Abstract:
An image forming apparatus includes a removable image forming unit including at least a carriage having an ink jet head, and a recording medium conveyance member, and includes a gap adjustment mechanism including a carriage travel lever unit having first and second levers separably engaged with each other. The second lever includes an operation part for, in gearing with the first lever, causing the carriage to vertically travel so that a gap between the ink jet head and a sheet on the recording medium conveyance member is adjusted.

Description:
BACKGROUND 
   1. Field 
   This patent specification describes an image forming apparatus, and more particularly an image forming apparatus having an improved operability and maintainability associated with an image forming mechanism. 
   2. Related Art 
   A background image forming apparatus such as an ink jet printer includes a mechanism for adjusting a gap between a recording sheet and an ink jet head including a port for discharging ink. The gap adjustment mechanism is provided to a guide rod for supporting a carriage having a head. The gap adjustment mechanism includes a lever having an operation unit partially exposing itself to outside of the image forming apparatus, and when a user operates the lever according to a type of paper, the gap adjustment mechanism causes the guide rod to move up and down. When the guide rod moves up and down, the carriage supported by the guide rod moves up and down so that a gap between a sheet and the head is adjusted. 
   However, the gap adjustment mechanism is not configured for an image forming apparatus wherein the image forming unit is removable. 
   SUMMARY 
   This patent specification describes an image forming apparatus which includes a removable image forming unit and a gap adjustment mechanism. The removable image forming unit includes at least a carriage having an ink jet head, and a recording medium conveyance member. The gap adjustment mechanism is configured to allow the removable image forming unit to be disengaged from the image forming apparatus, while also providing the functionality that allows a gap between a recording sheet and an ink jet head including a port for discharging ink to be adjusted. 
   The gap adjustment mechanism preferably includes a first portion and a second portion which are joined with and separated from each other with attachment and detachment of the removable image forming unit to and from the image forming apparatus. 
   In one example, the gap adjustment mechanism includes a carriage travel lever unit having first and second levers separably engaged with each other. The second lever includes an operation part for, in gearing with the first lever, causing the carriage to vertically travel so that a gap between the ink jet head and a sheet on the recording medium conveyance member is adjusted. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A more complete appreciation of the disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: 
       FIG. 1  is a schematic illustration of a configuration of an image forming apparatus according to an embodiment; 
       FIG. 2A  is a front view of a carriage included in the image forming apparatus of  FIG. 1 ; 
       FIG. 2B  is a bottom view of the carriage shown in  FIG. 2A ; 
       FIG. 3  is a frontal perspective view of the image forming apparatus of  FIG. 1 ; 
       FIG. 4  is another perspective appearance view of the image forming apparatus of  FIG. 1 ; 
       FIG. 5  is a perspective view of the image forming apparatus of  FIG. 1  with a first door opened and second and third doors (not shown) opened; 
       FIG. 6  is a perspective view of the image forming apparatus of  FIG. 1  with an image forming unit pulled out; 
       FIG. 7  is an illustration of a carriage support mechanism of a sliding rail according to an embodiment; 
       FIG. 8  is a schematic illustration for explaining the carriage support mechanism of  FIG. 7 ; 
       FIG. 9  is an illustration of a gap adjustment mechanism and peripherals thereof in an image forming apparatus according to an example; 
       FIG. 10  is a perspective view of the gap adjustment mechanism of  FIG. 9 ; 
       FIG. 11  is a perspective view of a portion of the image forming apparatus of  FIG. 1  with first and second lever units joined; 
       FIG. 12  is a perspective view of a portion of the image forming apparatus of  FIG. 1  with the first and second lever units separated; 
       FIG. 13  is a schematic illustration of an exemplary front edge of the second lever unit which includes a rollable ball member; and 
       FIG. 14  is a schematic illustration of another exemplary front edge of the second lever unit which includes a rotatable cylindrical member. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   In describing preferred embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of this patent specification is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents that operate in a similar manner. Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, particularly to  FIG. 1 , an image forming apparatus according to a preferred embodiment is described. 
   A general configuration of the image forming apparatus according to the embodiment is described below referring to  FIG. 1 . As shown in  FIG. 1 , an image forming apparatus  1  includes an image forming unit  2 , an image reading unit  11 , a cartridge loading unit  35 , and a sheet feeding cassette  41 . The image forming apparatus  1  further includes a sheet discharge tray  7 , a separation roller  42 , a friction pad  43 , a pair of sheet feeding rollers  49 , and pairs of sheet discharge rollers  74 ,  75 ,  76 , and  77  including discharge rollers and spurs. 
   The image forming unit  2  is attachably and detachably mounted to the image forming apparatus  1 , and includes a carriage  23  and a guide rod  21  for guiding the carriage  23 . The carriage  23  includes heads (not shown) having respective discharge ports for discharging ink in yellow, magenta, cyan, black 1, and black 2 (hereinafter referred to as Y, M, C, B- 1 , and B- 2 , respectively) onto a sheet. The image forming unit  2  further includes a conveyance belt  31 , a drive roller  32 , a driven roller  33 , a pressure roller  36 , a charge roller  37 , and a guide member (platen)  38 . The conveyance belt  31  is stretched around the drive roller  32  and the driven roller  33  with adequate tension. 
   The image reading unit  11  includes an exposure glass  12 , a first traveling body  15 , a second traveling body  18 , a lens  19 , and an image reading element  20  such as a CCD. The first traveling body  15  includes a light source  13  for illuminating a document and a mirror  14 . The second traveling body  18  includes two mirrors  16  and  17 . The image reading unit  11  is arranged at an upper position of the image forming apparatus  1 . The first and second traveling bodies  15  and  18  are arranged so as to be able to make a reciprocating motion in a main scanning direction. 
   The cartridge loading unit  35  accommodates ink cartridges  34 C,  34 B- 1 ,  34 B- 2 ,  34 M, and  34 Y. 
   The sheet feeding cassette  41  stores a plurality of sheets P, and can be inserted to and extracted from a front side of the image forming apparatus  1  (a front side in  FIG. 1 ). 
   In the image reading unit  11 , the image reading element  20  is located behind the lens  19 . The first and second traveling bodies  15  and  18  scan an image to obtain image data, and send an image signal representing the image data to the image reading element  20 . The image reading element  20  receives and digitizes the image signal, and processes the digitized image signal. 
   The image forming unit  2  forms an image on a sheet P according to the processed image signal. In detail, the drive roller  32 , driven by a drive motor (not shown), rotates at a predetermined rotation speed so that the conveyance belt  31  rotates at a predetermined speed. The charge roller  37  having a voltage applied from a high-voltage power supply (not shown) charges the conveyance belt  31 . The conveyance belt  31  is guided by the guide member  38  in an area facing the image forming unit  2 . The pressure roller  36  presses the sheet P onto the conveyance belt  31  at a position facing the drive roller  32 . 
   Each of the ink cartridges  34 C,  34 B- 1 ,  34 B- 2 ,  34 M, and  34 Y including ink liquid is connected to a supply pump (not shown). The supply pump is operated as necessary to supply the ink liquid to the carriage  23 . The ink cartridges  34 C,  34 B- 1 ,  34 B- 2 ,  34 M, and  34 Y are attachably and detachably mounted in the cartridge loading unit  35 . 
   The image forming apparatus  1  can receive data of an image from an external equipment via one of a communication cable and a network, and process the data. The image forming unit  2  forms an image from the data. The external equipment for inputting the data to be used by the image forming unit  2  to form the image includes an image processing apparatus such as a computer, an image reading apparatus such as an image scanner, an imaging apparatus such as a digital camera, and so forth. 
   As shown in  FIG. 2A  and as described above, the carriage  23  includes heads  24 C,  24 B- 1 ,  24 B- 2 ,  24 M, and  24 Y (hereinafter the suffixes representing the colors are omitted as necessary). As shown in  FIG. 2B , each of the heads  24  (hereinafter each of the heads  24  is represented as head  24  as necessary) includes 384 discharge ports  24   a  arranged in two rows×192 columns. The head  24  determines a distance in a sub-scanning direction in which recording can be performed while the sheet P is stopped. The distance represents a height of one line. After recording of one line is finished, the sheet P is conveyed in the main scanning direction so that next one line can be recorded. 
   Next, an image forming operation of the image forming apparatus  1  is described below referring to  FIG. 1 . 
   After an original is set on the exposure glass  12  of the image reading unit  11 , when a start button (not shown) is pressed, the first and second traveling bodies  15  and  18  start traveling. The first traveling body  15  emits light from the light source  13 . The light is reflected from a surface of the original. While emitting the light, the first traveling body  15  further reflects the reflected light toward the second traveling body  18 . The mirrors  16  and  17  of the second traveling body  18  reflect the directed light into the image reading element  20  through the lens  19 . An image on the original is read through the above operations so that image data is generated. Alternatively, image data is sent from the external equipment (not shown) via a communication cable and so forth. 
   The sheet feeding cassette  41  feeds the sheet P to the separation roller  42  and the friction pad  43  so that the sheet P is separated from the rest and is conveyed one after another. The separated sheet P is conveyed by the pair of sheet feeding rollers  49  into the image forming unit  2 . In the image forming unit  2 , the sheet P is pressed by the pressure roller  36  onto the conveyance belt  31 . The sheet P electrostatically adheres to a surface of the conveyance belt  31  having been charged by the charge roller  37 , and is conveyed to a position facing the carriage  23 . When the sheet P comes to the position, the conveyance belt  31  stops moving. Then, while reciprocating according to the image data the carriage  23  discharges predetermined ink liquid at a predetermined position on the sheet P in a stationary state so that one line of an image is recorded on the sheet P. After the one line is recorded in the main scanning direction, the conveyance belt  31  is driven for a predetermined time to move the sheet P for the one line, and is stopped. Then, as described above, while reciprocating in the main scanning direction, the carriage  23  discharges the ink liquid according to the image data to record a next line of the image. The operation is repeated a predetermined number of times to form the image on the sheet P. Then, the sheet P is conveyed to the discharge tray  7  by the pairs of sheet discharge rollers  74 ,  75 ,  76 , and  77 . 
   Next, attachment and detachment of the image forming unit  2  to and from the image forming apparatus  1  are described below referring to  FIGS. 3 to 6 . 
   As shown in  FIGS. 3 and 4 , a housing of the image forming apparatus  1  includes a first door  50 , a second door  51 , and a third door  54 . The first door  50  is arranged on a side face of the image forming apparatus  1 . The second and third doors  51  and  54  are arranged on a front face of the image forming apparatus  1 . 
   When the first, second, and third doors  50 ,  51 , and  54  are opened, the image forming unit  2  can be detached from and attached to the image forming apparatus  1 . 
   As shown in  FIG. 5 , the image forming apparatus  1  includes a connector unit  200 , a connector unit  201 , a lower rail  202 , and a rail guide  203 . The connector unit  200  includes connectors  200   a ,  200   b ,  200   c ,  200   d , and  200   e . The connector unit  200  is arranged on the image forming unit  2 , and can be connected with the connector unit  201 . The connector unit  201  includes connectors (not shown), and is arranged on the first door  50  of image forming apparatus  1 . The lower rail  202  is arranged on the image forming unit  2 , and is supported by the rail guide  203 . 
   When the first door  50  is opened, connections of the connectors  200   a  to  200   e  with the corresponding connectors of the connector unit  201  are cut. In other words, opening the first door  50  electrically disconnects the image forming unit  2  from the image forming apparatus  1 . 
   After the connection between the image forming unit  2  and the image forming apparatus  1  is cut by the opening of the first door  50 , the second and third doors  51  and  54  (not shown) are opened. Then, the image forming unit  2  is drawn from the image forming apparatus  1  in a frontward direction. 
   As a result, the image forming unit  2  is pulled out of the image forming apparatus  1  as shown in  FIG. 6 . As shown in  FIG. 6 , the image forming unit  2  and the cartridge loading unit  35  are integrally formed according to the embodiment, and the cartridge loading unit  35  can be attached to and detached from the image forming apparatus  1  together with the image forming unit  2 . 
   When the image forming unit  2  and the cartridge loading unit  35  are separately formed, the connection between an ink supply path (not shown) extending from the cartridge loading unit  35  to the image forming unit  2  and the image forming unit  2  needs to be cut to pull the image forming unit  2  out of the image forming apparatus  1 . 
   In the case, ink may leak out from the ink supply path. In the embodiment, on the other hand, since the image forming unit  2  and the cartridge loading unit  35  are integrally formed, the disconnection between the ink supply path and the image forming unit  2  is not required. As a result, ink does not leak from the ink supply path. 
     FIG. 7  illustrates a supporting mechanism for the carriage  23 . As shown in  FIG. 7 , the carriage  23  is translatably supported by the guide rod  21  and a sliding rail  22  in the main scanning direction. The guide rod  21  is provided with a gap adjustment mechanism  100  which is described later in detail referring to  FIGS. 9 and 10 . The guide rod  21  penetrates the carriage  23  to support the carriage  23 , and is mounted on a side panel (not shown) of the image forming unit  2 . The sliding rail  22  includes a hood  22   a  for supporting the sliding rail  22 . 
   As shown in  FIG. 8 , the carriage  23  is provided with an arm  23   a  extending toward the sliding rail  22 , and with a sliding member  23   b  arranged on a leading edge of the arm  23   a . The sliding member  23   b  contacts a side face of a rail of the hood  22   a  to support the carriage  23 . 
   Next, the gap adjustment mechanism  100  is described below in detail referring to drawings. The gap adjustment mechanism  100  is used when printing is performed on a sheet having large thickness such as cardboard to maintain an appropriate gap between the sheet and the head  24 . When the gap adjustment mechanism  100  is operated, the guide rod  21  moves up and down. When the guide rod  21  moves up and down, the carriage  23  supported by the guide rod  21  moves up and down together with the guide rod  21 . As a result, the gap between the sheet and the head  24  mounted to the carriage  23  is adjusted. 
   As shown in  FIG. 9 , the gap adjustment mechanism  100  includes a first lever unit  110  and a second lever unit  120 . The first lever unit  110  includes an eccentric plate  111  and an arm unit  113 . The eccentric plate  111  is provided with a hole  111   a  and a stopper  111   b . The stopper  111   b  is provided with a convex portion  111   c.    
   The arm unit  113  includes a concave portion  113   a  for mounting the arm unit  113 , a side plate mount hole  113   b  loosely pierced with a notched screw  211 , a spring hold hole  113   c , a guide member  113   d , and a joint concave portion  113   e . The convex portion  111   c  is to be set into the concave portion  113   a  of the arm unit  113 . 
   The second lever unit  120  includes a joint convex portion  121  having a front edge  121   a , a mount hole  122 , and a cover unit  123  serving as an operation unit. The cover unit  123  includes a tab  123   a.    
   The image forming unit  2  includes a side plate  2   a . The first lever unit  110  is rotatably mounted to the side plate  2   a . The side plate  2   a  includes regulation members  210   a  and  210   b , and a hold hole  213 . The image forming apparatus  1  includes a wall  1   a . The wall  1   a  includes a pin  150  and a regulation protrusion  151 . 
   The first and second lever units  110  and  120  are configured to be separated from and joined with each other cooperatively with attachment and detachment of the image forming unit  2 . 
   The guide rod  21  is provided with a leading edge. The hole  111   a  of the eccentric plate  111  has a substantially D shape at a position off a center of the eccentric plate  111 . The leading edge of the guide rod  21  is trimmed into the same substantially D shape as the hole  111   a , and is engaged with the hole  11   a . The regulation members  210   a  and  210   b  on the side face  2   a  of the image forming unit  2  are arranged above and below, respectively, the stopper  111   b  of the eccentric plate  111 . The stopper  111   b  abuts on one of the regulation members  210   a  and  210   b  to regulate an amount of rotation of the eccentric plate  111 . 
   With the notched screw  211  screwed into the side plate  2   a  of the image forming unit  2 , the first lever unit  110  can be rotatably mounted to the side plate  2   a  of the image forming unit  2 . The spring hold hole  113   c  holds an end of a twist spring  212 . Another end of the twist spring  212  is held by the hold hole  213  indicated by a dashed line in  FIG. 9 . The hold hole  213  is arranged at such a position on the side plate  2   a  that a distance between the hold hole  213  and the spring hold hole  113   c  becomes the shortest within a rotatable range of the arm unit  113  when the stopper  111   b  is positioned at a midpoint between the regulation members  210   a  and  210   b . Therefore, when the stopper  111   b  is positioned at the midpoint, a force applied by the twist spring  212  to the arm unit  113  reaches maximum. The force applied by the twist spring  212  causes the arm unit  113  to rotate in one of clockwise and anti-clockwise directions in  FIG. 9  so that the stopper  111   b  abuts on one of the regulation members  210   a  and  210   b . In other words, the stopper  111   b  is always forced to abut on one of the regulation members  210   a  and  210   b . As a result, vibration of the image forming apparatus  1  is prevented from causing the gap adjustment mechanism  100  to move so that the gap between the head  24  and the sheet does not shift. 
   The guide member  113   d  is arranged at a right end of the arm unit  113  in  FIG. 9 . The guide member  113   d  includes an inclined plane inclining to a front side toward the joint concave portion  113   e  as shown in  FIG. 10 . The inclined plane receives the front edge  121   a  of the joint convex portion  121  of the second lever unit  120  so that the front edge  121   a  abuts on the inclined plane to guide the joint convex portion  121  into the joint concave portion  113   e.    
   The second lever unit  120  is roratably mounted on the wall  1   a  of the image forming apparatus  1  with the mount hole  122  put on the pin  150  extending from the wall  1   a  by using a ring (not shown). The joint convex portion  121  extends frontward at a left end of the second lever unit  120 . When the image forming unit  2  is installed in the image forming apparatus  1 , the joint convex portion  121  is joined with the joint concave portion  113   e  of the arm unit  113 . A right end of the second lever unit  120  is provided with the cover unit  123  having an arc shape. A part of the cover unit  123  and the tab  123   a  are exposed from a window  51   a  arranged on a side face of the second door  51  as shown in  FIG. 4  The wall  1   a  of the image forming apparatus  1  is provided with the regulation protrusion  151  for regulation rotation of the second lever unit  120  due to self weight. 
   Next, a shift operation of the gap between the head  24  and the sheet is described below referring to  FIG. 9 . At first, a user pinches the tab  123   a , and moves the tab  123   a  to a lower side. When the tab  123   a  is moved to the lower side, the second lever unit  120  rotates in the clockwise direction centering on the mount hole  122 . When the second lever unit  120  rotates in the clockwise direction, the joint convex portion  121  pushes up the joint concave portion  113   e  of the first lever unit  110  against the force applied by the twist spring  212 . Then, the arm unit  113  of the first lever unit  110  rotates in the anti-clockwise direction centering on the side plate mount hole  113   b , and as a result, the concave portion  113   a  pushes down the convex portion  111   c . The convex portion  111   c  is pushed down to move the stopper  111   b  downward to part from the regulation member  210   a  arranged above the stopper  111   b . When the stopper  111   b  moves downward, the eccentric plate  111  rotates in the clockwise direction. The clockwise rotation of the eccentric plate  111  causes the guide rod  21  engaged with the eccentric plate  111  to move upward. As a result, the carriage  23  moves upward. 
   When the user moves the tab  123   a  further down, and the stopper  111   b  is caused to move to a position lower than the midpoint between the regulation members  210   a  and  210   b , the force applied by the twist spring  212  changes from a force causing the stopper  111   b  to move upward to a force causing the stopper  111   b  to move downward. The force applied by the twist spring  212  and the force applied by the user to push down the tab  123   a  cause the stopper  111   b  to abut on the regulation member  210   b  arranged below the stopper  111   b . As a result, the gap between the head  24  and the sheet is shifted from a position for plain paper to a position for cardboard. 
   The first and second lever units  110  and  120  can be joined as shown in  FIG. 11 , and can be separated as shown in  FIG. 12 . 
   As shown in  FIG. 11 , when the image forming unit  2  is placed inside the image forming apparatus  1 , the joint convex portion  121  of the second lever unit  120  is joined with the joint concave portion  113   e  of the first lever unit  110 . As shown in  FIG. 12 , when the image forming unit  2  is slid in a frontward direction and removed from the image forming apparatus  1 , the first lever unit  110  and the second lever unit  120  are separated from each other. A right side part of the second lever unit  120  arranged at the right of the mount hole  122 , which includes the cover unit  123 , is heavier than a left side part of the second lever unit  120  arranged at the left of the mount hole  122 , which includes the joint convex portion  121 . Therefore, when the second lever unit  120  is released from the joint concave portion  113   e  of the first lever unit  110 , the second lever unit  120  rotates in the clockwise direction centering on the mount hole  122 . Then, a lower end of the cover unit  123  abuts on the regulation protrusion  151 , and the regulation protrusion  151  stops the second lever unit  120  to rotate. Therefore, the regulation protrusion  151  prevents the joint convex portion  121  from not abutting on the inclined plane of the guide member  113   d.    
   On the other hand, even when the first lever unit  110  is released from the joining with the second lever unit  120 , the force applied by the twist spring  212  keeps the stopper  111   b  to abut on one of the regulation members  210   a  and  210   b . Therefore, the guide member  113   d  of the first lever unit  110  is regulated so as to abut on the joint convex portion  121 . 
   When the image forming unit  2  is slid into the image forming apparatus  1  (in a backward direction in  FIG. 12 ), the once removed image forming unit  2  is again placed inside the image forming apparatus  1 . When the image forming unit  2  is slid, the front edge  121   a  of the joint convex portion  121  of the second lever unit  120  abuts on the inclined plane of the guide member  113   d  of the first lever unit  110 . When the image forming unit  2  is further slid into the image forming apparatus  1  with the front edge  121   a  of the joint convex portion  121  abutting on the inclined plane of the guide member  113   d , the joint convex portion  121  is guided by the inclined plane to move to a lower side. As the front edge  121   a  of the joint convex portion  121  has a spherical shape so that the front edge  121   a  has small frictional drag on the inclined plane, the front edge  121   a  smoothly moves on the inclined plane. When the image forming unit  2  is further slid into the image forming apparatus  1  to mount the image forming unit  2  on the image forming apparatus  1 , the joint convex portion  121  is guided by the inclined plane to join with the joint concave portion  113   e  of the first lever unit  110 . As a result, the first lever unit  110  and the second lever unit  120  are joined with each other. 
   While the front edge  121   a  of the joint convex portion  121  has a spherical shape in the embodiment, the front edge, in another example, may include a ball member so that the joint convex portion includes a rollable ball. In the case, a concave member is provided at a front end of the joint convex portion so as to receive the ball member. When the front edge abuts on the inclined plane to move toward the joint concave portion, the ball member rolls. As a result, the frictional drag between the inclined plane and the front edge is reduced, and the joint convex portion can smoothly move on the inclined plane. The shape of the member included in the front edge is not limited to the ball shape as shown in  FIG. 13 . The front edge may include a cylindrical member so that the joint convex portion includes a rotatable cylinder as shown in  FIG. 14  instead. Similar to the front edge shown in  FIG. 13 , when the front edge shown in  FIG. 14  abuts on the inclined plane to move, the cylindrical member rotates, and the frictional drag between the inclined plane and the front edge can be reduced. 
   While the user pinches the tab  123   a  to move the tab up and down so that the gap between the head  24  and the sheet can be manually adjusted, the gap may be adjusted in another way. For example, the gap may be automatically adjusted by driving the second lever unit by a motor. In such a case, the user sets a type of paper in an operation section, and the motor can be driven based on, for example, set information to rotate the second lever unit so that the gap between the head and the sheet is adjusted. In another example, a thickness detection sensor for detecting a thickness of the sheet may be provided in a sheet conveyance route, and the gap may be adjusted by driving the motor based on output information of the thickness detection sensor to rotate the second lever unit. The thickness detection sensor may be a transmit photodetector. The transmit photodetector detects a thickness of the sheet from an amount of light transmitted the sheet. As the sheet becomes thicker, the amount of light transmitted the sheet becomes smaller. Therefore, when the amount of light is smaller than a predetermined value, it is judged that the sheet is cardboard, and the motor is driven to rotate the second lever unit so that the gap between the head and the sheet is shifted to the position for cardboard. 
   While in the examples and embodiments described supra the first and second lever units  110  and  120  include the joint concave portion  113   e  and convex portion  121 , respectively, and the first and second lever units  110  and  120  are separated from and joined wit each other cooperatively with attachment and detachment of the image forming unit  2 , in another example, the first lever unit can include a joint convex portion and the second lever unit can includes a joint concave portion instead. In the case, a guide member for guiding the joint convex portion of the first lever unit to the joint concave portion of the second lever unit can be provided at a left end of the second lever unit. In such an example, when the image forming unit is attached to the image forming apparatus, the joint convex portion of the first lever unit abuts on an inclined plane provided to the guide member of the second lever unit. Further, when the image forming unit is slid in an attaching direction, the joint convex portion of the first lever unit pushes the inclined plane. As a result, the second lever unit rotates, and the joint convex portion of the first lever unit relatively moves on the inclined plane to join with the joint concave portion of the second lever unit. 
   Further, while in the examples and embodiments described supra the regulation members  210   a  and  210   b  for regulating the rotation of the first lever unit  110  are arranged on the side face  2   a  of the image forming unit  2 , the regulation members may be arranged on an outer casing covering the side face of the image forming unit. 
   The above-described specific examples and embodiments are illustrative, and many variations can be introduced on these examples and embodiments without departing from the spirit of the disclosure or from the scope of the appended claims. For example, elements and/or features of different examples and illustrative embodiments may be combined with each other and/or substituted for each other within the scope of this disclosure and appended claims. 
   This patent specification is based on a Japanese patent application, No. JP2005-079038 filed on Mar. 18, 2005 in the Japan Patent Office, the entire contents of which are incorporated by reference herein.