Patent Publication Number: US-11385590-B1

Title: Image carrier unit and image forming apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2021-054457 filed Mar. 29, 2021. 
     BACKGROUND 
     (i) Technical Field 
     The present disclosure relates to an image carrier unit and an image forming apparatus. 
     (ii) Related Art 
     The following process cartridge is known (refer to Japanese Patent No. 3507227). The process cartridge includes an electrophotographic photoconductor, a process member that operates the electrophotographic photoconductor, a cartridge frame that accommodates the electrophotographic photoconductor and the process member and includes a guide portion engaged with a linear-motion guide of an electrophotographic image forming apparatus body, a protection cover that covers a portion of the electrophotographic photoconductor exposed to the outside, that is fitted to the linear-motion guide of the cartridge frame parallel to the guide portion of the cartridge frame, and that is removably attached to the cartridge frame. The protection cover includes an interfering portion. The interfering portion comes into contact with the electrophotographic image forming apparatus body when the process cartridge is incompletely inserted into and fitted to a streak groove in the electrophotographic image forming apparatus body shorter than the length of the process cartridge in an attachment-removal direction. When the interfering portion comes into contact with the electrophotographic image forming apparatus body while the protection cover is fitted to the streak groove, the cartridge frame is attached to the electrophotographic image forming apparatus body while leaving the protection cover incompletely attached. 
     The following photoconductor unit is also known (Japanese Patent No. 4835682). The photoconductor unit includes a photoconductor pivotally supported by the housing to be rotatable and at least partially exposed from the housing. The photoconductor unit is inserted into an image forming apparatus in an axial direction of the photoconductor. The photoconductor unit includes a light-shielding sheet directly fixed to a housing to cover part of the photoconductor on a first side in the axial direction, a hard cover disposed adjacent to the light-shielding sheet on a second side in the axial direction or disposed to overlap part of the light-shielding sheet, fitted to a portion of the housing at the second end in the axial direction, and positioned with respect to the housing to form a grip for insertion into the image forming apparatus, and a buffer member interposed between the hard cover and the photoconductor. The hard cover has a length that allows the photoconductor unit to be gripped on the hard cover. The light-shielding sheet, the hard cover, and the buffer member are integrally removable from the photoconductor. 
     SUMMARY 
     Aspects of non-limiting embodiments of the present disclosure relate to a structure that prevents a printing operation from being performed while a protection cover is attached to an image carrier. 
     Aspects of certain non-limiting embodiments of the present disclosure address the features discussed above and/or other features not described above. However, aspects of the non-limiting embodiments are not required to address the above features, and aspects of the non-limiting embodiments of the present disclosure may not address features described above. 
     According to an aspect of the present disclosure, there is provided an image carrier unit insertable into and removable from an apparatus housing, the image carrier unit including: an image carrier; a protection cover removable from and attachable to the image carrier and including a covering portion and a block, the covering portion covering an exposed portion of the image carrier, the block being disposed on a near side in an insertion-removal direction and protruding in a direction crossing the insertion-removal direction; and a surface opposing a far side of the block in the insertion-removal direction, wherein the block is pressed by a protrusion movable toward the apparatus housing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the present disclosure will be described in detail based on the following figures, wherein: 
         FIG. 1  is a cross-sectional schematic diagram of an example of a schematic structure of an image forming apparatus; 
         FIG. 2  is a cross-sectional schematic diagram illustrating a unit structure in the image forming apparatus; 
         FIG. 3  is a perspective view of the entire structure of a protection cover; 
         FIG. 4A  is a cross-sectional schematic diagram of a structure of a block of the protection cover, and  FIG. 4B  is a cross-sectional schematic diagram of the protection cover attached to a photoconductor unit; 
         FIG. 5A  is a cross-sectional schematic diagram, taken in the axial direction, of the photoconductor unit to which the protection cover is attached, and  FIG. 5B  is a front view of the photoconductor unit to which the protection cover is attached; 
         FIG. 6  is a perspective view illustrating attachment of the photoconductor unit to an apparatus housing; and 
         FIGS. 7A and 7B  are cross-sectional schematic diagrams illustrating the relationship between a protrusion and the protection cover left unremoved. 
     
    
    
     DETAILED DESCRIPTION 
     With reference to the drawings, the present disclosure will be described further in detail below while taking exemplary embodiments and specific examples as examples. However, the present disclosure is not limited to these exemplary embodiments and specific examples. 
     In the following description with reference to the drawings, the drawings are schematic, and have the ratios between the dimensions different from the actual ones. For ease of understanding, components other than those used for the description are omitted from the drawings as appropriate. 
     For ease of understanding the following description, throughout the drawings, the front-rear direction is indicated as an X axis direction, the left-right direction is indicated as a Y axis direction, and the vertical direction is indicated as a Z axis direction. 
     (1) Entire Structure and Operation of Image Forming Apparatus (1.1) Entire Structure of Image Forming Apparatus 
       FIG. 1  is a cross-sectional schematic diagram of an example of a schematic structure of an image forming apparatus  1  according to the present exemplary embodiment. 
     The image forming apparatus  1  includes an image forming portion  10 , a sheet feeder  20  attached to a first end of the image forming portion  10 , a sheet discharger  30  disposed at a second end of the image forming portion  10  and to which printed sheets are discharged, and an image processor (not illustrated) that generates image information based on print information transmitted from a host device. 
     The image forming portion  10  includes a system controller (not illustrated), exposure devices  12 , photoconductor units  13 , development devices  14 , a transfer device  15 , sheet transport devices  16   a ,  16   b , and  16   c , a fixing device  17 , and a driving device (not illustrated). The image forming portion  10  forms image information received from the image processor into a toner image on a sheet fed from the sheet feeder  20 . 
     The sheet feeder  20  feeds sheets to the image forming portion  10 . Specifically, the sheet feeder  20  includes multiple sheet containers that accommodate sheets of different types (for example, different in material, thickness, sheet size, or paper grain). The sheet feeder  20  feeds sheets picked up from one of these sheet containers to the image forming portion  10 . 
     The sheet discharger  30  discharges sheets carrying images output from the image forming portion  10 . Thus, the sheet discharger  30  includes a discharged-sheet receiver that receives sheets to which images have been output. The sheet discharger  30  may have a function of performing postprocessing, such as cutting or stapling, on a stack of sheets output from the image forming portion  10 . 
     (1.2) Structure and Operation of Image Forming Portion 
     In the image forming apparatus  1  with this structure, each sheet picked up from one of the sheet containers in the sheet feeder  20  designated by a print job for each print is fed to the image forming portion  10  at the timing of image formation. 
     The photoconductor units  13  serving as examples of image forming units include photoconductor drums  31  that are arranged parallel to each other below the exposure devices  12  and serve as image carriers driven to rotate. A charging roller  32 , the exposure device  12 , the development device  14 , a first transfer roller  52 , and a cleaning blade  34  are arranged in the rotation direction of each photoconductor drum  31 . 
     Each development device  14  includes a development housing  41  that accommodates a developer inside. Inside the development housing  41 , a development roller  42  is disposed to oppose the corresponding photoconductor drum  31 . 
     The development devices  14  have substantially the same structure except for the development housings  41  accommodating different developers to respectively form toner images of yellow (Y), magenta (M), cyan (C), and black (K). 
     A replaceable toner cartridge T and a developer feeder  60  are disposed above each development device  14 . The toner cartridge T accommodates a developer (toner including a carrier). The developer feeder  60  feeds the developer from the toner cartridge T to the development device  14 . In the present exemplary embodiment, toner cartridges Ty, Tm, and Tc for yellow (Y), magenta (M), and cyan (C) and two toner cartridges Tk for black (K) are removably attached. 
     The surface of each rotating photoconductor drum  31  is charged by the corresponding charging roller  32  with electricity, and receives an electrostatic latent image formed from latent-image-forming light emitted from the exposure device  12 . The electrostatic latent image formed on the photoconductor drum  31  is developed by the development roller  42  as a toner image. 
     The transfer device  15  includes an intermediate transfer belt  51 , first transfer rollers  52 , and a second transfer roller  53 . To the intermediate transfer belt  51 , the toner images of different colors formed on the photoconductor drums  31  of the photoconductor units  13  are transferred in a superposed manner. The first transfer rollers  52  sequentially transfer (first-transfer) the toner images of different colors formed by the photoconductor units  13  to the intermediate transfer belt  51 . The second transfer roller  53  collectively transfers (second-transfers) the toner images of different colors transferred to the intermediate transfer belt  51  in a superposed manner to a sheet serving as a recording medium. 
     The toner images of different colors formed on the photoconductor drums  31  of the photoconductor units  13  are sequentially electrostatically transferred (first-transferred) onto the intermediate transfer belt  51  by the first transfer rollers  52  that have received a predetermined transfer voltage from, for example, a power supply (not illustrated) controlled by the system controller. Thus, a superposed toner image including toner of different colors is formed. 
     In accordance with movement of the intermediate transfer belt  51 , the superposed toner image on the intermediate transfer belt  51  is transported to the second transfer portion TR where the second transfer roller  53  is pressed against a back-up roller  65  with the intermediate transfer belt  51  interposed therebetween. 
     Concurrent with the arrival of the superposed toner image at the second transfer portion TR, a sheet is fed from the sheet feeder  20  to the second transfer portion TR. A predetermined second transfer voltage is applied from a power supply controlled by the system controller to the back-up roller  65  that opposes the second transfer roller  53  with the intermediate transfer belt  51  interposed therebetween. The superposed toner image on the intermediate transfer belt  51  is thus collectively transferred to a sheet. 
     Remaining toner on the surface of each photoconductor drum  31  is removed by the cleaning blade  34 , and collected into a waste toner container (not illustrated). Each charging roller  32  recharges the surface of the corresponding photoconductor drum  31  with electricity. 
     The fixing device  17  includes an endless fixing belt  17   a  that rotates unidirectionally, and a pressing roller  17   b  that is in contact with the peripheral surface of the fixing belt  17   a  and rotates unidirectionally. A nip portion (fixing area) is formed in an area where the fixing belt  17   a  and the pressing roller  17   b  are in pressure contact with each other. 
     The sheet to which the toner image is transferred by the transfer device  15  is transported to the fixing device  17  via the sheet transport device  16   a  while having the toner image unfixed. The sheet P transported by the fixing device  17  has the toner image fixed by the fixing belt  17   a  and the pressing roller  17   b  with the effects of pressure contact and heating. 
     The sheet P subjected to fixing is fed to the sheet discharger  30  via the sheet transport device  16   b.    
     To output images on both surfaces of each sheet, the sheet is turned upside down by the sheet transport device  16   c  and fed again to the second transfer portion TR in the image forming portion  10 . After the toner image is transferred and the transfer image is fixed, the sheet is fed to the sheet discharger  30 . The sheet fed to the sheet discharger  30  is discharged to the discharged-sheet receiver after being subjected to postprocessing such as cutting or stapling as appropriate. 
     (2) Unit Structure and Attachment Operation of Image Forming Apparatus 
       FIG. 2  is a cross-sectional schematic diagram of a unit structure of the image forming apparatus  1 . The structure and an attachment operation of the photoconductor unit  13  and the development device  14  will be described below with reference to the drawings. 
     As illustrated in  FIG. 2 , in the image forming apparatus  1 , the photoconductor unit  13  and the development device  14  are removably accommodated in an apparatus housing  90 . 
     (2.1) Photoconductor Unit 
     In each photoconductor unit  13 , as illustrated in  FIG. 2 , the photoconductor drum  31  is rotatably (drawn with arrow A in  FIG. 2 ) supported by a unit housing  35 . The unit housing  35  accommodates the charging roller  32 , a cleaning roller  33 , the cleaning blade  34 , and a transport auger  36  that transports toner removed by the cleaning blade  34  to a waste toner transporter  200  (refer to  FIGS. 7A and 7B ). 
     A hook-shaped hook  37  that is engaged with a guide  91  in the apparatus housing  90  is integrated with the unit housing  35 . The hook  37  protrudes upward (in the Z direction) to the uppermost position of the photoconductor unit  13 , and extends from the near side to the far side of the photoconductor unit  13 . The hook  37  is engaged with the guide  91  in the apparatus housing  90  to guide the photoconductor unit  13  to be attached to the apparatus housing  90 . 
     A protection cover  100  that covers the surface of the photoconductor drum  31  exposed to the outside for protection is removably attached to the photoconductor unit  13 . The protection cover  100  prevents the surface of the photoconductor drum  31  from being damaged due to falling or vibrations while the photoconductor unit  13  is unused. The protection cover  100  is removed after the photoconductor unit  13  is attached to the apparatus housing  90 . 
     (2.2) Development Device 
     As illustrated in  FIG. 2 , in the development device  14 , the development roller  42  is rotatably supported by the development housing  41 . The development housing  41  accommodates an agitation auger  43 A and a supply auger  43 B. The portion in the development housing  41  around the agitation auger  43 A and the supply auger  43 B is filled with the developer, and is covered with a cover member  44 . 
     The development roller  42  includes a hollow cylindrical development sleeve  42 A rotatably supported by the development housing  41 , and a magnet  42 B that is a solid cylindrical magnet member disposed inside the development sleeve  42 A and fixed to the development housing  41 . 
     The development sleeve  42 A holds the developer on its outer periphery with the magnetic force of the magnet  42 B, and transports the developer with rotation of the development sleeve  42 A (indicated with arrow B in  FIG. 2 ) to the electrostatic latent image on the photoconductor drum  31 . 
     (2.3) Protection Cover 
       FIG. 3  is a perspective view of the entire structure of the protection cover  100 .  FIG. 4A  is a cross-sectional schematic diagram of a structure of a block  120  of the protection cover  100 , and  FIG. 4B  is a cross-sectional schematic diagram of the protection cover  100  attached to the photoconductor unit  13 . The structure of the protection cover  100  will be described below with reference to the drawings. 
     The protection cover  100  includes a covering portion  110  and a block  120 . The covering portion  110  covers an exposed portion of the surface of the photoconductor drum  31  exposed to the outside. The block  120  is integrated with the covering portion  110  and disposed in front of the photoconductor unit  13  in the insertion-removal direction. The protection cover  100  is formed from synthetic resin, such as polypropylene, that is solid without being significantly deformed when gripped by a user. 
     The covering portion  110  extends in the longitudinal direction of the photoconductor unit  13  to cover the exposed surface of the photoconductor drum  31 . An attachment portion  111  fitted into the unit housing  35  is formed on the far side of the covering portion  110  in the insertion-removal direction of the photoconductor unit  13 . 
     The block  120  is a quadrangular prism having a predetermined thickness, width, and height. The block  120  includes a tab  121  on the bottom surface. The tab  121  extends to the near side in the insertion-removal direction to be grippable from the front side of the apparatus housing  90 . As illustrated in the cross section in  FIGS. 4A and 4B , the tab  121  is thinned in the thickness direction, and has a nonslip portion  121   a  on the back surface to be gripped by a user when the user draws out the tab  121  to the near side. The block  120  has a larger width on the bottom surface where the tab  121  is disposed than on the upper surface to facilitate gripping of the protection cover  100  (W 1 &gt;W 2  in  FIG. 3 ). 
     A rib  122  is formed on an upper surface  120   a  of the block  120 . The rib  122  extends in the direction crossing the insertion-removal direction and protrudes upward. As illustrated in  FIG. 4B , the unit housing  35  disposed on the near side in the insertion-removal direction of the photoconductor unit  13  includes a handle  38  grippable (indicated with arrows in  FIG. 4B ) together with the tab  121  of the protection cover  100 . The handle  38  includes a rib  38   b  on a lower surface  38   a  thereof. The rib  38   b  protrudes downward and extends in a direction crossing the insertion-removal direction. 
     A gap G between the upper surface  120   a  of the block  120  and the lower surface  38   a  of the handle  38  is narrowed so that the handle  38  and the tab  121  come into contact with each other when gripped. The rib  38   b  on the lower surface  38   a  of the handle  38  and the rib  122  on the upper surface  120   a  of the block  120  overlap each other in the insertion-removal direction at different positions. Thus, the protection cover  100  is prevented from being shifted to the near side when the photoconductor unit  13  and the protection cover  100  are gripped together. 
     (3) Attachment of Photoconductor Unit and Operation of Protection Cover 
       FIG. 5A  is a cross-sectional schematic diagram, taken in the axial direction, of the photoconductor unit  13  to which the protection cover  100  is attached, and  FIG. 5B  is a front view of the photoconductor unit  13  to which the protection cover  100  is attached.  FIG. 6  is a perspective view illustrating attachment of the photoconductor unit  13  to the apparatus housing  90 .  FIG. 7  is a cross-sectional schematic diagram illustrating the relationship between a protrusion and the protection cover  100  left unremoved. 
     The operation of the protection cover  100  will be described below with reference to the drawings. 
     As illustrated in  FIG. 5A , the protection cover  100  that protects the exposed portion of the photoconductor drum  31  is attached to the photoconductor unit  13 . The protection cover  100  is removably attached to the photoconductor unit  13  while having the attachment portion  111  fitted into a hole of the unit housing  35  on the far side in the insertion-removal direction of the photoconductor unit  13 . 
     In the protection cover  100  attached to the photoconductor unit  13 , the block  120  on the near side opposes, in the insertion-removal direction of the photoconductor unit  13 , a surface  35   a  of the unit housing  35  on the near side to be in contact with the surface  35   a . Thus, when an external force is exerted on the block  120 , the block  120  receives the external force while coming into contact with the surface  35   a  of the unit housing  35  on the near side (drawn with arrows F and FR in  FIG. 5A ). 
     In the vertical direction crossing the insertion-removal direction, the block  120  opposes the handle  38  integrated with the unit housing  35  and protruding from the surface  35   a  on the near side while having the gap G therebetween. Thus, the photoconductor unit  13  is attachable while the user grips the handle  38  together with the tab  121  integrated with the bottom surface of the block  120 . 
     As illustrated in  FIG. 6 , the photoconductor unit  13  to which the protection cover  100  is attached is caused to slide toward the guide  91  (refer to an arrow in  FIG. 6 ) while the development device  14  is attached to the apparatus housing  90  in advance, and the hook  37  of the photoconductor unit  13  is moved to the far side while being placed on the guide  91 . Then, a set lever (not illustrated) that has a rotation support on the development device  14  is rotated toward the photoconductor unit  13  to fix the photoconductor unit  13  to the apparatus housing  90 . Thereafter, the protection cover  100  is removed from the photoconductor unit  13 . 
     The operation of the protection cover  100  to operate the image forming apparatus  1  while the protection cover  100  is left attached to the photoconductor unit  13  attached to the apparatus housing  90  will be described with reference to  FIGS. 7A and 7B . 
     As illustrated in  FIG. 7A , the waste toner transporter  200  serving as an example of a body member that allows the image forming apparatus  1  to operate by moving to the front side of the apparatus housing  90  is removably attached to the image forming apparatus  1 . The waste toner transporter  200  transports waste toner discharged from the photoconductor unit  13  and the developer discharged from the development device  14  to a reclaim container  220  (refer to  FIG. 1 ). 
     The waste toner transporter  200  includes a protrusion  210  that protrudes toward the apparatus housing  90  on a surface  200   a  opposing the photoconductor unit  13 . The protrusion  210  is a columnar body reinforced with a rib. The protrusion  210  has a height with which the protrusion  210  overlaps the block  120  in the protection cover  100  by an overlapping amount exceeding a range within which a sensor SR determines the position of the waste toner transporter  200  as being normal when the waste toner transporter  200  moves to a predetermined fixed position toward the apparatus housing  90 . Specifically, the protrusion  210  has a height with which the protrusion  210  overlaps the block  120  by an overlapping amount equal to or higher than ⅓ of the thickness of the block  120 . Thus, as illustrated in  FIG. 7B , when the protection cover  100  of the photoconductor unit  13  attached to the apparatus housing  90  is left attached without being removed, the waste toner transporter  200  fails to move to a predetermined fixed position while having the protrusion  210  coming into contact with the block  120 . Thus, an actuator AC of the front cover fails to be detected by the sensor SR, and the image forming apparatus  1  fails to operate. 
     The block  120  pressed by the protrusion  210  comes into contact with the surface  35   a  of the unit housing  35  and fails to move further in a direction in which the protrusion  210  moves. Thus, the waste toner transporter  200  fails to move to the predetermined fixed position, and the image forming apparatus  1  fails to shift to an operable state. 
     This structure prevents a printing operation from being performed while the protection cover  100  is left attached. The protrusion  210  may be disposed on a front cover of the openable image forming apparatus  1 . However, when the protrusion  210  is disposed on a rotatable front cover, the protrusion  210  may obliquely come into contact with the block  120  and may be displaced. Moreover, when obliquely coming into contact with the block  120 , the protrusion  210  may buckle upon receipt of the load also in the direction crossing the protrusion direction. Thus, the protrusion  210  preferably moves horizontally toward the block  120 . When perpendicularly coming into contact with the opposing surface of the block  120 , the protrusion  210  is prevented from being displaced or buckling without receiving the load in the direction crossing the protrusion direction. 
     The foregoing description of the exemplary embodiments of the present disclosure has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the principles of the disclosure and its practical applications, thereby enabling others skilled in the art to understand the disclosure for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the disclosure be defined by the following claims and their equivalents.