Patent Publication Number: US-9405210-B2

Title: Image forming apparatus and image forming unit

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2014-147072 filed Jul. 17, 2014. 
     BACKGROUND 
     Technical Field 
     The present invention relates to an image forming apparatus and an image forming unit. 
     SUMMARY 
     According to an aspect of the invention, there is provided an image forming apparatus including: 
     an image holder that is mounted at a predetermined mount position; 
     a charging member that charges the image holder; 
     a cleaning member that cleans the charging member; 
     a holding member that holds the charging member and the cleaning member, includes amount section on which the cleaning member is mounted, is urged toward the image holder side, and recedes when the image holder is mounted at the predetermined mount position; and 
     a drop-out prevention section that is disposed at a position facing the mount section which is included in the holding member at a receding position and that prevents the cleaning member from dropping out from the mount section. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the present invention will be described in detail based on the following figures, wherein: 
         FIG. 1  is a view schematically illustrating a configuration of an image forming apparatus to which an exemplary embodiment is applied; 
         FIG. 2  is a view illustrating a holding member; 
         FIGS. 3A and 3B  are views illustrating an assembly order of the image forming apparatus and, particularly, an assembly order during mounting a charging member and a cleaning member; 
         FIG. 4  is a view illustrating the charging member and the cleaning member when viewed from a direction of arrow TV in  FIG. 3B ; 
         FIG. 5  is a view illustrating a comparative example of a holding member; and 
         FIG. 6  is a view illustrating another comparative example of a holding member. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, an exemplary embodiment of the invention will be described with reference to the accompanying drawings. 
       FIG. 1  is a view schematically illustrating a configuration of an image forming apparatus  1  to which the exemplary embodiment is applied. The image forming apparatus  1  is provided with an image forming unit  10  that forms a toner image on a sheet as an example of a recording material, a fixing unit  20  that heats and presses to fix the toner image formed on the sheet by the image forming unit  10 , and a sheet supplying unit  30  that supplies a sheet to the image forming unit  10 . 
     The image forming unit  10  is provided with a photosensitive drum  11  as an example of an image holder. Further, in the image forming unit  10 , a charging member  12 , an exposure device  13 , a developing device  14 , a transfer device  15 , a cleaning device  16 , a cleaning member  18 , and a holding member  19  are provided. 
     The photosensitive drum  11  includes a photosensitive layer on the outer circumferential surface thereof and performs rotational driving in an arrow direction (counterclockwise direction) in  FIG. 1 . 
     The charging member  12  is configured of a charging roll that is in contact with the photosensitive drum  11  and charges the rotating photosensitive drum  11  to a predetermined potential. To be more specific, the charging member  12  applies a voltage to the photosensitive drum  11  so as to charge the photosensitive drum  11  to the predetermined potential. 
     The exposure device  13  selectively exposes portions of the photosensitive drum  11  charged to the predetermined potential by the charging member  12  and forms an electrostatic latent image. 
     The developing device  14  develops the electrostatic latent image formed on the photosensitive drum  11  by using toner and forms a toner image on the photosensitive drum  11 . 
     The transfer device  15  is formed into a roll-like shape and is disposed along an axial direction of the photosensitive drum  11 . The transfer device  15  applies a bias voltage to a transfer unit Tp, thereby transferring the toner image on the photosensitive drum  11  (toner image held by the photosensitive drum  11 ) to the sheet. In other words, the transfer device  15  forms an electric field between the transfer device  15  and the photosensitive drum  11  and transfers the toner image on the photosensitive drum  11  to the sheet. 
     The cleaning device  16  includes a cleaning blade disposed to be in contact with the photosensitive drum  11  and removes toner or the like remaining on the photosensitive drum  11 . 
     The cleaning member  18  is configured of a roll-like member that is in contact with the charging member  12  and performs cleaning of the charging member  12 . 
     The holding member  19  holds the charging member  12  and the cleaning member  18 . Two holding members  19  are provided so as to correspond to one end and the other end of the charging member  12  and the cleaning member  18  in the axial direction, respectively. In other words, the holding members  19  are provided on the front side of the paper surface in  FIG. 1  and on the back side of the paper surface in  FIG. 1 , respectively. 
     Further, although not illustrated in  FIG. 1 , an accommodation member (container)  200  (see  FIGS. 3A and 3B ) which accommodates the holding member  19  is provided. 
     A sheet storage section  41 , a pull-in roll  43 , and a pick-out mechanism  44  are provided in the sheet supplying unit  30 . The sheet storage section  41  is a rectangular parallelepiped, of which the topside is opened and sheets are stored inside. The pull-in roll  43  comes into contact with the uppermost sheet from a bundle of sheets stored in the sheet storage section  41  and delivers the uppermost sheet toward the pick-out mechanism  44  side. The pick-out mechanism  44  is configured to include a feed roll that is disposed, for example, to be rotatable, and a retard roll of which rotation is limited. The pick-out mechanism  44  picks out, one by one, the sheets delivered from the pull-in roll  43 . Then, the picked sheet is delivered toward a transport roll  45 . 
     The transport rolls  45  are configured to include a pair of roll-like members. After stopping the sheet sent from the pick-out mechanism  44  for a while, the transport roll  45  transports the sheet again at a predetermined timing. A sheet path  811  is provided on the downstream side from the transport roll  45 . Pre-registration rolls  851  and registration rolls  852  are attached on the sheet path  811 . 
     The pre-registration rolls  851  transport the sheet transported by the transport rolls  45  toward the downstream side and forma loop in cooperation with the registration rolls  852 . In addition, the registration rolls  852  stop for a while and thus the transporting of the sheet is stopped temporarily. Then the registration rolls rotate again in accordance with the timing such that a registration adjustment of the transfer unit Tp is performed and the sheet is supplied. 
     In addition, a receiving unit  400  that receives image data from a PC or a scanning device (not illustrated) is provided in the image forming apparatus  1 . Further, a controller  500  that controls operations of the image forming unit  10 , the fixing unit  20 , and the sheet supplying unit  30 , as a whole, are provided. 
     In addition, an image processing unit  600  that outputs image data to the exposure device  13  after an image process is performed to the image data received by the receiving unit  400  is provided. Further, a user interface (UI)  700  that receives an instruction from a user and displays a message or the like for the user is provided. 
     The controller  500  is configured to have a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and a hard disk drive (HDD) (none illustrated). A processing program retained in the ROM or HDD is executed in the CPU. The processing programs, various tables, parameters, or the like are stored in the ROM. The RAM is used as a work area or the like during the execution of various programs by the CPU. 
       FIG. 2  is a view illustrating the holding member  19 . In other words,  FIG. 2  is a view illustrating the one holding member  19  of the two provided holding members  19 . The other holding member  19  is formed to have the same shape as the one holding member  19 . To be more exact, according to the exemplary embodiment, the one holding member  19  and the other holding member  19  are formed to have the same shape except that the holding members are formed to be vertically symmetrical to each other. Here, the one holding member  19  is described. 
     As illustrated in  FIG. 2 , in the holding member  19 , a plate-like base section  19 A that is positioned on the back side in  FIG. 2 , and a protrusion section  19 B that protrudes from one side surface (side surface in the front side in  FIG. 2 ) of the base section  19 A are provided. The protrusion section  193  includes a right-side surface  191 , a left-side surface  192 , a top surface  193 , and an under surface  194 . 
     In addition, in the holding member  19 , a first accommodation groove  19 C that is formed from the top surface  193  of the holding member  19  toward the inside of the holding member  19  and a second accommodation groove  19 D that is formed from the left-side surface  192  of the holding member  19  toward the inside of the holding member  19  are provided. 
     In addition, on the top surface  193  of the holding member  19 , a first opening  19 E that causes the inside and the outside of the first accommodation groove  19 C to communicate with each other is formed. The detailed description thereof will be provided later. According to the exemplary embodiment, the charging member  12  is mounted on the inside of the first accommodation groove  19 C. During the mounting, the charging member  12  passes through the first opening  19 E. 
     Further, on the left-side surface  192  of the holding member  19 , a second opening  19 F that causes the inside and the outside of the second accommodation groove  19 D to communicate with each other is formed. The cleaning member  18  is mounted on the inside of the second accommodation groove  19 D to be described in detail later) and during the mounting, the cleaning member  18  passes through the second opening  19 F. 
       FIGS. 3A and 3B  are views illustrating an assembly order of the image forming apparatus  1  and, particularly, an assembly order during mounting the charging member  12  and the cleaning member  18 . 
     During mounting the charging member  12  and the cleaning member  18 , as illustrated in  FIG. 3A , first, the cleaning member  18  is mounted on the inside of the second accommodation groove  19 D provided in the holding member  19 . 
     According to the exemplary embodiment, the inside of the second accommodation groove  19 D corresponds to amount section on which the cleaning member  18  is mounted and according to the exemplary embodiment, first, the cleaning member  18  is mounted on the mount section. To be more specific, the cleaning member  18  passes through the second opening  19 F (also see  FIG. 2 ) and is mounted on the inside of the second accommodation groove  19 D. 
     Although not described above, according to the exemplary embodiment, as illustrated in  FIG. 3A , the accommodation member (container)  200  that accommodates the holding member  19  is provided. Here, on the accommodation member  200 , a first side wall  201 , a second side wall  202 , and a bottom  203  are provided. 
     The first side wall  201  is disposed such that a part thereof faces the left-side surface  192  of the holding member  19 . The second side wall  202  is disposed to face the right-side surface  191  of the holding member  19 . The bottom  203  is disposed to face the under surface  194  of the holding member  19 . In addition, according to the exemplary embodiment, the height of the first side wall  201  is less than the height of the second side wall  202 . 
     Further, a coil spring  210  that urges the holding member  19  upward in  FIGS. 3A and 3B  (urges to a side where the photosensitive drum  11  is provided) is provided between the under surface  194  of the holding member  19  and the bottom  203  of the accommodation member  200 . 
     Here, according to the exemplary embodiment, when mounting of the cleaning member  18  on the holding member  19  is performed, the holding member  19  is displaced upward by the coil spring  210 . In this way, the second opening  19 F of the holding member  19  is exposed. According to the exemplary embodiment, first, the cleaning member  18  is mounted on the inside of the second accommodation groove  19 D through the exposed second opening  19 F. 
     Then, according to the exemplary embodiment, as illustrated in  FIG. 3B , the charging member  12  is mounted on the first accommodation groove  19 C of the holding member  19 . In other words, according to the exemplary embodiment, the inside of the first accommodation groove  19 C functions as a charging member mount section on which the charging member  12  is mounted and the charging member  12  is mounted on the charging member mount section. 
     Although not described above, the charging member  12  and the cleaning member  18  are configured to include, for example, a shaft  31  and an elastic member  32  such as a sponge, rubber, or the like as illustrated in  FIG. 3B . 
     Next, as illustrated in  FIG. 3B , mounting of the photosensitive drum  11  is performed. To be more specific, according to the exemplary embodiment, the photosensitive drum  11  is mounted at a predetermined mount position on the upper side in  FIG. 3B  from the charging member  12 . When the photosensitive drum  11  is mounted, the charging member  12  is pressed from the upper side in the drawing and, thereby, the holding member  19  moves downward in the drawing. In other words, the holding member  19  recedes in a direction of being separated from the mount position of the photosensitive drum  11 . 
     When the holding member  19  recedes, as illustrated in  FIG. 3B , the first side wall  201  of the accommodation member  200  is positioned at the position facing the second opening  19 F provided in the holding member  19 . In this way, according to the exemplary embodiment, the cleaning member  18  is prevented from dropping out through the second opening  19 F. In other words, even when the cleaning member  18  is caused to drop out from the holding member  19  through the second opening  19 F, the cleaning member  18  comes into contact with the first side wall  201  that functions as the drop-out prevention section and the movement of the cleaning member  18  is regulated thereto. 
     According to the exemplary embodiment, when the holding member  19  recedes, the first side wall  201  of the accommodation member  200  is positioned at the position facing the second opening  19 F. Before the holding member  19  recedes, as illustrated in  FIG. 3A , the second opening  19 F is disposed at a position (position on the upper side in the drawing from the first side wall  201 ) which is different from the position where the second opening  19 F faces the first side wall  201 . Accordingly, according to the exemplary embodiment, before the holding member  19  recedes, the mounting of the cleaning member  18  on the inside of the second accommodation groove  19 D is performed without being interrupted by the first side wall  201 . 
       FIG. 4  is a view illustrating the charging member  12  and the cleaning member  18  when viewed from a direction of arrow IV in  FIG. 3B . In  FIG. 4 , the photosensitive drum  11  is not illustrated. 
     According to the exemplary embodiment, as described above, dropping out of the cleaning member  18  from the holding member  19  is prevented using the first side wall  201 ; however, the first side wall  201  may be formed to face the entire region in the longitudinal direction of the cleaning member  18  or may be formed to face a part of the cleaning member  18  (one end or the other end of the cleaning member  18 ) as illustrated in  FIG. 4 . 
     Bearings that support the cleaning member  18  in a state in which the cleaning member  18  is rotatable are provided in the one end and the other end of the cleaning member  18 , respectively. According to the exemplary embodiment, the first side wall  201  is provided so as to face each of the two bearings. To be more exact, according to the exemplary embodiment, the first side wall  201  is provided so as to face the second openings  19 F described above which are included in the two holding members  19 . 
     In a case where the first side wall  201  is formed to face the one end and the other end of the cleaning member  18  as described above without forming the first side wall  201  to face the entire region in the longitudinal direction of the cleaning member  18 , interference between the elastic member  32  and the first side wall  201  is avoided as illustrated in  FIG. 4  and flexibility of a layout is increased. In addition, in a case where the first side wall  201  is positioned at a position where the first side wall  201  does not interfere with the elastic member  32  (case where the first side wall  201  is not provided at a position facing the elastic member  32 ), the elastic member  32  may have a larger diameter and it is expected that performance of cleaning is improved compared to a case where the elastic member  32  has a small diameter. 
     A functional section such as the first side wall  201  which prevents the cleaning member  18  from dropping out may be configured of a separate member from the accommodation member  200 . In addition, the functional section that prevents the dropping out may be formed to be integral to the accommodation member  200 . In other words, the functional section may be formed of a part of the accommodation member  200 . In a case where the functional section and the accommodation member  200  are formed to be integral to each other (case where the functional section is formed of a part of the accommodation member  200 ), the number of components is decreased and a manufacturing cost is decreased compared to a case where the functional section is formed of a separate member. 
       FIGS. 5 and 6  are views illustrating a comparative example of the holding member  19 . 
     According to the comparative example illustrated in  FIG. 5 , in the holding member  19 , the first accommodation groove  19 C that accommodates the charging member  12  and a through-hole  19 G into which the cleaning member  18  is inserted are provided. 
     According to the comparative example, during the assembly, a process is needed, in which the cleaning member  18  penetrates through the through-hole  19 G and, thus time and effort are required for assembly compared to the configuration according to the exemplary embodiment. 
     In other words, according to the comparative example, during the assembly, movement of the cleaning member  18  and movement of the holding member  19  along the axial direction of the cleaning member  18  are needed and, thus time and effort are required. To be more exact, according to the comparative example, a process of moving the charging member  12  in a radial direction (process of moving the charging member  12  downward from the upper side in the drawing) and a process of moving the cleaning member  18  or the like along the axial direction of the cleaning member  18  are mixed and, thus time and effort are needed. 
     Meanwhile, in the configuration according to the exemplary embodiment, since both the charging member  12  and the cleaning member  18  are caused to move in the radial direction such that the assembly is performed, the assembly is easy compared to the comparative example illustrated in  FIG. 5 . 
     Next, the comparative example illustrated in  FIG. 6  will be described. 
     According to the comparative example illustrated in  FIG. 6 , similar to the exemplary embodiment, two accommodation grooves of the first accommodation groove  19 C that accommodates the charging member  12  and the second accommodation groove  19 D that accommodates the cleaning member  18  are formed. Further, according to the comparative example, a mount position of the first accommodation groove  19 C and a mount position of the second accommodation groove  19 D are displaced from each other in the axial direction of the charging member  12  and the cleaning member  18 ; that is, the first accommodation groove  19 C is positioned on the outer side (in a case where the center of the charging member  12  in the axial direction is a reference point, a side separated from the reference point) from the second accommodation groove  19 D. 
     When an assembly order in the comparative example illustrated in  FIG. 6  is described, first, the cleaning member  18  is mounted to the second accommodation groove  19 D from the upper side in  FIG. 6 . Next, the charging member  12  is mounted to the first accommodation groove  19 C in the same way as from the upper side in  FIG. 6 . Then, the photosensitive drum  11  is mounted on the upper side of the charging member  12  in  FIG. 6 . 
     According to the comparative example, since the charging member  12  and also the cleaning member  18  are mounted on the holding member  19  from the upper side in  FIG. 6 , movement of the cleaning member  18  or the like in the axial direction as illustrated in  FIG. 5  is not needed and the assembly is simpler compared to the configuration illustrated in  FIG. 5 . In addition, according to the comparative example, since the charging member  12  is positioned on the upper side of the cleaning member  18  in the drawing and the photosensitive drum  11  is positioned on the upper side of the charging member  12  in the drawing, only the simple set of the cleaning member  18  and the charging member  12  on the holding member  19  prevents these members from dropping out. 
     Meanwhile, according to the comparative example illustrated in  FIG. 6 , the first accommodation groove  19 C positioned on the upper side is needed to be provided on the outer side from the second accommodation groove  19 D positioned on the lower side in the configuration. In this case, the holding member  19  is increased in size and, thereby, the overall apparatus is increased in size. 
     To be more exact, in recent years, the entire length of the charging member  12  is shortened and there is no difference between the length of the charging member  12  and that of the cleaning member  18  in accordance with weight lightening and miniaturization. Regardless of such a situation, according to the comparative example illustrated in  FIG. 6 , the charging member  12  has to be longer than the cleaning member  18  and, thus it is unlikely to achieve the weight lightening and miniaturization. 
     Next, when the configuration according to the exemplary embodiment is described, each of the charging member  12  and the cleaning member  18  is caused to move in the radial direction and is mounted on the holding member  19 . Therefore, the assembly may be performed without the movement in the axial direction unlike the comparative example illustrated in  FIG. 5  and, thus the process of the assembly is simplified compared to the comparative example illustrated in  FIG. 5 . 
     Further, in the configuration according to the exemplary embodiment, the openings (first opening  19 E and second opening  19 F) are separately provided such that the charging member  12  and the cleaning member  18  are accommodated in the accommodation grooves (first accommodation groove  19 C and second accommodation groove  19 D) by using the openings, respectively. In this way, unlike in  FIG. 6 , an increase of the holding member  19  in size is suppressed. 
     In other words, according to the exemplary embodiment, the passage (cleaning member passage) through which the cleaning member  18  passes when the cleaning member  18  is mounted on the holding member  19  and the passage (charging member passage) through which the charging member  12  passes when the charging member  12  is mounted on the holding member  19  are formed separately from each other. Therefore, there is no need for the charging member  12  to be longer than the cleaning member  18  and, thereby, instead of the holding member  19  illustrated in  FIG. 6 , the holding member  19  illustrated in  FIG. 2  which is smaller is employed. Accordingly, in the configuration according to the exemplary embodiment, the miniaturization of the entire apparatus is achieved compared to the comparative example illustrated in  FIG. 6 . 
     Meanwhile, as in the exemplary embodiment, when the passages for mounting the charging member  12  and the cleaning member  18  are separately provided and the openings for mounting the charging member  12  and the cleaning member  18  are separately provided, the movement of the cleaning member  18  is not likely to be regulated in a type as illustrated in  FIG. 6 . Specifically, the movement of the cleaning member  18  is unlikely to be regulated by the charging member  12 . As a result, in the configuration according to the exemplary embodiment, only the simple mounting of the cleaning member  18  on the holding member  19  may cause the cleaning member  18  to drop out from the holding member  19 . 
     According to the exemplary embodiment, as described above, when the charging member  12  is pressed by the photosensitive drum  11  and the holding member  19  recedes, the second opening  19 F is positioned at a position facing the first side wall  201  of the accommodation member  200 . Accordingly, the second opening  19 F is blocked and the cleaning member  18  is prevented from dropping out from the second opening  19 F. 
     Here, in the configuration according to the exemplary embodiment, the cleaning member  18  is prevented from dropping out without a user&#39;s special operation for preventing the cleaning member  18  from dropping out. In other words, according to the exemplary embodiment, only the mounting itself of the cleaning member  18 , the charging member  12 , and the photosensitive drum  11  prevents the cleaning member  18  from dropping out. 
     To be more exact, according to the exemplary embodiment, the cleaning member  18  is prevented from dropping out without any special assembly processes. In other words, according to the comparative example illustrated in  FIG. 6 , although the cleaning member  18  is prevented from dropping out without any special assembly processes, the apparatus becomes increased in size according to the comparative example. According to the exemplary embodiment, the cleaning member  18  is prevented from dropping out without any special assembly processes and, further, the increase of the apparatus in size is suppressed. 
     Other Configurations 
     According to a configuration of the image forming apparatus  1 , the photosensitive drum  11  and members positioned around the photosensitive drum  11  are all unitized and form an image forming unit; however, the charging member  12 , the cleaning member  18 , the holding member  19 , and the accommodation member  200  may be included in the image forming unit. 
     To be more specific, according to the apparatus configuration, there may be an embodiment in which a surrounding portion represented by reference sign  1 A in  FIG. 1  is unitized as the image forming unit and the image forming unit is attachable to and detachable from the main body side of the image forming apparatus  1 . 
     In such an embodiment, the image forming unit may include the charging member  12 , the cleaning member  18 , the holding member  19 , and the accommodation member  200  which are described above. Here, although there is a case where a replacement with a new image forming unit is performed due to the abrasion of the photosensitive drum  11 , the charging member  12 , the cleaning member  18 , the holding member  19 , and the accommodation member  200  are also replaced during the replacement. 
     The foregoing description of the exemplary embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention 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 invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.