Patent Publication Number: US-9411254-B2

Title: Charging device with charging and cleaning members

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2013-065301 filed Mar. 27, 2013. 
     BACKGROUND 
     (i) Technical Field 
     The present invention relates to a charging device, an assembly, and an image forming apparatus. 
     (ii) Related Art 
     An image forming apparatus such as a copying machine or a printer uses a charging device that charges an image carrier on which an electrostatic latent image is formed. 
     SUMMARY 
     According to an aspect of the invention, there is provided a charging device including a charging member and a cleaning member. The charging member is driven and rotated while in contact with an outer peripheral surface of an image carrier which rotates, and charges the image carrier. The cleaning member is driven and rotated while in contact with an outer peripheral surface of the charging member and cleans the outer peripheral surface of the charging member. In the charging device, a radius of the charging member is less than a radius of the cleaning member. 
    
    
     
       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 schematic view of a structure of an image forming apparatus according to an exemplary embodiment; 
         FIG. 2  is a schematic front view of a replacement cartridge; 
         FIG. 3  is a schematic sectional view of the replacement cartridge; 
         FIG. 4  is a partial enlarged schematic view of a charging device; 
         FIGS. 5A and 5B  each show a method of measuring friction force f1; 
         FIGS. 6A and 6B  each show a method of measuring friction force f2; 
         FIG. 7A  is a schematic sectional view of a replacement cartridge according to a first comparative example; 
         FIG. 7B  is a schematic sectional view of a replacement cartridge according to a second comparative example; and 
         FIG. 8  is a plan view of a plate member according to a modification. 
     
    
    
     DETAILED DESCRIPTION 
     An exemplary charging device, an exemplary assembly, and an exemplary image forming apparatus according to an exemplary embodiment are hereunder described on the basis of the drawings. 
       FIG. 1  is a schematic view of a structure of an image forming apparatus  10  according to an exemplary embodiment. An arrow UP shown in  FIG. 1  indicates an upward direction (vertical direction).  FIG. 2  is a schematic front view of a replacement cartridge  66  serving as an exemplary assembly.  FIG. 3  is a schematic sectional view of the replacement cartridge  66 .  FIG. 4  is a partial enlarged schematic view of a charging device  68 . 
     In  FIG. 1 , an image processing section  12  that performs image processing on image data that is input is provided in an internal portion of a body  10 A of the image forming apparatus  10 . 
     The image processing section  12  processes the input image data into pieces of gradation data of four colors, yellow (Y), magenta (M), cyan (C), and black (K). An exposure device  14  that receives the processed gradation data, and that performs image exposure using laser beams LB is provided in the center of the interior of the body  10 A. 
     Four image forming units  16 Y,  16 M,  16 C, and  16 K corresponding to yellow (Y), magenta (M), cyan (C), and black (K) are disposed above the exposure device  14  so as to be spaced apart from each other in a horizontal direction. When the image forming units  16 Y,  16 M,  16 C, and  16 K need not be distinguished by color, the reference characters Y, M, C, and K are omitted. 
     These four image forming units  16 Y,  16 M,  16 C, and  16 K all have the same structure. These four image forming units  16 Y,  16 M,  16 C, and  16 K each include a columnar image carrier  18  that is rotationally driven at a predetermined speed; a first charging member  20  that charges an outer peripheral surface of the image carrier  18 ; a developing device  22  that develops an electrostatic latent image (formed on the outer peripheral surface of the image carrier  18  that is charged by the aforementioned image exposure by the exposure device  14 ) using toner of a predetermined color, to make visible the electrostatic latent image as a toner image; and a cleaning blade  24  that cleans the outer peripheral surface of the image carrier  18 . A cleaning member  64  that is driven and rotated while in contact with the outer peripheral surface of the associated columnar charging member  20  and that cleans the outer peripheral surface of the associated charging member  20  is provided on the lower side of the associated charging member  20 . 
     In  FIG. 2 , each charging device  68  includes the associated cleaning member  64  and the associated charging member  20  that constitutes the corresponding image forming unit  16  shown in  FIG. 1 . Each replacement cartridge  66  serving as an exemplary assembly includes the associated image carrier  18 , the associated charging member  20 , and the associated cleaning member  64 . Each replacement cartridge  66  is replaceable with respect to the body  10 A. 
     Here, the outer peripheral surface of each image carrier  18  and its associated charging member  20  contact each other, and each charging member  20  is driven and rotated by the rotation of its associated image carrier  18 . 
     Each charging device  68  is described in detail below. 
     The exposure device  14  is provided with four semiconductor lasers (not shown) having a common structure for the four image forming units  16 Y,  16 M,  16 C, and  16 K. These semiconductor lasers emit laser beams LB-Y, LB-M, LB-C, and LB-K in accordance with the pieces of gradation data. 
     The laser beams LB-Y, LB-M, LB-C, and LB-K that are emitted from the associated semiconductor lasers illuminate a rotating polygon mirror  26  via an f-O lens (not shown), and are deflected by the rotating polygon mirror  26  and used for scanning. The laser beams LB-Y, LB-M, LB-C, and LB-K deflected by the polygon mirror  26  and used for the scanning obliquely scan and expose exposure points on the associated image carriers  18  from therebelow via an imaging lens and mirrors (not shown). 
     Since the exposure device  14  scans and exposes images on the associated image carriers  18  from therebelow, for example, toner may drop onto the exposure device  14  from, for example, the developing devices  22  of the four image forming units  16 Y,  16 M,  16 C, and  16 K that are positioned above the exposure device  14 . Therefore, a portion around the exposure device  14  is hermetically sealed by a rectangular parallelepiped frame  28 . In addition, transparent windows  30 Y,  30 M,  30 C, and  30 K, formed of glass, are provided at a top portion of the frame  28  for transmitting the four laser beams LB-Y, LB-M, LB-C, and LB-K to the image carriers  18  of the associated image forming units  16 Y,  16 M,  16 C, and  16 K. 
     A first transfer unit  21  is provided above the image forming units  16 Y,  16 M,  16 C, and  16 K. The first transfer unit  21  includes an endless intermediate transfer belt  32 , a driving roller  40 , a tension applying roller  36 , a cleaning blade  38 , and first transfer rollers  34 Y,  34 M,  34 C, and  34 K. The intermediate transfer belt  32  is wound upon the driving roller  40 . The driving roller  40  is rotationally driven and circulates the intermediate transfer belt  32  in the direction of an arrow. The intermediate transfer belt  32  is also wound upon the tension applying roller  36 . The tension applying roller  36  applies tension to the intermediate transfer belt  32 . The cleaning blade  38  cleans an outer peripheral surface of the intermediate transfer belt  32 . The first transfer rollers  34 Y,  34 M,  34 C, and  34 K are disposed opposite to the associated image carriers  18 Y,  18 M,  18 C, and  18 K with the intermediate transfer belt  32  being nipped therebetween. 
     Toner images of corresponding colors, yellow (Y), magenta (M), cyan (C), and black (K), which have been successively formed on the image carriers  18  of the image forming units  16 Y,  16 M,  16 C, and  16 K are transferred to the intermediate transfer belt  32  so as to be superimposed upon each other by the four first transfer rollers  34 Y,  34 M,  34 C, and  34 K. 
     A second transfer roller  42  is provided opposite to the driving roller  40  with the intermediate transfer belt  32  being nipped therebetween. The toner images of the corresponding colors, yellow (Y), magenta (M), cyan (C), and black (K), which have been transferred to the intermediate transfer belt  32  so as to be superimposed upon each other are transported by the intermediate transfer belt  32 , and are second-transferred to a sheet material P serving as an exemplary recording medium that is nipped by the driving roller  40  and the second transfer roller  42  and that is transported along a sheet transport path  56 . 
     A fixing device  44  that fixes the toner images transferred to the sheet material P to the sheet material P by heat and pressure is provided downstream of the second transfer roller  42  in the direction of transport of the sheet material P (hereunder simply referred to as “downstream”). 
     Discharge rollers  46  are provided downstream of the fixing device  44 . The discharge rollers  46  discharge the sheet material P to which the toner images are fixed to a discharge section  48  that is provided at a top portion of the body  10 A of the image forming apparatus  10 . 
     A sheet-feed member  50  in which sheet materials P are stacked is provided at a lower side of the interior of the body  10 A of the image forming apparatus  10 . A sheet-feed roller  52  that sends out sheet materials P that are stacked in the sheet-feed member  50  to the sheet transport path  56  is provided. A separation roller  54  that transports the sheet materials P by separating them one by one is provided downstream of the sheet-feed roller  52 . A positioning roller  58  that adjusts a transport timing is provided downstream of the separation roller  54 . Therefore, a sheet material P supplied from the sheet-feed member  50  is sent out to a position where the intermediate transfer belt  32  and the second transfer roller  42  contact each other (that is, a second transfer position) by the positioning roller  58  that rotates at a predetermined timing. 
     Further, transport rollers  60  are provided next to the discharge rollers  46 . The transport rollers  60  transport the sheet material P to whose one surface images are fixed by the fixing device  44  to a duplex-printing transport path  62  without the sheet material P being discharged onto the discharge section  48  by the discharge rollers  46 . This causes the sheet material P that is transported along the duplex-printing transport path  62  to be transported again to the positioning roller  58  with the front and back surfaces of the sheet material P reversed. Then, toner images are transferred and fixed to the back surface of the sheet material P, and the sheet material P is discharged onto the discharge section  48 . 
     In the image forming apparatus  10 , images are formed on a sheet material P as follows. 
     First, pieces of gradation data of corresponding colors are successively output to the exposure device  14  from the image processing section  12 . The laser beams LB-Y, LB-M, LB-C, and LB-K that are emitted from the exposure device  14  in accordance with the pieces of gradation data scan and expose the outer peripheral surfaces of the image carriers  18  that are charged by the associated charging members  20 , so that electrostatic latent images are formed on the outer peripheral surfaces of the associated image carriers  18 . The electrostatic latent images that are formed on the image carriers  18  are made visible as toner images of the corresponding colors, yellow (Y), magenta (M), cyan (C), and black (K), by the developing devices  22 Y,  22 M,  22 C, and  22 K. 
     The toner images of the corresponding colors, yellow (Y), magenta (M), cyan (C), and black (K), which are formed on the image carriers  18  are transferred to the circulating intermediate transfer belt  32  so as to be superimposed upon each other by the first transfer rollers  34  of the first transfer unit  21  that are disposed along the upper sides of the image forming units  16 Y,  16 K,  16 C, and  16 K. 
     Toner images of the corresponding colors that are transferred to the circulating intermediate transfer belt  32  so as to be superimposed upon each other are second-transferred to the sheet material P by the second transfer roller  42 , the sheet material P being transferred to the sheet transport path  56  from the sheet-feed member  50  by the sheet-feed roller  52 , the separation roller  54 , and the positioning roller  58  at a predetermined timing. 
     The sheet material P to which the toner images are transferred is further transported to the fixing device  44 . The toner images that are transferred to the sheet material P are fixed to the sheet material P by the fixing device  44 , after which the discharge rollers  46  discharge the sheet material P onto the discharge section  48  that is provided at the top portion of the body  10 A of the image forming apparatus  10 . 
     Further, when images are to be formed on both surfaces of the sheet material P, the sheet material P to whose one surface images are fixed by the fixing device  44  are transported to the duplex-printing transport path  62  via the transport rollers  60  by switching the transport direction without the sheet material P being discharged onto the discharge section  48  by the discharge rollers  46 . Then, the sheet material P is transported along the duplex-printing transport path  62 , so that the front and back surfaces of the sheet material P are reversed and the sheet material P is transported again to the positioning roller  58 . Then, the toner images are transferred and fixed to the back surface of the sheet material P, after which the discharge rollers  46  discharge the sheet material. P onto the discharge section  48 . 
     The charging device  68  is described in detail below. 
     In  FIGS. 2, 3, and 4 , the cleaning member  64  extending in an axial direction of the charging member  20  is provided so as to oppose the charging member  20 . The cleaning member  64  includes a columnar core member  70  and a foaming member  72 . The core member  70  extends in the axial direction of the charging member  20 . The foaming member  72  serving as an exemplary elastic member is disposed at an outer periphery of the core member  70  and is spirally wound around an outer peripheral surface of the core member  70  while in contact with the outer peripheral surface of the charging member  20 . In the exemplary embodiment, the foaming member  72  is formed of, for example, a urethane resin foam material that is elastically deformable. For example, the foaming member  72  is secured to the outer peripheral surface of the core member  70  by using a double-sided tape (not shown). 
     Further, as shown in  FIG. 4 , cylindrical holding members  78  are provided at two end portions of the foaming member  72 . The holding members  78  prevent the two end portions of the foaming member  72  from being separated from the core member  70  as a result of interposing the end portions of the foaming member  72  between the associated holding members  78  and the core member  70 . 
     Two end portions of the cleaning member  64  are rotatably supported by bearing members  74  from outer sides of the holding members  78  that are provided at two end portions of the cleaning member  64 . The bearing members  74  support the cleaning member  64  with the foaming member  72  being compressed by a predetermined amount at the outer peripheral surface of the charging member  20 . By this structure, the cleaning member  64  is driven and rotated as the charging member  20  rotates by friction force that is generated between the foaming member  72  and the charging member  20 . 
     In the charging device  68 , the radius of the charging member  20  is less than the radius of the cleaning member  64 . 
     More specifically, in  FIGS. 3 and 4 , if the radius of the charging member  20  is R and the radius of the cleaning member  64  is r (that is, the radius when the foaming member  72  is compressed against the charging member  20 ), an example of a combination of the radius R of the charging member  20  and the radius r of the cleaning member  64  is 3.5 mm for the radius R and 4.0 mm for the radius r. The radius R may be on the order of 3.0 mm. 
     These numbers are not particularly limited. In the cleaning member  64 , these numbers are determined considering, for example, processing costs, processing precision, and ease of making the core member  70 . 
     In addition, the charging member  20  is, for example, one in which charging rubber  23  is formed around the core member  22 . The diameter of the core member  22  is also determined for the purpose of, for example, reducing costs by reducing the thickness of the charging rubber  23  that is expensive in addition to being determined, for example, by processing costs, processing precision, and ease of making the core member  22 . 
     When the radius R of the charging member  20  is less than the radius r of the cleaning member  64 , the peripheral speed of the charging member  20  that is driven and rotated by the rotation of the image carrier  18  is higher than that when the radius R of the charging member  20  is greater than or equal to the radius r of the cleaning member  64 . Since the peripheral speed of the charging member  20  is increased at the position where the foaming member  72  and the outer peripheral surface of the charging member  20  contact each other, the cleaning member  64  that is driven and rotated by the rotation of the charging member  20  tends to slide with respect to the charging member  20 . In addition, the larger the mass of the cleaning member  64 , the more easily the cleaning member  74  slides with respect to the charging member  20  due to inertia. 
     In  FIG. 3 , when friction force f 2  between the cleaning member  64  and the charging member  20  is less than friction force f 1  between the charging member  20  and the image carrier  18 , the cleaning member  64  tends to slide with respect to the charging member  20 . 
     An exemplary method of measuring friction forces is illustrated in  FIGS. 5A to 6B .  FIGS. 5A and 5B  each show a method of measuring the friction force f1.  FIGS. 6A and 6B  each show a method of measuring the friction force f2.  FIGS. 5A and 5B  are front views of the measuring method.  FIGS. 6A and 6B  are side views of the measuring method. 
     In  FIG. 5A , the image carrier  18  is singly placed on a base  100 . In addition, a polyethylene terephthalate (PET) film  110  having one end fixed and, for example, having a width L of the charging rubber  23  of the charging member  20  is wound so as to cover the image carrier  18 , and a load P is applied to the other end. In this state, a push force that pushes the image carrier  18  from the axial direction (that is, the direction of an arrow) is measured. 
     When the force is static friction force, a force when the image carrier  18  starts moving is measured, whereas, when the force is kinetic friction, a force after the image carrier  18  starts moving is measured. For both the static friction force and kinetic friction force, the force that is measured at the single image carrier  18  is NO. 
     In  FIG. 5B , the charging member  20  is placed on the image carrier  18  so that an axis of the image carrier  18  and an axis of the charging member  20  are vertically placed side by side with respect to the base  100 . Similarly to the method shown in  FIG. 5A , a polyethylene terephthalate (PET) film  110  having a width L of the charging rubber  23  of the charging member  20  is wound so as to cover the image carrier  18  and the charging member  20 , and a load P is applied to the other end. In this state, a push force that pushes the image carrier  18  from the axial direction (that is, the direction of an arrow) is measured. The force in this case is N1. 
     Using the measured N 1  and N 0  , the friction force f 1  between the charging member  20  and the image carrier  18  is determined by f 1 =N 1 −N 0 . 
     In  FIG. 6A , using a method that is similar to the method shown in  FIG. 5A , a push force N 2  that pushes the single charging member  20  in the axial direction (that is, in the direction of an arrow) is measured. 
     In  FIG. 6B , using a method that is similar to the method shown in  FIG. 5B , the charging member  20  and the cleaning member  64  are combined, and a push force N 3  that pushes the charging member  20  from the axial direction (that is, in the direction of an arrow) is measured. 
     Using the measured N 2  and N 3  , the friction force f 2  between the charging member  20  and the cleaning member  64  is determined by f2=N 3  −N 2 . 
     In order to reduce the friction force f 2  between the charging member  20  and the cleaning member  64 , the foam density of the foaming member  72  is substantially 20 to 120 kg/m 3 . When sponges having foam densities of 15, 20, 40, 50, 60, 70, 80, 90, 100, 120, 150, 180, and 200 kg/m 3  are formed into cylindrical rollers or spirally wound rollers, and the friction forces f 1  and f 2  are measured, the friction force f 2  is reduced suddenly at a foam density that is less than or equal to 20 kg/m 3 , and the cleaning member no longer rotates. At a foam density that is greater than or equal to 120 kg/m 3 , the relationship becomes f 2 &gt;f 1 , as a result of which an image failure occurs because the rotation of the charging member becomes unstable. A more desirable result is obtained when the foam density is on the order of from 50 to 90 kg/m 3 . 
     An example and comparative examples are hereunder given, and changes in ratios between the number of rotations of a charging member  20  and the number of rotations of a cleaning member  64  when the printing speed is increased are compared with each other. Numerical values indicated below are examples, so that other numerical values may be used. 
     In the example, a cleaning member  64  whose radius r is 4.0 mm and the charging member  20  whose radius R is 3.5 mm are used. 
     The cleaning member  64  is one in which urethane foam member, which is an example of a foaming member  72 , is spirally wound around a core member  70  whose radius is 2.0 mm at an angle of 25 degrees with respect to an axial direction. The thickness of the foaming member  72  is selected so that the radius r of the cleaning member  64  becomes 4.0 mm when the radius r of the foaming member  72  is that when it is compressed against the charging member  20 . The thickness and width of the foaming member  72  are 2.5 mm and 6 mm, respectively. 
       FIG. 7A  is a schematic sectional view of a replacement cartridge  66  according to a first comparative example. In the first comparative example, a cleaning member  64  in which the diameter r of a foaming member  72  formed around the entire peripheral surface of a core member  70  is 4.0 mm is used. A charging member  201  whose diameter R is 4.5 mm is also used. 
       FIG. 7B  is a schematic sectional view of a replacement cartridge according to a second comparative example. In the second comparative example, a cleaning member  64  used in the example and whose diameter r is 4.0 mm is used. A charging member  201  whose diameter R is 4.5 mm is also used. 
     Using a laser interferometer, the number of rotations of the charging member  20  and the number of rotations of the cleaning member  64  are measured by changing the peripheral speed of an image carrier  18 . More specifically, from the numbers of rotations (rpm) calculated by monitoring the position of a surface of each of the image carrier, the charging member, and the cleaning member for approximately 10 rotations, and from the outside diameter (mm) of each member, the peripheral speed (mm/s) is calculated. Methods of measuring the numbers of rotations are not limited to the above-described measuring method. The numbers of rotations may be measured by inserting a wire in each of the members. 
       FIG. 8  gives the measurement results. The horizontal axis indicates the peripheral speed of the image carrier  18  that corresponds to the printing speed. The vertical axis indicates the ratio between the number of rotations of the cleaning member  64  and the number of rotations of the charging member  20  (that is, the number of rotations of the cleaning member  64 /the number of rotations of the charging member  20 ). The measurement results show that the smaller the ratio, the cleaning member  64  slides with respect to the charging member  20 . 
     In the first comparative example, even if the peripheral speed of the image carrier  18  is increased, there is almost no difference between the number of rotations of the charging member  20  and the number of rotations of the cleaning member  64 . In the second comparative example, if the peripheral speed of the image carrier  18  is increased, the numbers of rotations start to differ from each other, and the cleaning member  64  starts sliding with respect to the charging member  20 . 
     Therefore, it is understood that when the foaming member  72  is spirally wound around the core member  70  and contact resistance is reduced by reducing the contact area between the cleaning member  64  and the charging member  20 , the cleaning member  64  starts sliding with respect to the charging member  20 . 
     In contrast, it is understood that, in the example, when the cleaning member  64  starts sliding with respect to the charging member  20  from a state in which the peripheral speed of the image carrier  18  is low, the more the peripheral speed of the image carrier  18  is increased, the more noticeably the cleaning member  64  slides with respect to the charging member  20 . 
     From this, it is understood that causing the radius R of the charging member  20  to be less than the radius r of the cleaning member  64  is highly effective in causing the cleaning member  64  to slide with respect to the charging member  20 . 
     As shown in  FIG. 1 , toner images that are formed on the outer peripheral surfaces of the image carriers  18  that rotate are transferred to the intermediate transfer belt  32  that circulates. Then, any foreign material, such as toner, remaining on any of the outer peripheral surfaces of the image carriers  18  without being transferred to the intermediate transfer belt  32  is removed from the any of the outer peripheral surfaces of the image carriers  18  by the associated cleaning blade  24 . 
     Here, any foreign material, such as an external additive included in developer and having a small particle size, moves past the cleaning blade  24 . The foreign material, such as an external additive, that has moved past the cleaning blade  24 , adheres to the outer peripheral surface of the charging member  20 . 
     In  FIG. 4 , any foreign material, such as an external additive, adhered to the outer peripheral surface of the charging member  20  that rotates is wiped off from the outer periphery of the charging member  20  by the foaming member  72  as a result of sliding of the cleaning member  64  with respect to the charging member  20 . This further enhances cleaning capability and further increases the life of the charging member. 
     When the cleaning member  64  slides more with respect to the charging member  20 , end portions  72 A of the spirally wound foaming member  72  of the cleaning member  64  scrape off any foreign material from the outer peripheral surface of the charging member  20 , to further increase cleaning capability and further increase the life of the charging member. 
     Further, when the end portions  72 A of the foaming member  72  each have a portion that protrudes beyond its central portion, each end portion  72 A of the foaming member  72  of the cleaning member  64  that is driven and rotated is pushed against the outer peripheral surface of the charging member  20  and is elastically deformed (elastically compressed) in a height direction and a widthwise direction of the foaming member  72 , so that each end portion  72 A is pressed into the foaming member  72  and flocculates. Then, each end portion  72 A of the foaming member  72  of the cleaning member  64  that is driven and rotated is brought out of contact with the charging member  20 , so that each end portion  72 A is elastically restored to its original state. This restoring force causes flocculated foreign material, such as an external additive, to be brought out of its dense state and repelled from the outer peripheral surface of the charging member  20 . 
     This further enhances the cleaning capability of the cleaning member  64 . Here, since the foaming member  72  is spirally disposed around the core member  70 , the foaming member  72  is restored to its original state in the widthwise direction, so that a component force in the axial direction also acts upon the foreign material adhered to the charging member  20 . 
     Part of the removed foreign material accumulates in an internal portion of the foaming member  72 , and another part of the removed foreign material falls and is trapped in a foreign material chamber (not shown), which is provided below the cleaning member  64  in a downward (gravitation) direction. Any foreign material existing on the surface of the charging member  20  and brought out from the dense state may move to the image carrier  18  and may be collected by an image-carrier cleaning device (not shown). 
     The cleaning member  64  uniformly removes any foreign material, such as an external additive, adhered to the outer peripheral surface of the charging member  20 , so that charging failure of the image carrier  18  is suppressed. Therefore, the quality of toner images that are formed on the image carriers  18  is increased. 
     By increasing the quality of the toner images that are formed on the image carriers  18 , the quality of an output image that is formed on a sheet material P is increased. 
     An exemplary embodiment and examples according to the present invention are described in detail. However, the present invention is not limited to such an exemplary embodiment and examples. It is obvious to any person skilled in the art that other exemplary embodiments and examples are possible within the scope of the present invention. 
     Although, in the exemplary embodiment, a foaming member formed of an elastically deformable urethane resin, which is an exemplary elastic material serving as a material of the foaming member  72 , is used, a foaming member formed of other materials, such as rubber materials, may also be used. 
     Although, in the exemplary embodiment, each replacement cartridge  66  is constituted by an image carrier  18 , a charging member  20 , and a cleaning member  64 , each replacement cartridge  66  may also be constituted by an image carrier  18 , a charging member  20 , a cleaning member  64 , and other additional structural components, such as a developing device.