Patent Publication Number: US-7720422-B2

Title: Fuser cleaning apparatus and method of operating a fuser cleaning device for use with an image forming device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims the benefit of Korean Patent Application No. 2006-123933, filed Dec. 7, 2006, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   Aspects of the present invention relate to a fuser cleaning apparatus and a method of operating a fuser cleaning apparatus for use with an image forming device, in which a contaminated fuser of the image forming device is cleaned by a heating of a heating roller of the fuser while the heating roller is not in motion. 
   2. Description of the Related Art 
   In an electro-photographic image forming device, a latent image is formed on a photosensitive drum to which toner is adhered. The toner is developed into a visible image using developer and the visible toner image is then transferred to a print medium, such as paper or a transparency. The image transferred to the print medium is fixed to the print medium by passing the print medium through a fuser. Once the print medium has passed through the fuser, the print medium is discharged from the image forming apparatus. 
   The fuser applies heat and pressure to the print medium to fix the image to the print medium. To this end, the fuser includes a heating roller to apply heat to the print medium and a pressure roller to apply pressure to the print medium. The heating roller and the pressure roller are provided along a conveyance path of the print medium. 
   As a result, it is frequently necessary to clean a fuser that becomes contaminated with toner. According to a conventional method of cleaning a fuser, a fusing temperature of the fuser is set to a high preset temperature in a cleaning mode via a heating of the heating roller while rotating the heating and pressure rollers. When the fusing temperature reaches the preset temperature, the medium (i.e., a sheet of paper) is picked up and passed between the heating and pressure rollers to remove melted toner. 
   The fuser further includes a guide member, which is referred to as a claw, to smoothly discharge media while preventing them from being wound around the photosensitive drum. As the number of sheets of media printed on increases, an increasing amount of toner that attaches to the guide member ends up being fixed to the guide member due to the fusing temperature increases during fusing processes. However, according to the conventional cleaning method, melting toner contaminants on the guide member is difficult since the cleaning operation is performed while the heating roller rotates. Rather, toner contaminants on the heating and pressure rollers may be added to toner contaminants on the guide member. 
   Thus, the conventional cleaning method is not effective to clean contaminants on the guide member. If the contaminants fixed to the guide member scratch a medium to be discharged, undesired vertical black lines may be printed on the medium and the medium may also be jammed. 
   SUMMARY OF THE INVENTION 
   Therefore, it is an aspect of the invention to provide a fuser cleaning apparatus and a method of operating a fuser cleaning apparatus for use with an image forming device in which media are prevented from being scratched and jammed during fusing processes due to residual contaminants on a guide member which are hard to clean. 
   In accordance with an aspect of the invention, there is provided a fuser cleaning apparatus, the apparatus comprising a fuser including a guide member to guide a print medium conveyed through the image forming device, and heating and pressure rollers to fix an image to the print medium; a power source to power the conveyance of the print medium and to rotate the fuser; a heater to heat the heating roller to melt contaminants fixed to the guide member; and a controller to drive the heater while the fuser is not rotated and to pass the print medium through the fuser to remove the melted contaminants from the guide member. 
   In accordance with an aspect of the invention, there is provided a fuser cleaning method for use with an image forming device comprising a fuser including a guide member and heating and pressure rollers to fix an image transferred to a print medium, the method comprising: heating the fuser, when a cleaning mode for the fuser has been set, by driving a heater thereof while the fuser does not rotate to melt contaminants on the guide member; and passing the print medium through the fuser to absorb and remove the melted contaminants. 
   In accordance with an aspect of the invention, there is provided a method of operating a cleaning mode of a fuser of an image forming apparatus, comprising: setting a fuser cleaning temperature; activating a power source of the image forming apparatus to convey the print medium through the apparatus to a first position; when the print medium reaches the predetermined position, deactivating the power source and activating a heater of the fuser to heat the fuser; when the temperature of the fuser reaches the fuser cleaning temperature, reactivating the power source to convey the print medium to a second position and deactivating the heater; and when the print medium reaches the second position, ending the cleaning mode. 
   Additional and/or other aspects and 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 
     These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: 
       FIG. 1  is a schematic diagram of a fuser cleaning apparatus for an image forming device according to an embodiment of the present invention; 
       FIG. 2  is a control block diagram of a structure for controlling the cleaning apparatus of  FIG. 1 ; 
       FIG. 3  illustrates operation control timings of first and second motors and a heater when performing a fuser cleaning operation according to an embodiment of the present invention; 
       FIGS. 4A to 4D  illustrate states of a fuser in the order in which the fuser is cleaned according to an embodiment of the present invention; 
       FIG. 5  illustrates a print medium, on which stripe images are developed at regular intervals to absorb and remove toner remnants of the fuser according to an embodiment of the present invention; 
       FIG. 6  is a flow chart illustrating a fuser cleaning method for an image forming device according to an embodiment of the present invention; 
       FIG. 7  is a schematic diagram illustrating a fuser cleaning apparatus for an image forming device according to another embodiment of the present invention; 
       FIG. 8  is a control block diagram of a structure to control the cleaning apparatus of  FIG. 7 ; 
       FIG. 9  illustrates operation control timings of an integrated motor and a heater when performing a fuser cleaning operation according to an embodiment of the present invention; and 
       FIG. 10  is a flow chart illustrating a fuser cleaning method for an image forming device according to another embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE EMBODIMENTS 
   Reference will now be made in detail to the present embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures. 
     FIG. 1  is a schematic diagram of a fuser cleaning apparatus  200  for use with an image forming device according to an embodiment of the present invention. The fuser cleaning apparatus  200  includes an exposure device  210 , a photosensitive drum  220 , a developing roller  230 , a transfer roller  240 , a fuser  250 , a pickup roller  261 , a paper feed sensor  271 , and first and second motors  281  and  282 . The exposure device  210  generates a laser beam, which forms a latent electrostatic image on a surface of the photosensitive drum  220 . The developing roller  230  causes toner to adhere to the photosensitive drum  220 . The developing roller  230  also develops the latent electrostatic image formed on the photosensitive drum  220  into a toner image. The transfer roller  240  is provided under the photosensitive drum  220  to transfer the toner image formed on the photosensitive drum to a medium (i.e., paper, or transparencies, and hereinafter referred to as “paper”). 
   The fuser  250  applies heat and pressure to the paper carrying the transferred toner image so as to fix the toner image to the paper. The fuser  250  includes a heating roller  251  to generate high heat and a pressure roller  252  that is in close contact with the heating roller  251 . The heating roller  251  includes a heater  253  to generate the high heat. A heating lamp provided in the heating roller  251  or an electric heating coil inserted between inner and outer circumferential surfaces of the heating roller may be used as the heater  253 . The fuser  250  also includes a temperature sensor  291  provided near the heating roller  251  to sense the temperature of the surface of the heating roller. The pressure roller  252  closely contacts the heating roller  251  at a constant pressure and rotates at the same speed as the heating roller  251 . 
   The pickup roller  261  is provided at a beginning position of a paper conveyance path P to pick up each sheet of paper from a paper feed cassette (not shown) in which sheets of paper are stacked. The paper conveyance path P is a path along which the paper is conveyed until the paper is discharged through paper exit rollers  266 ,  267 ,  268 , and  269  after being picked up by the pickup roller  261 . Conveying rollers  262  and  263 , which convey the picked-up sheet of paper, registration rollers  264  and  265 , which align the front end of the sheet of paper that is being conveyed, the paper exit rollers  266 ,  267 ,  268 , and  269 , which discharge the sheet of paper, the photosensitive drum  220 , the transfer roller  240 , and the fuser  250  are provided along the paper conveyance path P. 
   The paper feed sensor  271  senses a sheet of paper that is being conveyed and is provided near the registration rollers  264  and  265  to sense that the sheet of paper is moving to the photosensitive drum  220 . The paper feed sensor outputs a first sensed signal. The first sensed signal is used to determine exposure and developing timings. 
   A paper exit sensor  272  is provided in the paper conveyance path P downstream of the paper feed sensor  271 , and, more specifically, downstream of the fuser  250 . The paper exit sensor  272  senses a sheet of paper that passes through the fuser  250  and outputs a second sensed signal. The second sensed signal is used to determine the time to complete printing. 
   The first and second motors  281  and  282  respectively transfer motive force to the components. The first motor  281  is connected to the photosensitive drum  220  and the components (i.e., the developing roller  230 , the transfer roller  240 , the registration rollers  264  and  265 , the conveying rollers  262  and  263 , and the pickup roller  261 ) that are provided in the paper conveyance path P upstream of the photosensitive drum  220 . The second motor  282  is a drive source to drive the components (i.e., the heating roller  251 , the pressure roller  252 , and the paper exit rollers  266 ,  267 ,  268 , and  269 ) that are provided in the paper conveyance path P downstream of the photosensitive drum  220 . 
   The fuser cleaning apparatus of the present invention includes a controller  201  to control overall operations of the fuser cleaning apparatus as shown in  FIG. 2 . The controller  201  receives a setting command input by the user from a host computer  100  and performs a printing operation. 
   Although fuser cleaning operations may be performed each time a printing operation is performed, it is more effective to perform fuser cleaning operations when a fuser cleaning mode has been set. The fuser cleaning mode may be set based on the type and size of the product and/or on the number of printed sheets of paper. Taking into consideration the fact that printing of tens of thousands of sheets severely contaminates a guide member of the fuser, the setting of the fuser cleaning mode on the number of printed sheets may be advantageous. 
   The fuser cleaning mode may be set directly by the user through the host computer  100  or may be automatically set when the total number of printed sheets of paper counted in printing operations reaches a preset number. When the fuser cleaning mode is automatically set, the controller  201  uses print count information that is obtained by counting, through a counter  202 , the total number of sheets of paper printed in printing operations. 
     FIG. 3  illustrates operation control timings of the first and second motors and the heater when performing a fuser cleaning operation according to the present invention, and  FIGS. 4A to 4D  illustrate fuser cleaning processes. 
   If the fuser is significantly contaminated as a result of the performance of a number of printing operations, it is necessary to perform a fuser cleaning operation to separate toner remnants B that may be fixed to a guide member  254  from the guide member  254  as shown in  FIG. 4A . When a fuser cleaning mode has been set, the controller  201  controls operations of the first and second motors  281  and  282  and the heater  253  as shown in  FIG. 3 . Specifically, the controller  201  simultaneously turns the heater  253  and the first motor  281  on and turns the second motor  282  off. Accordingly, the heating roller  251  is heated by the heater  253  while the heating roller  251  is not in motion and a sheet of paper S is picked up and conveyed along the paper conveyance path P. 
   At time T a  when the sheet of paper S reaches a specific position A, the controller  201  turns off the first motor  281  (see  FIG. 4B ). The temperature sensor  291  senses a temperature of the surface of the heating roller  251  and provides a signal indicating the sensed temperature to the controller  201 . The controller  201  then determines whether the temperature sensed by the temperature sensor  291  has reached a preset temperature of the fuser cleaning mode. Here, according to an embodiment of the invention, the preset temperature of the fuser cleaning mode is the maximum allowable temperature that is equal to or greater than the temperature required to fuse toner when performing a printing operation in a normal printing mode. When the heating roller has been heated to the preset temperature, the controller  201  turns the heater  253  off and simultaneously turns both the first and second motors  281  and  282  on so as to introduce the sheet of paper S that is waiting at the specific position A into a gap between the heating roller  251  and the pressure roller  252  (see  FIG. 4C ). 
   As the sheet of paper S passes between the heating roller  251  and the pressure roller  252 , the paper S absorbs and removes toner remnants B that have been melted from the guide member  254  (see  FIG. 4B ). Here, it is possible to pass a sheet of paper S, on which toner images are developed in stripes L at regular intervals as shown in  FIG. 5 , between the heating roller  251  and the pressure roller  252 , instead of passing a blank sheet of paper between them to increase the absorption efficiency of toner remnants. 
   According to an embodiment of the present invention, the controller  201  sets the fuser cleaning mode according to a cleaning mode setting command input from the host computer  100 . According to an alternate embodiment, the controller  201  determines whether to set the fuser cleaning mode according to the number of printed sheets counted by the counter  202 . 
   If the fuser cleaning mode is set, the controller  201  then performs a fuser cleaning operation to clean contaminants on the fuser as shown in  FIG. 6 . 
   First, the controller  201  sets a fuser cleaning temperature H c  to be higher than a fusing temperature set to be appropriate for printing ( 301 ). The controller  201  turns the first motor  281  on, turns the second motor  282  off, and turns the heater  253  ( 303 ) on. Accordingly, the heating roller  251  is heated by the heater  253  while the heating roller  251  is not in motion and a sheet of paper S is picked up and conveyed along the paper conveyance path P. 
   While the sheet of paper S is conveyed, the controller  201  determines whether the sheet of paper S has been detected by the paper feed sensor  271  ( 305 ). If the sheet of paper S is determined to have been detected, the controller  201  counts an elapsed time T using an internal timer ( 307 ) and determines whether the counted time T has reached a preset time T a . The preset time T a  corresponds to the time required for the sheet of paper S to reach the specific position A from the paper feed sensor  271 . 
   When the elapsed time T has reached the preset time T a , the controller  201  determines whether a surface temperature H of the heating roller  251  sensed by the temperature sensor  291  has reached the preset cleaning temperature H c  ( 313 ). If the surface temperature H is determined to have not reached the preset cleaning temperature H c , the controller  201  returns to operation  311  to maintain the heating operation. 
   If the surface temperature H is determined to have reached the preset cleaning temperature H c , the controller  201  turns the first and second motors  281  and  282  on and turns the heater  253  off ( 315 ). Accordingly, the sheet of paper introduced between the heating roller  251  and the pressure roller  252  absorbs and removes toner remnants on the guide member  254  that are melted from the guide member  254  by the heating of the heating roller  251 . 
   The controller  201  then determines whether the sheet of paper has been detected by the paper exit sensor  272  ( 317 ). If the sheet of paper has not been determined to have been detected by the paper exit sensor  272 , the controller  201  returns to operation  315  to maintain the cleaning operation so as to absorb and remove toner remnants from the paper guide memory  254 . 
   If the determination of operation  317  is that the sheet of paper has been detected by the paper exit sensor  272 , the controller  201  determines that the toner remnants absorption and removal operation has been completed and terminates the cleaning operation. 
   Although the first and second motors  281  and  282  are used as driving sources to drive the components in the above embodiments, according to another embodiment of the invention, the paper pickup, conveyance, development, transfer, fusing, and exit processes may be performed using a single motor. 
   Another embodiment of the invention is shown in  FIGS. 7 to 10 . According to this embodiment, a single motor performs a fuser cleaning operation and, as in the above embodiments, the heating roller is heated while it is not in motion to separate toner remnants fixed to the guide member from the guide member with a sheet of paper being passed between the heating roller and the pressure roller to clean the toner remnants. 
   As shown in  FIG. 7 , a fuser cleaning apparatus for an image forming device according to the present invention includes an integrated motor  283 . The integrated motor  283  drives a photosensitive drum  220 , a developing roller  230 , a transfer roller  240 , registration rollers  264  and  265 , conveying rollers  262  and  263 , a pickup roller  261 , a heating roller  251 , a pressure roller  252 , and paper exit rollers  266 ,  267 ,  268 , and  269  provided along a paper conveyance path P. 
   As shown in  FIG. 8 , the controller  201  sets a cleaning mode according to a fuser cleaning mode setting command from a host computer  100  or according to the total number of printed sheets to be counted by a counter  202 . If the cleaning mode is set, the controller  201  controls operations of the integrated motor  283  and the heater  253  as shown in  FIG. 9 . 
   Reference will now be made to  FIG. 10  which is a flow chart illustrating a fuser cleaning method for an image forming device. As shown in  FIG. 10 , first, the controller  201  sets a fuser cleaning temperature H c  to be higher than a fusing temperature set for normal printing ( 401 ). The controller  201  turns the integrated motor  283  on and turns the heater  253  off ( 403 ). Then, a sheet of paper S is picked up and conveyed along the paper conveyance path P. Here, the integrated motor  283  rotates the heating roller  251  and the heater  253  is not in operation. 
   While the sheet of paper S is conveyed, the controller  201  determines whether the sheet of paper S has been detected by the paper feed sensor  271  ( 405 ). If the sheet of paper S has been determined to be detected, the controller  201  counts an elapsed time T using an internal timer ( 407 ) and determines whether the counted time T has reached a preset time T a . The preset time T a  corresponds to the time required for the sheet of paper S to reach the specific position A from the paper feed sensor  271 . 
   When the elapsed time T has reached the preset time T a , the controller  201  turns the integrated motor  283  off and turns the heater  253  on. Accordingly, the heating roller  251  is heated by the heater  253  while the heating roller  251  is not in motion and the sheet of paper S waits at the specific position A. 
   The controller  201  then determines whether a surface temperature H of the heating roller  251  that is sensed by the temperature sensor  291  has reached the preset cleaning temperature H c  ( 413 ). If the surface temperature H is determined to have not reached the preset cleaning temperature H c , the controller  201  returns to operation  411  to maintain the heating operation. 
   If the determination of operation  413  is that the surface temperature H has reached the preset cleaning temperature H c , the controller  201  turns the integrated motor  283  on and turns the heater  253  off ( 415 ). Accordingly, the sheet of paper introduced between the heating roller  251  and the pressure roller  252  absorbs and removes toner remnants that are melted from the guide member  254  by heating of the heating roller  251 . 
   The controller  201  then determines whether the sheet of paper has been detected by the paper exit sensor  272  ( 417 ). Depending on this determination, the controller  201  returns to operation  415  to maintain the cleaning operation or terminates the cleaning operation. 
   As is apparent from the above description, aspects of the present invention provide a fuser cleaning apparatus and method of operating a fuser cleaning apparatus for use with an image forming device which have a variety of advantages. For example, heat is efficiently transferred to a guide member of a fuser to allow for relatively easy performance of a cleaning operation of the fuser since a heating roller of the fuser is heated by a heater while the heating roller is not in motion. Also, it is possible to prevent melted toner remnants from contaminating the heating roller since a sheet of paper which has waited at an entrance of the fuser is conveyed and passed between the heating and pressure rollers of the fuser after the heating roller is heated while the heating roller is not in motion. 
   Although a few embodiments 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 these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.