drum type photoconductors  121 Bk,  121 Y,  121 C, and  121 M respectively; a charging device  220  that charges each surface of the photoconductors  121 Bk,  121 Y,  121 C, and  121 M; and a developing device  230  that forms the toner image on the photoconductors  121 Bk,  121 Y,  121 C, and  121 M. Each of the photoconductors  121 Bk,  121 Y,  121 C, and  121 M is configured so as to be rotatably driven in counterclockwise in  FIG. 1 . 
     Toner containers  17 Bk,  17 Y,  17 C, and  17 M stores a toner for black, a toner for yellow, a toner for cyan, and a toner for magenta, respectively, and is detachably attached to a toner container mounting member (not illustrated) mounted on the apparatus body  11 , at a position away from the photoconductors  121 Bk,  121 Y,  121 C, and  121 M with an intermediate transfer belt  125  (one example of the image carrier) in between, the position being above of the intermediate transfer belt  125 . 
     A transfer unit  120  includes: the intermediate transfer belt  125  onto an outer circumferential surface of which the toner image is transferred; a drive roller  125   a ; a driven roller  125   b ; a primary transfer roller  126 ; and a cleaning device  240  that removes toner remaining on a surface of the intermediate transfer belt  125 . 
     The intermediate transfer belt  125  is stretched between the drive roller  125   a  and the driven roller  125   b , is driven by the drive roller  125   a  while abutting on circumferential surfaces of the photoconductors  121 Bk,  121 Y,  121 C, and  121 M, and endlessly runs synchronously with the photoconductors  121 Bk,  121 Y,  121 C, and  121 M. 
     A description will be given in performing color printing. Surroundings of the photoconductors  121 Bk,  121 Y,  121 C, and  121 M are evenly charged (charging process), a laser light is irradiated to surfaces of the electrically charged photoconductors  121 Bk,  121 Y,  121 C, and  121 M based on image data to form latent images (exposure process), and the latent images visualized by toner (developing process). Then the toner images formed through the visualization are transferred onto the intermediate transfer belt  125  by the primary transfer roller  126 . 
     The toner images of the respective colors (black, yellow, cyan, and magenta) to be transferred onto the intermediate transfer belt  125  are superposed on each other on the intermediate transfer belt  125  through transfer timing adjustment, turning into a color toner image. 
     A secondary transfer roller  210  transfers, at a nip part N, the color toner image having been formed on the surface of the intermediate transfer belt  125  onto the recording paper P conveyed from the paper feed tray  14  through a conveyance path  190 . The nip part N is formed between the secondary transfer roller  210  and the drive roller  125   a  with the intermediate transfer belt  125  in between. 
     The fixing section  13  fixes the toner image on the recording paper P through thermal compression. The recording paper P on which the color image has been formed and subjected to fixing processing is discharged onto a discharge tray  151 . 
       FIG. 2  is a sectional view showing the transfer unit  120  and its peripheral configuration, as viewed from the back side of the image forming apparatus  1  illustrated in  FIG. 1 .  FIG. 3  is a sectional view showing the cleaning device  240  and its peripheral configuration, as viewed from the back side of the image forming apparatus  1  illustrated in  FIG. 1 .  FIG. 4  is a perspective view showing a configuration of the cleaning device  240  and  FIG. 5  is a partial perspective sectional view showing the configuration of the cleaning device  240 .  FIG. 6  is a view showing the cleaning device  240  from which a fur brush roller  242  and a collecting roller  243  are removed, as viewed from the direction indicated as A in  FIG. 4 .  FIG. 7A  is a view showing a conveyance screw  245  and  FIG. 7B  is a view showing a toner crushing member  247 .  FIG. 8A  is a perspective view showing the toner crushing member  247  and a swing support shaft adjustment sheet  248  when they are unattached to one another, and  FIG. 8B  is a view showing the toner crushing member  247  to which the swing support shaft adjustment sheet  248  is attached by a double-sided tape, as viewed from the direction indicated as B in  FIG. 8A . 
     The cleaning device  240  includes a casing  241 , to which the fur brush roller  242 , the collecting roller  243 , a cleaning blade  244 , the conveyance screw  245 , a seal member  246 , the toner crushing member  247 , and the swing support shaft adjustment sheet  248 , that constitute the cleaning device  240 , are attached. The casing  241  includes a toner storing container  249 . A disposed position of the toner storing container  249  is, for example, the lower left corner in  FIG. 3 . 
     The fur brush roller  242  is arranged so as to face the driven roller  125   b  with the intermediate transfer belt  125  in between. The fur brush roller  242  cleans the surface of the intermediate transfer belt  125  while rotating in contact with the intermediate transfer belt  125  and electrically attracts toner remaining on the surface of the intermediate transfer belt  125 . The fur brush roller  242  is formed by having, for example a nonwoven fabric comprising a filament made of resin, wound around whole of its rotation axis. The rotation axis of the fur brush roller  242  (a first rotation axis) extends in parallel with the driven roller  125   b  that is a width direction of the intermediate transfer belt  125 , and is pivotally supported by the casing  241 . The fur brush roller  242  is one example of a removing roller in the scope of the claims. 
     The collecting roller  243  is made of, for example, metal. The collecting roller  243  makes contact with the surface of the fur brush roller  242  and electrically collects, from the fur brush roller  242 , the toner having been collected by the fur brush roller  242 . A rotation axis of the collecting roller  243  (a second rotation axis) extends in parallel with the fur brush roller  242  and is pivotally supported by the casing  241 . 
     The cleaning blade  244  is constituted of a flat plate member, and extends in parallel with the collecting roller  243 . The cleaning blade  244  is attached to the casing  241  in a manner such that a tip thereof touches the surface of the collecting roller  243 , and scrapes off the toner having been collected by the collecting roller  243  from the surface of the collecting roller  243 . The scraped off toner drops into the toner storing container  249  and remains therein. 
     The toner storing container  249  is partitioned from the fur brush roller  242  and the collecting roller  243  by the seal member  246 , and stores the toner having been collected by the collecting roller  243  and scraped off by the cleaning blade  244 . The toner storing container  249  includes the conveyance screw  245 . 
     The conveyance screw  245  extends in parallel with the collecting roller  243 , and its rotation axis  2451  (a third rotation axis) is pivotally supported by the casing  241 . A fin  2452  formed in a spiral shape for conveying the toner is arranged on a circumferential surface of the rotation axis  2451  of the conveyance screw  245 . The fin  2452  rotates around the rotation axis  2451  so that the conveyance screw  245  conveys the toner to a direction that the rotation axis  2451  extends. The toner having been conveyed in this manner moves to a waste toner tank (not illustrated) through an un-illustrated opening portion provided at the toner storing container  249 . 
     The seal member  246  is a sheet-like member and made of, for example, materials having flexibility such as urethane. A part of the seal member  246  is attached to the toner storing container  249  so as to flexibly touch the surface of the collecting roller  243 . The seal member  246  is arranged so that the toner attached to the surface of the collecting roller  243  can pass through the position where a tip of the seal member  246  touches the surface of the collecting roller  243  but the toner scraped off from the collecting roller  243  by the cleaning blade  244  is stopped from flowing back to the fur brush roller  242  side from the toner storing container  249 . 
     The toner crushing member  247  crushes the toner accumulated in the toner storing container  249 . The toner crushing member  247  is fixed to an inner wall of the casing  241  and extends toward the direction that the rotation axis  2451  of the conveyance screw  245  extends. The toner crushing member  247  is made up to include a supporting portion  2471  arranged above the rotation axis  2451  of the conveyance screw  245  in parallel with the rotation axis  2451 , and a plurality of elastic pieces  2472  extending from the supporting portion  2471  to the conveyance screw  245 . The toner crushing member  247  is made of, for example, a synthetic resin material having flexibility. With the synthetic resin material having flexibility, the toner crushing member  247  is capable of easily crushing the toner accumulated in the toner storing container  249 . 
     The elastic pieces  2472  are swung by making contact with the fin  2452  that rotates in association with the rotation of the conveyance screw  245 . Each of the elastic pieces  2472  includes a base end portion  2473  formed at a side of the supporting portion  2471 . A width W 1  (illustrated in  FIG. 7B ) of the base end portion  2473  is designed so as to be narrower than a width that is calculated by deducting thickness of adjacent two fin parts  2452 A of the fin  2452 , the fin  2452  being provided along the extending direction of the rotation axis  2451 , from width of a pitch P 1  (illustrated in  FIG. 7A ) of the adjacent two fin parts  2452 A of the fin  2452 . Thus, the base end portion  2473  can be fitted between the adjacent two fin parts  2452 A of the fin  2452 . As illustrated in  FIG. 8A , each of the elastic pieces  2472  includes a raised portion  2474  rising toward the seal member  246 , thus the elastic pieces  2472  can touch the seal member  246 . Considering the strength, 90 degrees is a desirable angle to be formed between the base end portion  2473  and the raised portion  2474 . It is not intended, however, to limit the angle between the base end portion  2473  and the raised portion  2474  to be the aforementioned angle. 
     The elastic pieces  2472  abut on the conveyance screw  245  and swing in association with the rotation of the conveyance screw  245 . In other words, when the conveyance screw  245  rotates, the elastic pieces  2472  ride over the fin  2452  as the fin  2452  moves in association with the rotation of the conveyance screw  245  (relative positional movement against the elastic pieces  2472 ), and then fit into intervals between adjacent two fin parts  2452 A of the fin  2452 . Accordingly, the elastic pieces  2472  swing between the conveyance screw  245  and the seal member  246 . The elastic pieces  2472  crash, by this swing, the waste toner piled up within the toner storing container  249 . 
     In addition, by the above described swing, the elastic pieces  2472  repeat moving between a position where the raised portion  2474  becomes in contact with the seal member  246  and a position where the raised portion  2474  becomes in non-contact with the seal member  246 . The elastic pieces  2472  and the raised portion  2474  vibrate the seal member  246  with a help of the aforesaid movement. By this vibration, the elastic pieces  2472  inhibit foreign objects from being bitten in between the collecting roller  243  and seal member  246 , and make the bitten foreign objects be dropped. 
     In this embodiment, a pitch P 2  (illustrated in  FIG. 7B ) of the elastic pieces  2472  is a half of the pitch P 1  of the fin parts  2452 A, and two of the elastic pieces  2472  are arranged at each pitch between the adjacent two fin parts  2452 A. With this arrangement, when the conveyance screw  245  starts to rotate, the two of the elastic pieces  2472  initially arranged at the pitch P 1  in the extending direction of the rotation axis  2451  move to the direction toward the seal member  246  by a pressure from the fin  2452 , and the raised portion  2474  makes contact with the seal member  246 . At this time, another two of the elastic pieces  2472  that are to be arranged at the pitch P 1  next do not receive the pressure from the fin  2452 , and are arranged to be located at a non-contacting position with the seal member  246 . It is not intended, however, to limit the number of the elastic pieces  2472  arranged at pitch P 1  to the aforementioned number. 
     When the conveyance screw  245  further rotates, the another two of the elastic pieces  2472  that are to be arranged at the pitch P 1  next move to the direction toward the seal member  246  by the pressure from the fin  2452 , and the raised portion  2474  of the elastic pieces  2472  makes contact with the seal member  246 . At this time, the two of the elastic pieces  2472  initially arranged at the pitch P and the elastic pieces  2472  formed there at are released from the pressure from the fin  2452  and go back to the non-contacting position with the seal member  246 . 
     The toner crushing member  247  is formed desirably with material firmer than the seal member  246 . For example, a dilute resin sheet around 100 μm such as PET (polyethylene terephthalate) is used. 
     A screw direction of the conveyance-screw is left hand (i.e., connecting the lower left side to the upper right side). When viewing the rotation axis  2451  from the right side in  FIG. 7A , the conveyance screw rotates clockwise, so that the direction toward the left side in  FIG. 7A  is a conveyance direction of the toner. 
     As illustrated in  FIG. 8A  and  FIG. 8B , at a border between the supporting portion  2471  and the elastic pieces  2472  of the toner crushing member  247 , the swing support shaft adjustment sheet  248  is attached. The swing support shaft adjustment sheet  248  serves as a member for adjusting a swing support shaft for the elastic pieces  2472  to be a bottom end portion  248   a  of the swing support shaft adjustment sheet  248 . The swing support shaft is a base shaft when the elastic pieces  2472  are swung by the rotation of the conveyance screw  245  (the pressure from the fin  2452 ). In other words, the swing support shaft adjustment sheet  248  is capable of setting a swing range of the elastic pieces  2472  to be narrow, by shortening the length of the elastic pieces  2472  extending toward the conveyance screw  245  from the bottom end portion  248   a  of the swing support shaft adjustment sheet  248 . With this arrangement, it is possible to adjust a power that the elastic pieces  2472  scrape off toner and a power to vibrate the seal member  246  (i.e., the amount that the raised portion  2474  moves the seal member  246  by its pressure). A sheet thicker than the toner crushing member  247 , for example, a resin sheet around 250 μm such as PET (polyethylene terephthalate) is used for the swing support shaft adjustment sheet  248 . 
     In general image forming apparatuses, an intermediate transfer belt makes contact with a recording medium, so that sometimes foreign objects such as paper powder flow into a cleaning device along with toner. When the foreign objects that flew into the cleaning device along with the toner are bitten in between a collecting roller and a seal member, a gap appears between the collecting roller and the seal member, which causes the toner in a toner storing container to flow back into the intermediate transfer belt. In the worst case, there is an occurrence of a phenomenon called toner drop, in which the recording medium is stained. 
     In contrast, in the embodiment of the present disclosure, when the conveyance screw  245  rotates, the plurality of the elastic pieces  2472  of the toner crushing member  247  is swung by the fin  2452  provided on the conveyance screw  245 , and in association with the swing, a contact and non-contact are repeated by the raised portion  2474  formed respectively at the elastic pieces  2472  with respect to the seal member  246 . Thus, the elastic pieces  2472  can vibrate the seal member  246 . This vibration inhibits foreign objects from being bitten in between the collecting roller  243  and the seal member  246 , and makes the bitten foreign objects be dropped. That is, the embodiment is capable of suppressing situations such that the foreign objects get in between the collecting roller  243  and the seal member  246 , and eliminating such situations promptly. Furthermore, it is possible to accurately prevent a gap from appearing between the collecting roller  243  and the seal member  246 . 
       FIG. 9A  is a view showing a state in which the elastic pieces  2472  are fitted between intervals of the adjacent two fin parts  2452 A of the fin  2452  provided on the conveyance screw  245  (within the aforesaid pitch P 1 ) (minimum movable position of swing range), and  FIG. 9B  is a view showing a state in which the elastic pieces  2472  ride over the fin  2452  provided on the conveyance screw  245  (maximum movable position of swing range). 
     When the conveyance screw  245  rotates, the plurality of elastic pieces  2472  is swung by the fin  2452  provided on the conveyance screw  245 , as described above. When the swing is made, the elastic pieces  2472  perform movement for fitting into intervals of the adjacent two fin parts  2452 A of the fin  2452 , as illustrated in  FIG. 9A , and perform movement of riding over the fin  2452 , as illustrated in  FIG. 9B . The raised portion  2474  formed respectively at the elastic pieces  2472  makes contact with the seal member  246  at the time of the riding-movement, and becomes non-contact with the seal member  246  at the time of the fitting-movement. 
       FIG. 10A  is a view schematically showing a state in which paper powder M is bitten between the collecting roller  243  and the seal member  246 , and  FIG. 10B  is a view schematically showing a state in which the paper powder M is falling off. When the raised portion  2474  of the elastic pieces  2472 , which comprises the toner crushing member  247 , comes in contact with the seal member  246  and the seal member  246  vibrates, the paper powder M falls off, as illustrated in  FIG. 10B . 
     The embodiment above has been describing the case in which the plurality of the elastic pieces  2472  is arranged at each pitch between the adjacent two fin parts of the fin  2452 , but a single elastic piece  2472  may be arranged between each pitch. 
     In another embodiment, as illustrated in  FIG. 11 , the elastic pieces  2472  comprising the toner crushing member  247  may be formed such that a tip portion  2474   a  of the raised portion  2474  protrudes at an upstream side (or downstream side) in the conveyance direction, forming an L shape, and may be formed widely within limits keeping the tip portion  2474   a  from contacting with the adjoining tip portion  2474   a . With this arrangement, an area where the raised portion  2474  and the seal member  246  come in contact is widened, and the power to vibrate the seal member  246  can be enlarged. Thus, it is possible to more effectively prevent a gap from appearing between the collecting roller  243  and the seal member  246 . 
     The present disclosure is not limited to the embodiments described above and various modifications thereto can be made. In the above, described as one embodiment of the image forming apparatus according to the present disclosure is a multifunction peripheral, but it is merely an example. Different electronic devices, for example another image forming apparatus having functions such as a copy function, a facsimile function, and a printing function, may be used. 
     Further, the configurations and processes of the embodiment described with reference to  FIGS. 1 to 11  are merely exemplary, and not intended to limit the scope of the disclosure. 
     Various modifications and alterations of this disclosure will be apparent to those skilled in the art without departing from the scope and spirit of this disclosure, and it should be understood that this disclosure is not limited to the illustrative embodiments set forth herein.