Patent Publication Number: US-8526844-B2

Title: Cleaning device and image forming apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2010-143764 filed on Jun. 24, 2010. 
     BACKGROUND 
     1. Technical Field 
     The present invention relates to a cleaning device and an image forming apparatus. 
     2. Related Art 
     There is a related technology for cleaning a discharge member of a charging device. 
     SUMMARY 
     According to a first aspect of the invention, there is provided a cleaning device including: a cleaning member that is disposed so as to be movable along a length direction of, and in contact with, a discharge member of a charging device and cleans the discharge member; a guide member that is disposed along the length direction of the discharge member and guides the cleaning member in the length direction of the discharge member; and a drive device which, when executing a cleaning operation where the drive device reciprocally moves the cleaning member along the guide member from a standby position set on one length direction end portion of the discharge member or a return operation where the drive device returns the cleaning member along the guide member to the standby position, applies to the cleaning member a driving force in an opposite direction of a moving direction in which movement of the cleaning member is to be started and thereafter applies to the cleaning member a driving force in the moving direction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       An exemplary embodiment of the present invention will be described in detail based on the following figures, wherein: 
         FIG. 1  is a general view showing the configuration of an image forming apparatus pertaining to the exemplary embodiment; 
         FIG. 2  is a general view showing the configuration of an image forming unit pertaining to the exemplary embodiment; 
         FIG. 3  is a perspective view showing the configuration of a charging device pertaining to the exemplary embodiment; 
         FIG. 4  is a perspective view showing a cutaway of part of the configuration of the charging device pertaining to the exemplary embodiment; 
         FIG. 5  is a perspective view showing a cutaway of part of the configuration of the charging device pertaining to the exemplary embodiment; 
         FIG. 6  is a general view showing the configuration of a cleaning device pertaining to the exemplary embodiment; 
         FIG. 7  is a general view showing a state where a cleaning device body is positioned in a turn-back position in the configuration of the cleaning device pertaining to the exemplary embodiment; 
         FIG. 8  is a general view showing a state where the cleaning device body is tilted in a standby position in the cleaning device pertaining to the exemplary embodiment; 
         FIG. 9  is a general view showing a state where the cleaning device body is tilted towards the opposite side of the direction in  FIG. 8  when the cleaning device body is in the standby position in the cleaning device pertaining to the exemplary embodiment; 
         FIG. 10  is a general view showing a state where the cleaning device body is tilted outside the standby position in the cleaning device pertaining to the exemplary embodiment; and 
         FIG. 11  is a general view showing a state where the cleaning device body is tilted towards the opposite side of the direction in  FIG. 10  when the cleaning device body is outside the standby position in the cleaning device pertaining to the exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     An exemplary embodiment pertaining to the present invention will be described below on the basis of the drawings. 
     (Configuration of Image Forming Apparatus Pertaining to Present Exemplary Embodiment) 
     First, the configuration of an image forming apparatus  10  pertaining to the present exemplary embodiment will be described.  FIG. 1  is a general view showing the configuration of the image forming apparatus  10  pertaining to the present exemplary embodiment. 
     In order to facilitate understanding of the description hereinafter, in the drawings, the X-axis direction denotes a front-back direction, the Y-axis direction denotes a left-right direction, and the Z-axis direction denotes an up-down direction. The directions indicated by arrows X, −X, Y, −Y, Z, and −Z denote front, back, right, left, up, and down, respectively. Further, in drawings showing a configuration two-dimensionally, a X or a Z accompanied by a circled dot means an arrow from the back to the front of the page and a −X or a −Z accompanied by a circled times means an arrow from the front to the back of the page. 
     As shown in  FIG. 1 , the image forming apparatus  10  is equipped with an image forming apparatus body  11  inside of which are housed components. Inside the image forming apparatus body  11 , there are disposed a recording medium housing unit  12  in which a recording medium P such as paper is housed, an image forming section  14  that forms images on the recording medium P, a conveyance section  16  that conveys the recording medium P from the recording medium housing unit  12  to the image forming section  14 , and a controller  20  that controls the working of each part of the image forming apparatus  10 . Further, on the side portion of the image forming apparatus body  11 , there is disposed a recording medium ejection unit  18  to which is ejected the recording medium P on which an image has been formed by the image forming section  14 . 
     The image forming section  14  is equipped with image forming units  22 Y,  22 M,  22 C, and  22 K (hereinafter “ 22 Y to  22 K”) that form toner images of each color of yellow (Y), magenta (M), cyan (C), and black (K), an intermediate transfer belt  24  onto which are transferred the image images that have been formed by the image forming units  22 Y to  22 K, first transfer rolls  26  serving as one example of first transfer members for transferring onto the intermediate transfer belt  24  the toner images that have been formed by the image forming units  22 Y to  22 K, a second transfer roll  28  serving as one example of a second transfer member for transferring from the intermediate transfer belt  24  to the recording medium P the toner images that have been transferred onto the intermediate transfer belt  24  by the first transfer rolls  26 , and a fixing device  30  that fixes to the recording medium P the toner images that have been transferred from the intermediate transfer belt  24  to the recording medium P by the second transfer roll  28 . 
     The image forming units  22 Y to  22 K are juxtaposed and placed in the vertical direction central portion of the image forming apparatus  10  along the horizontal direction. Further, each of the image forming units  22 Y to  22 K has a photoconductor  32  (one example of a charged body) that rotates in one direction (a clockwise direction in  FIG. 1 ). 
     Around each of the photoconductors  32 , in order from the upstream side in the rotating direction of the photoconductor  32 , there are disposed a charging device  60  that charges the photoconductor  32 , a developing device  38  that forms a toner image by developing an electrostatic latent image that has been formed as a result of the photoconductor  32  charged by the charging device  60  being exposed to light, and a neutralizing device  40  that neutralizes developer remaining on the photoconductor  32  after image transfer (see  FIG. 2 ). 
     In the image forming units  22 Y,  22 M, and  22 C, the charging device  60  is configured by a charging roll. In the image forming unit  22 K, the charging device  60  is, as shown in  FIG. 2 , configured by a scorotron charging device. The specific configuration of this scorotron charging device  60  will be described later. 
     Further, above the image forming units  22 Y to  22 K, as shown in  FIG. 1 , there are disposed exposure devices  36  that form electrostatic latent images by exposing each of the photoconductors  32  charged by the charging device  60  to light. The exposure devices  36  are configured to form the electrostatic latent images on the basis of image signals sent from the controller  20 . Examples of the image signals sent from the controller  20  include image signals that the controller  20  has acquired from the outside. In  FIG. 1  and  FIG. 2 , arrows L indicate exposure light beams from the exposure devices  36 . 
     The intermediate transfer belt  24  is, as shown in  FIG. 1 , formed annularly and placed on the underside of the image forming units  22 Y to  22 K. On the inner peripheral side of the intermediate transfer belt  24 , there are disposed wrap rolls  41 ,  42 ,  43 ,  44 ,  45 , and  46  around which the intermediate transfer belt  24  is wrapped. The intermediate transfer belt  24  is configured to circulatingly move (rotate) in one direction (a counter-clockwise direction in  FIG. 1 ) while contacting the photoconductors  32  as a result of any of the wrap rolls  41 ,  42 ,  43 ,  44 ,  45  and  46  being driven to rotate. The wrap roll  42  is configured as an opposing roll that opposes the second transfer roll  28 . 
     Further, on the outer peripheral side of the intermediate transfer belt  24 , there is disposed a neutralizing device  25  that contacts the outer peripheral surface of the intermediate transfer belt  24  and neutralizes developer remaining on the intermediate transfer belt  24  after image transfer. 
     The first transfer rolls  26  oppose the photoconductors  32  across the intermediate transfer belt  24 . The positions between the first transfer rolls  26  and the photoconductors  32  are configured as first transfer positions where the toner images formed on the photoconductors  32  are transferred onto the intermediate transfer belt  24 . Further, the first transfer rolls  26  contact the intermediate transfer belt  24  and are configured to rotate following the circulatingly moving intermediate transfer belt  24 . 
     The second transfer roll  28  opposes the wrap roll  42  across the intermediate transfer belt  24 . The position between the second transfer roll  28  and the wrap roll  42  is configured as a second transfer position where the toner images transferred onto the intermediate transfer belt  24  are transferred onto the recording medium P. 
     In the conveyance section  16 , there are disposed a feed roll  46  that feeds the recording medium P housed in the recording medium housing unit  12 , a conveyance path  48  on which the recording medium P fed by the feed roll  46  is conveyed, and multiple conveyance rolls  50  that are placed along the conveyance path  48  and convey the recording medium P fed by the feed roll  46  to the second transfer position. 
     The fixing device  30  is placed on the conveyance direction downstream side of the second transfer position and fixes to the recording medium P the toner images that have been transferred at the second transfer position. On the conveyance direction downstream side of the fixing device  30 , there are disposed ejection rolls  52  that eject to the recording medium ejection unit  18  the recording medium P to which the toner images have been fixed. 
     Next, the image forming operations of forming an image on the recording medium P in the image forming apparatus  10  pertaining to the present exemplary embodiment will be described. 
     In the image forming apparatus  10  pertaining to the present exemplary embodiment, the recording medium P fed by the feed roll  46  from the recording medium housing unit  12  is sent to the second transfer position by the multiple conveyance rolls  50 . 
     Meanwhile, in the image forming units  22 Y to  22 K, the photoconductors  32  charged by the charging devices  60  are exposed to light by the exposure devices  36 , whereby electrostatic latent images are formed on the photoconductors  32 . Those electrostatic latent images are developed by the developing devices  38 , whereby toner images are formed on the photoconductors  32 . The toner images of each color formed by the image forming units  22 Y to  22 K are superimposed on the intermediate transfer belt  24  in the first transfer positions, whereby a color image is formed. Then, the color image formed on the intermediate transfer belt  24  is transferred to the recording medium P in the second transfer position. 
     The recording medium P onto which the toner images have been transferred is conveyed to the fixing device  30 , and the toner images that have been transferred are fixed by the fixing device  30 . The recording medium P to which the toner images have been fixed is ejected to the recording medium ejection unit  18  by the ejection rolls  52 . As described above, the series of image forming operations is performed. 
     (Configuration of Charging Devices  60 ) 
     Next, the configuration of the charging devices  60  will be described. 
     Each of the charging devices  60  is, as shown in  FIG. 2 , equipped with a shield case  62  serving as one example of a guide member and made of stainless steel in which an open portion  62 A is formed on the photoconductor  32  side. The shield case  62  is configured in the form of a long and slender box that extends along the axis-of-rotation direction of the photoconductor  32  (see  FIG. 3 ). In an upper wall  62 B of the shield case  62 , there is formed a ventilation opening  62 C for ventilation. 
     Inside the shield case  62 , as shown in  FIG. 2 , a discharge wire  64  serving as one example of a discharge member is disposed along the axis-of-rotation direction of the photoconductor  32 . The discharge wire  64  is configured by a metal wire of tungsten, for example. The discharge member may also be a discharge member configured by a metal wire coated with a resin or by a tabular metal plate; it suffices as long as the discharge member is one by which discharge is performed. 
     The discharge wire  64  is configured to perform a discharge operation where it generates a negative charge as a result of a voltage being applied thereto from a power source  68  (see  FIG. 6 ) and supplies this negative charge to the surface of the photoconductor  32 . Because of this discharge operation, the photoconductor  32  is charged. 
     On the open side of the shield case  62  and between the discharge wire  64  and the photoconductor  32 , a grid  66  having multiple openings is placed along the axis-of-rotation direction of the photoconductor  32 . 
     In the grid  66 , the negative charge generated by the discharge wire  64  passes through the openings in the grid  66  and is supplied to the photoconductor  32 , and the passage amount of the negative charge passing through the grid  66  is controlled by a grid voltage applied from a power source (not shown). Thus, the charge potential of the photoconductor  32  is controlled. 
     Specifically, when the voltage (electrical potential) of the grid  66  is high with respect to the electrical potential of the photoconductor  32 , the negative charge moves toward the photoconductor  32  because of that electrical potential difference, so the passage amount of the negative charge is large, and when the electrical potential difference between the photoconductor  32  and the grid  66  becomes smaller as a result of the negative charge being supplied to the photoconductor  32 , the passage amount of the negative charge decreases. 
     The charging device  60  is also, as shown in  FIG. 4  and  FIG. 5 , equipped with a cleaning device  70  that cleans the discharge wire  64  and the grid  66 . The cleaning device  70  is equipped with a cleaning device body  74 , which is housed inside the shield case  62  so as to be movable along the lengthwise direction of the shield case  62 , and a moving device  71 , which moves the cleaning device body  74  in one direction and in the other direction of the lengthwise direction of the shield case  62 . 
     The cleaning device body  74  is configured to include an upper plate  74 A, which is placed along the inner surface of the upper wall  62 B of the shield case  62 , and side plates  74 D and  74 E, which are placed along the inner surfaces of side walls  62 D and  62 E of the shield case  62 . 
     On the upper portion of the upper plate  74 A, there is disposed a sandwiching portion  74 B that extends out above the upper wall  62 B of the shield case  62  through the ventilation opening  62 C and sandwiches the upper wall  62 B between itself and the upper plate  74 A. 
     The moving device  71  is equipped with a feed screw  72  that is rotatably supported on the side portion of the side wall  62 D of the shield case  62 . The feed screw  72  is configured to include a rotating shaft  72 A, which extends along the lengthwise direction of the shield case  62 , and a thread  72 B, which is formed helically on the outer periphery of the rotating shaft  72 A. 
     In the cleaning device body  74 , there is disposed a coupling portion  76  that is coupled to the feed screw  72 . The coupling portion  76  extends out from the side plate  74 D of the cleaning device body  74  towards the side of the side wall  62 D and extends upward along the outer surface of the side wall  62 D. Additionally, the feed screw  72  is screwed into the distal end portion of the coupling portion  76 . The moving mechanism that moves the cleaning device body  74  is not limited to the feed screw  72  and may also, for example, be of a configuration using a mechanical element such as a belt. 
     In the present exemplary embodiment, as described above, the charging device  60  is configured such that the side wall  62 D of the shield case  62  is sandwiched by the coupling portion  76  and the side plate  74 D of the cleaning device body  74 . Thus, the movement of the cleaning device body  74  in the direction of arrow Y and the direction of arrow −Y is regulated by the side wall  62 D of the shield case  62 , and the cleaning device body  74  is guided along the lengthwise direction of the shield case  62  (the direction of arrow X and the direction of arrow −X). That is, in the present exemplary embodiment, the side wall  62 D of the shield case  62  functions as a guide member that guides the cleaning device body  74  (specifically, the side plate  74 D and the coupling portion  76 ) in the direction of arrow X and the direction of arrow −X, and the side plate  74 D of the cleaning device body  74  and the coupling portion  76  function as guided members. 
     The cleaning device body  74  is sandwiched by the side wall  62 D and the side wall  62 E between the side wall  62 D and the side wall  62 E of the shield case  62 . That is, the movement of the cleaning device body  74  in the direction of arrow Y and the direction of arrow −Y is regulated also by the side wall  62 D and the side wall  62 E, and the cleaning device body  74  is guided along the lengthwise direction of the shield case  62  (the direction of arrow X and the direction of arrow −X). Consequently, in the present exemplary embodiment, it can also be said that the side wall  62 D and the side wall  62 E of the shield case  62  function as guide members that guide the cleaning device body  74  (specifically, the side plate  74 D and the side plate  74 E) in the direction of arrow X and the direction of arrow −X and that the side plate  74 D and the side plate  74 E of the cleaning device body  74  function as guided members. 
     Moreover, in the present exemplary embodiment, the charging device  60  is configured such that the upper wall  62 B of the shield case  62  is sandwiched by the sandwiching portion  74 B and the upper plate  74 A of the cleaning device body  74 . Thus, the movement of the cleaning device body  74  in the direction of arrow Z and the direction of arrow −Z is regulated by the upper wall  62 B of the shield case  62 , and the cleaning device body  74  is guided along the lengthwise direction of the shield case  62  (the direction of arrow X and the direction of −X). Consequently, in the present exemplary embodiment, it can also be said that the upper wall  62 B of the shield case  62  functions as a guide member that guides the cleaning device body  74  (specifically the upper plate  74 A and the sandwiching portion  74 B) in the direction of arrow X and the direction of arrow −X and that the upper plate  74 A and the sandwiching portion  74 B of the cleaning device body  74  function as guided members. It suffices for the present exemplary embodiment to have at least one of the above-described configurations that functions as a guide member that guides the cleaning device body  74 ; further, as the guide member that guides the cleaning device body  74 , another configuration may also be used. 
     Between the side plate  74 D and the side plate  74 E of the cleaning device body  74 , there are disposed a grid cleaning member  80 , which contacts and cleans the grid  66 , and a support member  82 , on which the grid cleaning member  80  is supported. The grid cleaning member  80  is configured by a so-called cleaning brush in which numerous hairs for cleaning are implanted. 
     On the side plate  74 D and the side plate  74 E, there are disposed grid sandwiching portions  74 G and  74 H for sandwiching the grid  66  between themselves and the grid cleaning member  80 . 
     The support member  82  is, in the present exemplary embodiment, configured by two support members  82 A and  82 B, and each of those two support members  82 A and  82 B is formed in an L shape when seen from the front (when seen from one lengthwise direction end side of the shield case  62 ). One end portion of each of the support members  82 A and  82 B is fixed to the inner surfaces of the side plate  74 D and the side plate  74 E, and the grid cleaning member  80  is fixed to the other end portions of the support members  82 A and  82 B. 
     Further, between the side plate  74 D and the side plate  74 E of the cleaning device body  74  and between the upper wall  62 B of the shield case  62  and the grid cleaning member  80 , there are disposed a discharge wire cleaning member  84 , which serves as one example of a cleaning member that contacts and cleans the discharge wire  64 , and a support member  86 , on which the discharge wire cleaning member  84  is supported. 
     In the present exemplary embodiment, the discharge wire cleaning member  84  is configured to be movable along the length direction of the discharge wire  64  as a result of being disposed in the cleaning device body  74  that is movable along the lengthwise direction of the shield case  62 . Further, the discharge wire cleaning member  84  contacts the discharge wire  64  from above. The discharge wire cleaning member  84  is, for example, configured by a cloth member such as nonwoven cloth or by a porous member such as foam. The support member  86  is fixed to the cleaning device body  74  via an elastic member (not shown) such as a spring and is pressed against the discharge wire  64 . 
     In a position opposing the discharge wire cleaning member  84 , there is disposed a discharge wire cleaning member  85  that sandwiches the discharge wire  64  between itself and the discharge wire cleaning member  84  and contacts and cleans the discharge wire  64  from below. 
     In the present exemplary embodiment, the feed screw  72  is, as shown in  FIG. 6 , configured to rotate as a result of driving force from a motor  78  serving as one example of a drive device being transmitted to the rotating shaft  72 A via a gear train  79 . Thus, in the cleaning device  70 , when the feed screw  72  forwardly rotates, the cleaning device body  74  moves in one direction (the direction of arrow X in  FIG. 6 ) of the lengthwise direction of the shield case  62 , and when the feed screw  72  reversely rotates, the cleaning device body  74  moves in the other direction (the direction of arrow −X in  FIG. 6 ) of the lengthwise direction of the shield case  62 . In accompaniment with the movement of the cleaning device body  74 , the grid cleaning member  80  wipes the grid  66 , and the discharge wire cleaning member  84  and the discharge wire cleaning member  85  wipe the discharge wire  64 , whereby the grid  66  and the discharge wire  64  are cleaned. 
     In the present exemplary embodiment, a standby position in which the cleaning device body  74  stands by when the cleaning device  70  is not performing a cleaning operation is set on one length direction end side of the discharge wire  64  (the shield case  62 ) and outside the range (charging range) in which the discharge wire  64  discharges with respect to the photoconductor  82 . In  FIG. 6 , the cleaning device body  74  is shown in a state where it is positioned in the standby position. 
     Further, in the present exemplary embodiment, the other end side of the shield case  62  is configured as a turn-back position at which the cleaning device body  74  turns back. In  FIG. 7 , the cleaning device body  74  is shown in a state where it is positioned in the turn-back position. 
     The cleaning device body  74  is configured such that, in the standby position, it is separated from the discharge wire  64  by an unillustrated separation mechanism (retract mechanism). Further, in the present exemplary embodiment, the cleaning device  70  does not have a detector that detects the position of the cleaning device body  74  including a detector that detects that the cleaning device body  74  is positioned in the standby position. 
     In the transmission path on which the driving force from the motor  78  is transmitted to the rotating shaft  72 A, there is disposed a torque limiter  77  that allows a drive shaft  78 A of the motor  78  to idle when a predetermined rotational load arises in the rotating shaft  72 A. 
     Thus, when the cleaning device body  74  is positioned in the standby position and a driving force in the direction of arrow −X is applied with respect to the cleaning device body  74 , a rotational load exceeding the predetermined rotational load arises in the feed screw  72  as a result of the cleaning device body  74  striking a side wall  74 J and not advancing, and the drive shaft  78 A of the motor  78  idles. 
     Further, when the cleaning device body  74  is positioned in the turn-back position and a driving force in the direction of arrow X is applied with respect to the cleaning device body  74 , a rotational load exceeding the predetermined rotational load arises in the feed screw  72  as a result of the cleaning device body  74  striking a side wall  741  and not advancing, and the drive shaft  78 A of the motor  78  idles. 
     In the present exemplary embodiment, as described above, the feed screw  72  that produces a moving force with respect to the cleaning device body  74  is disposed on one side of the shield case  62 , so it becomes easier for the cleaning device body  74  to tilt with respect to the shield case  62  when the cleaning device  74  moves. 
     Further, in the present exemplary embodiment, the cleaning device body  74  is configured by resin, which is an insulator, and the shield case  62  and the feed screw  72  are configured by metal. When the cleaning device body  74  is put into reciprocal motion, it moves while the cleaning device body  74  and the shield case  62  come into contact with and separate from each other, or moves while being pressed against one side, because of gutters (clearances) between it and the shield case  62 . In so doing, sometimes the portions of the cleaning device body  74 , which is configured by resin, that contact the shield case  62 , which is configured by metal, become worn down over time such that the frictional force gradually becomes larger. When the phenomenon of the frictional force becoming larger is observed, there is seen a phenomenon (gnawing) where the cleaning device body  74  is pressed against one side of the shield case  62 , tilting becomes larger on the opposite side because of that reaction force, and for that reason the cleaning device body  74  is further pressed against the one side of the shield case  62  such that friction increases. 
     Due to these, sometimes the cleaning device body  74  ends up catching on the side wall  62 D or the side wall  62 E of the shield case  62  as a result of the cleaning device body  74  tilting with respect to the shield case  62 , and the cleaning device body  74  stops. 
     Further, in the motor  78 , there is disposed a controller  90  that controls the driving of the motor  78 . Specifically, the controller  90  manages the rotational time (rotational amount) of the motor  78  and causes the motor  78  to move the cleaning device body  74  to the desired position. 
     In the present exemplary embodiment, the cleaning device  70  is configured such that a cleaning operation, where the cleaning device body  74  is reciprocally moved from the standby position along the shield case  62 , and a return operation, where the cleaning device body  74  is returned to the standby position along the shield case  62 , are executed as a result of the controller  90  controlling the driving of the motor  78 . The cleaning operation and the return operation are both moving operations of the cleaning device body  74  whose terminal points are the standby position. 
     Additionally, in the present exemplary embodiment, because of the drive control by the controller  90 , the motor  78  is configured such that, when executing at least one of the cleaning operation and the return operation, it applies to the cleaning device body  74  a driving force in an opposite direction of a moving direction in which movement of the cleaning device body  74  is to be started and thereafter applies to the cleaning device body  74  a driving force in the moving direction. In the present exemplary embodiment, the moving direction in which movement of the cleaning device body  74  is to be started specifically is the direction of arrow X (the direction towards the turn-back position) in the cleaning operation and the direction of arrow −X (the direction towards the standby position) in the return operation. The specific moving operation of the cleaning device body  74  will be described later. 
     In the present exemplary embodiment, the return operation of returning the cleaning device body  74  to the standby position is performed by operation from an operation portion  54  (see  FIG. 1 ). This return operation is executed as a result of an operation by a user from the operation portion  54  when, for example, charging trouble has arisen as a result of the cleaning device body  74  ending up stopping on the turn-back position side of the standby position in the cleaning operation or the like and image defects such as black bands resulting from that charging trouble have arisen. The operation from the operation portion  54  may also be turning on power after turning off power. 
     Further, in the present exemplary embodiment, because the cleaning device  70  does not have a detector that detects the position of the cleaning device body  74 , the return operation is performed when there is the potential for the cleaning device body  74  to not be positioned in the standby position. Specifically, the return operation is, for example, performed before discharge of the discharge wire  64  when power has been turned on in the image forming apparatus body  11 . In a state where power is not turned on, it is possible for the user to access the cleaning device  70  and move the cleaning device body  74 , so there is the potential for the cleaning device body  74  to not be positioned in the standby position. Power is, for example, turned on from the operation portion  54  (see  FIG. 1 ). 
     Further, the return operation is performed before discharge of the discharge wire  64  when the charging device  60  has been installed in the image forming apparatus body  11 . In a state where the charging device  60  is removed from the image forming apparatus body  11 , it is possible for the user to access the cleaning device  70  and move the cleaning device body  74 , so there is the potential for the cleaning device body  74  to not be positioned in the standby position. Installation of the charging device  60  in the image forming apparatus body  11  is performed when the charging device  60  installed in the image forming apparatus body  11  is temporarily removed to replace or perform maintenance on a part and is reinstalled and when the charging device  60  installed in the image forming apparatus body  11  is removed and a new charging device  60  is installed in the image forming apparatus body  11  (so as to replace the previously installed charging device  60 ). 
     In the present exemplary embodiment, a fuse is disposed in the new charging device  60 , and the fact that the charging device  60  is new is detected as a result of the fuse being cut when the new charging device  60  is installed in the image forming apparatus body  11 . Further, the fact that the charging device  60  that has been removed from the image forming apparatus body  11  has been reinstalled in the image forming apparatus body  11  is detected by a detector (not shown). 
     The cleaning operation is, for example, executed each time the image forming apparatus  10  forms images on a predetermined number of sheets (e.g., 3,000 sheets). Both when power has been turned on in the image forming apparatus body  11  and when the charging device  60  has been installed in the image forming apparatus body  11 , there is the potential for the discharge wire  64  and the grid  66  to be dirty, so the cleaning device  70  may also be configured to perform the cleaning operation after the return operation or instead of the return operation. 
     (Action Pertaining to Present Exemplary Embodiment) 
     Next, the action pertaining to the present exemplary embodiment will be described. 
     First, the cleaning operation in the cleaning device  70  will be described. Here, first, the cleaning operation executed each time the image forming apparatus  10  forms images on the predetermined number of sheets (e.g., 3,000 sheets) will be described. 
     When images are formed on the predetermined number of sheets (e.g., 3,000 sheets) by the image forming section  14  after the cleaning device  70  has performed the cleaning operation a previous time, the controller  90  drives the motor  78  such that the feed screw  72  forwardly rotates an amount corresponding to the rotational amount by which the cleaning device body  74  reaches the turn-back position from the standby position. Thus, the cleaning device body  74  moves from the standby position (see  FIG. 6 ) to the turn-back position (see  FIG. 7 ) along one direction (the direction of arrow X) of the lengthwise direction of the shield case  62 . 
     In this manner, when the cleaning device body  74  moves, the discharge wire  64  is cleaned from one lengthwise direction end portion thereof to its other end portion by the discharge wire cleaning member  84  and the discharge wire cleaning member  85 , and the grid  66  is cleaned from one lengthwise direction end portion thereof to its other end portion by the grid cleaning member  80 . 
     In a case where the cleaning device body  74  is tilted in the standby position with respect to the shield case  62  as indicated by the solid lines in  FIG. 8 , the posture of the cleaning device body  74  changes as a result of the feed screw  72  forwardly rotating, so that the tilting of the cleaning device body  74  is eliminated as indicated by the two-dot chain lines in  FIG. 8 , and thereafter the cleaning device body  74  moves from the standby position to the turn-back position along one direction (the direction of arrow X) of the lengthwise direction of the shield case  62 . For this reason, a situation where the cleaning device body  74  catches on the side wall  62 D or the side wall  62 E of the shield case  62  and stops is eliminated or prevented. 
     Before the feed screw  72  is forwardly rotated, that is, before the cleaning device body  74  is moved from the standby position (see  FIG. 6 ) to the turn-back position (see  FIG. 7 ), the controller  90  may also drive the motor  78  such that the feed screw  72  reversely rotates one to two rotations. Thus, in a case where the cleaning device body  74  is tilted in the standby position as indicated by the solid lines in  FIG. 9 , the posture of the cleaning device body  74  changes, so that the tilting is eliminated as indicated by the two-dot chain lines in  FIG. 9 . For this reason, a situation where the cleaning device body  74  catches on the side wall  62 D or the side wall  62 E of the shield case  62  and stops is eliminated or prevented. 
     Next, the controller  90  drives the motor  78  such that the feed screw  72  reversely rotates an amount corresponding to the rotational amount by which the cleaning device body  74  reaches the standby position from the turn-back position. Thus, the cleaning device body  74  moves from the turn-back position (see  FIG. 7 ) to the standby position (see  FIG. 6 ) along the other direction (the direction of arrow −X) of the lengthwise direction of the shield case  62 , the discharge wire  64  is cleaned by the discharge wire cleaning member  84  and the discharge wire cleaning member  85 , and the grid  66  is cleaned by the grid cleaning member  80 . 
     Next, the return operation of returning the cleaning device body  74  to the standby position will be described. 
     The return operation is performed before discharge of the discharge wire  64  when the charging device  60  has been reinstalled in the image forming apparatus body  11 . The return operation is also performed before discharge of the discharge wire  64  when a new charging device  60  has been installed in the image forming apparatus body  11 . The return operation is also performed before discharge of the discharge wire  64  when power has been turned on in the image forming apparatus body  11 . The return operation is also executed as a result of the user operating from the operation portion  54  when, for example, charging trouble has arisen as a result of the cleaning device body  74  ending up stopping on the turn-back position side of the standby position in the cleaning operation or the like and image defects such as black bands resulting from that charging trouble have arisen. 
     When the return operation is executed, the controller  90  drives the motor  78  such that the feed screw  72  forwardly rotates one to two rotations. Thus, in a case where the cleaning device body  74  is tilted as indicated by the solid lines in  FIG. 10 , the posture of the cleaning device  74  changes, so that the tilting is eliminated as indicated by the two-dot chain lines in  FIG. 10 . In a case where the cleaning device body  74  is not tilted, the cleaning device body  74  moves a little in the direction of arrow X in correspondence to the feed screw  72  making one to two rotations. 
     In the present exemplary embodiment, the controller  90  drives the motor  78  such that the feed screw  72  forwardly rotates one to two rotations as a rotational amount (rotational time) in a minimum range in which the posture of the cleaning device body  74  becomes corrected (changes), but the rotational amount (rotational time) for correcting the posture of the cleaning device body  74  may also be three or more rotations; it suffices for the rotational amount (rotational time) to be a rotational amount (rotational time) that is smaller than the rotational amount for returning the cleaning device body  74  to the standby position and specifically a rotational amount (rotational time) that is smaller than the rotational amount by which the cleaning device body  74  reaches the standby position from the turn-back position. It suffices for the rotational amount (rotational time) to be in a range in which the posture of the cleaning device body  74  becomes corrected (changes). 
     Next, the controller  90  drives the motor  78  such that the feed screw  72  reversely rotates an amount corresponding to the rotational amount by which the cleaning device body  74  reaches the standby position from the turn-back position. Thus, in a case where the cleaning device body  74  is tilted as indicated by the solid lines in  FIG. 11 , the posture of the cleaning device body  74  changes, so that the tilting is eliminated as indicated by the two-dot chain lines in  FIG. 11 . Moreover, the cleaning device body  74  moves in the other direction (the direction of arrow −X) of the lengthwise direction of the shield case  62 . In a case where the cleaning device body  74  is not tilted, the cleaning device body  74  simply moves in the other direction (the direction of arrow −X) of the lengthwise direction of the shield case  62 . 
     In a case where the cleaning device body  74  is not positioned in the turn-back position at the time when the feed screw  72  has started reversely rotating, that is, in a case where the cleaning device body  74  is positioned on the standby position side of the turn-back position, the feed screw  72  is reversely rotated even after the cleaning device body  74  has reached the standby position, but a rotational load arises in the feed screw  72  as a result of the cleaning device body  74  striking the side wall  74 J in the standby position and not advancing, and the drive shaft  78 A of the motor  78  idles because of the torque limiter  77 . 
     In this manner, when the return operation is executed, the motor  78  applies to the cleaning device body  74  a driving force in the direction of arrow X, which is the opposite direction of the moving direction (the direction of arrow −X) in which movement of the cleaning device body  74  is to be started in the execution of the cleaning operation, and thereafter the motor  78  moves the cleaning device body  74  in the direction of arrow −X. Thus, the tilting of the cleaning device body  74  that has stopped outside the standby position as a result of its posture tilting with respect to the shield case  64  is eliminated, and the cleaning device body  74  returns to the standby position. 
     In the present exemplary embodiment, the return operation described above is performed to return the cleaning device body  74  to the standby position by turning on power in the image forming apparatus body  11  or by installing the charging device  60  in the image forming apparatus body  11 , so it becomes unnecessary to detect the position of the cleaning device body  74 . 
     When the charging device  60  is reinstalled in the image forming apparatus body  11 , or when a new charging device  60  is installed in the image forming apparatus body  11 , or when power is turned on in the image forming apparatus body  11 , there is also the potential for the discharge wire  64  and the grid  66  to be dirty, so the cleaning operation described above may also be performed after the return operation described above has been performed. 
     Moreover, when the charging device  60  is reinstalled in the image forming apparatus body  11 , or when a new charging device  60  is installed in the image forming apparatus body  11 , or when power is turned on in the image forming apparatus body  11 , the cleaning operation described below may also be performed instead of the return operation described above. 
     When the cleaning operation is executed, the controller  90  drives the motor  78  such that the feed screw  72  reversely rotates one to two rotations. Thus, in a case where the cleaning device body  74  is tilted as indicated by the solid lines in  FIG. 11 , the posture of the cleaning device body  74  changes, so that the tilting is eliminated as indicated by the two-dot chain lines in  FIG. 11 . In a case where the cleaning device body  74  is not tilted, the cleaning device body  74  moves a little in the direction of arrow −X in correspondence to the feed screw  72  making one to two rotations. 
     In the present exemplary embodiment, the controller  90  drives the motor  78  such that the feed screw  72  reversely rotates one to two rotations as a rotational amount (rotational time) in a minimum range in which the posture of the cleaning device body  74  becomes corrected (changes), but the rotational amount (rotational time) for correcting the posture of the cleaning device body  74  may also be three or more rotations; it suffices for the rotational amount (rotational time) to be a rotational amount (rotational time) that is smaller than the rotational amount for moving the cleaning device body  74  to the turn-back position and specifically a rotational amount (rotational time) that is smaller than the rotational amount by which the cleaning device body  74  reaches the turn-back position from the standby position. It suffices for the rotational amount (rotational time) to be in a range in which the posture of the cleaning device body  74  becomes corrected (changes). 
     Next, the controller  90  drives the motor  78  such that the feed screw  72  forwardly rotates an amount corresponding to the rotational amount by which the cleaning device body  74  reaches the turn-back position from the standby position. Thus, in a case where the cleaning device body  74  is tilted as indicated by the solid lines in  FIG. 10 , the posture of the cleaning device body  74  changes, so that the tilting is eliminated as indicated by the two-dot chain lines in  FIG. 10 . Moreover, the cleaning device body  74  moves in one direction (the direction of arrow X) of the lengthwise direction of the shield case  62 . In a case where the cleaning device body  74  is not tilted, the cleaning device body  74  simply moves in the one direction (the direction of arrow X) of the lengthwise direction of the shield case  62 . 
     In a case where the cleaning device body  74  is positioned in the standby position at the time when the feed screw  72  has started forwardly rotating, the cleaning device body  74  moves from the standby position to the turn-back position. Thus, the discharge wire  64  is cleaned from one lengthwise direction end portion thereof to its other end portion by the discharge wire cleaning member  84  and the discharge wire cleaning member  85 , and the grid  66  is cleaned from one lengthwise direction end portion thereof to its other end portion by the grid cleaning member  80 . 
     In a case where the cleaning device body  74  is not positioned in the standby position at the time when the feed screw  72  has start forwardly rotating, that is, when the cleaning device body  74  is positioned on the turn-back position side of the standby position, the feed screw  72  forwardly rotates even after the cleaning device body  74  has reached the turn-back position, but a rotational load arises in the feed screw  72  as a result of the cleaning device body  74  striking the side wall  741  in the turn-back position and not advancing, and the drive shaft  78 A of the motor  78  idles because of the torque limiter  77 . 
     Next, the controller  90  drives the motor  78  such that the feed screw  72  reversely rotates an amount corresponding to the rotational amount by which the cleaning device body  74  reaches the standby position from the turn-back position. Thus, the cleaning device body  74  moves in the other direction (the direction of arrow −X) of the lengthwise direction of the shield case  62  from the turn-back position to the standby position, the discharge wire  64  is cleaned by the discharge wire cleaning member  84  and the discharge wire cleaning member  85 , and the grid  66  is cleaned by the grid cleaning member  80 . 
     In this manner, when the cleaning operation is executed, the motor  78  applies to the cleaning device body  74  a driving force in the direction of arrow −X, which is the opposite direction of the moving direction (the direction of arrow X) in which movement of the cleaning device body  74  is to be start in the execution of the cleaning operation, and thereafter moves the cleaning device body  74  in the direction of arrow X. Thus, the tilting of the cleaning device body  76  that has stopped outside the standby position as a result of its posture tilting with respect to the shield case  62  is eliminated, and the cleaning device body  74  returns to the standby position. 
     In the present exemplary embodiment, the cleaning operation described above is performed to return the cleaning device body  74  to the standby position by turning on power in the image forming apparatus body  11  or by installing the charging device  60  in the image forming apparatus body  11 , so it becomes unnecessary to detect the position of the cleaning device body  74 . 
     Further, in this manner, in the present exemplary embodiment, a detector itself that detects the position of the cleaning device body  74  is unnecessary, and a member that electrically protects the detector from the voltage applied to the discharge wire  64  is also unnecessary, so the device can be made compact. The configuration of the present exemplary embodiment is also applicable to a configuration having a detector that detects the position of the cleaning device body  74 . 
     The present invention is not limited to the exemplary embodiment described above, and various modifications, alterations, and improvements are possible.