Abstract:
A developing device and an image forming apparatus having the same include a frame having a knob part, a photosensitive body provided in front of the knob part with respect to a first direction of mounting the developing device, and a rotation guide part provided in front of the photosensitive body with respect to the first direction, and to guide a rotational motion of the developing device. When the developing device is removed from the image forming apparatus, the knob part is rotated upward. A first protrusion is provided on a side surface of the frame to determine a mounting position of the developing device. When the knob part is rotated upward, the first protrusion is rotated in the same direction as the knob part. Accordingly, the developing device has an improved mounting/removing structure adequate to compactly manufacture the image forming apparatus, and improves handling convenience in mounting and removing the developing device.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of Korean Patent Application No. 2007-95069, filed Sep. 19, 2007 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    Aspects of the present invention relate to an image forming apparatus, and more particularly, to a developing device removably mounted in a main body of the image forming apparatus, and an image forming apparatus having the developing device. 
         [0004]    2. Description of the Related Art 
         [0005]    An image forming apparatus, such as a printer, a copying machine, or a fax machine, forms an image on a printing medium according to an inputted image signal. Of the various types of image forming apparatuses, an electrophotographic image forming apparatus prints an image on the printing medium, such as paper, through feeding, developing, transferring, fusing, and discharging processes. 
         [0006]    An image forming apparatus generally includes a cartridge type developing device in which a photosensitive body, a charging body and a developing body are integrally formed as a unit. The developing device is removably mounted in a main body of the image forming apparatus. 
         [0007]    For the developing device to operate reliably and develop an image of high quality, the developing device should be stably mounted in a correct position in the main body. In addition, to provide a user with convenience in replacing the developing device or inspecting the interior of the image forming apparatus, the developing device should be mounted in the main body to be easily removable. 
         [0008]    U.S. Pat. No. 5,937,240 discloses a developing device of an image forming apparatus, which can be mounted and removed to and from a main body only by pushing and pulling a knob of the developing device. 
         [0009]    The disclosed developing device of U.S. Pat. No. 5,937,240 includes a first protrusion and a second protrusion which are formed on a side surface. The first protrusion determines a mounting position of the developing device. The second protrusion is positioned in a rear of the first protrusion with respect to a mounting direction of the developing device. The second protrusion maintains a posture of the developing device, and serves as a rotational center when the developing device is removed from the main body. The main body of the image forming apparatus is formed with a guide groove to guide the first protrusion and the second protrusion. The guide groove is formed with a positioning recess at a lower end thereof. 
         [0010]    The disclosed developing device of U.S. Pat. No. 5,937,240 further includes a photosensitive body gear mounted to an end of a photosensitive body. When the developing device is mounted in the main body of the image forming apparatus, the photosensitive body gear is engaged with a driving gear mounted in the main body. 
         [0011]    The operation of mounting and removing the developing device to and from the main body of the image forming apparatus will now be explained briefly. First, the first protrusion of the developing device is fitted into the guide groove of the main body, and the developing device is pushed in. The first protrusion and the second protrusion are guided by the guide groove. When the first protrusion is received in the positioning recess, the mounting of the developing device is completed. At this time, the photosensitive body gear is engaged with the driving gear. 
         [0012]    When a user pulls the developing device from the main body, the developing device is rotated about the second protrusion. The first protrusion and the photosensitive body gear move upward, and are separated from the positioning recess and the driving gear, respectively. In such a state, when a user pulls even more on the developing device, the first protrusion and the second protrusion are guided by the guide groove, and the developing device is removed from the main body. 
         [0013]    However, when the above described developing device of U.S. Pat. No. 5,937,240 rotates on the second protrusion, the moving range of the developing device is large. Thus, the above described developing device requires a large surrounding space for movement. Especially, a portion of the developing device which is spaced farthest from the second protrusion (i.e., a portion having the largest moving range) is positioned in a substantially center portion in the main body of the image forming apparatus. However, many other components are arranged densely in the center portion in the main body. Thus, a size of the image forming apparatus is increased to provide sufficient space for movement of the developing device in the center portion in the main body, which makes it difficult to compactly manufacture the image forming apparatus. 
         [0014]    After the developing device is mounted in the main body of the image forming apparatus, when the driving gear is rotated by a driving source mounted in the main body, a rotational force is transmitted to the photosensitive body through the photosensitive body gear. In such a power transmission process, the developing device may vibrate. In order to restrain the vibration of the developing device, a press device may also be provided in the main body to press the developing device downward. 
         [0015]    However, when the developing device disclosed in U.S. Pat. No. 5,937,240 is removed from the main body, the developing device is rotated largely in a direction opposite to the direction of a pressing force of the press device. In other words, while the pressing force of the press device acts downward, a portion of the developing device is rotated upward to be removed from the main body. Thus, when intending to remove the developing device from the main body of the image forming apparatus, a user should apply a force to the developing device that is larger than the pressing force of the press device. However, to aid the removal of the developing device from the main body, if the pressing force of the press device is set to be relatively lower in consideration of handling convenience, stably restraining the vibration of the developing device becomes more difficult. Conversely, if the pressing force of the press device is set to be relatively higher, handling convenience is deteriorated as removal of the developing device from the main body becomes more difficult. 
         [0016]    The developing device is mounted with components (for example, terminals) on an upper surface thereof, which are contacted with components mounted in the main body when the developing device is installed in the main body. However, when the developing device is rotated upward in order to be removed from the main body, the components mounted on the upper surface of the developing device may be damaged by forced contact with the components mounted in the main body. 
       SUMMARY OF THE INVENTION 
       [0017]    Therefore, it is an aspect of the invention to have a developing device and an image forming apparatus having the same, which has an improved mounting/removing structure adequate to compactly manufacture the image forming apparatus. 
         [0018]    It is another aspect of the invention to have a developing device and an image forming apparatus having the same, which improves handling convenience in mounting and removing the developing device. 
         [0019]    It is yet another aspect of the invention to have a developing device and an image forming apparatus having the same, which reduces possibility of damages to components mounted on an upper surface of the developing device when the developing device is removed from a main body of the image forming apparatus. 
         [0020]    Additional aspects and/or advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention. 
         [0021]    In accordance with an aspect of the invention, there is a developing device removably mounted in an image forming apparatus, including: a frame having a knob part; a photosensitive body provided in front of the knob part with respect to a first direction for mounting the developing device; and a rotation guide part provided in front of the photosensitive body with respect to the first direction, and to guide a rotational motion of the developing device. 
         [0022]    In accordance with an aspect of the invention, when the developing device is to be removed from the image forming apparatus, the knob part may be rotated upward. 
         [0023]    In accordance with an aspect of the invention, the developing device may further include a first protrusion to protrude outward from a side surface of the frame to determine a mounting position of the developing device in the image forming apparatus. When the knob part is rotated upward, the first protrusion may be rotated in the same direction as the knob part. 
         [0024]    In accordance with an aspect of the invention, the rotation guide part may be positioned in front of the first protrusion with respect to the first direction. 
         [0025]    In accordance with an aspect of the invention, the photosensitive body may have a rotating shaft, and may be mounted adjacent to the rotation guide part. The first protrusion may be coaxial with the rotating shaft of the photosensitive body. 
         [0026]    In accordance with an aspect of the invention, the rotation guide part may include a rotation guide surface provided on a lower surface of the frame. The rotation guide surface may have an arc shape. 
         [0027]    In accordance with an aspect of the invention, the developing device may further include a second protrusion to protrude outward from the side surface of the frame to a rear of the first protrusion to guide movement of the developing device in the image forming apparatus. 
         [0028]    In accordance with an aspect of the invention, the frame may include an upper surface with a terminal at a front portion of the developing device to supply power to a memory or a switch operating member to operate a micro switch mounted in the image forming apparatus, and in front of the rotation guide part. 
         [0029]    In accordance with another aspect of the invention, there is a developing device removably mounted in an image forming apparatus, including: a knob part provided to rotate upward along with the developing device relative to the image forming apparatus; and a positioning protrusion provided at a front portion of the developing device in front of the knob part with respect to a direction for mounting the developing device into the image forming apparatus. When the knob part is rotated upward, the positioning protrusion may be rotated upward together with the knob part. 
         [0030]    In accordance with yet another aspect of the invention, there is an image forming apparatus including: a main body; and a developing device removably mounted in the main body, the developing device including: a frame having a knob part; a first protrusion to protrude outward from a side surface of the frame, the first protrusion being positioned at a front portion of the developing device in front of the knob part with respect to a first direction for mounting the developing device into the main body; and a rotation guide part provided in the frame at the front portion of the developing device in front of the first protrusion with respect to the first direction, and to guide a rotational motion of the developing device. 
         [0031]    In accordance with an aspect of the invention, the main body may include a positioning recess to receive the first protrusion. When the knob part is rotated upward relative to the image forming apparatus, the first protrusion may be rotated upward and may escape from the positioning recess. 
         [0032]    In accordance with an aspect of the invention, the rotation guide part may include a rotation guide surface provided on a lower surface of the frame, and the main body may include a support part to support the rotation support surface. 
         [0033]    In accordance with an aspect of the invention, when the knob part is rotated upward relative to the image forming apparatus, the rotation guide surface may perform a sliding motion while being supported by the support part. 
         [0034]    In accordance with an aspect of the invention, the developing device may further include a photosensitive body having a rotating shaft and mounted adjacent to the rotation guide part, and the first protrusion may be coaxial with the rotating shaft of the photosensitive body. 
         [0035]    In accordance with an aspect of the invention, the developing device may further include a photosensitive body gear mounted to an end portion of the photosensitive body, and the main body may include a driving gear to be engaged with the photosensitive body gear. When the knob part is rotated upward, the photosensitive body gear may be rotated upward and may be disengaged from the driving gear. 
         [0036]    In accordance with an aspect of the invention, a developing device to be removably mounted in an image forming apparatus, includes: a frame comprising an outward shape of the developing device; a photosensitive body to form an electrostatic latent image and being contained within the frame in a front portion thereof; and a rotation guide part formed on a bottom portion of the frame to correspond to the photosensitive body and comprising a rotation guide surface formed to smoothly guide a rotational movement of the developing device relative to the image forming apparatus. 
         [0037]    Additional aspects and/or advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0038]    These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the aspects, taken in conjunction with the accompanying drawings, of which: 
           [0039]      FIG. 1  is a sectional view illustrating various components of an image forming apparatus according to an aspect of the present invention; 
           [0040]      FIG. 2  is a perspective view illustrating a part of a main body and a developing device of the image forming apparatus according to an aspect of the present invention; 
           [0041]      FIG. 3  is a bottom perspective view illustrating the developing device according to an aspect of the present invention; 
           [0042]      FIG. 4  is a side view illustrating a state in which the developing device according to an aspect of the present invention is mounted in the main body of the image forming apparatus; and 
           [0043]      FIGS. 5 and 6  are views for explaining an operation of removing the developing device according to an aspect of the present invention from the image forming apparatus. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0044]    Reference will now be made in detail to aspects of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. The aspects are described below in order to explain the present invention by referring to the figures. 
         [0045]      FIG. 1  is a sectional view illustrating various components of an image forming apparatus according to an aspect of the present invention. As shown in  FIG. 1 , an image forming apparatus includes a main body  10 , which forms an external shape of the image forming apparatus and supports the various components accommodated therein. Inside the main body  10  are mounted a feeding device  20 , a laser scanning device  30 , a developing device  100 , a transfer device  40 , a fusing device  50 , a discharge device  60 , and a duplex printing device  70 . 
         [0046]    The main body  10  also includes a cover  11  that is hingedly coupled to the main body  10  to reveal or cover an opening of the main body  10 . A user can open the cover  11  and obtain access to the interior of the main body  10  through the opening of the main body  10 , to inspect the interior of the main body  10  or replace expendable components (i.e., consumables), such as the developing device  100 . 
         [0047]    The feeding device  20  feeds a printing medium, e.g., a paper S, towards the developing device  100 . The feeding device  20  includes a feeding tray  21  to load the paper S thereon, a pickup roller  22  to pick up the paper S stored in the feeding tray  21  sheet by sheet, and a feeding roller  23  to feed the picked-up paper S towards the developing device  100 . 
         [0048]    The developing device  100  supplies toner to an electrostatic latent image formed on a photosensitive body  110  to develop the electrostatic latent image into a toner image. The developing device  100  is provided in a cartridge form, and is removably mounted in the main body  10 . The operation of mounting and removing the developing device  100  and structures related thereto will be explained later. 
         [0049]    The developing device  100  includes a photosensitive body  110 , on a surface of which the electrostatic latent image is formed by the laser scanning device  30 , a charging roller  121  to charge the photosensitive body  110 , a developing roller  122  to supply toner to the electrostatic latent image formed on the photosensitive body  110 , and a supply roller  123  to supply toner to the developing roller  122 . 
         [0050]    The transfer device  40  transfers the toner image formed on the photosensitive body  110  onto the paper S. The transfer device  40  includes a transfer roller  41  mounted in the main body  10  in an opposing arrangement to the photosensitive body  110 . The transfer roller  41  presses the paper S toward the photosensitive body  110  so that the toner image formed on the surface of the photosensitive body  110  is transferred onto the paper S. 
         [0051]    The fusing device  50  fuses the transferred toner image to the paper S. The fusing device  50  includes a heating roller  51  having a heat source therein, and a first press roller  52  and a second press roller  53  which are pressed to the heating roller  51  with a predetermined pressure. When the paper S passes between the heating roller  51  and the press rollers  52  and  53 , the toner image is fused to the paper S by heat transferred from the heating roller  51  and pressure generated between the heating roller  51  and the press rollers  52  and  53 . 
         [0052]    The discharge device  60  includes a first discharge roller  61 , a second discharge roller  62 , and a third discharge roller  63  which are sequentially mounted so as to discharge the paper S, that had passed through the fusing device  50 , to the outside of the main body  10 . 
         [0053]    The duplex printing device  70  feeds the paper S, on one surface of which an image has been printed, to an upstream side of the developing device  100 , so that an image is printed also on another surface of the paper S. The duplex printing device  70  includes a duplex printing guide  72  which forms a duplex printing path  71 , and duplex printing rollers  73  mounted in the duplex printing path  71  to feed the paper S. In a duplex printing operation, while the paper S, on one surface of which an image has been printed, is not discharged by the third discharge roller  63 , but rather, the paper S is reversely fed to the duplex printing path  71  at a specific point of time. Thereafter, the paper S is fed again to the developing device  100  by the duplex printing rollers  71 , and then passed through the developing device  100  and the fusing device  50 . Accordingly, an image is printed on the another surface of the paper S. 
         [0054]      FIG. 2  is a perspective view illustrating a part of the main body and the developing device of the image forming apparatus according to an aspect of the present invention,  FIG. 3  is a bottom perspective view illustrating the developing device according to an aspect of the present invention, and  FIG. 4  is a side view illustrating a state in which the developing device according to an aspect of the present invention is mounted in the main body of the image forming apparatus. As shown in  FIGS. 2 to 4 , the developing device  100  includes a frame  130  which forms an exterior shape thereof, and a knob part (or a handle)  131  provided at a rear portion of the frame  130  to enable a user to grasp the developing device  100 . 
         [0055]    Also, as shown in  FIG. 1 , the photosensitive body  110  is rotatably mounted in the frame  130 . The photosensitive body  110  is positioned in the front of the developing device  100  and in a forward direction of the knob part  131  with respect to a direction of mounting the developing device  100  into the main body  10  (“A” direction in  FIG. 2 ). The photosensitive body  110  has a rotating shaft  111 , which is made of a conductive material. The rotating shaft  111  protrudes outward from both side (or lateral) surfaces of the frame  130  (shown in  FIGS. 2  and  3 ), and is electrically connected to a power supply part (not shown) or a ground contact part (not shown) provided in the main body  10  while the developing device  100  is mounted in the main body  10 . 
         [0056]    A photosensitive body gear  112  is mounted to one end of the photosensitive body  110  (shown in  FIG. 3 ), and a driving gear  12  is mounted in the main body  10  to correspond to the photosensitive body gear  112  (as shown in  FIG. 4 ). When the developing device  100  is mounted into the main body  10 , the photosensitive body gear  112  is engaged with the driving gear  12 . When the driving gear  12  is rotated by a driving source (not shown) provided in the main body  10 , a rotational force is transmitted to the photosensitive body  110  through the photosensitive body gear  112 . 
         [0057]    As shown in  FIGS. 3 and 4 , the frame  130  of the developing device  100  is provided with rotation guide parts  140  which are disposed in the front of the photosensitive body  110  with respect to the “A” direction. As shown in  FIGS. 2 and 4 , the main body  10  is provided with support parts  13  to correspondingly support the rotation guide parts  140  of the frame  130 . Only the support part  13  provided in the left side of the main body  10  is illustrated in  FIG. 2 , and the illustration of the support part  13  provided in the right side of the main body  10  is omitted. In an aspect of the present invention, two rotation guide parts  140  are shown, each being located at the lateral sides of the developing device  100 . 
         [0058]    Describing in detail, the rotation guide parts  140  are positioned in front (or forward) of the rotating shaft  111  of the photosensitive body  110 . Also, the rotation guide parts  140  are positioned below the rotating shaft  111  of the photosensitive body  110 . When the developing device  100  is to be removed from the main body  10 , the rotation guide parts  140  guide a rotational movement of the developing device  100  while the rotation guide parts  140  are being supported by the support parts  13 . The rotation guide parts  140  may include rotation guide surfaces  141  provided at a lower surface of the frame  130 . The rotation guide surfaces  141  are respectively provided at both side edge portions of the developing device  100  corresponding to the support parts  13  of the main body  10 . It is preferred, though not required, that the rotation guide surfaces  141  are formed in an arc shape (or rounded) so as to smoothly guide the rotational movement of the developing device  100 . In other words, the surface of the rotation guide surfaces  141  are shaped to aid the rotational movement of the developing device  100  while the rotation guide parts  140  are being supported by the support parts  13 . In aspects of the present invention, the rotation guide parts  140  are a part of the frame  130  that corresponds to the photosensitive body  110  so that the rotation guide parts  140  are parts of the frame  130  that partially surround the photosensitive body  110 . Accordingly, the rotation guide parts  140  have a curvature that corresponds to a curvature of the photosensitive body  110 . 
         [0059]    The frame  130  is provided with first protrusions  150  which protrude outward from both side surfaces of the frame  130 . The first protrusions  150  have a role of guiding the movement of the developing device  100  when the developing device  100  is mounted or removed into/from the main body  10 . In addition, the first protrusions  150  have a role of determining the mounting position of the developing device  100 . The first protrusion  150  protruding outward from the right side surface of the frame  130  is illustrated in  FIG. 2 , and the first protrusion protruding outward from the left side surface of the frame  130  is illustrated in  FIG. 3 . 
         [0060]      FIG. 2  also shows a portion of the main body that contains a raised surface with structures that mount the developing device  100 . As shown in  FIG. 2 , the main body  10  is provided with guide rails  14  to slidingly guide the first protrusions  150  of the frame when the developing device  100  is being inserted into the main body  10 . Only the guide rail  14  provided in the left side of the main body  10  is illustrated in  FIG. 2 . The main body  10  is further provided with positioning recesses  15  located in front (or forward) of the guide rails  14  with respect to the “A” direction. When the developing device  100  is mounted into the main body  10 , the first protrusions  150  are received in the positioning recesses  15  after being guided by the guide rails  14 . Thereby, the mounting position of the developing device  100  is determined by the positioning recesses  15 . 
         [0061]    As shown in  FIG. 4 , the first protrusions  150  are positioned adjacent to the rotation guide parts  140 , but to the rear (or rearward) of the rotation guide parts  140 . The first protrusions  150  are formed to surround the rotating shaft  111  of the photosensitive body  110 , and may be formed coaxially with the rotating shaft  111 . That is, in aspects of the present invention, the first protrusion  150  is a tube like protrusion that sheathes the rotating shaft  111 , and has a circular cross section. In other aspects, the first protrusion  150  may have other cross sectional shape, such as hemispheric or rectangular shapes. 
         [0062]    The frame  130  is further provided with second protrusions  160  protruding outward from both side surfaces of the frame  130  at the rear (or rearward) of the first protrusions  150 . When the developing device  100  is mounted or removed into/from the main body  10 , the second protrusions  160  guide the movement of the developing device  100  together with the first protrusions  150 . 
         [0063]    Although it is not illustrated in the drawings, a press device may be provided in the main body  10  to press the developing device  100  downward. The press device is disposed at a position corresponding to the photosensitive body  110  above the developing device  100 , so as to restrain movement of the developing device  100  due to vibrations generated during the operation of the photosensitive body  110 . The pressing force of the press device on the developing device  100  is shown by an arrow P in  FIG. 4 . As shown in  FIG. 4 , pressing force of the press device is applied to a location on the developing device  100  that is opposite to the rotation guide parts  140 . Accordingly, the pressing force is almost evenly distributed to the first protrusions  150  and the positioning recesses  15 , and to the rotation guide parts  140  and the support parts  13  for greater stability of the mounted developing device  100 . 
         [0064]    As shown in  FIGS. 2 and 4 , a memory  170  may be mounted in the developing device  100 . Information including an identification (ID) of the developing device, residual quantity of toner, quantity of waste toner, and the like are stored in the memory  170 . In order to supply power to the memory  170 , a terminal  171  is provided in the front of the rotation guide parts  140  on an upper surface of the frame  130 . When the developing device  100  is mounted into the main body  10 , the terminal  171  is connected to a power terminal (not shown) provided in the main body  10 . 
         [0065]    A switch operating member  180  is provided in the front of the rotation guide parts  140  on the upper surface of the frame  130 . When the developing device  100  is mounted or removed into/from the main body  10 , the switch operating member  180  operates a micro switch (not shown) provided in the main body  10 . When the developing device  100  is mounted into the main body  10 , and the switch operating member  180  presses the micro switch, a control part of the image forming apparatus determines that the developing device  100  has been installed. On the other hand, when the developing device  100  is removed from the main body  10 , and the switch operating member  180  is separated from the micro switch, the control part determines that the developing device  100  has been removed. 
         [0066]    Hereinafter, the operation of mounting and removing the developing device  100  into and from the main body  10  of the image forming apparatus according to an aspect of the present invention will be explained with reference to  FIGS. 2 and 4  to  6 .  FIGS. 5 and 6  are views for explaining the operation of removing the developing device from the image forming apparatus. 
         [0067]    First, the operation of mounting the developing device  100  will be explained with reference to  FIG. 2 . A user grasps the knob part  131  of the developing device  100 , and puts the first protrusions  150  of the developing device  100  on the guide rails  14  of the main body  10 . Thereafter, the user pushes in the developing device  100  in the “A” direction, so that the first protrusions  150  are guided by the guide rails  14 . When the developing device  100  is inserted to a specific extent, the second protrusions  160  are advanced onto the guide rails  14 , and guide the movement of the developing device  100  together with the first protrusions  150 . The developing device  100  is then further inserted further in the “A” direction until the first protrusions  150  are received in the positioning recesses  15 . The mounting position of the developing device  100  is thereby determined, and the mounting operation is completed as shown in  FIG. 4 . 
         [0068]    When the developing device  100  is completely installed, the photosensitive body gear  112  is engaged with the driving gear  12  of the main body  10 . In such a state, if a printing command is inputted, a driving force is transmitted to the photosensitive body  110  to rotate the photosensitive body  110 , and thus the image forming operation is carried out. 
         [0069]    Next, the operation of removing the developing device  100  will be explained. The user grasps the knob part  131  of the developing device  100 , and raises the developing device  100 . The rotation guide parts  140 , supported by the support parts  13  of the main body  10 , serve as a pivot, and the knob part  131  is rotated in a “B” direction (or in an arc) as shown in  FIG. 5 . The rotation guide parts  140  perform a sliding motion while contacting the support parts  13  of the main body  10 , and guide the rotational movement of the developing device  100  relative to the support parts  13 . 
         [0070]    When the developing device  100  is rotated, the first protrusions  150  and the photosensitive body gear  112  positioned in the rear of the rotation guide parts  140  are rotated upward and draw a small arc. Thereby, the first protrusions  150  escape from the positioning recesses  15  of the main body  10 , and the photosensitive body gear  112  is disengaged from the driving gear  12  of the main body  10 . Accordingly, the developing device  100  is turned into a state capable of being removed from the main body  10 . 
         [0071]    Thereafter, the user grasps the knob part  131 , and pulls out the developing device  100  in a “C” direction. The “C” direction is generally opposite to the “A” direction. As shown in  FIG. 6 , the developing device  100  is guided by the first protrusions  150  and the guide rails  14  as the developing device  100  is removed from the main body  10 . 
         [0072]    As understood from  FIG. 5 , when the developing device  100  is rotated about the rotation guide parts  140 , a portion of the developing device  100  which is positioned in the center portion of the main body  10  (a front portion of the developing device that includes the memory  170 ) pivots within a small range, which is advantageous in compactly manufacturing the image forming apparatus. In addition, a moving range of a portion (shown by arrow P in  FIG. 5 ) of the developing device  100  which is pressed by the press device is not large. Accordingly, though the pressing force of the press device is set to be large, the user can remove the developing device  100  from the main body  10  with a small force. Also, since the terminal  171  and the switch operating member  180  positioned in the front of the rotation guide parts  140  are rotated downward when the developing device  100  is rotated, the terminal  171  and the switch operating member  180  are prevented from being damaged due to interference with other components which would otherwise occur because the terminal  171  and the switch operating member  180  also become disengaged from corresponding components in the main body  10 . Also, it is apparent from  FIGS. 4 and 5  that the first protrusions  150 , the front portion of the developing device that includes the memory  170 , and a location on the developing device  100  where the pressing force P of the press device is applied, are all located within a short distance of the rotation guide parts  140  to enable application of only a small force to remove the developing device  100 , and a small resulting rotational movement of the developing device  100 . 
         [0073]    As is apparent from the above description, the developing device  100  according to aspects of the present invention is advantageous in compactly manufacturing the image forming apparatus, because the developing device  100  is constituted so as to be rotated within a small range in the center portion of the main body  10  of the image forming apparatus in which many other components are arranged densely. 
         [0074]    Further, since the moving range of a portion of the developing device which is pressed by the press device is small, a user can easily remove the developing device from the main body by rotating the developing device with a small force. 
         [0075]    Still further, damage to the components mounted on the upper surface of the developing device can be reduced when the developing device is removed from the main body. 
         [0076]    Although a few aspects of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in the aspects without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.