Patent Publication Number: US-2015063836-A1

Title: Fuser Member Conditioning Systems and Methods

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     None. 
     BACKGROUND 
     1. Field of the Disclosure 
     The present disclosure relates generally to systems used to fuse toner in image forming devices and, more particularly, to systems and methods of conditioning a fuser member used to fuse toner. 
     2. Description of the Related Art 
     In the electrophotographic (EP) print process an image is exposed on a photo-conductor, toner is attracted to the exposed image, and toner is deposited on media. The toner is made of plastic particles which must be heated and pressed to permanently fuse the toner to the media. Devices which perform this fusing are known as fusers. 
     Fusers typically have a top-release layer that contacts the toner and the media. The top-release layer is designed so that toner does not cling to the fuser and instead remains on the media. Over time, the top-release layer will wear due to contact with the media. Worn fusers have reduced gloss which creates print defects. 
     Fusers may be internally heated or externally heated. Externally heated fusers use a lamp to heat the top-release layer. In unusual conditions, such as during a paper jam, the lamp may heat unevenly due to media partially blocking the top-release layer. This may cause the top-release layer to flow and create a gloss band at the edge of the media. The gloss band may cause print defects on subsequent pages. 
     Accordingly, it will be appreciated that it is desirable to condition a fuser&#39;s top-release layer to restore it to uniform gloss. 
     SUMMARY 
     Provided is a method of operating an image forming device. The image forming device includes a fusing member having a top-release layer and a pressure member configured to engage the top-release layer. The method includes disengaging the pressure member from the top-release layer, heating the top-release layer to at least the melting temperature of the top-release layer while rotating the fusing member with the pressure member disengaged from the top-release layer, cooling the top-release layer to less than the melting temperature of the top-release layer while rotating the fusing member with the pressure member disengaged from the roller surface coating, and reengaging the pressure member with the top-release layer. 
     Also provided is a method of conditioning a fusing member having a top-release layer. The method includes heating the top-release layer to at least the melting temperature of the top-release layer while rotating the fusing member and while no pressure member engages the top-release layer, and cooling the top-release layer to less than the melting temperature of the top-release layer while rotating the fusing member. 
     Also provided is an image forming device having a fusing member having a top-release layer, a pressure member configured to engage with the top-release layer to press media against the top-release layer, and a controller. The controller is configured to condition the top-release layer by disengaging the pressure member from the top-release layer, heating the top-release layer to at least the melting temperature of the top-release layer while rotating the fusing member with the pressure member disengaged from the top-release layer, cooling the top-release layer to less than the melting temperature of the top-release layer with the pressure member disengaged from the top-release layer, and reengaging the pressure member with the top-release layer. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above-mentioned and other features and advantages of the various embodiments, and the manner of attaining them, will become more apparent and will be better understood by reference to the accompanying drawings. 
         FIG. 1  is a block diagram of an imaging system according to one example embodiment. 
         FIGS. 2 and 3  are diagrams of the fuser shown in  FIG. 1  according to one example embodiment. In  FIG. 2 , a top-release layer is in contact with a belt. In  FIG. 3 , the top-release layer is not in contact with the belt. 
         FIG. 4  is a flowchart of a method of conditioning a fusing member according to one example embodiment. 
         FIG. 5  is a flowchart of a method of operating an image forming device according to another example embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The following description and drawings illustrate embodiments sufficiently to enable those skilled in the art to practice the present invention. It is to be understood that the disclosure is not limited to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or carried out in various ways. For example, other embodiments may incorporate structural, chronological, electrical, process, and other changes. Examples merely typify possible variations. Individual components and functions are optional unless explicitly required, and the sequence of operations may vary. Portions and features of some embodiments may be included in or substituted for those of others. The scope of the application encompasses the appended claims and all available equivalents. The following description is, therefore, not to be taken in a limited sense and the scope of the present invention is defined by the appended claims. 
     Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the terms “connected,” “coupled,” and “mounted,” and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings. In addition, the terms “connected” and “coupled” and variations thereof are not restricted to physical or mechanical connections or couplings. 
     Spatially relative terms such as “top”, “bottom”, “front”, “back”, “rear” and “side” “under”, “below”, “lower”, “over”, “upper”, and the like, are used for ease of description to explain the positioning of one element relative to a second element. These terms are generally used in reference to the position of an element in its intended operational position within an image forming device. Further, terms such as “first”, “second”, and the like, are used to describe various elements, regions, sections, etc. and are not intended to be limiting. Like terms refer to like elements throughout the description. 
     Referring now to the drawings and particularly to  FIG. 1 , there is shown a block diagram depiction of an imaging system  20  according to one example embodiment. Imaging system  20  includes an image forming device  22  and a computer  24 . Image forming device  22  communicates with computer  24  via a communications link  26 . As used herein, the term “communications link” generally refers to any structure that facilitates electronic communication between multiple components and may operate using wired or wireless technology and may include communications over the Internet. 
     In the example embodiment shown in  FIG. 1 , image forming device  22  is a multifunction machine (sometimes referred to as an all-in-one (AIO) device) that includes a controller  28 , a print engine  30 , a laser scan unit (LSU)  31 , an imaging unit  32 , a toner cartridge  35 , a user interface  36 , a media feed system  38 , a media input tray  39  and a scanner system  40 . Image forming device  22  may communicate with computer  24  via a standard communication protocol, such as, for example, universal serial bus (USB), Ethernet or IEEE 802.xx. Image forming device  22  may be, for example, an electrophotographic printer/copier including an integrated scanner system  40  or a standalone electrophotographic printer. 
     Controller  28  includes a processor unit and associated memory  29  and may be formed as one or more Application Specific Integrated Circuits (ASICs). Memory  29  may be any volatile or non-volatile memory or combination thereof such as, for example, random access memory (RAM), read only memory (ROM), flash memory and/or non-volatile RAM (NVRAM). Alternatively, memory  29  may be in the form of a separate electronic memory (e.g., RAM, ROM, and/or NVRAM), a hard drive, a CD or DVD drive, or any processing device convenient for use with controller  28 . Controller  28  may be, for example, a combined printer and scanner controller. 
     In the example embodiment illustrated, controller  28  communicates with print engine  30  via a communications link  50 . Controller  28  communicates with imaging unit  32  and processing circuitry  44  thereon via a communications link  51 . Controller  28  communicates with toner cartridge  35  and processing circuitry  45  therein via a communications link  52 . Controller  28  communicates with media feed system  38  via a communications link  53 . Controller  28  communicates with scanner system  40  via a communications link  54 . Controller  28  communicates with fuser  37  via a communications link  58 . User interface  36  is communicatively coupled to controller  28  via a communications link  55 . Processing circuitry  44 ,  45  may provide authentication functions, safety and operational interlocks, operating parameters and usage information related to imaging unit  32  and toner cartridge  35 , respectively. Controller  28  processes print and scan data and operates print engine  30  during printing and scanner system  40  during scanning. 
     Computer  24 , which is optional, may be, for example, a personal computer, network server, tablet computer, smartphone, or other hand-held electronic device including memory  60 , such as volatile and/or nonvolatile memory, an input device  62 , such as a keyboard and/or a mouse, and a display  64 , such as a monitor. Computer  24  also includes a processor, input/output (I/O) interfaces, and may include at least one mass data storage device, such as a hard drive, a CD-ROM and/or a DVD unit (not shown). 
     Computer  24  includes in its memory  60  a software program including program instructions that function as an imaging driver  66 , e.g., printer/scanner driver software, for image forming device  22 . Imaging driver  66  is in communication with controller  28  of image forming device  22  via communications link  26 . Imaging driver  66  facilitates communication between image forming device  22  and computer  24 . One aspect of imaging driver  66  may be, for example, to provide formatted print data to image forming device  22 , and more particularly to print engine  30 , to print an image. Another aspect of imaging driver  66  may be, for example, to facilitate collection of scanned data from scanner system  40 . 
     In some circumstances, it may be desirable to operate image forming device  22  in a standalone mode. In the standalone mode, image forming device  22  is capable of functioning without computer  24 . Accordingly, all or a portion of imaging driver  66 , or a similar driver, may be located in controller  28  of image forming device  22  so as to accommodate printing and/or scanning functionality when operating in the standalone mode. 
     Print engine  30  includes laser scan unit (LSU)  31 , toner cartridge  35 , imaging unit  32 , and a fuser  37 , all mounted within image forming device  22 . Imaging unit  32  includes a developer unit  34  that houses a toner sump and a toner delivery system. The toner delivery system includes a toner adder roll that provides toner from the toner sump to a developer roll. A doctor blade provides a metered uniform layer of toner on the surface of the developer roll. Imaging unit  32  also includes a cleaner unit  33  that houses a photoconductive drum and a waste toner removal system. 
     The electrophotographic imaging process is well known in the art and, therefore, will be briefly described. During an imaging operation, laser scan unit  31  creates a latent image on the photoconductive drum in cleaner unit  33 . Toner is transferred from the toner sump in developer unit  34  to the latent image on the photoconductive drum by the developer roll to create a toned image. The toned image is then transferred to a media sheet received in imaging unit  32  from media input tray  39 . Next, the toned image is fused to the media sheet in fuser  37  and sent to an output location or to one or more finishing options such as a duplexer, a stapler or a hole-punch. Toner remnants are removed from the photoconductive drum by the waste toner removal system housed within cleaner unit  33 . As toner is depleted from developer unit  34 , toner is transferred from toner cartridge  35  into developer unit  34 . Controller  28  provides for the coordination of these activities occurring during the imaging process. 
       FIG. 2  shows components of fuser  37  according to one example embodiment. Fusing member  202  has a shaft  204  supported by a printer frame (not shown). Shaft  204  is encircled by a rigid core  206 , by a flexible support layer  208 , and by a top-release layer  210 . Top-release layer  210  contains, for example, perfluoroalkoxy (PFA). A heat transport layer (not shown) is located between the top-release layer  210  and the flexible support layer  208 . Shaft  204  is rotatably coupled to a motor (not shown). 
     A lamp  212  is positioned adjacent to top-release layer  210  to heat top-release layer  210  for fusing toner. A reflector  214  directs heat from lamp  212  to top-release layer  210 . In this example, the fuser is an externally heated fuser since the heating element, lamp  212 , is external to the fusing member  202 . By contrast, internally heated fusers contain a heating element located within a fusing member. 
     In  FIG. 2 , a belt  216  is pressed against top-release layer  210  by roller  218  and roller  220 . Roller  222  provides tension in belt  216 . In operation, toner is fused onto media by passing the media between belt  216  and top-release layer  210  while rotating fusing member  202 . During fusing, heat is transferred from top-release layer  210  to the toner while pressure is applied to the toner by belt  216  acting as a pressure member. Note that, in other embodiments, a roller may act as a pressure member to apply pressure to toner. 
     In  FIG. 3 , roller  218 , roller  220 , roller  222 , and belt  216  are disengaged from top-release layer  210 . Mechanisms to provide this translation are well known in the art and include, for example, solenoids, rack-and-pinions, cams, etc. It is advantageous to disengage belt  216  from top-release layer  210  during fuser conditioning, as is described below. 
       FIG. 4  shows an example embodiment of a method  400  of conditioning a fusing member having a top-release layer using the present invention. The method of conditioning a fusing member restores uniform gloss to the top-release layer. This method may be employed, for example, after the top-release layer has become worn and causes print defects on the fused media. The method utilizes an image forming device that has been configured to disengage one or more pressure members from a fusing-member top-release layer. 
     At block  402 , the method  400  heats the top-release layer to at least the melting temperature of the top-release layer while rotating the fusing member and while no pressure member engages the top-release layer. Heating the top-release layer to at least its melting temperature causes it to flow and heal gloss imperfections such as scratches. Since, at block  402 , no pressure member engages the top-release layer, the top-release layer is free to flow without disturbance from pressure members. Such disturbances may create non-uniformities in the top-release layer which may cause print defects. 
     At block  404 , the method  400  cools the top-release layer to less than the melting temperature of the top-release layer while rotating the fusing member. Rotating the fusing member prevents the top-release layer from sagging due to gravity. 
     The inventors have found that, for a top-release layer that contains perfluoroalkoxy, good results were achieved by heating the top-release layer to between 310 and 325 degrees Celsius, inclusive, for between 30 and 180 seconds, inclusive. Optimum results were achieved by heating the top-release layer to between 315 and 320 degrees Celsius, inclusive, for between 60 and 90 seconds, inclusive. 
       FIG. 5  shows an example embodiment of a method  500  of operating an image forming device using the present invention. The method of operating an image forming device restores uniform gloss to a top-release layer. The method utilizes an image forming device that has been configured to disengage and reengage a pressure member from the fusing-member top-release layer. 
     At block  502 , the method  500  disengages the pressure member from the top-release layer. 
     At block  504 , the method  500  heats the top-release layer to at least the melting temperature of the top-release layer while rotating the fusing member with the pressure member disengaged from the top-release layer. Heating the top-release layer to at least its melting temperature causes it to flow and heal gloss imperfections such as scratches or gloss bands. Since, at block  504 , no pressure member engages the top-release layer, the top-release layer is free to flow without disturbance from pressure members. Such disturbances may create non-uniformities in the top-release layer which may cause print defects. 
     At block  506 , the method  500  cools the top-release layer to less than the melting temperature of the top-release layer while rotating the fusing member with the pressure member disengaged from the roller surface coating. Rotating the fusing member prevents the top-release layer from sagging due to gravity. 
     At block  508 , the method  500  reengages the pressure member with the top-release layer. Once the pressure member is reengaged with the top-release layer, the fuser is ready to fuse toner to media. 
     At block  510 , a determination is made to see if the image forming device experienced a paper jam. If it did, the method proceeds to block  502 . During a paper jam, residual heat from a lamp may transfer unevenly to the top-release layer due to paper partially blocking the top-release layer. This uneven heating may cause a gloss band that may cause a print defect. In block  502 ,  504 ,  506 , and  508 , the method conditions the top-release layer to cure the gloss band. 
     At block  512 , a determination is made to see if the image forming device has printed at least a threshold number of pages. If it did, the method proceeds to block  502 . The threshold number of pages may correspond to when wear on the top-release layer is expected to start causing print defects. Conditioning the top-release layer may prevent these print defects. 
     Note that, in image forming device  22  shown in  FIG. 1 , controller  28  may be configured to perform one or more methods of the invention. For example, controller  28  may be configured to condition the top-release layer by disengaging the pressure member from the top-release layer, heating the top-release layer to at least the melting temperature of the top-release layer while rotating the fusing member with the pressure member disengaged from the top-release layer, cooling the top-release layer to less than the melting temperature of the top-release layer with the pressure member disengaged from the top-release layer, and reengaging the pressure member with the top-release layer. In this example, controller  28  controls activation of lamp  212 , the motor coupled to shaft  204 , and the mechanism that disengages belt  216  from top-release layer  210 , via communications link  58 . 
     Controller  28  may be further configured to condition the top-release layer automatically after detecting that the image forming device experienced a paper jam. Controller  28  may be configured to condition the top-release layer automatically after detecting that the image forming device has printed at least a threshold number of pages. Controller  28  may automatically condition the top-release layer upon detecting either a threshold number of pages or upon detecting a paper jam, or controller  28  may only look for one of these events. Alternatively, controller  28  may be configured to condition the top-release layer upon receiving a user input. 
     The foregoing description of several embodiments has been presented for purposes of illustration. It is not intended to be exhaustive or to limit the application to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. It is understood that the invention may be practiced in ways other than as specifically set forth herein without departing from the scope of the invention. It is intended that the scope of the application be defined by the claims appended hereto.