Patent Publication Number: US-2023152727-A1

Title: Image forming apparatus

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to an image forming apparatus, such as an electrophotographic copying machine or a printer, to which a process cartridge is detachably attached. 
     Description of the Related Art 
     Japanese Patent Application Laid-Open No. 2013-076925 discloses an image forming apparatus to which a cartridge is detachably attached, the cartridge including a cleaning member that cleans a discharge member, such as a discharge wire. Such a cartridge attached to the image forming apparatus in Japanese Patent Application Laid-Open No. 2013-076925 includes a photoconductor on which an electrostatic latent image is to be formed, a discharge member extending along the photoconductor opposite the photoconductor, and a cleaning unit that moves along the extending direction of the discharge member, to clean the discharge member. The cleaning unit includes a body portion movable along the extending direction of the discharge member and an operation portion protruding graspably from the body portion. 
     However, according to Japanese Patent Application Laid-Open No. 2013-076925, if the cleaning unit has not moved to the standby position at an end portion of the cartridge at the time of cleaning of the discharge wire, the cleaning unit blocks the optical path of a laser. According to Japanese Patent Application Laid-Open No. 2013-076925, with the cleaning unit blocking the optical path of the laser, the apparatus itself can operate. In this case, as a problem, no image is acquired at a part at which the optical path of the laser is blocked in image output. 
     SUMMARY OF THE INVENTION 
     It is desirable to disable, in a case where a cleaning member that cleans a charge member is located at any cleaning position in attachment of a process cartridge to an image forming apparatus, attachment of the process cartridge to the image forming apparatus. 
     According to one aspect of the present invention, provided is an image forming apparatus including: a process cartridge attachable to the image forming apparatus, the process cartridge including: a photoconductive drum; a charge member configured to charge the photoconductive drum; and a cleaning unit including: a cleaning member configured to clean the charge member; and an operation portion to be operated by a user in order to move the cleaning member between a cleaning position for cleaning the charge member and a retraction position for retraction from the cleaning position; a guide portion configured to guide the process cartridge in a direction of attachment to the image forming apparatus; a stopper configured to butt against the process cartridge guided in the direction of attachment by the guide portion, to restrict movement of the process cartridge in the direction of attachment; and a lever portion connected to the stopper, the lever portion being configured to move together with the stopper, in which the stopper is movable between a first position that butts against the process cartridge guided in the direction of attachment by the guide portion and a second position that does not butt against the process cartridge guided in the direction of attachment by the guide portion, in a case where the cleaning member is located at the cleaning position in attachment of the process cartridge to the image forming apparatus, the stopper located at the first position butts against the process cartridge guided in the direction of attachment by the guide portion such that the process cartridge is disabled from being attached to the image forming apparatus, and in a case where the cleaning member is located at the retraction position in attachment of the process cartridge to the image forming apparatus, the lever portion moves due to a press by the cleaning unit and the stopper moves from the first position to the second position such that the process cartridge is enabled to be attached to the image forming apparatus. 
     Further features of the present invention will become apparent from the following description of exemplary embodiments (with reference to the attached drawings). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view of an image forming apparatus according to an embodiment of the present invention; 
         FIG.  2    is a schematic view of the image forming apparatus according to the embodiment of the present invention with a CRG cover closed; 
         FIG.  3    is a schematic view of the image forming apparatus according to the embodiment of the present invention with the CRG cover opened; 
         FIG.  4    is an enlarged perspective view of part of the image forming apparatus according to the embodiment of the present invention; 
         FIGS.  5 A and  5 B  are each a perspective view of a process cartridge according to the embodiment of the present invention; 
         FIGS.  6 A and  6 B  are each an enlarged sectional schematic view of part of the image forming apparatus according to the embodiment of the present invention; and 
         FIG.  7    is a perspective view of process cartridges attached to the image forming apparatus according to the embodiment of the present invention. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     An embodiment will be described in detail below with reference to the drawings. 
     &lt;Configuration of Image Forming Apparatus&gt; 
     The configuration of an image forming apparatus  1  according to the embodiment of the present invention will be described in detail with reference to  FIGS.  1  to  4    and  FIGS.  6 A and  6 B . 
     The image forming apparatus  1  includes an apparatus body  1   a , a CRG cover  11 , a blocking member  21 , a spring  22 , an upper support member  23   a , a lower support member  23   b , an LED exposure unit  40 , and a process cartridge  50 . The image forming apparatus  1  further includes a conveying roller  70 , a sheet conveying belt  73 , transfer rollers  74   y ,  74   m ,  74   c , and  74   k , a fixing unit  80 , and a pair of discharge rollers  91 . 
     The apparatus body  1   a  has a CRG guide  60  as a guide recessed portion at which the inside of the apparatus body  1   a  is exposed outward. The CRG guide  60  as a guide portion has a function of guiding the process cartridge  50  for attachment to the apparatus body  1   a.    
     The CRG cover  11  as a cover is openably attached to the apparatus body  1   a  of the image forming apparatus  1 . When remaining closed, the CRG cover  11  is loaded with a sheet P as a recording material discharged by the pair of discharge rollers  91 . With the process cartridge  50  attached to the image forming apparatus  1 , the CRG cover  11  is located right above the process cartridge  50  in a vertical direction. 
     The blocking member  21  blocks attachment of the process cartridge  50  to the apparatus body  1   a  in a case where an operation portion  240  of a cleaning unit  200 , to be described below, is located out of a retraction position in the process cartridge  50 . Such blocking members  21  are provided one-to-one at CRG guides  60 . Note that no blocking members  21  are illustrated in  FIGS.  1  to  3   . The configuration of a blocking member  21  will be described in detail below. 
     As illustrated in  FIG.  6 A , the spring  22  as a biasing member has applied a force to the blocking member  21  in the direction in which part of the blocking member  21  protrudes outward from the apparatus body  1   a.    
     As illustrated in  FIGS.  6 A and  6 B , the upper support member  23   a  is provided inside the apparatus body  1   a  and extends in the slide direction of the blocking member  21  above the blocking member  21 . The upper support member  23   a  is not exposed outward from the CRG guide  60  when viewed in the direction of A in  FIG.  4   . 
     As illustrated in  FIGS.  6 A and  6 B , the lower support member  23   b  is provided inside the apparatus body  1   a  and extends in the slide direction of the blocking member  21  below the blocking member  21 . The lower support member  23   b  is not exposed outward from the CRG guide  60  when viewed in the direction of A in  FIG.  4   . 
     The LED exposure unit  40  irradiates the surface of a photoconductive drum  51   y ,  51   m ,  51   c , or  51   k  with light based on an image signal, to form an electrostatic latent image. 
     Above the sheet conveying belt  73 , a plurality of process cartridges  50  is attached along the front-back direction parallel to the conveying direction of a sheet P. Herein, exemplarily, the number of attachable process cartridges  50  is four. Referring to  FIG.  3   , with the CRG cover  11  opened, each process cartridge  50  is detachably attachable to the apparatus body  1   a  through an opening  10  and thus is replaceable. Note that the configuration of such a process cartridge  50  will be described in detail below. 
     Due to driving of a motor not illustrated, the conveying roller  70  drives rotationally to rotate the sheet conveying belt  73  clockwise in  FIG.  2   . 
     The sheet conveying belt  73  as a conveying member conveys a sheet P in synchronization with the respective color toner images formed on the photoconductive drums  51   y ,  51   m ,  51   c , and  51   k.    
     The transfer rollers  74   y ,  74   m ,  74   c , and  74   k  are provided inside the sheet conveying belt  73 . Due to application of voltage, the transfer rollers  74   y ,  74   m ,  74   c , and  74   k  transfer, in sequence, the color toner images formed on the photoconductive drums  51   y ,  51   m ,  51   c , and  51   k , respectively, to the sheet P being conveyed on the sheet conveying belt  73 . 
     The fixing unit  80  includes a fixing roller  81  including a built-in heater not illustrated and a pressure roller  82 . The fixing unit  80  applies heat and pressure with the fixing roller  81  and the pressure roller  82  to the sheet P having the toner images transferred by the transfer rollers  74   y ,  74   m ,  74   c , and  74   k , so that the toner images are fixed to the sheet P. The fixing unit  80  conveys the sheet P having the toner images fixed thereto to the pair of discharge rollers  91 . 
     The pair of discharge rollers  91  discharges the sheet P conveyed by the fixing unit  80  onto the CRG cover  11 . 
     &lt;Configuration of Process Cartridge&gt; 
     The configuration of a process cartridge  50  for the image forming apparatus  1  according to the embodiment of the present invention will be described in detail with reference to  FIGS.  5 A and  5 B . 
       FIGS.  5 A and  5 B  are each a perspective view of a process cartridge  50 . 
     The process cartridge  50  includes a photoconductive drum  51   y ,  51   m ,  51   c , or  51   k , a retainment roller  54 , a charge unit  55 , a guide protruding portion  56 , and a development roller  62 . 
     Such process cartridges  50  are attached such that photoconductive drums  51   y ,  51   m ,  51   c , and  51   k  are arrayed in the front-back direction. The photoconductive drums  51   y ,  51   m ,  51   c , and  51   k  each drive rotationally counterclockwise at a predetermined rate in  FIG.  2   . 
     Such retainment rollers  54  are provided one-to-one to the photoconductive drums  51   y ,  51   m ,  51   c , and  51   k , and are each a member including a metallic rotary shaft covered with a roll body that is conductive and foam-elastic. Each retainment roller  54  collects and temporarily retains toner remaining on the surface of the corresponding photoconductive drum  51   y ,  51   m ,  51   c , or  51   k  after transfer. At the time of cleaning, each retainment roller  54  returns the retained toner to the corresponding photoconductive drum  51   y ,  51   m ,  51   c , or  51   k . Note that the respective toners returned to the photoconductive drums  51   y ,  51   m ,  51   c , and  51   k  are transferred to the sheet conveying belt  73 , leading to collection by a cleaning unit not illustrated. 
     The charge unit  55  includes a charge wire  52 , a vent  110 , a vent  111 , a cleaning unit  200 , and a counter electrode not illustrated, and charges the surface of the photoconductive drum  51   y ,  51   m ,  51   c , or  51   k , uniformly. 
     The charge wire  52  serves as a metallic wire that generates corona discharge in response to application of a predetermined voltage. The charge wire  52  is disposed opposite the photoconductive drum  51   y ,  51   m ,  51   c , or  51   k  above the photoconductive drum  51   y ,  51   m ,  51   c , or  51   k , and extends along the axial direction of the photoconductive drum  51   y ,  51   m ,  51   c , or  51   k  (right-and-left direction). 
     The charge wire  52  as a charge member corresponds to a tabular electrode in a substantially U shape, in side view, opposite the counter electrode not illustrated. The counter electrode includes a grid electrode located between the charge wire  52  and the photoconductive drum  51   y ,  51   m ,  51   c , or  51   k , and a pair of shield electrodes located ahead of and behind the charge wire  52 . 
     The vent  110  serves as an air inlet that guides air outside the charge unit  55  to the charge wire  52 . 
     The vent  111  serves as a guide enabling movement of the cleaning unit  200  and as an outlet for discharging air around the charge wire  52 . The vent  111  extends along the right-and-left direction identical to the extending direction of the charge wire  52 . 
     The guide protruding portion  56  protrudes from a side face of the process cartridge  50  in the direction orthogonal to the direction of attachment to the apparatus body  1   a.    
     Development rollers  62   y ,  62   m ,  62   c , and  62   k  are capable of supplying toner to the photoconductive drum  51   y ,  51   m ,  51   c , and  51   k , respectively. The development rollers  62   y ,  62   m ,  62   c , and  62   k  each regulate, together with a thickness-regulation blade not illustrated, toner supplied by a supply roller not illustrated from a storage portion  63 , to a certain thickness, and bears and conveys the regulated toner having the certain thickness. The development rollers  62   y ,  62   m ,  62   c , and  62   k  each develop, with the borne toner, an electrostatic latent image formed on the corresponding photoconductive drum  51   y ,  51   m ,  51   c , or  51   k , resulting in formation of a toner image on the corresponding photoconductive drum  51   y ,  51   m ,  51   c , or  51   k.    
     &lt;Configuration of Cleaning Unit&gt; 
     The configuration of a cleaning unit  200  for a process cartridge  50  for the image forming apparatus  1  according to the embodiment of the present invention will be described in detail with reference to  FIGS.  5 A and  5 B . 
     The cleaning unit  200  corresponds to a member that is attached to a process cartridge  50  and cleans the charge wire  52 . The cleaning unit  200  includes a wire cleaner  210  and an operation portion  240 . 
     The wire cleaner  210  wipes out foreign matter adhering to the charge wire  52 , in sliding contact with the charge wire  52  in the vent  111 . 
     The operation portion  240  is capable of moving along the vent  111  in response to an operation from a user and includes a protruding portion  241 . Referring to  FIGS.  5 A and  5 B , the protruding portion  241  protrudes downward from the process cartridge  50  in the direction of attachment to the apparatus body  1   a . The protruding portion  241  has an inclined face  242  at its lower end as a leading end in the protruding direction. 
     In response to a left-and-right operation from the user to the operation portion  240 , the cleaning unit  200  having such a configuration as above cleans the entire region, which is necessary for charge of the photoconductive drum  51   y ,  51   m ,  51   c , or  51   k , in the charge wire  52 . 
     In this case, referring to  FIGS.  5 A and  5 B , movement of the cleaning unit  200  to the right end of the process cartridge  50  causes the cleaning unit  200  to be located out of a charge range necessary at the time of image forming with the photoconductive drum  51   y ,  51   m ,  51   c , or  51   k . The cleaning unit  200  located out of the charge range does not block the optical path of a laser emitted from the LED exposure unit  40  to the photoconductive drum  51   y ,  51   m ,  51   c , or  51   k . The location is defined as the retraction position of the cleaning unit  200 . 
     The cleaning unit  200  located within the charge range blocks the optical path of a laser emitted from the LED exposure unit  40  to the photoconductive drum  51   y ,  51   m ,  51   c , or  51   k . The location is defined as the cleaning position of the cleaning unit  200 . 
     &lt;Configuration of Blocking Member&gt; 
     The configuration of a blocking member  21  in the image forming apparatus  1  according to the embodiment of the present invention will be described in detail with reference to  FIGS.  4 ,  6 A,  6 B, and  7   . 
       FIG.  6 A  illustrates a cleaning-unit detecting portion  21   a  having not been pressed by a protruding portion  241 .  FIG.  6 B  illustrates the cleaning-unit detecting portion  21   a  having been pressed by the protruding portion  241 . 
     A blocking member  21  includes a cleaning-unit detecting portion  21   a  and a CRG stopper  21   b.    
     The cleaning-unit detecting portion  21   a  as a lever portion is connected to the CRG stopper  21   b  and moves together with the CRG stopper  21   b . The cleaning-unit detecting portion  21   a  has received the force applied by the spring  22  through the CRG stopper  21   b  in the direction of protrusion from the apparatus body  1   a  (right direction in  FIG.  6 A ) and protrudes slidably from an attachment face  1   b  for a process cartridge  50  of the apparatus body  1   a . The protruding direction of the cleaning-unit detecting portion  21   a  is opposite to the retracting direction of the blocking member  21  (direction of A in  FIG.  4   ). The retracting direction of the blocking member  21  is orthogonal to the direction of attachment of a process cartridge  50  to the apparatus body  1   a.    
     The cleaning-unit detecting portion  21   a  protrudes, between adjacent process cartridges  50 , from the attachment face  1   b  for a process cartridge  50  of the apparatus body  1   a . With the cleaning unit  200  located at the retraction position, the cleaning-unit detecting portion  21   a  is located opposite the protruding portion  241 . The cleaning-unit detecting portion  21   a  has an inclined face  21   c  inclining downward at its leading end in the protruding direction of the cleaning-unit detecting portion  21   a.    
     The CRG stopper  21   b  is provided inside the apparatus body  1   a  and has received the force applied by the spring  22  in the right direction in  FIG.  6 A . The CRG stopper  21   b  is disposed between the upper support member  23   a  and the lower support member  23   b . Due to the upper support member  23   a  and the lower support member  23   b , the CRG stopper  21   b  is guided for a slide in the direction of A in  FIG.  4    identical to the retracting direction of the CRG stopper  21   b  or in the opposite direction to the direction of A. The CRG stopper  21   b  slides together with the cleaning-unit detecting portion  21   a . The CRG stopper  21   b  butts against the process cartridge  50  guided in the direction of attachment by the CRG guide  60 , to restrict movement in the direction of attachment of the process cartridge  50 . 
     &lt;Operation of Attachment of Process Cartridge to Apparatus Body&gt; 
     The operation of attachment of a process cartridge  50  to the apparatus body  1   a  of the image forming apparatus  1  according to the embodiment of the present invention will be described in detail with reference to  FIGS.  4  to  7   . 
     The operation of attachment of a process cartridge  50  to the apparatus body  1   a  with the cleaning unit  200  located at the retraction position will be described. 
     First, the guide protruding portion  56  of the process cartridge  50  is inserted, from above, into a CRG guide  60  in the apparatus body  1   a.    
     Then, the guide protruding portion  56  moves downward while being guided by the CRG guide  60 . In this case, with the cleaning unit  200  of which the inclined face  242  of the protruding portion  241  abuts on the inclined face  21   c  of the cleaning-unit detecting portion  21   a , the cleaning-unit detecting portion  21   a  is pushed inside the apparatus body  1   a  against the force applied by the spring  22 . 
     The cleaning-unit detecting portion  21   a  pushed inside by the inclined face  242  of the protruding portion  241  slides in the opposite direction to the protruding direction and additionally the CRG stopper  21   b  moves in the retracting direction (direction of A in  FIG.  4   ) for location at the retraction position, leading to such a state as illustrated in  FIG.  7   . In this case, due to the upper support member  23   a  and the lower support member  23   b , the CRG stopper  21   b  is guided for movement in the retracting direction. 
     In this state, with no interference with the CRG stopper  21   b , the guide protruding portion  56  can be inserted from above in the CRG guide  60 . Thus, the process cartridge  50  is attached to the apparatus body  1   a . As above, the blocking member  21  retracted due to a press by the cleaning unit  200  located at the retraction position enables attachment of the process cartridge  50  to the apparatus body  1   a . Movement of the cleaning unit  200  and retraction of the blocking member  21  can be carried out with the operation portion  240 . 
     Next, the operation of attachment of a process cartridge  50  to the apparatus body  1   a  with the cleaning unit  200  located at the cleaning position instead of the retraction position will be described. 
     First, the guide protruding portion  56  of the process cartridge  50  is inserted, from above, into a CRG guide  60  in the apparatus body  1   a.    
     Then, the guide protruding portion  56  moves downward while being guided by the CRG guide  60 . In this case, because the inclined face  242  of the protruding portion  241  does not abut on the inclined face  21   c  of the cleaning-unit detecting portion  21   a , the cleaning-unit detecting portion  21   a  is not pushed inside. Therefore, the cleaning-unit detecting portion  21   a  does not slide in the opposite direction to the protruding direction and additionally the CRG stopper  21   b  is not retracted. 
     In this state, the guide protruding portion  56  abuts on the CRG stopper  21   b  due to interference with the CRG stopper  21   b . Thus, the guide protruding portion  56  is not inserted, from above, in the CRG guide  60 . Thus, the process cartridge  50  is not attached to the apparatus body  1   a.    
     Such blocking members  21  as above are provided one-to-one at the CRG guides  60 . Therefore, in a case where the cleaning unit  200  is located at the cleaning position in any of four process cartridges  50  guided, respectively, by four CRG guides  60 , attachment of the process cartridge  50 , of which the cleaning unit  200  is located at the cleaning position, is blocked by the blocking member  21 . 
     As described above, the blocking member  21  slides and retracts, due to a press by the protruding portion  241 , orthogonally to the direction of attachment of the process cartridge  50  to the apparatus body  1   a , enabling attachment of the process cartridge  50  to the apparatus body  1   a . Thus, the length of the apparatus body  1   a  in the direction of attachment can be shortened. 
     Provision of the spring  22  that applies a force to the blocking member  21  in the opposite direction to the retracting direction of the blocking member  21  enables reliable protrusion of the cleaning-unit detecting portion  21   a  from the attachment face  1   b.    
     Protrusion of the cleaning-unit detecting portion  21   a  from the attachment face  1   b  of the apparatus body  1   a  between adjacent process cartridges  50  enables a reduction in the size of the apparatus body  1   a.    
     Due to interference with the guide protruding portion  56  with the cleaning unit  200  located at the cleaning position, the blocking member  21  blocks attachment of the process cartridge  50  to the apparatus body  1   a . Thus, with the cleaning unit  200  located at the cleaning position, the guide protruding portion  56  guided by the CRG guide  60  interferes with the blocking member  21 . 
     According to the present embodiment, a cleaning unit  200  is attached to a process cartridge  50  and is capable of moving between the cleaning position for cleaning the charge wire  52  and the retraction position for retraction from the cleaning position. A blocking member  21  blocks attachment of the process cartridge  50  to the apparatus body  1   a  with the cleaning unit  200  located at the cleaning position, disabling attachment of the process cartridge  50  to the image forming apparatus  1 . This leads to prevention of image deterioration, such as an image partially lost, based on any process cartridge  50  attached to the apparatus body  1   a.    
     The present invention is not limited to the above embodiment, and thus various modifications can be made without departing from the gist of the invention. 
     Specifically, a slidable cleaning-unit detecting portion  21   a  is provided in the above embodiment, but this is not limiting. Thus, a turnable cleaning-unit detecting portion may be provided. In this case, in attachment of a process cartridge to the apparatus body, such a cleaning unit detecting portion turns due to a press by the operation portion of the cleaning unit, so that the CRG stopper  21   b  is retracted. 
     In the above embodiment, the image forming apparatus  1  is provided as a color printer (single function printer (SFP)), but this is not limiting. Thus, the image forming apparatus may include a reading unit at the upper portion of the apparatus body as a multi-function peripheral. In this case, the reading unit is turnable in order to open the CRG cover  11 , so that a similar effect can be acquired. 
     In the above embodiment, a process cartridge  50  includes a photoconductive drum  51   y ,  51   m ,  51   c , or  51   k , a retainment roller  54 , a charge unit  55 , and a development roller  62 . However, a process cartridge is required to include at least a charge unit  55 . 
     While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions. 
     This application claims the benefit of Japanese Patent Application No. 2021-184723, filed Nov. 12, 2021, which is hereby incorporated by reference herein in its entirety.