Patent Publication Number: US-7899361-B2

Title: Photosensitive medium supporting apparatus, developing cartridge and image forming apparatus having the same and method to assemble and disassemble a developing cartridge

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority under 35 U.S.C. §119(a) from Korean Patent Application No. 2007-29986 filed Mar. 27, 2007 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present general inventive concept relates to an image forming apparatus. More particularly, the present general inventive concept relates to a photosensitive medium supporting apparatus to support a photosensitive medium, a developing cartridge and an image forming apparatus having the same, and methods to assemble and disassemble a developing cartridge. 
     2. Description of the Related Art 
     Generally, image forming apparatuses are provided with a photosensitive medium on which predetermined electrostatic latent images are formed. The photosensitive medium is disposed to rotate with respect to a supporting shaft fixed to an image forming apparatus. That is, the supporting shaft is disposed through a center of the photosensitive medium to have a substantially cylindrical shape so that photosensitive medium can rotate with respect to the supporting shaft. 
     Furthermore, at one end of the photosensitive medium is disposed a gear to rotate integrally with the photosensitive medium with respect to the supporting shaft. As a result, when the photosensitive medium is disposed at the image forming apparatus, the gear of the photosensitive medium receives power from a drive gear disposed in a main body so that the photosensitive medium rotates with respect to the supporting shaft. 
     At this time, to allow the photosensitive medium to maintain a predetermined position with respect to the image forming apparatus, the supporting shaft needs to be fixed not to rotate together with the photosensitive medium and move in an axial direction of the photosensitive medium. 
     For this, in conventional image forming apparatuses, a fixing ring is disposed at the supporting shaft so as to prevent the supporting shaft from moving in an axial direction of the photosensitive medium, and at least one set of screws are used to fix the supporting shaft to a supporting member to prevent the supporting shaft from rotating together with the photosensitive medium. 
     As described above, to use separate parts for the prevention of a rotation of the supporting shaft and an axial direction movement of the supporting shaft needs a lot of parts making it inconvenient to assembly. 
     SUMMARY OF THE INVENTION 
     The present general inventive concept has been developed in order to overcome the above drawbacks and other problems associated with the conventional arrangement. An aspect of the present general inventive concept is to provide a photosensitive medium supporting apparatus that does not use separate parts and can prevent a supporting shaft to support a photosensitive medium from moving in an axial direction and rotating, a developing cartridge and an image forming apparatus having the same, and methods to assemble and disassemble the developing cartridge. 
     Additional aspects and utilities of the present general inventive concept will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the general inventive concept. 
     The foregoing and/or other aspects and utilities of the of the generals present inventive concept may be achieved by providing a rotation body supporting apparatus, which includes a supporting shaft to rotatably support a rotation body and to have a fixing groove formed at one portion of the supporting shaft that projects from one end of the rotation body, a first shaft supporting member to support the one portion of the supporting shaft that projects from the one end of the rotation body and to have a fixing projection that is inserted into the fixing groove of the supporting shaft, and a second shaft supporting member to support an other portion of the supporting shaft that projects from the other end of the rotation body. 
     The foregoing and/or other aspects and utilities of the general inventive concept may also be achieved by providing a photosensitive medium supporting apparatus usable with a developing cartridge, the apparatus including one of a supporting shaft to rotatably support a photosensitive medium and to have a fixing groove and a fixing projection formed at one portion of the supporting shaft that projects from one end of the photosensitive medium, a first shaft supporting member to support the one portion of the supporting shaft that projects from the one end of the photosensitive medium and to have one of a fixing projection and a fixing groove that is inserted into the fixing groove or the fixing projection of the supporting shaft, and a second shaft supporting member to support the other portion of the supporting shaft that projects from the other end of the photosensitive medium. 
     The supporting shaft may further include one of a second fixing groove and a second fixing projection formed below the fixing groove or the fixing projection, and the first shaft supporting member may further include one of a second fixing projection and a second fixing groove that is inserted into the second fixing groove or the second fixing projection of the supporting shaft. 
     The foregoing and/or other aspects and utilities of the general inventive concept may also be achieved by providing a developing cartridge of an image forming apparatus including a supporting shaft to rotatably support a photosensitive medium and to have a fixing groove formed at one portion of the supporting shaft that projects from one end of the photosensitive medium, a frame to have a photosensitive medium hole through which some portion of the photosensitive medium is exposed, a first shaft supporting member disposed inside the frame to support the one portion of the supporting shaft that projects from the one end of the photosensitive medium and to have a fixing projection that is inserted into the fixing groove of the supporting shaft, and a second shaft supporting member disposed inside the frame to face the first shaft supporting member to support an other portion of the supporting shaft that projects from the other end of the photosensitive medium. 
     The photosensitive medium may include a photosensitive drum formed in a substantially hollow cylindrical shape, a first flange disposed at one end of the photosensitive drum, and to have a through hole into which the supporting shaft is inserted, and a second flange disposed at an other end of the photosensitive drum, and to have a gear formed on an outer circumferential surface of the second flange and a through hole into which the supporting shaft is inserted. 
     Each of the first and second flanges may include a projection portion formed on a side of each of the first and second flanges to contact each of the first and second shaft supporting members. 
     The foregoing and/or other aspects and utilities of the general inventive concept may also be achieved by providing a developing cartridge usable with an image forming apparatus, the developing cartridge including a supporting shaft to rotatably support a photosensitive medium and to have a fixing groove formed at one portion of the supporting shaft that projects from one end of the photosensitive medium, a used toner collecting frame unit to have first and second shaft supporting members that are formed to support both portions of the supporting shaft to project from both ends of the photosensitive medium, a fixing projection formed at the first shaft supporting member to be inserted into the fixing groove of the supporting shaft, a toner supply frame unit disposed opposite to the used toner collecting frame unit with respect to the photosensitive medium, and first and second side plates disposed at both sides of the used toner collecting frame unit and the toner supply frame unit. 
     The toner supply frame unit may include first and second coupling members that are formed to support the both portions of the supporting shaft to project from both ends of the photosensitive medium outside the first and second shaft supporting members of the used toner collecting frame unit. 
     The developing cartridge of the image forming apparatus may further include a charging roller unit disposed above the photosensitive medium between the used toner collecting frame unit and the toner supply frame unit. 
     The foregoing and/or other aspects and utilities of the general inventive concept may also be achieved by providing an image forming apparatus including a printing medium feeding unit to supply a printing medium, and a developing cartridge to form images corresponding to printing data, the developing cartridge comprising a supporting shaft to rotatably support a photosensitive medium and to have a fixing groove formed at one portion of the supporting shaft that projects from one end of the photosensitive medium, a frame to have a photosensitive medium hole through which a portion of the photosensitive medium is exposed, a first shaft supporting member disposed inside the frame to support the one portion of the supporting shaft that projects from the one end of the photosensitive medium and to have a fixing projection that is inserted into the fixing groove of the supporting shaft, and a second shaft supporting member disposed inside the frame to face the first shaft supporting member to support an other portion of the supporting shaft that projects from an other end of the photosensitive medium, a transferring roller rotatably disposed to contact the photosensitive medium to transfer the image formed on the photosensitive medium onto a printing medium supplied from the printing medium feeding unit, and a discharging unit to discharge the printing medium having the images formed thereon. 
     The foregoing and/or other aspects and utilities of the general inventive concept may also be achieved by providing a method to assemble a developing cartridge of an image forming apparatus, the method including inserting a supporting shaft into a photosensitive medium so that a fixing groove of the supporting shaft is exposed outside one end of the photosensitive medium, inserting the fixing groove of the supporting shaft into a fixing projection of a used toner collecting frame unit so that the supporting shaft with the photosensitive medium is assembled with the used toner collecting frame unit, installing a toner supply frame unit opposite to the used toner collecting frame unit with respect to the photosensitive medium, installing a charging roller unit above the photosensitive medium between the used toner collecting frame unit and the toner supply frame unit, and assembling first and second side plates at both sides of the used toner collecting frame unit and the toner supply frame unit. 
     The foregoing and/or other aspects and utilities of the general inventive concept may also be achieved by providing a method to disassemble a developing cartridge of an image forming apparatus, the method including separating first and second side plates from the developing cartridge, separating a charging roller unit, separating a toner supply frame unit from a used toner collecting frame unit, separating a fixing groove of a supporting shaft from a fixing projection of the used toner collecting frame unit so that the supporting shaft with a photosensitive medium is separated from the used toner collecting frame unit, and separating the supporting shaft from the photosensitive medium. 
     The foregoing and/or other aspects and utilities of the general inventive concept may also be achieved by providing a photosensitive medium for a developing cartridge detachably mounted to an image forming apparatus, the photosensitive medium including a supporting shaft to rotatably support the photosensitive medium, to project from both ends of the photosensitive medium, and to have a fixing groove, wherein the fixing groove is formed at one portion of the supporting shaft that projects from one end of the photosensitive medium to be inserted into a fixing projection of a first shaft supporting member disposed at the developing cartridge. 
     The foregoing and/or other aspects and utilities of the general inventive concept may also be achieved by providing a supporting shaft usable with a developing cartridge detachably mounted to an image forming apparatus, including two portions at opposite ends of the supporting shaft to project from two ends of a photosensitive medium of the developing cartridge and to be supported by first and second shaft supporting members that are disposed at the developing cartridge; and a fixing groove formed at one portion of the supporting shaft that projects from one end of the photosensitive medium to be inserted into a fixing projection of the first shaft supporting member, wherein when the fixing groove of the supporting shaft is inserted into the fixing projection of the first shaft supporting member, the supporting shaft is fixed with respect to the first and second shaft supporting members to rotatably support the photosensitive medium. 
     The foregoing and/or other aspects and utilities of the general inventive concept may also be achieved by providing a frame for a developing cartridge detachably mounted to an image forming apparatus, the frame including first and second shaft supporting members to support a supporting shaft, wherein the supporting shaft projects from both ends of a photosensitive medium of the developing cartridge and has a fixing groove formed at one portion of the supporting shaft to project from one end of the photosensitive medium, and wherein the first shaft supporting member has a fixing projection formed to be inserted into the fixing groove of the supporting shaft. 
     The foregoing and/or other aspects and utilities of the general inventive concept may also be achieved by providing a developing apparatus usable with an image forming apparatus, including a photosensitive medium having opposite ends, a supporting shaft to rotatably support the photosensitive medium and having two end portions, each of the two end portions of the supporting shaft extending pass the opposite ends of the photosensitive medium, respectively, and at least one of the two end portions having one of at least one fixing groove and at least one fixing projection to interconnect with an other of the at least one fixing groove and the at least one fixing projection of the image forming apparatus. 
     The foregoing and/or other aspects and utilities of the general inventive concept may also be achieved by providing an image forming apparatus, including a frame including a shaft supporting member having at least one of a fixing groove and a fixing projection, and a developing apparatus, including a photosensitive medium having opposite ends, a supporting shaft having two end portions and to rotatably support the photosensitive medium, each of the two end portions of the supporting shaft extending pass the opposite ends of the photosensitive medium, respectively, and at least one of the two end portions having an other of the one fixing groove and the one fixing projection to interconnect with the at least one of the fixing groove and the fixing projection of the frame. 
     The foregoing and/or other aspects and utilities of the general inventive concept may also be achieved by providing a developing apparatus including a photosensitive drum having a gear formed on a surface thereof and a hole formed therein in a rotation axis thereof, a shaft rotatably inserted in the hole, having a first end having a groove, and having a second end, and a frame including a first shaft supporting member having a first supporting groove to correspond to the groove of the first end and having a second supporting groove to correspond to the second end. 
     Other aspects, advantages and salient features of the general inventive concept will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, discloses embodiments of the general inventive concept. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and/or other aspects and utilities of the present general inventive concept will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: 
         FIG. 1  is a perspective view illustrating a photosensitive medium supporting apparatus according to an embodiment of the present general inventive concept; 
         FIG. 2  is a perspective view illustrating a supporting shaft of the photosensitive medium supporting apparatus of  FIG. 1  to be inserted into a fixing projection of a first shaft supporting member; 
         FIG. 3  is a partially cut-out, perspective view illustrating the photosensitive medium supporting apparatus of  FIG. 1  taken along a line III-III in  FIG. 1 ; 
         FIG. 4  is a partially cut-out, perspective view illustrating a supporting shaft with one fixing groove to be inserted into a first shaft supporting member with one fixing projection in a photosensitive medium supporting apparatus according to an embodiment of the present general inventive concept; 
         FIG. 5  is a partially cut-out, perspective view illustrating a supporting shaft with one fixing projection to be inserted into a first shaft supporting member with one fixing groove in a photosensitive medium supporting apparatus according to an embodiment of the present general inventive concept; 
         FIGS. 6 to 11  are perspective views illustrating a method to assemble a developing cartridge according to an embodiment of the present general inventive concept; 
         FIG. 6  is a perspective view illustrating a supporting shaft that is about to be inserted into a photosensitive medium according to an embodiment of the present general inventive concept; 
         FIG. 7  is a perspective view illustrating a supporting shaft with a photosensitive medium that is about to be assembled to a used toner collecting frame unit according to an embodiment of the present general inventive concept; 
         FIG. 8  is a perspective view illustrating a toner supply frame unit that is about to be assembled to a used toner collecting frame unit with a photosensitive medium according to an embodiment of the present general inventive concept; 
         FIG. 9  is a perspective view illustrating a charging roller unit that is about to be assembled to a subassembly of a used toner collecting frame unit and a toner supply frame unit according to an embodiment of the present general inventive concept; 
         FIG. 10  is a perspective view illustrating first and second side plates that are about to be assembled to a subassembly of a used toner collecting frame unit, a toner supply frame unit, and a charging roller unit according to an embodiment of the present general inventive concept; 
         FIG. 11  is a perspective view illustrating a developing cartridge of an image forming apparatus according to an embodiment of the present general inventive concept that is completely assembled through processes of  FIGS. 6 to 10 ; 
         FIG. 12  is a sectional view illustrating the developing cartridge of  FIG. 11  taken along a line XII-XII in  FIG. 11 ; 
         FIG. 13  is a sectional view illustrating the developing cartridge of  FIG. 11  taken along a line XIII-XIII in  FIG. 11 ; 
         FIG. 14  is a sectional view schematically illustrating an image forming apparatus with a developing cartridge according to an embodiment of the present general inventive concept; 
         FIG. 15  illustrates a method of assembling a developing cartridge of an image forming apparatus according to an embodiment of the present general inventive concept; and 
         FIG. 16  illustrates a method of disassembling a developing cartridge of an image forming apparatus according to an embodiment of the present general inventive concept. 
     
    
    
     Throughout the drawings, like reference numerals will be understood to refer to like parts, components and structures. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made in detail to the embodiments of the present general inventive concept, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present general inventive concept by referring to the figures. 
     The matters defined in the description, such as a detailed construction and elements thereof, are provided to assist in a comprehensive understanding of the general inventive concept. Thus, it is apparent that the present general inventive concept may be carried out without those defined matters. Also, well-known functions or constructions are omitted to provide a clear and concise description of exemplary embodiments of the present general inventive concept. 
       FIG. 1  is a perspective view illustrating a photosensitive medium supporting apparatus according to an embodiment of the present general inventive concept. 
     Referring to  FIG. 1 , a photosensitive medium supporting apparatus  1  according to an embodiment of the present general inventive concept includes a photosensitive medium  3 , a supporting shaft  10 , and first and second shaft supporting members  21  and  22 . 
     The photosensitive medium  3  rotates with respect to the supporting shaft  10 , and predetermined images are formed on a surface of the photosensitive medium  3 . The photosensitive medium  3  includes a photosensitive drum  4  that has a substantially hollow cylindrical shape and a photoconductive layer on a surface thereof, and first and second flanges  5  and  6  that are coupled to both ends of the photosensitive drum  4 . The photosensitive medium  3  has a similar structure as that of a photosensitive medium  110  of an image forming apparatus illustrated in  FIG. 13 . 
     A gear  6   a  is formed at an outer circumferential surface of the second flange  6  and is meshed with a drive gear  303  ( FIG. 13 ) disposed in the image forming apparatus to receive power. A through hole  5   c  into which the supporting shaft  10  is inserted is formed at a center of each of the first and second flanges  5  and  6 . The through holes  5   c  are formed so that the first and second flanges  5  and  6  can smoothly rotate with respect to the supporting shaft  10 . A projection portion  5   b  may be formed on a side surface of each of the first and second flanges  5  and  6  that face outside. The projection portions  5   b  may minimize an area of a contacting portion on which each of the first and second flanges  5  and  6  of the photosensitive medium  3  contacts each of the first and second shaft supporting members  21  and  22  when the photosensitive medium  3  rotates. In addition, the first and second flanges  5  and  6  are fixed to opposite ends of the photosensitive drum  4  by a coupling method using elasticity of the flanges  5  and  6 , adhesion, etc. Therefore, the first and second flanges  5  and  6  rotate integrally with the photosensitive drum  4 . 
     The supporting shaft  10  is disposed through a center of the photosensitive medium  3  in an axial direction of the photosensitive medium  3 . The supporting shaft  10  has a substantially circular section and is longer than the photosensitive medium  3 . Therefore, the supporting shaft  10  is inserted into the photosensitive medium  3  so that portions near opposite ends of the supporting shaft  10  projects from both ends of the photosensitive medium  3 . A fixing groove  11  is formed at one portion of the supporting shaft  10  that projects from one end of the photosensitive medium  3  near the one end of the photosensitive medium  3 , that is, the first flange  5 . The fixing groove  11  is formed substantially parallel to the first flange  5  to form the one end of the photosensitive medium  3 . That is, the fixing groove  11  is formed to extend over the width of the supporting shaft  10  perpendicular to a center axis  10   c  of the supporting shaft  10 . The fixing groove  11  has a substantially square section and a depth t smaller than a dimension of a radius of the supporting shaft  10 . Accordingly, a dimension of the depth t of the fixing groove  11  may be determined so that the fixing groove  11  and a fixing projection  25  to be inserted into the fixing groove  11  prevent the supporting shaft  10  from rotating with respect to the first and second shaft supporting members  21  and  22  or moving in an axial direction of the photosensitive medium  4 . Also, a second fixing groove  12  may be formed to be substantially symmetric with respect to the center axis  10   c  of the supporting shaft  10  on the supporting shaft  10  under the fixing groove  11 . That is, as illustrated in  FIG. 2 , the supporting shaft  10  has a pair of fixing grooves  11  and  12  that is formed at upper and lower portions of the supporting shaft  10  parallel with each other in a direction perpendicular to the supporting shaft  10 . The second fixing groove  12  may be formed in substantially a same size as that of the fixing groove  12 . 
     In the above description, the supporting shaft  10  has two fixing grooves  11  and  12  that are formed vertically. Alternatively, the supporting shaft  10  can have only one fixing groove  11  as illustrated in  FIG. 4 . Accordingly, the first shaft supporting member  21  has only one fixing projection  25 . 
     Furthermore, in this embodiment, the pair of fixing grooves  11  and  12  is formed at the portion of the supporting shaft  10  to project from the one end of the photosensitive medium  3 . Alternatively, two pair of fixing grooves  11  and  12  may be formed at both portions of the supporting shaft  10  to project from both ends of the photosensitive medium  3 . 
     The first and second shaft supporting members  21  and  22  support the both portions of the supporting shaft  10  to project from both ends of the photosensitive medium  3 , and prevent the supporting shaft  10  from rotating with respect to the photosensitive medium  3  or moving in an axial direction of the photosensitive medium  3 . The first and second shaft supporting members  21  and  22  may be disposed at a frame of the developing cartridge or a main body of the image forming apparatus according to an installation method of the photosensitive medium.  FIG. 1  illustrates the first and second shaft supporting members  21  and  22  that are disposed at a used toner collecting frame  130  of a developing cartridge  100 . 
     The first shaft supporting member  21  is provided with a first shaft supporting groove  23  into which the supporting shaft  10  can be inserted. The first shaft supporting groove  23  is formed in a shape corresponding to a section of the supporting shaft  10  and has an opening portion  23   a  through which the supporting shaft  10  can be inserted. The first shaft supporting groove  23  is provided with the fixing projection  25  that is inserted into the fixing groove  11  of the supporting shaft  10 . In this embodiment, the supporting shaft  10  has the pair of fixing grooves  11  and  12 , so the first supporting groove  23  is provided with a pair of fixing projections  25  and  26 . Accordingly, at an upper side of the first shaft supporting groove  23  is formed the fixing projection  25  that is inserted into the fixing groove  11  formed at the upper side of the supporting shaft  10 , and at a lower side of the first shaft supporting groove  23  is formed the second fixing projection  26  that is inserted into the second fixing groove  12  formed at the lower side of the supporting shaft  10 . Therefore, when the supporting shaft  10  is inserted into the first shaft supporting groove  23  via the opening portion  23   a , the pair of fixing projections  25  and  26  is inserted into the pair of the fixing grooves  11  and  12  as illustrated in  FIG. 3 . 
     Because when the supporting shaft  10  is inserted into the first shaft supporting groove  23  of the first shaft supporting member  21 , the fixing projections  25  and  26  of the first shaft supporting groove  23  are inserted into the fixing grooves  11  and  12  of the supporting shaft  10 , the supporting shaft  10  cannot rotate with respect to the first shaft supporting member  21  or move in the axial direction thereof. 
     The second shaft supporting member  22  is provided with a second shaft supporting groove  24  that supports the other portion of the supporting shaft  10  to project from the other end of the photosensitive medium  3 . The other portion of the supporting shaft  10  to project from the other end of the photosensitive medium  3  has a substantially circular section so that the second shaft supporting groove  24  is formed in a shape into which the supporting shaft  10  with the circular section can be inserted. If the other portion of the supporting shaft  10  to be supported by the second shaft supporting groove  24  of the second shaft supporting member  22  is provided with fixing grooves as described above, the second shaft supporting groove  24  has a pair of fixing projections corresponding to the fixing grooves. 
     When assembling the photosensitive medium supporting apparatus  1  having the above-described structure, the supporting shaft  10  is inserted into the photosensitive medium  3  so that the fixing grooves  11  and  12  of the supporting shaft  10  is exposed outside one end of the photosensitive medium  3 . After that, the fixing groove  11  of the supporting shaft  10  is aligned with the fixing projection  25  of the first shaft supporting groove  23 , and the supporting shaft  10  with the photosensitive medium  3  is inserted into the first and second shaft supporting grooves  23  and  24  of the first and second shaft supporting members  21  and  22  so that the supporting shaft  10  is fixed to the first and second shaft supporting members  21  and  22 . As a result, the supporting shaft  10  does not rotate with respect to the first and second shaft supporting members  21  and  22  or move in the axial direction of the photosensitive medium  3 . 
     In above description, the fixing grooves  11  and  12  are formed at the supporting shaft  10 , and the fixing projections  25  and  26  are formed at the first shaft supporting groove  23  of the first shaft supporting member  21 . Alternatively, the fixing grooves  11  and  12  and fixing projections  25  and  26  may be formed at the opposite position. Accordingly, as illustrated in  FIG. 5 , a fixing projection  19  may be formed at a supporting shaft  10 ′, and a fixing groove  29  may be formed at a first shaft supporting groove  23 ′ of the first shaft supporting member  21 . The fixing projection  19  formed at the supporting shaft  10 ′ and the fixing groove  29  formed at the first shaft supporting groove  23 ′ are similar to the fixing projection  25  and fixing groove  11  of the above described embodiment; therefore, detailed descriptions of those are omitted. 
     In above description, the photosensitive medium supporting apparatus  1  is used to support a rotation of the photosensitive medium  3 . However, the photosensitive medium supporting apparatus  1  can be used as a rotation body supporting apparatus that supports a rotation of a rotation body having a similar structure to the photosensitive medium  3 . The rotation body may include a charging roller, a developing roller, a toner supplying roller, a transferring roller, etc. 
     Hereinafter, a developing cartridge having a photosensitive medium supporting apparatus according to an embodiment of the present general inventive concept will be explained with reference to  FIGS. 6 to 11 . 
     Referring to  FIGS. 8 and 10 , a developing cartridge  100  according to an embodiment of the present general inventive concept includes a photosensitive medium  110 , a supporting shaft  120 , a used toner collecting frame unit  130 , a toner supply frame unit  150 , a charging roller unit  170 , a first side plate  181 , and a second side plate  182 . 
     The photosensitive medium  110  is disposed to rotate with respect to the supporting shaft  120 , and predetermined electrostatic latent images are formed on a surface of the photosensitive medium  110 . The photosensitive medium  110  is similar to the photosensitive medium  3  of the photosensitive medium supporting apparatus  1  as described above. Therefore, a detailed description thereof is omitted. 
     The supporting shaft  120  supports the photosensitive medium  110  to rotate with respect to the used toner collecting frame unit  130  and has fixing grooves  121  and  122 . The supporting shaft  120  with the fixing grooves  121  and  122  is similar to the supporting shaft  10  of the photosensitive medium supporting apparatus  1  as described above. Therefore, a detailed description thereof is omitted. 
     The used toner collecting frame unit  130  removes and collects used toner to remain on the photosensitive medium  110 , and includes a used toner collecting frame  131 , a cleaning blade  132 , and first and second shaft supporting members  141  and  142 . 
     A used toner space  131   a  in which used toner to be removed from the photosensitive medium  110  is collected is disposed inside the used toner collecting frame  131 . The cleaning blade  132  is disposed at a front side of the used toner collecting frame  131  to remove used toner from the photosensitive medium  110 . The first and second shaft supporting members  141  and  142  are formed to support the supporting shaft  120  at both side surfaces of the used toner collecting frame  131 . The first and second shaft supporting members  141  and  142  are provided with first and second shaft supporting grooves  143  and  144  into which the supporting shaft  120  is inserted. At the first shaft supporting groove  143  is formed a fixing projection  145  that is inserted into the fixing grooves  121  and  122  of the supporting shaft  120 . The first and second shaft supporting grooves  143  and  144  are similar to the first and second shaft supporting grooves  23  and  24  of the photosensitive medium supporting apparatus  1  as described above. Therefore, detailed descriptions thereof are omitted. 
     The toner supply frame unit  150  stores a predetermined amount of toner, and supplies the stored toner to the photosensitive medium  110  to develop electrostatic latent images formed on the photosensitive medium  110  into visible images. The toner supply frame unit  150  is disposed opposite to the used toner collecting frame unit  130  with respect to the photosensitive medium  110 , and includes a toner supply frame  151 , a developing roller  152 , a toner supplying roller  153 , a toner regulating blade  154 , and first and second coupling members  161  and  162 . 
     A toner space  151   a  to store a predetermined amount of toner is disposed inside the toner supply frame  151 . The developing roller  152  is rotatably disposed near a front side of the toner supply frame  151  to supply the photosensitive medium  110  with toner. The toner supplying roller  153  is rotatably disposed at a side of the developing roller  152  to supply the developing roller  152  with toner. The toner regulating blade  154  is disposed to contact the developing roller  152  at an upper side of the developing roller  152  so that the toner regulating blade  154  charges and regulates toner that is moved onto the developing roller  152  by the toner supplying roller  153  into a thin toner layer. An agitator may be disposed in the toner space  151   a  to agitate toner to be stored therein. 
     The first and second coupling members  161  and  162  are disposed at both side surfaces of the toner supply frame  151  to support the supporting shaft  120 . The first and second coupling members  161  and  162 , as illustrated in  FIG. 13 , support the supporting shaft  120  outside the first and second shaft supporting members  141  and  142 . First and second coupling grooves  153  and  164  are formed at the first and second coupling members  161  and  162 , respectively. The first and second coupling grooves  163  and  164  are formed in a shape corresponding to the section of the supporting shaft  120  and have entrances  165  and  166  to allow the supporting shaft  120  to be inserted from a side direction. Therefore, the first and second coupling grooves  163  and  164  are inserted into the supporting shaft  120  via the entrances  165  and  166  so that the toner supply frame unit  150  is assembled with the used toner collecting frame unit  130 , thereby locating in a predetermined distance from the photosensitive medium  110 . 
     The charging roller unit  170  supports a charging roller  173  to charge the photosensitive medium  110 , and includes the charging roller  173  and a charging roller frame  171 . The charging roller  173  may be hinge-connected to the charging roller frame  171 . Furthermore, a charging roller cleaning member (not illustrated) to clean up a surface of the charging roller  173  and a charge eliminating roller (not illustrated) to eliminate voltage remaining on the photosensitive medium  110  may be disposed at the charging roller frame  171 . The charging roller frame  171  is provided with a laser beam hole  172  through which laser beam to be emitted from the light exposing unit  380  ( FIG. 14 ) passes. 
     The first and second side plates  181  and  182  are disposed at both sides of the toner supply frame unit  150  and the used toner collecting frame unit  130 , which locate at both sides with respect to the photosensitive medium  110 , and fix the toner supply frame unit  150  and the used toner collecting frame unit  130  not to move with respect to each other. As illustrated in  FIG. 13 , a supporting shaft hole  181   a  into which a respective end of the supporting shaft  120  is inserted is formed at each of the first and second side plates  181  and  182 . Also, at each of the first and second side plates  181  and  182  may be formed a developing roller shaft hole to support a shaft of the developing roller  152  ( FIG. 12 ) and a toner supplying roller shaft hole to support a shaft of the toner supplying roller  153  ( FIG. 12 ). 
     Hereinafter, an operation of a developing cartridge  100  with an above-described structure will be explained with reference to  FIG. 12 . 
     Toner to be stored at the toner space  151 a of the toner supply frame  151  is carried to the developing roller  152  by the toner supplying roller  153 . When the developing roller  152  rotates, the toner that is moved onto the developing roller  152  is regulated into a thin toner layer while passing beneath the toner regulating blade  154 . When the developing roller  152  continues to rotate, the thin toner layer is moved to face the photosensitive medium  110 . Then, toner to form the toner layer on the developing roller  152  is moved to the photosensitive medium  110 . The toner to be moved onto the photosensitive medium  110  develops the electrostatic latent images into visible images. The visible images that are formed on the photosensitive medium  110  are transferred onto a printing medium by a transferring roller  340  ( FIG. 14 ). Used toner that remains on the photosensitive medium  110  after the visible images are transferred onto the printing medium is removed by the cleaning blade  132  and collected in the used toner space  131   a  of the used toner collecting frame  131 . 
     After that, the photosensitive medium  110  having used toner removed is re-charged to a predetermined voltage by the charging roller  173 , and the above procedure is repeated for visible images to be formed on the photosensitive medium  110 . 
     In the developing cartridge  100  according to an embodiment of the present general inventive concept, as illustrated in  FIGS. 8 and 13 , because the fixing grooves  121  and  122  of the supporting shaft  120  are inserted into the fixing projections  145  of the first shaft supporting member  141  of the used toner collecting frame unit  130 , when the photosensitive medium  110  rotates with respect to the supporting shaft  120 , the supporting shaft  120  does not rotate with respect to the first and second shaft supporting members  141  and  142  of the used toner collecting frame  131  or move in the axial direction of the photosensitive medium  110 . 
     Hereinafter, an assembly procedure of a developing cartridge  100  according to an embodiment of the present general inventive concept having the above-described structure will be explained with reference to  FIGS. 6 to 11  and  FIG. 15 . 
     First, the supporting shaft  120  is inserted into the through hole  112   b  of the photosensitive medium  110  (operation  1510 ). A side of the supporting shaft  120  on which the fixing grooves  121  and  122  are formed is inserted into the gear formed second flange  112  of the photosensitive medium  110  as illustrated in  FIG. 6  so that the fixing grooves  121  and  122  of the supporting shaft  120  are exposed outside the first flange  111  with no gear as illustrated in  FIG. 7 . 
     The supporting shaft  120  coupled with the photosensitive medium  110  is inserted into the first and second shaft supporting grooves  143  and  144  of the first and second shaft supporting members  141  and  142  of the used toner collecting frame unit  130 . The fixing grooves  121  and  122  of the supporting shaft  120  are aligned with the fixing projections  145  formed at the first shaft supporting groove  143  of the first shaft supporting member  141 , and then, the supporting shaft  120  is inserted through the opening portions of the first and second shaft supporting grooves  143  and  144  of the first and second shaft supporting members  141  and  142  (operation  1520 ). As illustrated in  FIG. 8 , when the supporting shaft  120  is completely inserted into the first and second shaft supporting grooves  143  and  144 , the fixing grooves  121  and  122  formed at the supporting shaft  120  and the fixing projections  145  formed at the first shaft supporting groove  143  prevent the supporting shaft  120  from rotating or moving in the axial direction of the photosensitive medium  110 . 
     Then, the toner supply frame unit  150  is coupled with the used toner collecting frame unit  130  (operation  1530 ). Accordingly, the first and second coupling grooves  163  and  164  formed at the first and second coupling members  161  and  162  of the toner supply frame unit  150  may be inserted into the supporting shaft  120  outside the first and second shaft supporting members  141  and  142  of the used toner collecting frame unit  130  ( FIG. 13 ). As a result, the toner supply frame unit  150  is fixed to a position predetermined with respect to the photosensitive medium  110  as illustrated in  FIG. 9 . 
     As illustrated in  FIG. 9 , the charging roller unit  170  is disposed above the photosensitive medium  110  between the toner supply frame unit  150  and the used toner collecting frame unit  130  (operation  1540 ). At least one fixing portion (not illustrated) to fix the charging roller unit  170  may be formed at the used toner collecting frame  131  or the toner supply frame  151 . 
     As illustrated in  FIG. 10 , the first and second side plates  181  and  182  are assembled to the left and right sides of the toner supply frame unit  150  and the used toner collecting frame unit  130  (operation  1550 ) so that the assembly of the developing cartridge  100  is completed. When assembling the first and second side plates  181  and  182 , each of the both ends of the supporting shaft  120  is inserted into the supporting shaft hole  181   a  formed on each of the first and second side plates  181  and  182 . Also, if the first and second side plates  181  and  182  have shaft holes to support shafts of the developing roller  152  and the toner supplying roller  153 , each of the shaft holes is aligned and assembled with each the shafts of the developing roller  152  and the toner supplying roller  153 . 
     When disassembling a developing cartridge  100  according to an embodiment of the present general inventive concept that is assembled through the above-described procedure, the disassembly of the developing cartridge  100  is performed in the opposite order of the assembly procedure. Referring to  FIGS. 6-11  and  16 , in operation  1610 , the first and second side plates  181  and  182  are disassembled from the left and right sides of the toner supply frame unit  150  and the used toner collecting frame unit  130 . In operation  1620 , the charging roller unit  170  disposed above the photosensitive medium  110  between the toner supply frame unit  150  and the used toner collecting frame unit  130  is removed therefrom. In operation  1630 , the toner supply frame unit  150  is separated from the used toner collecting frame unit  130 . In operation  1640 , the fixing grooves  121  and  122  of the supporting shaft  120  are separated from the fixing projections  145  of the used toner collecting frame unit  130  so that the supporting shaft  120  with the photosensitive medium  110  is separated from the used toner collecting frame unit  130 . In operation  1650 , the supporting shaft  120  is separated from the photosensitive medium  110  to complete the disassembly procedure. 
     In the above description, the developing cartridge  100  is constituted of the used toner collecting frame unit  130 , the toner supply frame unit  150 , and the charging roller unit  170 . In other words, the frame of the developing cartridge  100  is formed of the used toner collecting frame  131 , the toner supply frame  151 , the charging roller frame  171 , and the first and second side plates  181  and  182 . Alternatively, although not illustrated, the developing cartridge  100  may use an integrally formed frame. Accordingly, first and second shaft supporting members to support a supporting shaft are disposed to face each other inside the integrally formed frame. Also, a photosensitive medium hole is formed at a bottom surface of the frame so that some portion of the photosensitive medium is exposed through the photosensitive medium hole. The developing cartridge is similar to the developing cartridge  100  according to the above-described embodiment except that the frame is integrally formed. Therefore, a detailed description thereof is omitted. 
     Hereinafter, an image forming apparatus having a developing cartridge according to an embodiment of the present general inventive concept will be explained with reference to  FIG. 14 . 
     Referring to  FIG. 14 , an image forming apparatus  300  having a developing cartridge according to an embodiment of the present general inventive concept includes a main body cover  310 , a printing medium feeding unit  320 , a conveying roller unit  330 , a light exposure unit  380 , a developing cartridge  370 , a fixing unit  350 , and a discharging unit  360 . 
     The main body cover  310  forms an appearance of the image forming apparatus  300 . Inside the main body cover  310  are disposed the printing medium feeding unit  320 , the conveying roller unit  330 , the light exposure unit  380 , the developing cartridge  370 , the fixing unit  340 , and the discharging unit  360 . 
     The printing medium feeding unit  320  is disposed at a lowest side inside the main body cover  310 , and holds a plurality of printing media P. A pickup roller  321  picks up the stored printing media P one by one to feed, and is disposed at a front end of the printing medium feeding unit  320 . 
     The conveying roller unit  330  includes at least a pair of conveying rollers, and coveys a printing medium P to be picked up by the printing medium feeding unit  320  between the transferring roller  340  and a photosensitive medium  110 . 
     The light exposure unit  380  is disposed above the developing cartridge  370 , and emits laser beam corresponding to printing data to the photosensitive medium  110  of the developing cartridge  370 . 
     The developing cartridge  370  supplies toner to electrostatic latent images formed by the laser beam emitted from the light exposure unit  380 , thereby developing the electrostatic latent images into toner images. The developing cartridge  370  is detachably disposed inside the main body cover  310  of the image forming apparatus  300 . Therefore, when the developing cartridge  370  is disposed inside the image forming apparatus  300 , as illustrated in  FIG. 13 , the gear  112   a  of the photosensitive medium  110  is meshed with the drive gear  303  to be disposed inside the main body cover  310 . The structure of the developing cartridge  370  is similar to the developing cartridge  100  according to an embodiment of the present general inventive concept as described above. Therefore, a detailed description thereof is omitted. 
     The transferring roller  340  is rotatably disposed to contact the photosensitive medium  110  of the developing cartridge  370  below the developing cartridge  370 , and transfers toner images formed on the photosensitive medium  110  onto a printing medium P conveyed from the printing medium feeding unit  320 . 
     The fixing unit  350  is disposed downstream the transferring roller  340 , and includes a pressure roller and a heat roller. The fixing unit  350  applies heat and pressure to the printing medium P to pass through between the heat and pressure rollers, thereby fixing the toner images onto the printing medium P. 
     The discharging unit  360  discharges the printing medium P to outside the image forming apparatus  300  after the printing medium P passes through the fixing unit  350  and the images are fixed onto the printing medium P. 
     Hereinafter, an operation of an image forming apparatus  300  according to an embodiment of the present general inventive concept having the above-described structure will be explained with reference to  FIG. 14 . 
     When receiving a printing order, the image forming apparatus  300  applies voltage to the charging roller  173  ( FIG. 12 ) of the developing cartridge  370  so as to charge the surface of the photosensitive medium  110  by a predetermined voltage. 
     After that, the image forming apparatus  300  operates a drive motor (not illustrated) to rotate the drive gear  303  ( FIG. 13 ). When the drive gear  303  rotates, the gear  112   a  of the photosensitive medium  110  meshed with the drive gear  303  rotates so that the photosensitive medium  110  rotates. Although the photosensitive medium  110  rotates, the supporting shaft  120  does not rotate together with the photosensitive medium  110  or move in the axial direction thereof because the fixing grooves  121  and  122  of the supporting shaft  120  are inserted into the fixing projections  145  of the first shaft supporting member  141 . 
     Furthermore, the image forming apparatus  300  operates the light exposure unit  380  to emit laser beam corresponding to printing data. The laser beam emitted from the light exposure unit  380  enters the photosensitive medium  110  through the laser beam hole  172  formed at the charging roller frame  171  ( FIG. 12 ) of the developing cartridge  370  to form electrostatic latent images corresponding to the printing data on the photosensitive medium  110  charged by the charging roller  173 . 
     When the photosensitive medium  110  continues to rotate due to the drive gear  303 , the electrostatic latent images on the photosensitive medium  110  moves to a position to face the developing roller  152 . Then, toner of the toner layer formed on the developing roller  152  moves to the surface of the photosensitive medium  110  to develop the electrostatic latent images into toner images. 
     Also, when receiving the printing order, the printing medium feeding unit  320  picks up a printing medium P from the stored printing media, and feeds the printing medium P to the conveying roller unit  330 . The conveying roller unit  330  causes the picked up printing medium P to enter between the transferring roller  340  and the photosensitive medium  110  of the developing cartridge  370 . 
     When the printing medium P enters between the transferring roller  340  and the photosensitive medium  110  of the developing cartridge  370 , the toner images formed on the rotating photosensitive medium  110  are transferred onto the printing medium P. 
     When the photosensitive medium  110  continues to rotate, used toner that remains on the surface of the photosensitive medium  110  after the toner images are transferred onto the printing medium P is removed by the cleaning blade  132 . The used toner to be removed from the photosensitive medium  110  is collected in the used toner space  131   a  formed in the used toner collecting frame  131 . 
     When the photosensitive medium  110  continues to rotate, a portion of the photosensitive medium  110  from which the used toner is removed faces to the charging roller  173  so that the portion of the photosensitive medium  110  is re-charged by the charging roller  173 . 
     The charged photosensitive medium  110  repeats the above procedure to transfer toner images onto a printing medium P. 
     The printing medium P onto which the toner images are transferred from the photosensitive medium  110  of the developing cartridge  370  is conveyed to the fixing unit  350 . When the printing medium P passes through between the pressure and heat rollers of the fixing unit  350 , the toner images are fixed onto the printing medium P. 
     The printing medium P onto which the toner images are fixed is discharged to outside the image forming apparatus  300  by the discharging unit  360 . 
     With a photosensitive medium supporting apparatus, a developing cartridge, and an image forming apparatus according to an embodiment of the present general inventive concept as described above, because fixing projections of a first shaft supporting members are inserted into fixing grooves formed at a supporting shaft, the supporting shaft is prevented from rotating or moving in an axial direction thereof. Therefore, separate portions to prevent the supporting shaft from rotating are not required, so that a number of parts may decrease. 
     With a photosensitive medium supporting apparatus and a developing cartridge according to an embodiment of the present general inventive concept, fixing grooves of a supporting shaft and fixing projections of a shaft supporting member can perform two functions as the prevention of rotation of a supporting shaft and the prevention of an axial direction movement of the supporting shaft, which may decrease manufacturing costs as compared to the conventional photosensitive medium supporting apparatus and developing cartridge. 
     Furthermore, with a photosensitive medium supporting apparatus and a developing cartridge according to the present general inventive concept, a supporting shaft is assembled with shaft supporting members by merely inserting fixing grooves of the supporting shaft into fixing projections of the shaft supporting members, which makes assembly easy. Therefore, assembly time may decrease. 
     Although a few embodiments of the present general inventive concept have been illustrated and described, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the general inventive concept, the scope of which is defined in the appended claims and their equivalents.