Patent Publication Number: US-7725051-B2

Title: Cartridge, image forming apparatus, and method for mounting and dismounting the cartridge in and from a main body of the image forming apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims benefit under 35 U.S.C. §119 (a) of Korean Patent Application No. 2005-89466, filed on Sep. 26, 2005, the entire content of which is incorporated herein by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an image forming apparatus such as a laser printer, a digital copier, and a facsimile. More particularly, the present invention relates to a process cartridge, an image forming apparatus incorporating the cartridge, and a method for mounting and dismounting the process cartridge in and from an image forming apparatus body. 
   2. Description of the Related Art 
   Generally, an electrophotographic image forming apparatus such as a laser printer, a digital copier, and a facsimile comprises a process cartridge including a developing unit or integrating a photosensitive body unit and a developing unit into a single module. A photosensitive body of the photosensitive body unit is exposed to a laser to form an electrostatic latent image thereon. The developing unit supplies developer to the photosensitive body to form a developer image corresponding to the electrostatic latent image. 
   Generally, the process cartridge is detachably mounted in an image forming apparatus body to easily repair or replace all parts of the cartridge. 
     FIGS. 1 ,  2 A and  2 B are views of a general process cartridge  1  in which the photosensitive body unit and the developing unit are integrated into a single module. 
   The process cartridge  1  comprises a photosensitive body casing  2  and a developing casing  8 . 
   In the photosensitive body casing  2 , a photosensitive body unit is formed which comprises a photosensitive body  7  having a drumlike configuration, a charging roller  8  for charging a surface of the photosensitive body  7 , and a cleaning member (not shown) such as a cleaning roller and a cleaning blade for cleaning the photosensitive body  7 . 
   On an upper portion of the photosensitive body casing  2 , a knob  6  is provided to carry and move the process cartridge  1 . 
   A first and a second side members  14   a ,  14   b  are provided on the opposite end portions of the photosensitive body casing  2 . 
   On the first and the second side members  14   a ,  14   b  are formed a first and a second guide protrusions  24  (only the first guide protrusion is shown) protruding to the outside to be coaxially aligned with an axis of the photosensitive body  7 . A third and a fourth guide protrusions  25  (only the third protrusion is shown) protrude outwardly from the side members a certain distance from the first and the second guide protrusions  24 . 
   As the process cartridge  1  is mounted in the image forming apparatus body, the first and the second guide protrusions  24  are guided along a first and a second guide recess  20   a  (only the first guide recess is shown) of a first and a second guide member  20  so as to be received in a receiving recess  20   b  of the first and the second guide recesses  20   a . The first and the second guide protrusions  24  each are received in the receiving recess  20   b  so as to position the process cartridge  1  in a mounting position. 
   As the process cartridge  1  is mounted in the image forming apparatus body  1 , the third and the fourth guide protrusions  25  are received in the first and the second guide recesses  20   a . As the process cartridge  1  is mounted and dismounted in or from the image forming apparatus body, the third and the fourth guide protrusions  25  guide the movement of the process cartridge  1  and operate as a hinge point supporting the rotation of the process cartridge  1  in the first and the second guide recesses  20   a.    
   Accordingly, as the process cartridge  1  is mounted in the image forming apparatus and then, pulled or pushed in first and second directions P 1 , P 2  by the knob  6 , the process cartridge  1  is minutely rotated in the direction of arrow a, b based on the third and the fourth guide protrusions  25  as a hinge point. As a result, the first and the second guide protrusions  24  are received in the receiving recess  20   b  or separated from the receiving recess  20   b  of the first and the second guide recesses  20   a.    
   The developing casing  8  may be formed integrally with or detachably from the photosensitive body casing  2 . 
   The developing casing  8  comprises a developing roller  10  contacting the photosensitive body  7  with a certain gap, a supply roller (not shown) supplying the developing roller  10  with developer, and a developer regulating blade (not shown) contacting the developing roller  10  to regulate the thickness of the developing layer. 
   The process of mounting and dismounting the process cartridge  1  in or from the image forming apparatus body for replacing or repairing the process cartridge  1  will be explained below. 
   To dismount the process cartridge  1  from the image forming apparatus body, the image forming apparatus body cover (not shown) is opened and the process cartridge  1  is pulled in the first direction P 1  by the knob  6 . 
   As a result, the process cartridge  1  rotated in the direction of arrow b using the third and the fourth guide protrusions  25  as a hinge point, as shown in  FIG. 2B  so that the first and the second guide protrusions  24  are moved upwardly and separated from the receiving recess  20   b  of the first and the second guide recesses  20   a.    
   Then, as the process cartridge  1  is pulled further in the first direction P 1  by the knob  6 , the four guide protrusions  24 ,  25  slide along the first and the second guide recesses  20   a  and are separated from the first and the second guide recesses  20   a.    
   Then, the process cartridge  1  is lifted upwardly and pulled out through the process cartridge body cover to the outside. 
   After the process cartridge  1  is pulled out of the image forming apparatus body to the outside, the process cartridge  1  is disassembled to repair problematic parts thereof or replaced with new one, if necessary. 
   After completing the repairing or replacing, the repaired or replaced process cartridge  1  is put through the image forming apparatus body cover into the image forming apparatus body to be mounted therein. 
   After fitting the first and the second guide protrusions  24  in the first and the second guide recesses  20   a , the process cartridge  1  is pushed in the second direction P 2  by the knob  6 . 
   As the process cartridge  1  is nearly mounted in the image forming apparatus body, the third and the fourth guide protrusions  25  fit in the first and the second guide recesses  20   a  and then, the process cartridge  1  is pushed further in the second direction P 2  by the knob  6 . Therefore, the first and the second guide protrusions  24  contact with an end portion wall  20   c  of the first and the second guide recesses  20   a  as shown in  FIG. 2B . 
   The process cartridge  1  is minutely rotated in the direction of arrow a using the third and the fourth guide protrusions  25  as a hinge point by inertial force and its own weight. Therefore, the first and the second guide protrusions  24  are inserted and received in the receiving recess  20   b  of the first and the second guide recesses  20   a , as shown in  FIG. 2A . Additionally, a photosensitive body gear  7   a  of one end portion of the photosensitive body  7  is meshed with a driving gear  21 , transmitting a driving force of a driving motor, of a main gear train of the image forming apparatus body. 
   However, as the conventional process cartridge  1  with the above structure is mounted in the image forming apparatus body, the four guide protrusions  24 ,  25  of the first and the second side members  14   a ,  14   b  should be simultaneously inserted into the first and the second guide recesses  20   a  of the first and the second guide members  20 . Accordingly, careful operations are required to accurately insert the four guide protrusions  24 ,  25  into the first and the second guide recesses  20   a  when the first and the second guide protrusions  24  are inserted in the first and the second guide recesses  20   a  and when the third and the fourth guide protrusions  25  are inserted into the first and the second guide recesses  20   a  after the first and the second guide protrusions  24  are inserted in the first and the second guide recesses  20   a . Additionally, in order to completely fit the first and the second guide protrusions  24  in the receiving recess  20   b  of the first and the second guide recesses  20   a , the process cartridge  1  should be continuously pushed in the second direction P 2  by the knob  6  so as not to be freely moved. 
   Further, as the conventional process cartridge  1  is dismounted from the image forming apparatus body, the first through the fourth guide protrusions  24 ,  25  should be completely separated from the first and the second guide recesses  20   a  of the first and the second guide members  20  to pull the process cartridge  1  out of the image forming apparatus body  1  to the outside. Accordingly, as the process cartridge  1  is dismounted and mounted in or from the image forming apparatus body, the time required to remove the process cartridge  1  from the image forming apparatus body is delayed by the length of the first and the second guide recesses  20   a . Additionally, if the process cartridge  1  is pulled out by force, the first and the second guide protrusions  24  and/or the third and the fourth guide protrusions  25  may be damaged. 
   SUMMARY OF THE INVENTION 
   Accordingly, the aspects of the present invention are to solve at least the above problem and/or disadvantages and to provide at least the advantages described below. Therefore, an object of the present invention is to provide a process cartridge that has a relatively simple construction to be easily mounted and dismounted in or from an image forming apparatus body, an image forming apparatus having the same, and a method for mounting and dismounting the process cartridge in or from the image forming apparatus body. 
   Another object of the present invention is to provide a process cartridge that includes a mount and dismount supporting part, which has the most effective moment in a knob, so as to easily and effectively be mounted and dismounted in or from an image forming apparatus body by the knob. The invention is also directed to an image forming apparatus having the process cartridge. The invention is also directed to a method for mounting and dismounting the process cartridge in or from the image forming apparatus body. 
   To achieve the above-described objects, a process cartridge of an image forming apparatus is provided, which can be detachably mounted in an image forming apparatus body. The process cartridge comprises at least one of a photosensitive body on which an electrostatic latent image is formed, and a developing member for developing the electrostatic latent image, and a housing receiving and supporting the at least one of the photosensitive body and the developing member. The housing comprises a first and a second guide protrusion protruding from a first surface and a second surface opposite the first surface of the housing and extending outwardly to position in a mounting position of the housing as the process cartridge is mounted in the image forming apparatus body, and a mount and dismount supporting part formed on a third surface, perpendicular to the first and the second surfaces of the housing to rotate the housing as the process cartridge is mounted in or dismounted from the image forming apparatus body. 
   The first and the second guide protrusions may be coaxially formed with an axis of the photosensitive body and/or the developing member. 
   The mount and dismount supporting part may comprise at least one hinge recess formed on the third surface adjacent to an edge of at least one of the first and the second surfaces. The at least one hinge recess comprises a first and a second hinge recess formed at a lower portion surface of a first and a second side plates of opposite ends of the housing and includes an inclined recess surface and a horizontal recess surface. 
   The housing may further comprise a knob formed above a line connecting the first or the second guide protrusion and the mount and dismount supporting part. 
   The housing may further comprise at least one of a third and a fourth guide protrusion protruding outward from the first and the second surfaces a certain distance from the first and the second guide protrusions in order to guide movement of the housing as the process cartridge is mounted in or dismounted from the image forming apparatus body. 
   To achieve the above-described object, an image forming apparatus is provided which comprises a process cartridge including at least one of a photosensitive body on which an electrostatic latent image is formed, and a developing member for developing the electrostatic latent image, and a housing receiving and supporting the at least one of the photosensitive body and the developing member, and a main body frame including a cartridge mount part having first and second guide rails with an opened top portion to mount the process cartridge, and a main body mount and dismount supporting part for rotating the process cartridge as the process cartridge is mounted in or dismounted from the image forming apparatus, wherein the housing comprises first and second guide protrusions protruding outwardly from a first surface and a second surface opposite the first surface of the housing and being guided along the first and the second guide rails in order to position a mounting position of the housing as the process cartridge is mounted in the image forming apparatus body, and a cartridge mount and dismount supporting part formed on a third surface, perpendicular to the first and the second surfaces, of the housing to correspond to the main body mount and dismount supporting part in order to rotate the housing in cooperation with the main body mount and dismount supporting part as the process cartridge is mounted in or dismounted from the image forming apparatus body. 
   The first and the second guide rails may comprise a receiving recess receiving the first and the second guide protrusions. 
   The first and the second guide protrusions may be coaxially formed with an axis of one of the photosensitive body and the developing member. 
   The cartridge mount and dismount supporting part may comprise at least one hinge recess formed on the third surface adjacent an edge of at least one of the first and the second surfaces, and the main body mount and dismount supporting part may comprise at least one hinge protrusion formed at the main body frame to correspond to the hinge recess. The at least one hinge recess may comprise a first and a second hinge recesses formed at a lower portion surface of first and second side plates on opposite ends of the housing and include an inclined recess surface and a horizontal recess surface, and the at least one hinge protrusion may comprise a first and a second hinge protrusions which are formed at the main body frame under the first and the second guide rails and include an inclined surface not contacting with the housing as the process cartridge is mounted in or dismounted from the image forming apparatus and a horizontal surface to mesh with the horizontal recess surface of the second hinge recess. 
   The housing may further comprise a knob formed above a line connecting the first or the second guide protrusion and the cartridge mount and dismount supporting part. 
   The housing may further comprise at least one of a third and a fourth guide protrusions protruding from the first and the second surfaces to the outside with a certain distance from the first and the second guide protrusions in order to guide the movement of the housing along the first and the second guide rails as the process cartridge is mounted in or dismounted from the image forming apparatus body. 
   To achieve the above-described object, a method for mounting and dismounting a process cartridge in and from an image forming apparatus comprises grasping a knob of the process cartridge, rotating the process cartridge around a hinge point of a cartridge mount and dismount supporting part formed on a lower surface of the process cartridge by pulling the knob, and pulling out the process cartridge outwardly. 
   The step of rotating the process cartridge may comprise rotating the process cartridge by supporting the cartridge mount and dismount supporting part on a main body mount and dismount supporting part of a main body frame, and separating first and second guide protrusions of opposite ends on the process cartridge from receiving recesses of first and second guide rails of the cartridge mount part of the main body frame. The main body mount and dismount supporting part may comprise at least one hinge protrusion formed on the main body frame, and the cartridge mount and dismount supporting part may comprise at least one hinge recess formed on a lower portion of the process cartridge corresponding to the hinge protrusion. 
   The step of pulling out the process cartridge outwardly may further comprise lifting the process cartridge to separate the first and the second guide protrusions of the process cartridge from the first and the second guide rails. 
   The method may further comprise locating the process cartridge on a cartridge mount part of the main body frame, sliding the process cartridge along the cartridge mount part, and supporting the cartridge mount and dismount supporting part of the process cartridge by the main body mount and dismount supporting part of the main body frame. 
   The step of locating the process cartridge on the cartridge mount part may comprise locating first and second guide protrusions on opposite ends of the process cartridge on first and second guide rails, corresponding to the first and the second guide protrusions of the cartridge mount part of the main body frame. 
   The step of sliding the process cartridge may comprise sliding the first and the second guide protrusions along the first and the second guide rails. 
   The step of supporting the cartridge mount and dismount supporting part by the main body mount and dismount supporting part may comprise fitting first and second hinge recesses of the cartridge mount and dismount supporting part of a lower portion surface of the process cartridge over first and second hinge protrusions, corresponding to the first and the second hinge recesses of the main body mount and dismount part of the main body frame. 
   The method may further comprise fitting the first and the second guide protrusions in a receiving recess of the first and the second guide rails. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above aspects and features of the present invention will be more apparent by describing certain embodiments of the present invention with reference to the accompanying drawings, in which: 
       FIG. 1  is a perspective view of a conventional process cartridge of an image forming apparatus; 
       FIGS. 2A and 2B  are side views of the process cartridge of  FIG. 1 ; 
       FIG. 3  is a schematic view of a laser printer using a process cartridge according to an embodiment of the present invention; 
       FIGS. 4A through 4C  are perspective views of a process cartridge of the laser printer of  FIG. 3 ; 
       FIG. 5  is a perspective view of a main body frame of the laser printer of  FIG. 3 ; 
       FIG. 6  is a perspective view of a cartridge mounting part and a laser printer main body mount and dismount supporting part of the laser printer main body frame of  FIG. 5 ; 
       FIGS. 7A through 7C  are side views of an example of a process of dismounting a process cartridge from the main body frame of the laser printer of  FIG. 5 ; and 
       FIGS. 8A and 8B  are side views of an example of a process of mounting a process cartridge in the main body frame of the laser printer of  FIG. 5 . 
   

   DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS 
   A process cartridge according to exemplary embodiments of the present invention, an image forming apparatus having the process cartridge, and a method for mounting and dismounting the process cartridge in or from an image forming apparatus body will be described in detail with reference to the annexed drawings. In the drawings, the same elements are denoted by the same reference numerals throughout the drawings. In the following description, detailed descriptions of known functions and configurations incorporated herein have been omitted for conciseness and clarity. 
     FIG. 3  is a schematic view of an image forming apparatus having a process cartridge according to an exemplary embodiment of the present invention. 
   The image forming apparatus according to an embodiment of the present invention is a laser printer  100  that prints and outputs data being input from an external device such as a personal computer (PC). 
   The laser printer  100  comprises a stacking unit  101  for stacking papers P, a feeding unit  102  for feeding the paper P from the stacking unit  101 , a process cartridge  106  forming a developer image on the paper P fed by the feeding unit  102 , a fixing unit  107  for fixing the developer image on the paper P with regular heat and pressure, and a discharge unit  108  for discharging the paper P fixed with the developer image. 
   The stacking unit  101  comprises a paper feeding cassette which has a paper press board elastically supported by an elastic spring to elastically lift and lower the paper P. 
   The feeding unit  102  comprises a pick-up roller  109  for feeding the paper P by a sheet from the stacking unit  101 , first and second feeding rollers  121 ,  122  for feeding the paper P fed from the pick-up roller  109 , and a register and back-up rollers  123 ,  125  for aligning a leading end of the paper P fed from the first and the second feeding rollers  121 ,  122 . 
   A paper sensor  130  is disposed at a rear side downstream in a paper feeding path of the register roller  123  to sense a position of the leading end of the paper P. 
   The process cartridge  106  comprises a photosensitive body unit  140 , a developing unit  160 , and a housing  118  integrally forming the photosensitive body unit  140  and the developing unit  160  into a single module to detachably mount the photosensitive body unit  140  and the developing unit  160  in the image forming apparatus body  114 . 
   The photosensitive body unit  140  comprises a photosensitive body  143 , and has opposite ends rotatably supported by a photosensitive body casing  141 . The photosensitive body  143  comprises an organic photoconductive (OPC) drum. 
   A photosensitive body gear (not shown) is formed at one side of a photosensitive body shaft  143   a  in the photosensitive body casing  141 . The photosensitive body gear is meshed with a driving gear (not shown) of a main gear train (not shown) receiving a driving force from a driving motor (not shown) provided in an image forming apparatus body  114  as the process cartridge  104  is mounted to a main body frame  160  (refer to  FIG. 5 ) of the image forming apparatus body  114 . 
   The construction of the main gear train is the same as the generally well-known one, and therefore, the detailed description thereof will be omitted for the sake of brevity. 
   Referring back to  FIG. 3 , a charge eraser  148 , a photosensitive body cleaner  149 , and a charger  152  are arranged along the rotating direction of the photosensitive body  143  to be adjacent to an outer circumference of the photosensitive body  143 . 
   The charge eraser  148 , for removing the potential charged on the photosensitive body  143 , comprises a charge erasing lamp. 
   The photosensitive body cleaner  149  is provided for removing waste developer remaining on the surface of the photosensitive body  143  of the developing unit  160 . The body cleaner  149  includes a cleaning member  150  such as a cleaning blade, to remove residual toner from the body  143  after the developer image is transferred onto a paper P by a transfer roller  105 , comprising a cleaning member  150  such as a cleaning blade. 
   The cleaning member  150  is attached to a fixing bracket  151  formed in the photosensitive body casing  141  to contact the photosensitive body  143  with a certain pressure. 
   The charger  152  comprises a charging roller disposed to contact the surface of the photosensitive body  143 , and a certain charge bias power is supplied by a charge bias power part (not shown) so as to form a certain charge potential on the surface of the photosensitive body  143 . 
   The developing unit  160  comprises a developing roller  163  arranged opposite the photosensitive body  143  with a certain gap in a developing casing  161 . A developing unit also includes supply roller  165  for supplying developer to the developing roller  163 , a developer regulating blade  167  for regulating a thickness of developer layer adhered on the developing roller  163 , and a developer storage part  169  for storing the developer. 
   The developing roller  163  attaches the developer to an electrostatic latent image, formed on the photosensitive body  143  by a laser scanning unit (LSU)  104 , to develop the latent image. The LSU  104  will be explained later, and the developing roller  163  is opposed to the photosensitive body  143  by a certain gap. The developing bias power part (not shown) supplies a certain developing bias power to the developing roller  163  that is lower than that supplied to the supply roller  165 . 
   The supply roller  165 , supplying the developer to the developing roller  163  by using the potential difference between the supply roller  165  and the developing roller  163 , is arranged to contact one side of the developing roller  163  and form a nip. The developer is conveyed to a lower space between the supply roller  165  and the developing roller  163  by the supply roller  165  in the developing casing  161 . 
   The developer supply bias power part (not shown) supplies a certain developer supply bias power to the supply roller  165  higher than that to the developing roller  163 . Accordingly, the developer of the lower space between the supply roller  165  and the developing roller  163  is charged by the supply roller  165 , and attaches to the developing roller  163  with a relatively lower potential and moves to the nip between the supply roller  165  and the developing roller  163 . 
   The developer regulating blade  167  regulates the thickness of the layer of the developer to form a thin layer a predetermined thickness. The developer is supplied to the developing roller  163  through the supply roller  165 . 
   The developer storage part  169  receives and stores the developer and is detachably provided in the developing casing  161 . In the developer storage part  169 , an agitator (not shown) is arranged to agitate the stored developer. The construction of the agitator is the same as the general one, and therefore, the detailed description thereof will be omitted for the sake of brevity. 
   As shown in  FIGS. 4A through 4C , the housing  118  comprises a first and a second side plate  250 ,  251  engaged with opposite ends of the photosensitive body casing  141  and the developing casing  161 . The housing  118  supports opposite ends of shafts of various rollers such as the photosensitive body  143 , the charging roller, the developing roller  163 , and supply roller  165 . The first and the second side plates  250 ,  251  form a first and a second surfaces of the housing  118 . 
   A first and a second guide protrusion  250   a ,  251   a  are formed on the external surface of the first and the second side plates  250 ,  251  to guide the movement of the housing  118  and position the housing  118  in the mounted position as the process cartridge  106  is mounted and dismounted in or from the main body frame  160 . 
   The first and the second guide protrusions  250   a ,  251   a  protrudes from the external surface of the first and the second side plates  250 ,  251  to enclose the photosensitive body shaft  143   a  and correspond to the photosensitive body shaft  143   a  in the configuration. 
   As the process cartridge  106  is mounted and dismounted in or from the main body frame  160 , the first and the second guide protrusions  250   a ,  251   a  are guided along a first and a second guide rails  261   a ,  262   a  of a cartridge mount part  261  and received in receiving recesses  261   b ,  262   b  so as to position the housing  118  in the mounted position. The cartridge mount part  261  will be explained later with reference to  FIGS. 5 and 6 . 
   Optionally, a third and a fourth guide protrusions  250   b ,  251   b  may be further formed on the external surface of the first and the second side plates  250 ,  251  so that the housing  118  is guided along the first and the second guide rails  261   a ,  262   a  of the main body frame  160  as the process cartridge  106  is mounted and dismounted in or from the main body frame  160  of the image forming apparatus body  114 . 
   The third and the fourth guide protrusions  250   b ,  251   b  protrude from the external surface of the first and the second side plates  250 ,  251  by a certain distance from the first and the second guide protrusions  250   a ,  251   a.    
   As shown in  FIGS. 4A through 4C , a cartridge mount and dismount supporting part  270  is formed on the lower portion surface of the first and the second side plates  250 ,  251  adjacent to the developing casing  161  to be supported by an image forming apparatus body mount and dismount supporting part  290  and to cooperate with the image forming apparatus body mount and dismount supporting part  290 . The lower portion surface of the first and the second side plates  250 ,  251  forms a third surface of the housing  118  perpendicular to the exterior surface of the first and the second side plates  250 ,  251 . 
   In cooperation with the main body mount and dismount supporting part  290 , the cartridge mount and dismount supporting part  270  operates as a hinge point for rotating the housing  118 , as the process cartridge  106  is mounted in or dismounted from the main body frame  160 . 
   The cartridge mount and dismount supporting part  270  comprises first and second hinge recesses  271 ,  273  formed on a lower portion surface to be adjacent to the edge of the lower portion of the exterior surface of the first and the second side plates  250 ,  251 . 
   The first and the second hinge recesses  271 ,  273  comprises an inclined recess surface  271   a ,  273   a  and a horizontal recess surface  271   b ,  273   b . The inclined recess surfaces  271   a ,  273   a  allow horizontal surfaces  291   b ,  293   b  of first and second hinge protrusions  291 ,  293  of the main body mount and dismount supporting part  290  to slidingly move or move without contact. The horizontal recess surface  271   b ,  273   b  are meshed with the horizontal surface  291   b ,  293   b  of the first and the second hinge protrusions  291 ,  293 . 
   As described above, the cartridge mount and dismount supporting part  270  is formed adjacent to the developing casing  161  on the bottom surface of the first and the second side plates  250 ,  251 , where the center of gravity of the process cartridge  106  is located. Therefore, a knob  280  can easily rotate the process cartridge  106  by a relatively small force as the process cartridge  106  is mounted in or dismounted from the image forming apparatus body. The knob  280  will be explained later. 
   The knob  280  is formed at one side of the upper portion of the developing casing  161  of the housing  118  to carry and move the process cartridge  106 . The knob  280  is upwardly and downwardly movable. 
   In the present embodiment, the knob  280  is formed at one side of the upper portion of the developing casing  161 ; however, this should not be considered as limiting. The knob  280  may be formed at another position in which the process cartridge  106  can be rotated by the knob  280  around the cartridge mount and dismount supporting part  270  functioning as a hinge point as the process cartridge  106  is mounted in or dismounted from the image forming apparatus body. For example, the knob may be formed on a proper position above a line connecting the first or the second guide protrusion  250   a ,  251   a  and the cartridge mount and dismount supporting part  270 . 
   As shown in  FIGS. 5 and 6 , the cartridge mount part  261  is formed on the main body frame  160  to mount the process cartridge  106 . 
   The cartridge mount part  261  comprises the first and the second guide rails  261   a ,  262   a  formed at upper portions of inner surfaces of a first and a second vertical wall  162   a ,  162   b . The first and the second guide rails  261   a ,  262   a  are inclined by certain angles and have curved surfaces with opened top portions so that the first through the fourth guide protrusions  250   a ,  251   a ,  250   b ,  251   b  of the process cartridge  106  can be easily moved therein. 
   The first and the second guide rails  261   a ,  262   a  comprise the receiving recesses  261   b ,  262   b  to receive the first and the second guide protrusions  250   a ,  251   a . The receiving recesses  261   b ,  262   b  may be semi-circular. 
   The main body mount and dismount supporting part  290  is formed on the inner surface of the first and the second vertical walls  162   a ,  162   b  under the first and the second guide rails  261   a ,  262   a  to support the cartridge mount and dismount supporting part  270  so that the housing  118  can be rotated as the process cartridge  106  is mounted in or dismounted from the image forming apparatus body. 
   The main body mount and dismount supporting part  290  comprises the first and the second hinge protrusions  291 ,  293  corresponding to the first and the second hinge recesses  271 ,  273  of the cartridge mount and dismount part  270 . 
   The first and the second hinge protrusions  291 ,  293  comprise a cutting surface or an inclined surface  291   a ,  293   a , which are cut so that the surfaces do not contact the housing  118  as the process cartridge  106  is mounted in or dismounted from the image forming apparatus body. Horizontal surfaces  291   b ,  293   b  mesh with the horizontal recess surfaces  271   b ,  273   b  of the first and the second hinge recesses  271 ,  273  to form a hinge point supporting the rotation of the housing  118 . 
   The process of mounting and dismounting the process cartridge  106  in or from the cartridge mount part  261  of the main body frame  160  will be explained with reference to  FIGS. 7A through 8B  as below. 
   Firstly, the main body cover  139  is opened, and the knob  280  of the process cartridge  106  is grasped by a user. 
   As shown in  FIG. 7B , the process cartridge  106  is pulled in a substantially horizontal direction D 1  by the knob  280 . 
   As a result, the first and the second hinge recesses  271 ,  273  of the cartridge mount and dismount supporting part  270  are supported by the first and the second hinge protrusions  291 ,  293  of the main body mount and dismount supporting part  290  so that the process cartridge  106  is rotated in the direction of arrow a based on the contacting point, as a hinge point, between the first and the second hinge recesses  271 ,  273  and the first and the second hinge protrusions  291 ,  293 . The first and the second guide protrusions  250   a ,  251   a  received in the receiving recesses  261   b ,  262   b  of the first and the second guide rails  261   a ,  262   a , are separated from the receiving recesses  261   b ,  262   b.    
   As shown in  FIG. 7C , the process cartridge  106  is lifted in the first direction D 2  by the knob  280  so that the guide protrusions  250   a ,  251   a ,  250   b ,  251   b  can be separated from the first and the second guide rails  261   a ,  262   a . Then, the process cartridge  106  is pulled out through the opening opened by the main body cover  139 . 
   After being pulled out, the process cartridge  106  is disassembled to repair problematic parts thereof or replaced with new one, if necessary. 
   After the repair or replacement is completed, the repaired or replaced process cartridge  106  is grasped by the knob  280  to be put into the main body  114  again through the opening opened by the main body cover  139 . 
   As shown in  FIG. 8A , the process cartridge  106  is positioned such that the first through the fourth guide protrusions  250   a ,  251   a ,  250   b ,  251   b  are placed on the first and the second guide rails  261   a ,  262   a  of the cartridge mount part  261 . 
   As a result, the first through the fourth guide protrusions  250   a ,  251   a ,  250   b ,  251   b  slide along the first and the second guide rails  261   a ,  262   a  by the weight of the process cartridge  106  such that the process cartridge  106  is lowered in the second direction D 3  (refer to  FIG. 8B ). 
   Then, as the first and the second guide protrusions  250   a ,  251   a  are received into the receiving recesses  261   b ,  262   b  of the first and the second guide rails  261   a ,  262   a  and the first and the second hinge recesses  271 ,  273  of the cartridge mount and dismount supporting part  270  receive the first and the second hinge protrusions  291 ,  293  of the main body mount and dismount supporting part  290  as shown in  FIG. 8B , the process cartridge  106  is stopped from moving in the second direction D 3 , and the process for mounting the process cartridge  106  is completed. At this time, the photosensitive body gear of one end of the photosensitive body shaft  143   a  is meshed with the driving gear of the main gear train of the main body  114  transmitting the driving force of the driving motor. 
   Referring back to  FIG. 4 , the LSU  104  is fixed at a fixing bracket  125  above the process cartridge  106 . The LSU  104  emits a laser beam onto the surface of the photosensitive body  143 , charged with a certain potential by the charger  152 , by using a laser diode according to image signals input from an external device such as a personal computer. Therefore, an electrostatic latent image can be formed which has a certain potential lower than a charged potential. 
   The transfer roller  105  is arranged under the photosensitive body  143  of the process cartridge  106 . 
   The transfer roller  105 , for transferring the developer image formed on the photosensitive body  143  onto the paper P, is arranged to pressurize the photosensitive body  143  with a certain pressure. A certain transfer bias power is supplied to the transfer roller  105  by the transfer bias power part (not shown) so that the developer image formed on the photosensitive body  143  can be transferred onto the paper P. 
   The fixing part  107  comprises a heating roller  126  for heating the developer image that was transferred from the photosensitive body  143  onto the paper P by the transfer roller  105 , and a press roller  127  for pressing the developer image. 
   The discharge unit  108  comprises a discharge roller  128  for discharging the printed paper P, and a stack  129  for stacking and supporting the discharged paper P. 
   As described above, the process cartridge  106  and the laser printer  100  having the process cartridge according to an embodiment of the present invention can guide the mounting of the housing  118  and position the housing  118  in a mounting position only by using the first and the second guide protrusions  250   a ,  251   a , as the process cartridge  106  is mounted in or dismounted from the main body frame  160 . Therefore, the process cartridge  106  can have a simpler structure and can be easily mounted in or dismounted from the image forming apparatus in comparison with the conventional process cartridge  1 . 
   The process cartridge  106  and the laser printer  100  having the process cartridge according to an embodiment of the present invention includes the cartridge mount and dismount supporting part  270  which is formed on the bottom surface of the first and the second side plate  250 ,  251  of the housing  118  and has the most efficient movement of the knob  280  so that the process cartridge  106  can be easily and efficiently mounted in or dismounted from the image forming apparatus by the knob  280 . 
   The process cartridge  106  and the laser printer  100  having the process cartridge according to an embodiment of the present invention includes the guide rails  261   a ,  262   a  with opened top portion, instead of including the guide recess  20   a  guiding the guide protrusions  24 ,  25  as the conventional process cartridge  1 , so as to be easily manufactured and have simpler structure. Additionally, the guide protrusions  24 ,  25  are not required to fit in the guide recess  20   a  to mount and dismount the process cartridge  106  in or from the main body frame  160 . Therefore, the time required to mount and dismount the process cartridge  106  in or from the main body frame  160  can be significantly shortened. Although the process cartridge  106  is pulled out by force, the first and the second guide protrusions  250   a ,  251   a  and/or the third and the fourth guide protrusions  250   b ,  251   b  are not damaged. 
   According to an embodiment of the present invention, the process cartridge and the image forming apparatus having the same are applied to the process cartridge  106  and the laser printer  100  having the process cartridge. The process cartridge  106  comprises the photosensitive body unit  140 , the developing unit  160 , and the housing  118  integrally forming the photosensitive body unit  140  and the developing unit  160  into a single module to be detachably mounted in or dismounted from the image forming apparatus main body  114 . However, this should not be considered as limiting. The process cartridge according to an embodiment of the present invention and the image forming apparatus having the process cartridge may be applied to a process cartridge (not shown) such as a developing cartridge comprising a developing unit, which includes a developing roller without a photosensitive body unit, and a housing, and to an image forming apparatus comprising one photosensitive body and a plurality of developing cartridges. 
   The operation of the laser printer  100  having the process cartridge  106  according to an embodiment of the present invention will be in detail explained with reference to  FIG. 3 . 
   As a print command on a document is input from the external device such as personal computer, a control part (not shown) of the printer  100  drives the pick-up roller  109  so that the uppermost paper P in the stack unit  101  is picked up by the pick-up roller  109  and fed to the register roller  123  by the first and the second feeding rollers  121 ,  122 . 
   The leading end of the paper P is fed to the register roller  124  and pressed and aligned by the nip between the register roller  123  and the back up roller  125 . 
   Then, as the paper P passes the nip between the register roller  123  and the back up roller  125  and continues to move, the leading end of the paper P actuates the paper sensor  130  between the register roller  123  and the transfer roller  105 , and the paper sensor  130  sends a paper sensing signal to the control part. 
   The control part counts the moving time of paper P from the paper sensor  130  to the transfer roller  105  according to the paper sensing signal, and after feeding the paper P during the preset required time arriving at the printing start position, operates the process cartridge  106  and the transfer roller  105 . 
   While the paper P is fed to the printing start position, an electrostatic latent image is formed on the photosensitive body  143  of the process cartridge  106  by the laser beam emitted from the LSU  104  according to the image signal. The electrostatic latent image formed on the photosensitive body  143  is developed into a visible developer image by the developing roller  163 . 
   Then, as the paper P arrives at the photosensitive body  143  of the process cartridge  106 , the developer image formed on the photosensitive body  143  is transferred onto the paper P by the transfer roller  105  under the control of the control part. 
   Passing the fixing unit  107 , the developer image transferred onto the paper P is fixed on the paper P by the heat and pressure of the heating roller  126  and the press roller  127 . The paper P fixed with the developer image is discharged to the stack  129  by the discharge roller  128  of the discharge unit  108 . 
   Then, the operations of picking up, developing, fixing and discharging the paper P are repeated according to the aforementioned method until all contents of the document are printed. 
   As described above, the process cartridge according to an embodiment of the present invention, the image forming apparatus having the cartridge, and the method for mounting and dismounting the process cartridge in and from the image forming apparatus can guide the mounting of the housing and position the housing in a mounting position only by using the first and the second guide protrusions as the process cartridge is mounted in or dismounted from the main body frame. Therefore, the process cartridge can have a simpler structure and can be easily mounted in or dismounted from the image forming apparatus in comparison with the conventional process cartridge. 
   The process cartridge according to an embodiment of the present invention and the image forming apparatus having the cartridge, and the method for mounting and dismounting the process cartridge in and from the image forming apparatus includes the cartridge mount and dismount supporting part which is formed on the bottom surface of the first and the second side plate of the housing and has the most efficient movement by the knob so that the process cartridge can be easily and efficiently mounted in or dismounted from the image forming apparatus by the knob. 
   The process cartridge according to an embodiment of the present invention and the image forming apparatus having the same, and the method for mounting and dismounting the process cartridge in and from the image forming apparatus includes the guide rails with opened top portion, instead of including the guide recess guiding the guide protrusions as the conventional process cartridge, so as to be easily manufactured and have a simpler structure. Additionally, the guide protrusions are not required to fit in the guide recess to mount and dismount the process cartridge in or from the main body frame. Therefore, the time required to mount and dismount the process cartridge in or from the main body frame can be significantly shortened. Although the process cartridge is pulled out by force, the guide protrusions are not damaged. 
   While the invention has been shown and described with reference to certain embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.