Patent Publication Number: US-7720411-B2

Title: Image forming apparatus

Description:
CROSS REFERENCE TO RELATED APPLICATION 
   This application claims priority from Japanese Patent Application No. 2007-060034, filed on Mar. 9, 2007, the entire subject matter of which is incorporated herein by reference. 
   FIELD 
   Aspects of the invention relate to image forming apparatuses such as electrophotographic printers and copiers. 
   BACKGROUND 
   A known image forming apparatus, e.g. an electrophotographic printer or copier, generally uses a light-emitting diode (LED) head array for exposing a photoconductive drum to light. 
   The LED head array is mounted on an inner side of a lid or top cover pivotally mounted to the top of a body of the image forming apparatus. When the lid is positioned at an open position, the LED head array is separated from the photosensitive drum of a process cartridge disposed in the body of the apparatus. 
   In the image forming apparatus, a toner cartridge is installed in a process cartridge. When the toner cartridge is replaced with a new one, the top cover should be opened so as to prevent the toner cartridge and the LED head array from interfering with each other. 
   However, to open the top cover, sufficient space is required above the image forming apparatus. If such space is not available, replacement of the toner cartridge can be difficult. 
   SUMMARY 
   Aspects of the invention provide an image forming apparatus configured to facilitate toner cartridge replacement even if sufficient space is not available above the image forming apparatus. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Illustrative aspects of the invention will be described in detail with reference to the following figures in which like elements are labeled with like numbers and in which: 
       FIG. 1  is a perspective view of an appearance of an image forming apparatus according to an illustrative embodiment of the invention; 
       FIG. 2A  is an side sectional view of an internal structure of the image forming apparatus of  FIG. 1  in which a side cover is eliminated; 
       FIG. 2B  is an enlarged sectional view showing an X portion of  FIG. 2A ; 
       FIG. 3  is a perspective view of the image forming apparatus where the side cover is eliminated and a front cover is opened; 
       FIG. 4  is a perspective view of the image forming apparatus where a cartridge holding member is pulled out from a body of the image forming apparatus from its storage position to a replacement position along with an LED supporting member; 
       FIG. 5  is a side sectional view of the image forming apparatus of  FIG. 4 ; 
       FIG. 6  is a perspective view of the image forming apparatus where the LED supporting member of  FIG. 4  is moved from a retaining position to a withdrawn position; 
       FIG. 7  is a side sectional view of the image forming apparatus of  FIG. 6 ; 
       FIG. 8  is a perspective view of an image forming apparatus according to an illustrative embodiment of the invention where an LED supporting member is moved from a retaining position to a withdrawn position; 
       FIG. 9  is a perspective view of another image forming apparatus according to an illustrative embodiment of the invention where an LED supporting member is moved from a retaining position to a withdrawn position; and 
       FIG. 10  is a perspective view of an image forming apparatus according to still another illustrative embodiment of the invention where an LED supporting member is moved from a retaining position to a withdrawn position. 
   

   DETAILED DESCRIPTION 
   An illustrative embodiment of the invention will be described in detail with reference to the accompanying drawings. An image forming apparatus according to aspects of the invention may be a multifunction printer (MFP) having a copier function, printer function, scanner function and facsimile function. It will be appreciated that aspects of the invention apply to other types of image forming apparatuses as well. 
   As shown in  FIG. 1 , an apparatus body  1  of the image forming apparatus includes side covers  1 A, a front cover  1 B, and a large-sized top cover  2 . The top cover  2  can become heavy when it contains a scanner and an automatic document feeder, which are not shown. 
   For ease of discussion, in the following description, the top or upper side, the bottom or lower side, the left or left side, the right or right side, the front or front side, and the rear or rear side of the image forming apparatus will be identified as indicated by the arrows in  FIG. 1 . The sides of the image forming apparatus according to the illustrative embodiment will be referenced as viewed from a vantage point in front of the image forming apparatus. Sides of individual objects of the image forming apparatus will be similarly identified based on the arranged/attached position of the object on/in the image forming apparatus in  FIG. 1 . 
   As shown in  FIGS. 2A and 3 , the front cover  1 B is pivotally mounted at its lower end to the apparatus body  1  such that the front cover  1 B moves between a closed position where the front cover  1 B stands in an upright position to an open position where the front cover  1 B protrudes frontward substantially horizontally. The front of the apparatus body  1  is opened and closed by the front cover  1 B. A cartridge holding member  3  and an LED supporting member  4  are accommodated in the apparatus body  1 . 
   The top cover  2  includes a support arm  2 A protruding downward at a rear end. The support arm  2 A is pivotally mounted to an upper end of a rear wall of the apparatus body  1 , so that the top cover  2  is released upward. The support arm  2   a  includes a cover portion  2 B extending to the front of the apparatus body  1  to cover the cartridge member  3  and the LED supporting member  4 . 
   As shown in  FIGS. 4 and 5 , the cartridge holding member  3  can be open-top box-shaped. A pair of slide rails  3 A is formed under the cartridge holding member  3 . The cartridge holding member  3  is configured to slide on a surface  1 C and the front cover  1 B positioned in the open position via the slide rails  3 A in the front and rear directions. 
   The slide rails  3 A protrude rearward from the rear wall of the cartridge holding member  3 , and are formed with engaging portions  3 B protruding upward at rear ends. Stoppers  1 D are formed on the inner surfaces of the side covers  1 A on the left and right sides of the apparatus body  1 . The stoppers  1 D are configured to catch the engaging portions  3 B respectively. 
   Thus, the cartridge holding member  3  is drawable from a storage position where it is accommodated in the apparatus body  1  as shown in  FIGS. 2A and 3  to a replacement position as shown in  FIGS. 4 and 5 . The cartridge holding member  3  can hold four toner cartridges  5  ( FIG. 6 ) and corresponding photosensitive drums  8  ( FIG. 2B ) which are arranged in the front-rear direction. The toner cartridges  5  are detachable from the cartridge holding member  3 . 
   The LED supporting member  4  can be a frame-like member covering the cartridge holding member  3  from above. In this instance, the LED supporting member  4  is pivotally connected to the cartridge holding member  3  at the rear end. The LED supporting member  4  is pivotally movable from a retaining position shown in  FIG. 2A  where each LED head array  6  is positioned relative to the corresponding photosensitive drum  8  to a withdrawn position as shown in  FIG. 7  where each LED head array  6  is withdrawn from the corresponding photosensitive drum  8 . At the withdrawn position, the LED supporting member  4  is maintained by a stopper, not shown, so that it stands slightly leaning rearward as shown in  FIGS. 6 and 7 . At this time, toner cartridges  5  received in the cartridge holding member  3  can be replaced. 
   The LED supporting member  4  supports four LED head arrays  6  arranged in association with the four photosensitive drums  8  mounted in the cartridge holding member  3 . The LED head arrays  6  are configured to expose the corresponding photosensitive drums  8  to light. 
   As shown in  FIGS. 4 and 5 , a pair of coil springs  7  is disposed at the front end of the cartridge holding member  3 . The coil springs  7  are fixed at their lower ends to a pair of bearing portions  3 C. When the cartridge holding member  3  is pulled out of the apparatus body  1  to the replacement position, the coil springs  7  resiliently maintain the LED supporting member  4  at a temporary stop position where the LED supporting member  4  is positioned slightly upward from the retaining position, that is positioned immediately before the retaining position. 
   Cam portions  4 A are formed on front left and right sides of the upper surface of the LED supporting member  4  as shown in  FIG. 4 . The cam portions  4 A protrude upward from the LED supporting member  4 . The cam portions  4 A are configured to cause the LED supporting member  4  to slide down from the temporary stop position to the retaining position while the cartridge holding member  3  is pushed into the storage position as shown in  FIG. 2A  from the replacement position as shown in  FIG. 5 . 
   As shown in  FIG. 3 , cam contact portions  2 C are formed on left and right sides of the cover portion  2 B of the top cover  2 . The cam contact portions  2 C protrude downward from the left and right sides of the cover portion  2 B in association with the cam portions  4 A. When the cam portions  4 A contact the cam contact portions  2 C, the LED supporting member  4  is moved to the retaining position. 
   For replacement of a toner cartridge  5  detachably mounted in the cartridge holding member  3 , the front cover  1 B can be tilted frontward to the open position until it protrudes horizontally as shown in  FIG. 3 . As shown in  FIGS. 4 and 5 , the cartridge holding member  3  can be pulled out from the apparatus body  1  along with the LED supporting member  4 , for example when the front cover  1 B is in a horizontal position. 
   The engaging portions  3 B, which are formed at the rear ends of the slide rails  3 A of the cartridge holding member  3 , are engaged with the stoppers  1 D formed on the inner surfaces of the side covers  1 A of the apparatus body  1 . Thus, the cartridge holding member  3  can be maintained in a replacement position out of the apparatus body  1  while remaining engaged with the apparatus body  1 . 
   When the cartridge holding member  3  is pulled out from the apparatus body  1  to the replacement position, the LED supporting member  4  leans upward to the temporary stop position due to the urging force of the coil springs  7 . 
   As shown in  FIGS. 6 and 7 , the LED supporting member  4  can be raised in a direction of the arrow until it is maintained in the withdrawn position where it stands leaning slightly rearward. In this state, a toner cartridge  5  detachably mounted in the cartridge holding member  3  can be replaced. 
   After the replacement of the toner cartridge  5  is finished, the LED supporting member  4  is tilted downward from the withdrawn position as shown in  FIGS. 4 and 5 . The LED supporting member  4  is resiliently maintained at the temporary stop position where it is tilted slightly upward from the retaining position by the coil springs  7  received in the bearing portions  3 C of the cartridge holding member  3 . The LED head arrays  6  supported by the LED supporting member  4  are not subjected to impact and thus can avoid being damaged. 
   As shown in  FIGS. 2A and 3 , the cartridge holding member  3  is pushed into the storage position in the apparatus body  1  along with the LED supporting member  4 . At this time, the cam portions  4 A protruding upward from the upper surface of the LED supporting member  4  are brought into contact with the cam contact portions  2 C of the top cover  2 , and the LED supporting member  4  is moved down to the retaining position against the urging force of the coil springs  7 . In this way, the cartridge holding member  3  and the LED holding member  4  are positioned and accommodated in the apparatus body  1 . 
   According to the image forming apparatus, even if a space cannot be found above the image forming apparatus, the toner cartridges  5  can be replaced irrespective of whether the top cover  2  is opened or closed. If the top cover  2  is heavy because a scanner and an automatic document feeder are assembled in the top cover  2 , the toner cartridges  5  can be replaced irrespective of whether the top cover  2  is opened or closed. 
   The LED supporting member  4  is withdrawn in a different direction than the direction in which the cartridge holding member  3  is pulled out. That is, the LED supporting member  4  is withdrawn upward pivotally on the rear end of the cartridge holding member  3 . As the LED supporting member  4  is moved out of the way, the toner cartridges  5  can be easily replaced. 
   When the LED supporting member  4  is lowered from the withdrawn position as shown in  FIGS. 4 and 5 , it is resiliently maintained at the temporary stop position by the urging force of the coil springs  7  where it is tilted slightly upward from the retaining position. Thus, the LED head arrays  6  can avoid being damaged by impact. 
   When the cartridge holding member  3  is pushed into the apparatus body  1  to the storage position along with the LED supporting member  4 , the LED supporting member  4  is pressed down to the retaining position against the urging force of the coil springs  7 . Thus, the LED head arrays  6  of the LED supporting member  4  can be easily and reliably positioned with respect to the corresponding photosensitive drums  8  in the cartridge holding member  3 . 
   The image forming apparatus of the invention is not limited to the above embodiment. As shown in  FIG. 8 , the LED supporting member  4  may be withdrawn in an upward direction pivotally on the right end of the cartridge holding member  3 . Alternatively, the LED supporting member  4  may be withdrawn in an upward direction pivotally on the left end of the cartridge holding member  3 . As shown in  FIG. 9 , the LED supporting member  4  may be pulled out rightward from the cartridge holding member  3  with respect to a longitudinal direction of each toner cartridge  5 . Alternatively, the LED supporting member  4  may be pulled out leftward from the cartridge holding member  3  with respect to the longitudinal direction of each toner cartridge  5 . 
   The coil springs  7  are used as a temporary stop device that resiliently receives the cartridge holding member  3  in the described illustrative embodiment. The invention is not limited to the coil springs  7 . Rubber or leaf spring may be used instead. The coil springs  7  are fixed to the cartridge holding member  3  in the described illustrative embodiment. However, as shown in  FIG. 8 , the coil springs  7  may be fixed to the LED supporting member  4 . 
   In the above configuration to move the LED supporting member  4  pivotally upward toward the apparatus body  1 , an elastic member, e.g. rubber R as shown in  FIG. 10 , may be disposed between the top cover  2  including a scanner and the LED supporting member  4 . With the rubber R, if the LED supporting member  4  is thrust open and contacts the top cover  2 , the rubber R can absorb the impact generated by the contact. Thus, the scanner in the top cover  2  and the LED head arrays  6  of the LED supporting member  4  can be protected. As shown in  FIG. 10 , when the LED supporting member  4  contacts the rubber R of the top cover  2 , the LED supporting member  4  can be maintained at the withdrawn position by the apparatus body  1  that is heavier in weight than the LED supporting member  4 . Thus, the LED supporting member  4  can be stably held at the withdrawn position. The elastic member may include a coil spring and a sponge. The elastic member may be disposed on the top cover  2  or the LED supporting member  4 . 
   In the above illustrative embodiment, the cartridge holding member  3  is inseparable from the apparatus body  1  by engaging the engaging portions  3 B of the slide rails  3 A with the stoppers  1 D of the apparatus body  1 . However, the cartridge holding member  3  may be completely separated from the apparatus body  1 . Even with this configuration, the LED supporting member  4  may be opened after the cartridge holding member  3  is completely removed from the apparatus body  1 , so that toner cartridge  5  can be replaced. 
   In the above illustrative embodiment, the LED head arrays  6  are used as a light source. Any suitable light source may be used such as an array of organic electroluminescent light emitting elements or fluorescent light emitting elements may be used. To control light amount from the light source, the light emitting elements may emit light selectively according to image data. Alternatively, a plurality of liquid crystal or lead-lanthanum-zirconate-titanate (PLZT) optical shutters may be arranged to selectively control the time to open/close each optical shutter. 
   While the features herein have been described in connection with various example structures and illustrative aspects, it will be understood by those skilled in the art that other variations and modifications of the structures and aspects described above may be made without departing from the scope of the invention. Other structures and aspects will be apparent to those skilled in the art from a consideration of the specification or practice of the features disclosed herein. It is intended that the specification and the described examples only are illustrative with the true scope of the inventions being defined by the following claims.