Patent Publication Number: US-11644787-B2

Title: Clutch mechanism for a development system

Description:
BACKGROUND 
     An image forming apparatus forms an image on a recording medium, for example, in an electrophotographic manner. An image forming apparatus using the electrophotographic method supplies toner to an electrostatic latent image formed on a photoconductor to form a visible toner image on the photoconductor, transfers the toner image to the recording medium via an intermediate transfer medium or directly to a recording medium, and then fixes the transferred toner image on the recording medium. 
     A development system may include a development cartridge capable of being detachably attached to the image forming apparatus. The development cartridge may include an assembly of elements for forming the visible toner image. The development cartridge may be detachably attached to a main body of the image forming apparatus and be a consumable item that is replaced when its service life is over. In a development cartridge using a contact development method, a developing roller and a photoconductor contact each other, thereby forming a development nip. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic configuration diagram illustrating an image forming apparatus according to an example; 
         FIG.  2    is a side view of a development cartridge according to an example, which illustrates a state in which a photosensitive drum and a developing roller contact each other to form a development nip; 
         FIG.  3    is a side view of a development cartridge according to an example, which illustrates a state in which a photosensitive drum and a developing roller are separated from each other to release a development nip; 
         FIG.  4    is a schematic configuration diagram of an image forming apparatus according to an example, which illustrates a state in which a developing unit is in a development position; 
         FIG.  5    is a schematic configuration diagram of an image forming apparatus according to an example, which illustrates a state in which a developing unit is in a release position; 
         FIG.  6    is a schematic configuration diagram illustrating an image forming apparatus according to an example; 
         FIG.  7    is a block diagram of an image forming apparatus according to an example; 
         FIGS.  8  and  9    are illustrations of a development system in printing and alienation orientations, according to an example; 
         FIGS.  10  and  11    include a perspective view and a rear view of a clutch mechanism, respectively, according to an example; 
         FIG.  12    is an exploded view of the clutch mechanism, according to an example; and 
         FIGS.  13 A and  13 B  are perspective views of a portion of the clutch mechanism, according to an example. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, examples of an electrophotographic image forming apparatus and a development system having a development cartridge will be described in detail with reference to the accompanying drawings. Elements having substantially the same configurations are denoted by the same reference numerals in the specification and the accompanying drawings, and thus, a repeated description thereof is omitted. 
     According to the disclosure, a development system includes a photosensitive unit including a photosensitive drum, a developing unit including a developing roller, the developing unit being coupled to the photosensitive unit such that the developing unit is movable to a development position where a development nip forms by contact between the developing roller and the photosensitive drum and is movable to a release position where the development nip is released, and a pressurizing unit to be shifted to a first position where the pressurizing unit applies an elastic force to the developing unit in a direction such that the developing unit is maintained in the development position, and is shifted to a second position where the pressurizing unit applies an elastic force to the developing unit in a direction such that the developing unit is maintained in the release position. 
     According to the disclosure, the photosensitive drum may include a drive plate to receive a driving force to rotate the photosensitive drum, the drive plate being provided on an end of the photosensitive drum. The developing roller may have a clutch mechanism to dampen a force generated when the clutch mechanism engages the drive plate of the photosensitive drum, the clutch mechanism being provided on an end of the developing roller. 
     According to the disclosure, an image forming apparatus may include a main body, and the above-described development system, which may be detachable from the main body. 
       FIG.  1    is a schematic configuration diagram illustrating an electrophotographic image forming apparatus, according to an example. An image forming apparatus according to the example prints a color image to a recording medium P in an electrophotographic manner. Referring to  FIG.  1   , the image forming apparatus may include a main body  1 , a plurality of development cartridges  2 , an exposure device  13 , a transfer device, and a fuser  15 . 
     For color printing, the plurality of development cartridges  2  may include four development cartridges  2  for developing images with cyan color, magenta color, yellow color, and black color, respectively. Toners, of cyan (C) color, magenta (M) color, yellow (Y) color, and black (K) color may be contained in the four development cartridges  2 , respectively. Although not illustrated, the toners of cyan color, magenta color, yellow color, and black color may be respectively contained in four toner supply containers, and may be respectively supplied from the four toner supply containers to the four development cartridges  2 . The image forming apparatus may further include development cartridges  2  for containing and developing toners of other various colors such as light magenta color and white color. Hereinafter, unless there is a particular description contrary thereto, items with reference characters C, M, Y, and K indicate elements for developing images with cyan color, magenta color, yellow color, and black color, respectively. 
     The main body  1  includes an opening  11  that provides a path for mounting/detaching the plurality of development cartridges  2 . A cover  12  opens and closes the opening  11 . The exposure device  13 , the transfer device, and the fuser  15  are arranged at the main body  1 . In addition, a recording medium transport unit for loading and transporting the recording medium P where an image is to be formed is arranged at the main body  1 . 
     In the example, each of the plurality of development cartridges  2  is an integrated development cartridge. Each development cartridge  2  may include a photosensitive unit  100  and a developing unit  200 . 
     The photosensitive unit  100  includes a photosensitive drum  21 . The photosensitive drum  21 . The photosensitive drum  21 , as a photoconductor or organic photoconductor on which an electrostatic latent image is formed, may include a conductive metal pipe and a photosensitive layer formed at an outer circumference of the conductive metal pipe. A charging roller  23  is an example of a charger that charges a surface of the photosensitive drum  21  to have a uniform surface potential. Instead of the charging roller  23 , a charging brush, a corona charger, or the like may be used. The photosensitive unit  100  may further include a cleaning roller (not shown) for removing foreign substances attached to a surface of the charging roller  23 . A cleaning blade  25  is an example of a cleaning member that removes residual toners and foreign substances attached to the surface of the photosensitive drum  21  after a transfer process described below. Instead of the cleaning blade  25 , a cleaning device in another form, such as a rotating brush, may be used. 
     The developing unit  200  includes a toner container  201 . The developing unit  200  supplies a toner in the toner container  201  to an electrostatic latent image formed on the photosensitive drum  21 , thereby developing the electrostatic latent image into a visible toner image. A developing method may include a one-component developing method using a toner and a two-component developing method using a toner and a carrier. In the example, the developing unit  200  employs the one-component developing method. A developing roller  22  supplies a toner to the photosensitive drum  21 . A developing bias voltage may be applied to the developing roller  22  to supply the toner to the photosensitive drum  21 . 
     The one-component developing method may be classified into a contact development technique in which the developing roller  22  and the photosensitive drum  21  rotate while contacting each other and a non-contact development technique in which the developing roller  22  and the photosensitive drum  21  rotate while being separate from each other by tens to hundreds of microns. In the example, a contact development technique in which the developing roller  22  and the photosensitive drum  21  contact each other and thus form a development nip N is used. A supply roller  27  supplies the toner in the toner container  201  to a surface of the developing roller  22 . To this end, a supply bias voltage may be applied to the supply roller  27 . The developing unit  20  may further include a regulating member (not shown) for regulating an amount of toner to be supplied by the developing roller  22  to the development nip N where the photosensitive drum  21  and the developing roller  22  contact each other. For example, the regulating member may be a doctor blade that elastically contacts the surface of the developing roller  22 . 
     The exposure device  13  radiates light modulated in correspondence with image information onto the photosensitive drum  21  and thus forms the electrostatic latent image on the photosensitive drum  21 . Examples of the exposure device  13  may include a laser scanning unit (LSU) using a laser diode as a light source and a light-emitting diode (LED) exposure device using an LED as a light source. 
     The transfer device may include an intermediate transfer belt  31 , first transfer rollers  32 , and a second transfer roller  33 . The intermediate transfer belt  31  temporarily receives a toner image developed on the photosensitive drum  21  of each of the development cartridges  2 C,  2 M,  2 Y, and  2 K. The intermediate transfer belt  31  is circulated while being supported by supporting rollers  34 ,  35 , and  36 . Four first transfer rollers  32  are positioned to face the photosensitive drums  21  of the development cartridges  2 C,  2 M,  2 Y, and  2 K with the intermediate transfer belt  31  therebetween. A first transfer bias voltage is applied to the four first transfer rollers  32  to firstly transfer toner images, which are developed on the photosensitive drums  21 , to the intermediate transfer belt  31 . Instead of the first transfer rollers  32 , a corona transfer device or a pin scorotron-type transfer device may be used. The second transfer roller  33  is positioned to face the intermediate transfer belt  31 . A second transfer bias voltage is applied to the second transfer roller  33  to transfer, to the recording medium P, the toner images that are firstly-transferred to the intermediate transfer belt  31 . 
     When a print command is transmitted from a host (not shown), etc., a controller  300  charges, by using the charging roller  23 , the surface of the photosensitive drum  21  to have a uniform surface potential. The exposure device  13  forms electrostatic latent images on the photosensitive drums  21  by scanning four light beams to the photosensitive drums  21  of the development cartridges  2 C,  2 M,  2 Y, and  2 K, the four light beams being modulated according to image information corresponding to cyan, magenta, yellow, and black colors, respectively. The developing rollers  22  of the development cartridges  2 C,  2 M,  2 Y, and  2 K supply C, M, Y, and K toners to the photosensitive drums  21 , respectively, thereby developing the electrostatic latent images into visible toner images. The developed toner images are firstly transferred to the intermediate transfer belt  31 . Recording media P loaded on a loading plate  17  are output one by one by a pick-up roller  16 , and are transported to a transfer nip by a feed roller  18 , the transfer nip being formed by the second transfer roller  33  and the intermediate transfer belt  31 . The toner images that are firstly-transferred to the intermediate transfer belt  31  are secondly transferred to the recording medium P due to the second transfer bias voltage applied to the second transfer roller  33 . When the recording medium P passes through the fuser  15 , the toner images are fixed on the recording medium P due to heat and pressure. The recording medium P on which fixing has been completed is externally discharged by a discharge roller  19 . 
     The development cartridges  2 C,  2 M,  2 Y, and  2 K may be sequentially detachably attached to the main body  1  through the opening  11  opened by the door  12 . That is, the plurality of development cartridges  2  may be mounted on the main body  1  by opening the door  12  and causing the development cartridges  2  to slide in a mounting direction B 1 . Also, the development cartridges  2  may be detached from the main body  1  by opening the door  12  and causing the development cartridges  2  to slide in a removal direction B 2 . 
     The development cartridges  2 C,  2 M,  2 Y, and  2 K may be mounted on the main body  1  in a tray manner. The main body  1  includes a tray  5  which is loaded with the development cartridges  2 C,  2 M,  2 Y, and  2 K which can be inserted into the main body  1  and retracted from the main body  1 . For example, after the door  12  is opened, and the tray  5  is brought out of the main body  1  by causing the tray  5  to slide in the removal direction B 2 , the development cartridges  2 C,  2 M,  2 Y, and  2 K may be loaded on the tray  5 . Next, the tray  5  may be inserted into the main body  1  by causing the tray  5  to slide in the mounting direction B 1 , and the door  12  may be closed. 
       FIGS.  2  and  3    are side views illustrating the development cartridge  2  according to an example.  FIG.  2    illustrates a state in which the photosensitive drum  21  and the developing roller  22  contact each other to form the development nip N. In this state, the developing roller  22  and photosensitive drum  21  may be referred to as being in a printing orientation where the developing roller  22  is in a printing or development or first position for the operation of printing.  FIG.  3    illustrates a state in which the photosensitive drum  21  and the developing roller  22  are separated from each other to release the development nip N. In this state, the developing roller  22  and photosensitive drum  21  may be referred to as being in an alienation orientation where the developing roller  22  is in an alienation or release or second position so as to be separated from the photosensitive drum  21  in a non-printing position. The developing roller  22  and photosensitive drum  21  may be set to the alienation orientation to reduce wear and tear of these components which may be caused due to friction between the developing roller  22  and photosensitive drum  21 . The developing roller  22  and photosensitive drum  21  may be set to the alienation orientation when the image forming apparatus is not in use, when the image forming apparatus is to be transported, or when the image forming apparatus is to be powered off, for example. The developing roller  22  and photosensitive drum  21  may be set to the alienation orientation when the development cartridge  2  is not in use, when the development cartridge  2  is to be transported, or when development cartridge  2  is to be removed from or inserted into the image forming apparatus, for example. 
     Referring to  FIGS.  2  and  3   , the development cartridge  2  includes the photosensitive unit  100  and the developing unit  200 . The photosensitive unit  100  includes a first frame  110  and the photosensitive drum  21  is supported by the first frame  110 . The developing unit  200  includes a second frame  210  and the developing roller  22  is supported by the second frame  210 . The developing unit  200  is coupled to the photosensitive unit  100  to be rotatable to the development position ( FIG.  2   ) in which the photosensitive drum  21  and the developing roller  22  contact each other to form the development nip N and a release position ( FIG.  3   ) in which the photosensitive drum  21  and the developing roller  22  are separated from each other to release the development nip N. For example, the developing unit  200  is coupled to the photosensitive unit  100  to be rotatable to the development position and the release position with respect to a hinge shaft  301 . 
     The development cartridge  2  further includes a pressurizing unit  400 . The pressurizing unit  400  is installed at the photosensitive unit  100  and elastically presses the developing unit  200 . A rotation direction of the developing unit  200  is determined according to a position of a portion pressed by the pressurizing unit  400 . The developing unit  200  includes first and second pressing portions  221  and  222 . The pressurizing unit  400  may move to a first position for pressing the first pressing portion  221  and a second position for pressing the second pressing portion  222 . For example, the pressurizing unit  400  is mounted on a rotation shaft  302  provided in the photosensitive unit  100  to be rotatable to the first and second positions. The first position is a position for pressing the first pressing portion  221  and rotating the developing unit  200  with respect to the hinge shaft  301  in a first direction A 1  for forming the development nip N, and the second position is a position for pressing the second pressing portion  222  and rotating the developing unit  200  with respect to the hinge shaft  301  in a second direction A 2  for releasing the development nip N. The pressurizing unit  400  applies an elastic force in a direction of maintaining the developing unit  200  in the development position to the developing unit  200  at the first position and applies an elastic force in a direction of maintaining the developing unit  200  in the release position to the developing unit  200  at the second position. 
     The first pressing portion  221  is at an opposite side to that of the developing roller  22 , based on a line L connecting the rotation shaft  302  and the hinge shaft  301  to each other, and the second pressing portion  222  is at the same side as the developing roller  22 , based on the line L. A first stopper  221   a  prevents the pressurizing unit  400  from rotating beyond the first pressing portion  221 . A second stopper  222   a  prevents the pressurizing unit  400  from rotating beyond the second pressing portion  222 . A first position determiner  221   b  is at an opposite side to that of the first stopper  221   a  based on a rotation direction of the pressurizing unit  400  and maintains the pressurizing unit  400  in the first position. A second position determiner  222   b  is at an opposite side to that of the second stopper  222   a  based on the rotation direction of the pressurizing unit  400  and maintains the pressurizing unit  400  in the second position. While being elastically compressed towards the rotation shaft  302 , the pressurizing unit  400  may rotate to the second position or the first position beyond the first and second position determiners  221   b  and  222   b . The pressurizing unit  400  includes an interference lever  440  which may be interfered with by an operating portion (not shown) of the main body  1  when the development cartridge  2  is loaded on the tray  1  and mounted on the main body  1 , such that the pressurizing unit  400  is rotated from the second position to the first position with respect to the rotation shaft  302 . 
     As illustrated in  FIG.  2   , in a state in which the pressurizing unit  400  is at the first position, the pressing member  420  contacts and pushes the first pressing portion  221 . A direction of an elastic force applied to the first pressing portion  221  by the pressurizing unit  400  is a direction of forming the development nip N. That is, the developing unit  200  is elastically biased to rotate in the first direction A 1  by an elastic force of the pressurizing unit  400  in the first position. The development nip N may be maintained in a formed state by the elastic force of the pressurizing unit  400 . 
     Thus, when the pressurizing unit  400  is at the first position, the pressurizing unit  400  provides a maintaining force maintaining the development nip N to the developing unit  200 . Until the pressurizing unit  400  reaches the line L from the first position, the maintaining force is continuously provided to the developing unit  200 . Accordingly, in spite of external shock applied to an image forming apparatus or operation shock of an image forming apparatus, the development nip N may be stably maintained in a formed state, and thus, stable image quality may be obtained. 
     As illustrated in  FIG.  3   , in a state in which the pressurizing unit  400  is at the second position, a direction of an elastic force applied to the second pressing portion  222  by the pressurizing unit  400  is a direction of releasing the development nip N. That is, the developing unit  200  is elastically biased to rotate in the second direction A 2  by an elastic force of the pressurizing unit  400  in the second position. Accordingly, the development nip N may be maintained in a released state by the elastic force of the pressurizing unit  400 . 
     Thus, when the pressurizing unit  400  is at the second position, the pressurizing unit  400  provides a releasing force releasing the development nip N to the developing unit  200 . Until the pressurizing unit  400  reaches the line L from the second position, the releasing force is continuously provided to the developing unit  200 . Accordingly, the development nip N may be stably maintained in a released state even during a process of providing the development cartridge  2  for manufacture, transport, and sales, and thus, deformation or destruction of the developing roller  22  and/or the photosensitive drum  21  may be reduced. 
     Through the above-described configuration, by moving the pressurizing unit  400  provided in the development cartridge  2  to the first and second positions, the development nip N may be easily formed/released. 
     A coupling form of the developing unit  200  and the photosensitive unit  100  is not limited to the examples described above. As another example, the developing unit  200  may be coupled to the photosensitive unit  100  to be slidable to a development position where the development nip N is formed and a release position where the development nip N is released. 
       FIGS.  4  and  5    are schematic configuration diagrams of an image forming apparatus according to an example, in which  FIG.  4    illustrates a state in which the developing unit  200  is in a development position, and  FIG.  5    illustrates a state in which the developing unit  200  is in a release position. 
     Referring to  FIGS.  4  and  5   , the developing unit  200  is coupled to the photosensitive unit  100  to be slidable to a development position ( FIG.  4   ) where the photosensitive drum  21  and the developing roller  22  contact each other to form the development nip N and a release position ( FIG.  5   ) where the photosensitive drum  21  and the developing roller  22  are separated from each other to release the development nip N. For example, the photosensitive unit  100  includes first and second guide slots  121  and  122 , and the developing unit  200  includes first and second guide protrusions  231  and  232  respectively inserted into the first and second guide slots  121  and  122 . The first and second guide slots  121  and  122  extend in a sliding direction of the developing unit  200  and are separate from each other in the sliding direction. A width W of the first and second guide slots  121  and  122  in a direction perpendicular to the sliding direction is a little greater than a width, for example, a diameter, of the first and second guide protrusions  231  and  232 . Thus, the developing unit  200  may slide along the first and second guide slots  121  and  122 , and at the same time, may rotate slightly. 
     The development cartridge  2  further includes the pressurizing unit  500 . The pressurizing unit  500  may include a first rotation member  510 , a second rotation member  520 , and an elastic member  530 . The first rotation member  510  includes a first hinge hole into which a first rotation shaft  131  provided in the photosensitive unit  100  is inserted, such that the first rotation member  510  may rotate around the first rotation shaft  131  via the first hinge hole. The second rotation member  520  includes a second hinge hole into which a second rotation shaft  241  provided in the developing unit  200  is inserted, such that the second rotation member  520  may rotate around the second rotation shaft  241  via the second hinge hole. The first and second rotation members  510  and  520  are elastically slidably connected between the first and second rotation shafts  131  and  241 . 
     The pressurizing unit  500  has a first position ( FIG.  4   ) where an elastic force is applied to the developing unit  200  to slide in a direction of forming the development nip N and a second position ( FIG.  5   ) where an elastic force is applied to the developing unit  200  to slide in a direction of releasing the development nip N. At the first position, the developing unit  200  is in the development position, and at the second position, the developing unit  200  is in the release position. Based on a line L 2  passing through the first rotation shaft  131  and perpendicular to an extending direction of the first and second guide slots  121  and  122 , that is, a sliding direction of the developing unit  200 , the second rotation shaft  241  is at the same side as the developing roller  22  at the first position and is at an opposite side thereof at the second position. Through the above-described configuration, elastic forces of the pressurizing unit  500  applied when the pressurizing unit  500  is at the first and second positions respectively work in a direction of forming and maintaining the development nip N and in a direction of releasing the development nip N. 
     As illustrated in  FIG.  4   , in a state in which the pressurizing unit  500  is at the first position, an elastic force of the pressurizing unit  500  is applied in a direction of causing the developing unit  200  to slide downwards. Accordingly, the development nip N may be maintained in a formed state by the elastic force of the pressurizing unit  500 . 
     As illustrated in  FIG.  5   , in a state in which the pressurizing unit  500  is at the second position, a direction of an elastic force applied to the developing unit  200  by the pressurizing unit  500  is a direction of releasing the development nip N. When the developing unit  200  slides in a direction in which the developing roller  21  approaches the photosensitive drum  21 , the elastic force of the pressurizing unit  500  is maintained in the direction of releasing the development nip N until the pressurizing unit  500  rotates and reaches the line L 2 . 
     When the developing unit  200  further slides, and thus, the pressurizing unit  500  rotates beyond the line L 2 , the direction of the elastic force of the pressurizing unit  500  is shifted to a direction of causing the developing unit  200  to slide in the direction in which the developing roller  22  approaches the photosensitive drum  21 . Accordingly, due to the elastic force of the pressurizing unit  500 , the developing unit  200  more easily slides in the direction in which the developing roller  22  approaches the photosensitive drum  21 . 
     When the pressurizing unit  500  reaches the first position, the developing roller  22  may contact the photosensitive drum  21  to form the development nip N as illustrated in  FIG.  4   , and the development nip N may be maintained in a formed state by the elastic force of the pressurizing unit  500 . 
     Through the above-described configuration, the pressurizing unit  500  provided in the development cartridge  2  itself may be shifted to the first and second positions by causing the developing unit  200  to slide with respect to the photosensitive unit  100 , and thus, the development nip N may be easily formed/released. 
     In the above-described example, a structure in which the photosensitive unit  100  includes first and second guide slots and the developing unit  200  includes first and second guide protrusions is employed. However, a structure in which the developing unit  200  includes first and second guide slots and the photosensitive unit  100  includes first and second guide protrusions may also be employed. The number of each of a guide slot and a guide protrusion is not limited to 2, and three or more may be provided. 
     As denoted by dashed lines in  FIGS.  4  and  5   , the main body  1  includes an operating portion  60  which may interfere with the developing unit  200 . Referring to  FIG.  5   , when the development cartridge  2  is mounted on the main body  1 , the operating portion  60  interferes with the developing unit  200  positioned in a release position and thus guides the developing unit  200  to move in a direction in which the developing roller  22  approaches the photosensitive drum  21 . For example, the operating portion  60  may be inclined downwards in the mounting direction B 1 . When the development cartridge  2  is mounted on the main body  1  in a state in which the pressurizing unit  500  is at the second position, the developing unit  200  is guided by the operating portion  60  to move in the direction in which the developing roller  22  approaches the photosensitive drum  21 , and the pressurizing unit  500  is rotated from the second position to the first position with respect to the first and second rotation shafts  131  and  241 . When the pressurizing unit  500  reaches the first position as illustrated in  FIG.  4   , the development nip N is formed. 
     A structure in which the development cartridge  2  is mounted on the main body  1  and then the operating portion  60  is moved in the mounting direction B 1  or the removal direction B 2  to rotate the pressurizing unit  500  to the first and second positions may be employed. Referring to  FIGS.  4  and  5   , for example, the operating portion  60  has a structure capable of, while moving in the removal direction B 2 , interfering with the developing unit  200  and causing the developing unit  200  to slide, thereby rotating the pressurizing unit  500  in the second position to the first position. For example, the operating portion  60  may be inclined downwards in the mounting direction B 1 . Through the above-described configuration, after the development cartridge  2  is mounted on the main body  1  in a state in which the pressurizing unit  500  is at the second position, the pressurizing unit  500  may be rotated from the second position to the first position while the operating portion  60  is moved in the removal direction B 2 . The mounting portion  60  may be moved in conjunction with a closing operation of the door  12 , and may be moved by a driver  70 . The driver  70  may be implemented, for example, by a linear motor, a solenoid actuator, or a rotary motor and a converter for converting rotary movement of the rotary motor into reciprocal movement of the operating portion  60 . 
       FIG.  6    is a schematic configuration diagram illustrating an image forming apparatus according to an example. The image forming apparatus according to the example is a single-color image forming apparatus. In  FIG.  6   , elements performing the same functions as those of the image forming apparatus illustrated in  FIG.  1    are denoted by the same reference numerals, and a repeated description thereof is omitted. 
     The development cartridge  2  includes the photosensitive unit  100  and the developing unit  200 . The photosensitive unit  100  includes the photosensitive drum  21  and the charging roller  23 . Reference numeral  24  denotes a cleaning roller for removing foreign substances attached on the charging roller  23 . The developing unit  200  includes the developing roller  22  and the supply roller  27 . First and second agitators  28   a  and  28   b  for stirring toner and carrying toner to the supply roller  27  may be arranged in the toner container  201 . Reference numeral  25  denotes a regulating member for regulating an amount of toner which is attached to the developing roller  22  and is supplied to the development nip N. 
     A transfer roller  14  faces the photosensitive drum  1 , and the recording medium P is transported between the photosensitive drum  21  and the transfer roller  14 . 
     Through the above-described configuration, the exposure device  13  forms an electrostatic latent image by scanning light modulated according to image information to the photosensitive drum  21 . The developing roller  22  forms a visible toner image on a surface of the photosensitive drum  21  by supplying toner to the electrostatic latent image. The recording medium P loaded on the loading plate  17  is transported to an area where the photosensitive drum  21  and the transfer roller  14  face each other by the pick-up roller  16  and the feed roller  18 , and the toner image is transferred from the photosensitive drum  21  to the recording medium P by a transfer bias voltage applied to the transfer roller  14 . When the recording medium P passes through the fuser  15 , the toner image is fixed on the recording medium P due to heat and pressure. The recording medium P on which fixing has been completed is discharged by the discharge roller  19 . 
       FIGS.  2  through  5    described example structures by which the developing roller  22  may be moved so as to contact the photosensitive drum  21  to form the development nip N, so that the developing roller  22  and photosensitive drum  21  are arranged in a printing orientation where the developing roller  22  is in a printing or development or first position for the operation of printing. 
       FIGS.  2  through  5    also described example structures by which the developing roller  22  may be moved so as to be spaced apart from the photosensitive drum  21  to release the development nip N, so that the developing roller  22  and photosensitive drum  21  are arranged in an alienation orientation where the developing roller  22  is in an alienation or release or second position so as to be separated from the photosensitive drum  21  in a non-printing position. The example structures illustrated in  FIGS.  2  through  5    may be applied to the image forming apparatus of  FIG.  1    as well as the image forming apparatus of  FIG.  6   . Further, the example structures illustrated in  FIGS.  2  through  5    may be applied to other kinds of image forming apparatuses. 
       FIG.  7    is a block diagram of an image forming apparatus according to an example. 
     Referring to  FIG.  7   , the image forming apparatus  1000  may include some or all of the features shown in the image forming apparatuses illustrated in  FIGS.  1  and  6   . With reference to  FIG.  7   , the image forming apparatus  1000  includes a controller  1010 , a display  1020 , a user interface  1030 , an image forming unit  1040 , a storage  1050 , a communication interface  1060 , and a driving source  1070 . 
     The controller  1010  may execute instructions stored in the storage  1050 . The controller  1010  may include, for example, a processor, an arithmetic logic unit, a central processing unit (CPU), a graphics processing unit (GPU), a digital signal processor (DSP), an image processor, a microcomputer, a field programmable array, a programmable logic unit, an application-specific integrated circuit (ASIC), a microprocessor, or combinations thereof. 
     The display  1020  may display information regarding the image forming apparatus  1000 . The display  1020  may include a liquid crystal display (LCD), a light emitting diode (LED) display, an organic light emitting diode (OLED) display, active matrix organic light emitting diode (AMOLED), flexible display, 3D display, a plasma display panel (PDP), a cathode ray tube (CRT) display, and the like, for example. The display  1020  may also include a touchscreen to receive the user input and therefore may also be utilized as a user interface. 
     The user interface  1030  may receive a user input to perform an operation or function of the image forming apparatus  1000 , and may provide a user with information regarding the image forming apparatus  1000 . The user interface  1030  may include, for example, a keyboard (e.g., a physical keyboard, virtual keyboard, etc.), a mouse, a joystick, a button, a switch, an electronic pen or stylus, a gesture recognition sensor (e.g., to recognize gestures of a user including movements of a body part), an input sound device or voice recognition sensor (e.g., a microphone to receive a voice command), a track ball, or combinations thereof. The user interface  1030  may further include a haptic device to provide haptic feedback to a user. The user interface  1030  may also include a touch screen, for example. 
     The image forming unit  1040  may perform an image forming job by forming an image on a recording medium to perform a job such as printing, copying, and faxing, for example. The image forming unit  1040  may include a print engine which receives a control signal from the controller  1010  to perform an image forming or printing operation. The image forming unit  1040  may include a development system including the development cartridge  2 . 
     The storage  1050  may include, for example, machine readable storage devices which may be any electronic, magnetic, optical, or other physical storage device that stores executable instructions. For example, the storage  1050  may include a nonvolatile memory device, such as a Read Only Memory (ROM), Programmable Read Only Memory (PROM), Erasable Programmable Read Only Memory (EPROM), and flash memory, a USB drive, a volatile memory device such as a Random Access Memory (RAM), a hard disk, floppy disks, a blue-ray disk, or optical media such as CD ROM discs and DVDs, or combinations thereof. 
     The image forming apparatus  1000  may be connected with another device such as a laptop, personal computer, tablet, mobile phone, server, or combinations thereof, in a wired and/or wireless manner, for example through a communication interface  1060 . The image forming apparatus  1000  may be connected over a network such as a local area network (LAN), wireless local area network (WLAN), wide area network (WAN), personal area network (PAN), virtual private network (VPN), or the like. For example, wireless communication between elements of the examples disclosed herein may be performed via a wireless LAN, Wi-Fi, Bluetooth, ZigBee, Wi-Fi direct (WFD), ultra wideband (UWB), infrared data association (IrDA), Bluetooth low energy (BLE), near field communication (NFC), a radio frequency (RF) signal, and the like. For example, the wired communication connection may be performed via a pair cable, a coaxial cable, an optical fiber cable, an Ethernet cable, and the like. 
     The driving source  1070  may be coupled directly or indirectly to a rotatable shaft to rotate a body, for example a roller of the image forming apparatus  1000 . The driving source  1070  may include a motor, a solenoid, another electromechanical device, or combinations thereof. For example, the driving source  1070  may include a motor, a gear coupled to a rotatable shaft, and a driving belt coupling the motor to the gear to drive rotation of the rotatable shaft according to a signal output from the controller  1010 . The rotatable shaft may be rotated in a first direction and a second direction by the driving source  1070 . The first direction may be referred to as a “forward” direction and the second direction may be referred to as a “reverse” direction. A driving source may be provided to drive more than one body. For example, a single driving source may be provided to cause more than one body to move or rotate. 
       FIGS.  8  and  9    are illustrations of a development system in printing and alienation orientations, respectively, according to an example. 
     Referring to  FIG.  8   , a development system  800  is illustrated, including the photosensitive drum  21 , developing roller,  22 , and supply roller  27 . The term photosensitive drum may be interchangeably used with the term photoconductor. In  FIG.  8   , the development system  800  is in the printing orientation, where the photosensitive drum  21  is in contact, for example frictional contact, with the developing roller  22 . An image forming operation, for example, a printing operation, can be performed while the development system  800  is in the printing orientation. In  FIG.  8    the developing roller  22  may be referred to as being in a printing or development or first position for performing an image forming operation such as printing, as discussed above with respect to the examples of  FIGS.  2  through  5   . 
     As illustrated in  FIG.  8   , at one end of the photosensitive drum  21 , a drive plate  810  is provided. The drive plate  810  may receive a driving force to rotate the photosensitive drum  21 , for example, as indicated in  FIG.  8    in the direction T 1 . The driving force may be provided to the drive plate  810  according to a control signal from the controller  1010  to perform an image forming or printing operation. The drive plate  810  may receive the driving force from the driving source  1070 , directly or indirectly. The drive plate  810  may have a cylinder shape and protrude from an end of the photosensitive drum  21 . The drive plate  810  is connected to a rotational drive shaft of the photosensitive drum  21  to rotate the photosensitive drum  21 . 
     As illustrated in  FIG.  8   , at one end of the developing roller  22  a clutch mechanism  820  is provided. The developing roller  22  may be driven by rotation of the photosensitive drum  21 , for example, as indicated in  FIG.  8    in the direction T 2 . The developing roller  22  may be driven by rotation of the photosensitive drum  21  by friction, and thus a separate driving source may not be provided for the developing roller  22  and a single driving source can be utilized to drive both the photosensitive drum  21  and the developing roller  22 . The clutch mechanism  820  may also be in contact with or engage a portion of the drive plate  810  when the development system  800  is in the printing orientation. The clutch mechanism  820  serves to dampen a force generated when the clutch mechanism  820  engages the drive plate  810  of the photosensitive drum  21 . As discussed above, the developing roller  22  is movable to a first position where the developing roller  22  is to receive a frictional driving force from the photosensitive drum  21  to rotate the developing roller  22 , and movable to a second position where the developing roller  22  and photosensitive drum  21  are spaced apart from one another. The clutch mechanism  820  engages the drive plate  810  when the developing roller  22  is moved from the second position to the first position. 
     The supply roller  27  may be rotated in the direction T 1  by rotation of the developing roller  22 . The supply roller  27  may include gearing provided at an end of the supply roller  27  which interacts with gearing provided at an end of the developing roller  22  to transfer rotation forces from the developing roller  22  to the supply roller  27 . 
     The clutch mechanism  820  is a low cost, compact, fully mechanical system which can be implemented in the development system  800  to prevent or reduce wear or damage to the development system  800 . 
     As illustrated in  FIG.  9   , the development system  800  is in the alienation orientation and the developing roller  22  is spaced apart from the photosensitive drum, for example by a distance x. Thus, mechanical wear can be reduced or prevented with respect to the photosensitive drum  21  and developing roller  22 . That is, if the photosensitive drum  21  and developing roller  22  are maintained in the printing orientation to form the development nip, over time the developing roller  22  may be deformed and the photosensitive drum  21  may be damaged. The deformation of the developing roller  22  and the damage to the photosensitive drum  21  may cause a change in the development nip and thus may reduce image quality. The reduction or prevention of mechanical wear by providing for the developing roller  22  to be spaced apart from the photosensitive drum  21 , allows the developing roller  22  to keep its form and increase its lifetime to allow for more rotations of the developing roller  22 . For example, when the photosensitive drum  21  is rotated while the developing roller  22  is in the second or alienation position, the developing roller  22  is not rotated by the friction force of the photosensitive drum  21 . The development system  800  may be transitioned between the alienation orientation and printing orientation by using the example structures discussed above with respect to  FIGS.  2  through  5   , however these are merely examples and other structures may be implemented to transition the development system  800  between the alienation orientation and printing orientation. 
     The development system  800  may be further provided with the clutch mechanism  820  which may provide a smooth transition of the development system  800  between the alienation orientation and the printing orientation. For example, when the developing roller  22  is moved from the second position (alienation position) to the first position (development position), there may be an initial jarring reaction between the photosensitive drum  21  and the developing roller  21 . The force generated by transitioning between the alienation orientation and the printing orientation may cause wear or damage to the photosensitive drum  21  and developing roller  22 . To reduce or prevent such wear and damage, the clutch mechanism  820  dampens the force generated when the development system  800  transitions between the alienation orientation and the printing orientation. 
     Referring to  FIGS.  10  and  11   , a perspective view and a rear view of the clutch mechanism  820  are respectively shown, according to an example.  FIG.  12    is an exploded view of the clutch mechanism  820 , according to an example. The clutch mechanism  820  may include a friction plate  821 , a plurality of urging members  822 , a freewheel  823 , a front plate  824 , and an outer housing  825 . 
     The friction plate  821  is a cylindrical ring-shaped member that has an outer circumferential surface  821   a  which contacts an outer circumferential surface  810   a  of the drive plate  810  when the development system  800  is in the printing orientation. The circumferential surface  821  of the friction plate  821  may have a rough, sandpaper like material, while the circumferential surface  810   a  of the drive plate  810  may have a rubber-like material. In another example, the circumferential surface  821  of the friction plate  821  may have a rubber like material, while the circumferential surface  810   a  of the drive plate  810  may have the rough, sandpaper like material. A coefficient of friction of the circumferential surface  821  of the friction plate  821  and the circumferential surface  810   a  of the drive plate  810  may be between about 0.5 and 1, to reduce or prevent slippage. The friction plate  821  can engage the drive plate  810  while the drive plate  810  is rotating, for example, when the developing roller  22  is moved from the second position to the first position, and the urging members  822  dampen the force generated when the friction plate  821  comes into contact with the drive plate  810  by pressing against a surface of the freewheel  823 . 
     The friction plate  821  may be formed together as a single integral piece with the outer housing  825 , which is provided on an interior circumferential surface  821   b  of the friction plate  821 . A height of the friction plate  821  having the cylindrical shape may be about one-fourth to one-third of the diameter of the friction plate. A radius of the friction plate  821  may be determined in view of the width x that the developing roller  22  is spaced apart from the photosensitive drum  21 , such that the friction plate  821  contacts the drive plate  810  at a same time that the developing roller  22  contacts the photosensitive drum  21 . For example, the circumferential surface  821   a  of the friction plate  821  may engage a circumferential surface  810   a  of the drive plate  810  while the drive plate  810  is rotating, when the developing roller  22  is moved from the second position to the first position to contact the photosensitive drum  21 . The diameter of the friction plate  821  is greater than a diameter of the developing roller  22 . The diameter of the drive plate  810   a  is less than a diameter of the photosensitive drum  21 . 
     As shown in  FIG.  12   , the outer housing  825  includes a plurality of holes, which may be rectangular in shape, to accommodate the urging members  822 . The holes may be of a same size as the holes provided in the freewheel  823  and front plate  824 , which are also provided so as to accommodate the urging members  822 . Elliptically-shaped holes  825   d  may also be provided in the outer housing  825  to reduce material usage. The shape and number of the holes  825   d  provided in the outer housing  825  may be varied. In  FIGS.  10 - 12    there are seven holes  825   d  provided in the outer housing  825 , however as stated above there may be less seven holes or more than seven holes. The outer housing  825  includes bolts, which may be provided circumferentially about the outer housing  825 , and may be used to secure the front plate  824  to the outer housing  825 , with the freewheel  823  disposed between the front plate  824  and the outer housing  825 . In  FIGS.  13 A- 13 B  the outer housing  825  includes four bolts  825   a - 825   d , however there may be more than four bolts or less than four bolts. The bolts  825   a - 825   d  may be provided in the outer housing  825  between the holes in which the urging members are provided. 
     The clutch mechanism  820  may include a plurality of urging members  822  which are provided on an interior side of the friction plate  821 . For example, the clutch mechanism  820  may include two to six urging members  822  which are arranged to be spaced apart from one another circumferentially about a center of the clutch mechanism  820 . In  FIGS.  13 A- 13 B , four urging members  822   a - 822   d  are illustrated. The urging members  822  may be of the same size or different size than one another. The urging members  822  may be springs, for example. The springs may be straight, or may be bent to be arc-shaped for example. Although not shown, additional urging members may be provided at a further interior portion of the clutch mechanism  820 , that is, closer to the center of the clutch mechanism than the urging members  822  depicted in  FIG.  10   . The additional urging members provided closer to the center may be of a smaller size than the urging members provided farther from the center. These additional urging members can provide additional dampening forces when the development system is transitioned from the alienation orientation to the printing orientation. 
     The freewheel  823  may be disposed between the front plate  824  and the outer housing  825 . The freewheel  823  may be shaped to have a cross-shape with a cylindrical protrusion  823   a  which protrudes from a center of the freewheel  823 . The freewheel  823  may rotate when the rotational drive shaft  22   a  of the developing roller  22  is rotated. 
     The front plate  824  may be disposed on one side of the freewheel  823  and the outer housing  825 , at a side closer to the developing roller  22  relative to the freewheel  823  and the outer housing  825 . The front plate  824  may include holes or windows to accommodate the urging members  822  and holes or windows through which bolts of the outer housing  825  are inserted so as to connect the front plate  824  to the outer housing  825 . In  FIG.  12   , the holes through which bolts  825   a - 825   d  are to be inserted are not shown. 
       FIGS.  13 A- 13 B  are views of a portion of the clutch mechanism  820 , according to an example. In  FIGS.  13 A- 13 B , the front plate  824  is omitted for purposes of clarity to depict the freewheel  823 . In  FIG.  13 A  the freewheel  823  is in an initial position, while in  FIG.  13 B  the freewheel  823  has been rotated a certain or predetermined amount due to a rotational force applied to the rotational drive shaft  22   a  of the developing roller  22 , such that the urging members  822   a - 822   d  contact or press against an interior surface of a hole or window of the freewheel  823  in which the urging members  822   a - 822   d  are correspondingly provided. The urging members  822   a - 822   d  may also contact or press against an interior surface of a hole or window of the front plate  824  and of a hole or window of the outer housing  825  in which the urging members  822   a - 822   d  are correspondingly provided. Because the urging members  822   a - 822   d  provide a resistive or dampening force, an initial force generated by the engagement of the developing roller  22  with the photosensitive drum  21  can be decreased. 
     As illustrated in  FIGS.  13 A- 13 B , the freewheel  823  may include arms  823   b ,  823   c ,  823   d , and  823   e . Each of the arms  823   b ,  823   c ,  823   d , and  823   e  may have straight or curved edges. In  FIGS.  13 A- 13 B , the arms  823   b ,  823   c ,  823   d , and  823   e  are curved. Between each of the arms  823   b ,  823   c ,  823   d , and  823   e  a space may be formed in which a corresponding bolt  825   a ,  825   b ,  825   c , and  825   d  of the outer housing  825  is provided. In  FIGS.  13 A- 13 B , the space between each of the arms is substantially u-shaped or v-shaped, however the disclosure is not so limited and the space may be differently shaped, for example, rectangular-shaped. Each bolt  825   a ,  825   b ,  825   c , and  825   d  of the outer housing  825  may be inserted through a corresponding hole or gap provided in the front plate  824  and the front plate  824  may be secured to the outer housing  825 . Also in  FIGS.  13 A- 13 B , a substantially rectangular hole is provided in an outer center of each of the arms in which a corresponding urging member  822   a ,  822   b ,  822   c , and  822   d  is provided. Likewise, a corresponding hole is provided in the front plate  824  to accommodate each corresponding urging member  822   a ,  822   b ,  822   c , and  822   d.    
     The cylindrical protrusion  823   a  may be connected to the rotational drive shaft  22   a  of the developing roller  22  so that when the developing roller  22  is rotated, the clutch mechanism  820  is also rotated via the connection of the cylindrical protrusion  823   a  to the rotational drive shaft  22   a  of the developing roller  22 . As illustrated in  FIGS.  13 A- 13 B , when the developing roller  22  is rotated the freewheel  823  is also rotated, and the urging members  822   a - 822   d  provides a dampening force by pressing against a portion of the freewheel. For example, as illustrated in  FIGS.  13 A- 13 B , when freewheel  823  is rotated in a clockwise direction, urging member  822   c  comes into contact with an interior wall  823   f  of the rectangular hole of the freewheel  823  in which urging member  822   c  is provided, so as to provide the dampening force. The urging member  822   c  may be compressed and provide a force in a direction opposite to a direction of the rotation of the freewheel  823  to provide the dampening force. Urging members  822   a ,  822   b , and  822   d  also provide a dampening force in a manner similar to that described above with respect to urging member  822   c . As discussed above, the urging members  822   a - 822   d  may contact or press against an interior surface of a hole or window provided in the free wheel  823 , front plate  824 , and outer housing  825 , in which the urging members  822   a - 822   d  are correspondingly provided, to provide the dampening force. 
     As mentioned above, the cylindrical protrusion  823   a  may be connected to the rotational drive shaft  22   a  of the developing roller  22 . A height of the cylindrical protrusion  823   a  may be greater than a height of the friction plate  821 . For example, the cylindrical protrusion  823   a  may be connected or secured to the rotational drive shaft  22   a  of the developing roller  22  by an adhesive such as glue, a fastener such as a screw, and the like. As another example, the cylindrical protrusion  823   a  may be connected or secured to the rotational drive shaft  22   a  of the developing roller  22  by having a hollow portion to which the rotational drive shaft  22   a  of the developing roller  22  is inserted and secured, or vice versa. 
     In another example, the cylindrical protrusion  823   a  may be omitted and the rotational drive shaft  22   a  of the developing roller  22  may be directly connected to the freewheel  823  of the clutch mechanism  820 . That is, the rotational drive shaft  22   a  of the developing roller  22  and the cylindrical protrusion  823   a  may be formed as a single integral piece to which the freewheel  823  (less the cylindrical protrusion  823   a  now integrally formed with the rotational drive shaft  22   a ) is mounted or connected to. As another example, the rotational drive shaft  22   a  of the developing roller  22 , the cylindrical protrusion  823   a , and the freewheel  823 , may be formed as a single integral piece to which the front plate  824  and outer housing  825  are mounted or connected to. 
     According to the examples described herein, the development system  800  includes a photosensitive drum  21  and developing roller  22  which can be provided in a printing orientation where friction contact between the developing roller  22  and photosensitive drum  21  transfers a rotation force to the developing roller  22 , and an alienation orientation where the photosensitive drum  21  and developing roller  22  are separated from one another. Urging member forces are generated by a clutch mechanism  820 , which includes a friction plate  821  and urging members  822 , to dampen the initial transition between the alienation and printing orientations. This allows for a smooth transition between the two orientations to reduce or prevent wear and damage to the developing roller  22  and photosensitive drum  21 . For example, as a stationary friction plate  821  comes into contact with a rotating drive plate  810 , the urging members  822  absorb the initial force generated by the engagement of the clutch mechanism  820  with the drive plate  810  and the developing roller  22  and the photosensitive drum  21 . The clutch mechanism  820  allows or assists in keeping the transition smooth for the developing roller  22  and the photosensitive drum  21  when moving from the alienation orientation to the printing orientation. 
     In the above examples, the clutch mechanism  820  is described as being applied to an end of the developing roller  22 . However, the disclosure is not so limited and other applications are within the scope of the disclosure. For example, the clutch mechanism  820  may be applied to an end of the supply roller  27  in a like manner as the clutch mechanism  820  is applied to an end of the developing roller  22 , and the friction plate may contact a portion of the developing roller  22 . For example, in a case where the supply roller  27  is driven by a separate driving source, the supply roller  27  may be selectively separated from the developing roller  22  to be in an alienation position. When the supply roller  27  is brought into contact with the developing roller  22  from the alienation position to a supply position to supply toner to the developing roller  22 , the clutch mechanism  820  may dampen a force generated when the clutch mechanism  820  provided at an end of the supply roller  27  engages a portion of the developing roller  22 . 
     While this disclosure has been shown and described with reference to examples thereof, it will be understood by one of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope as defined by the appended claims.