Patent Publication Number: US-9405238-B2

Title: Urging roller, cleaning device and image heating device

Description:
FIELD OF THE INVENTION AND RELATED ART 
     The present invention relates to an urging roller, a cleaning device and an image heating device usable with an electrophotographic image forming apparatus. 
     Various types of cleaning devices for cleaning a fixing device (image heating apparatus) in an electrophotographic image forming apparatus are known. 
     Japanese Laid-open Patent Application 2002-189373 discloses one of them, in which offset toner is collected from a fixing roller to a cleaning roller, and the toner collected to the cleaning roller is removed by a cleaning device using a cleaning web. 
     With this cleaning device, the cleaning web is press-contacted to a rotating cleaning roller to rub it, so that the toner collected on the cleaning roller is wiped off by the cleaning web. By moving the cleaning web at appropriate timing, an unused portion of the cleaning web rubs the cleaning roller. 
     An urging roller is used to urge the cleaning web to the cleaning roller, and it has a sponge layer (elastic layer) on which wire is spirally wound thereon. 
     However, in the case of the urging roller disclosed in Japanese Laid-open Patent Application 2002-189373, there is a liability that the toner soaked in the cleaning web may transfer onto the sponge layer of the urging roller. 
     SUMMARY OF THE INVENTION 
     According to an aspect of the present invention, there is provided an urging roller for urging a cleaning web to a rotatable member of an electrophotographic image forming apparatus, said urging roller comprising a shaft; an elastic layer provided on a peripheral surface of said shaft; a wire wound on a peripheral surface of said elastic layer; and a toner parting layer coating a peripheral surface of said elastic layer with said wire. 
     According to another aspect of the present invention, there is provided a cleaning device for cleaning a rotatable member for an electrophotographic image forming apparatus, said cleaning device comprising (i) a cleaning web for cleaning the rotatable member; (ii) a wound roller on which said cleaning web is wound; (iii) a winding-up roller for winding said cleaning web up; and (iv) an urging roller for urging said cleaning web to the rotatable member, said urging roller including (iv-i) a shaft, (iv-ii) an elastic layer provided on a peripheral surface of said shaft, (iv-iii) a wire wound on a peripheral surface of said elastic layer; and (iv-iv) a toner parting layer coating of peripheral surface of said elastic layer with said wire. 
     According to a further aspect of the present invention, there is provided an image heating apparatus comprising (i) a rotatable heating member for heating a toner image on a sheet; (ii) a collection rotatable member for collecting toner deposited on said rotatable heating member; (iii) a cleaning web for cleaning said collection rotatable member; (iv) a wound roller on which said cleaning web is wound; and (v) a winding-up roller for winding up said cleaning web; (vi) an urging roller for urging said cleaning web to the collection rotatable member, said urging roller including (vi-i) a shaft; (vi-ii) an elastic layer provided on a peripheral surface of said shaft; (vi-iii) a wire wound on a peripheral surface of said elastic layer; and (vi-iv) a toner parting layer coating a peripheral surface of said elastic layer with said wire. 
     Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic enlarged cross-sectional view of a fixing device. 
         FIG. 2  is a schematic view illustrating a general arrangement. 
         FIG. 3  is a block diagram of a control system of the fixing device. 
         FIG. 4  is an illustration of operation of the cleaning device (web unit). 
         FIG. 5  is an illustration of a cut-away portion provided in the cleaning web. 
         FIG. 6  is a schematic view of agglomeration mass of toner fixed on the collection roller. 
         FIG. 7  is an illustration of a web roller. 
         FIG. 8  is an illustration of a web roller. 
         FIG. 9  is an illustration of a web roller. 
         FIG. 10  is a schematic view of a conventional example web roller. 
         FIG. 11  is an enlarged perspective view of an end portion of the web roller. 
         FIG. 12  is an illustration of sliding operation at an end portion of the wire. 
         FIG. 13  is an enlarged perspective view of an end portion of the web roller. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     A fixing device as an image heating apparatus and an electrophotographic image forming apparatus provided with the fixing device according to an embodiment of the present invention will be described. The specific values in the following description of the embodiments are examples and do not limit the present invention. The embodiments are examples of the present invention, which is not limited to the specific examples. 
     [Embodiment 1] 
     &lt;Example of Image Forming Apparatus&gt; 
       FIG. 2  is a schematic view illustrating structures of the electrophotographic image forming apparatus  100  according to this embodiment. The image forming apparatus  100  is an electrophotographic full color laser beam printer of an in-line (tandem) and middle transfer belt type. It is capable of forming a full-color image on a recording material (recording paper) P in accordance with electrical image information supplied from a host apparatus  200  such as a personal computer to a control circuit portion (controlling means)  101  of the image forming apparatus. 
     In a main assembly A  100 A of the image forming apparatus  100 , there are provided first-fourth image forming stations U (UY, UM, UC, UK) arranged in the order named at predetermined intervals substantially along a horizontal direction. The image forming stations U have similar electrophotographic processing mechanisms which are different only in the colors of the image formed thereby. Each image forming station U comprises a drum type electrophotographic photosensitive member (drum)  1  as an image bearing member rotated at a predetermined peripheral speed in the counterclockwise direction indicated by an arrow. The image forming station U also comprises a charger (charging roller)  2 , a developing device  4 , a primary transfer charger (primary transfer roller)  5 , a drum cleaner  6  as a process means actable on the drum  1 . 
     The charger  2  electrically charges the surface of the drum  1  to a potential of a predetermined polarity. The developing device  4  develops an electrostatic latent image formed on the drum  1  with a developer (toner). The primary transfer charger  5  primary-transfers a toner image formed on the drum  1  onto the intermediary transfer belt  8 . The drum cleaner  6  cleans the drum surface after toner image transfer onto the intermediary transfer belt  8 . 
     The developing device  4  of the first image forming station UY contains a predetermined amount of yellow (Y) toner supplied by a supplying device  4   a  to form a toner image of yellow color on the drum  1 . The developing device  4  of the second image forming station UM contains a predetermined amount of magenta (M) toner supplied by the supplying device  4   a  to form a magenta toner image on the drum  1 . The developing device  4  of the third image forming station UC contains a predetermined amount of cyan (C) toner supplied by the supplying device  4   a  to form a cyan toner image on the drum  1 . The developing device  4  of the fourth image forming station UK contains a predetermined amount of black (K) toner by the supplying device  4   a  to form a black toner image on the drum  1 . 
     Above the first-fourth image forming stations U, there is provided a laser scanner  3 . The laser scanner  3  projects a beam corresponding to image information on the drum  1  in each of the image forming stations U to form an electrostatic latent image on the drum  1 . Although not shown in the Figure, the laser scanner  3  comprises a light source device and a polygonal mirror, with which the laser beam generated by the light source device is scanningly deflected by the rotation of the polygonal mirror. The scanning beam is deflected by a reflection mirror and is focused on the drum  1  of image forming station U by an fθ lens along the generatrix line of the drum  1 . By this, latent images are formed on the respective drums  1  of the image forming stations U in accordance with the respective the image signals. 
     Below the first-fourth image forming stations U, an intermediary transfer belt unit  7  is provided. The unit  7  comprises a driving roller  9  in a first image forming station (UY) side, a tension roller  10  in the fourth image forming station (UK) side, and a secondary transfer opposing roller  11  at a level lower than the driving roller  9 . It also comprises an intermediary transfer belt (belt)  8  which is a flexible endless belt stretched around these three rollers  9 - 11 . 
     The primary transfer charger  5  of each of the image forming stations U is disposed inside of the belt  8  and is contacted to the lower surface of the drum  1  opposed to the upper traveling part of the belt  8 . In each of the image forming stations U, a primary transfer portion is a contact portion between the drum  1  and the belt  8 . Belt  8  is rotated substantially at the same speed as the peripheral speed of the drum  1  in the clockwise direction indicated by an arrow by the driving roller  9 . Toward the secondary transfer opposing roller  11 , a secondary transfer roller  12  is urged with the belt  8  therebetween. A secondary transfer portion is the contact portion between the belt  8  and the secondary transfer roller  12 . 
     At a portion of the belt at the driving roller  9 , a belt cleaner  13  is provided. The cleaner  13  comprises a cleaning web (non-woven fabric)  13   a  for cleaning a belt surface after the secondary-transfer of the toner image onto the recording paper P from the belt  8 . Below the intermediary transfer belt unit  7 , a sheet feeding cassette  14  accommodating the recording sheets P and a recording paper feeding mechanism  15  is provided. 
     A full-color image forming operation is as follows. By the image forming operation of the image forming apparatus  100 , a Y chromatic toner image corresponding to the Y color component of the full-color image is formed on the drum  1  of the first image forming station UY. The toner image is primary-transferred onto the belt  8  in the primary transfer portion. On the drum  1  of the second image forming station UM, an M chromatic toner image corresponding to the M color component of the full-color image is formed. The toner image is primary-transferred superimposedly onto the Y chromatic toner image already transferred on the belt  8 , at the primary transfer portion. 
     On the drum  1  of the third image forming station UC, a C color toner image corresponding to the C color component of the full-color image is formed. The toner image is primary-transferred superimposedly onto the Y color+M color toner images already transferred onto the belt  8  in the primary transfer portion. On the drum  1  of the fourth image forming station UK, a K chromatic toner image corresponding to the K color component of the full-color image is formed. The toner image is primary-transferred superimposedly onto the Y color+M color+C color toner images already transferred onto the belt  8  in the primary transfer portion. 
     In the primary-transfer of the toner image from the drum  1  onto the belt  8  in the image forming station U, a bias voltage of a polarity opposite the regular charge polarity of the toner is applied to the primary transfer charger  5 . In this manner, a synthesized color toner image (unfixed) of four full-colors (Y+M+C+K) is formed on the belt  8 . The synthesized color toner image is formed with a predetermined marginal blank portion at  4  side edge portions of the recording paper P. In this embodiment, a leading end marginal blank portion is approx. 2-3 mm. 
     On the other hand, a recording sheet P is singled out and a predetermined control timing from the sheet feeding cassette  14  to the pair of registration rollers  16  along a paper path  15   a  and a paper path  15   b  of the recording paper feeding mechanism  15 . Then, the recording sheet is introduced into the secondary transfer portion at the predetermined control timing by the pair of registration rollers  16 . By this, in the process of the recording sheet P being fed through the secondary transfer portion, the four color superimposed toner image is secondary-transferred from the belt  8  onto the recording paper gradually. In the secondary-transfer, a bias voltage of a polarity opposite to the regular charge polarity of the toner is applied to the secondary transfer roller  12  to effect the image transfer. 
     The recording sheet P now carrying the secondary-transferred toner image is introduced into a fixing device  20  as an image heating apparatus through the paper path  15   c  and is subjected to a fixing process, and then is discharged onto a sheet discharge tray  17  as a full-color print through a paper path  15   d , a paper path  15   e  and a sheet discharge opening  16 . 
     The image forming apparatus  100  of the present invention is not limited to the full-color image formation, but is applicable to a monochromatic image having a desired mono-color or multi-color images having desired colors. In such a case, only the image forming station or stations U for the monochromatic color or multi-colors are operated. In the unnecessary image forming station or stations, the image forming operation is not carried out, although the drum  1  is rotated. 
     The same applies to the case of both side printing. In such a case, the recording sheet P already having the image on one side is discharged from the fixing device  20  and is switched by a flapper  18  to the paper path  15   f , and is introduced into a reversion path (switchback path)  15   g  and then into a both-side-printing path (refeeding paper path)  15   h . It is reintroduced into the paper path  15   b  and is fed to the secondary transfer portion in the face-reversed state. By this, a toner image is secondary-transferred onto the second side of the recording sheet P. Thereafter, it is discharged onto the sheet discharge tray  17  as a both sided print through the paper path  15   c , the fixing device  20 , the paper path  15   d , the paper path  15   e  and in the sheet discharge opening  16 , similarly to the case of the one-side printing. 
     Here, the fixing device  20  of the image forming apparatus  100  according to this embodiment effects oil-less fixing of the toner image recording sheet with heat and pressure, the toner containing parting material. 
     The toner used in the image formation contains (internally) a parting material such as a wax of paraffin or polyolefin or silicone oil. More specifically, in this embodiment, pulverized toner particle internally contains dispersed pigment and wax component. Polymerized toner containing such a wax component may be used. In the following descriptions, the parting material is wax, but the description applies to the case of using silicone oil as the parting material. 
     &lt;Image Fixing Device&gt; 
     In this embodiment, the fixing device (image heating apparatus)  20  of the electrophotographic image forming apparatus  100  fixes the toner image formed on the recording sheet P with the toner containing the parting material, while applying heat and pressure to the toner. The description will be made more specifically. 
       FIG. 1  is a schematic enlarged cross-sectional view of the fixing device  20  according to this embodiment.  FIG. 3  is a block diagram of a control system for the fixing device  20 . The fixing device  20  is a heat roller pair, external heating and oil-less fixing type. 
     The fixing device  20  comprises fixing rollers as a first rotatable member (rotatable heating member, heating member)  21  for heating the unfixed toner image (un-heated toner image) T on the recording sheet (recording material) in the nip N, and a pressing roller as a second rotatable member (pressing rotatable member, pressing member), constituting a pair of press-contact rollers. It further comprises an external heating belt unit  30  as an external heating means for externally heating the fixing roller  21 . It further comprises a fixing roller cleaning mechanism (cleaning device)  40  for cleaning an outer surface of the fixing roller  21 . 
     (1) Image Fixing Roller and Pressing Roller 
     The fixing roller  21  of this embodiment includes a cylindrical core metal  21   a  of aluminum, an elastic layer having a thickness of 3 mm on the outer peripheral surface thereof, and is a hollow roller having a diameter of 60 mm. The elastic layer  21   b  has a two-layer-structure including a lower layer and an upper layer as a heat resistive elastic layer (parting layer) contactable to an image surface of the recording sheet P. The lower layer is made of HTV (high temperature vulcanization type) silicone rubber layer, and the upper layer is a RTV (room temperature vulcanization type) silicone rubber layer. 
     The pressing roller  22  includes a cylindrical core metal  22   a  of aluminum, an elastic layer  22   b  having a thickness of 3 mm on the outer surface of the core metal, and a parting layer on the elastic layer  22   b , and it is a hollow roller having a diameter of 60 mm. The elastic layer  22   b  is a HTV silicone rubber layer, and the parting layer  22   c  is a fluorinated resin material layer. 
     By combining the fixing roller  21  and the pressing roller  22  which have the above-described layer structures, the parting property relative to the sharp melt toner is further enhanced In order to fix the images on both sides, the RTV or LTV (low temperature vulcanization type) silicone rubber having the high toner parting effect is used for the surface of the pressing roller  22  as well as the fixing roller  21 . 
     The fixing roller  21  is extended substantially horizontally and is rotatably supported at a fixed position by ball bearings (unshown) between side plates of the fixing device casing (chassis)  23  at the opposite end portions. At a rotation axis portion of the fixing roller  21 , there is provided a non-rotatable halogen heater  21   d  for the ink in the fixing roller  21  from the inside. 
     The pressing roller  22  is extended substantially in parallel with the fixing roller  21  below the fixing roller  21  in the substrate rotatably supported by ball bearings (unshown) between side plates of the fixing device casing  23  at the opposite end portions. At a rotation axis portion of the pressing roller  22 , there is provided with a known rotatable halogen heater  22   d  for heating the pressing roller  22  from the inside. 
     The ball bearings at the opposite end portions of the pressing roller  22  permit sliding motion toward the fixing roller  21 . The pressing roller  22  is urged to the fixing roller  21  by an urging member (unshown). By this, the pressing roller  22  is press contacted to the fixing roller  21  against the elastic forces of the elastic layers  21   b ,  22   b  at the predetermined pressure to form a fixing nip (heating nip) having a predetermined width measured in a recording paper feeding direction between the rollers  21 ,  22 . In this embodiment, the pressing roller  22  is press contacted to the fixing roller  21  at a total pressure of approx. 784 N (approx. 80 kg). 
     The fixing roller  21  and the pressing roller  22  are provided with respective gears fixed to the axial ends, and the gears are in meshing engagement with each other and are rotated by a driving force from a driving portion  102  controlled by the control circuit portion  101 . By this, the fixing roller  21  and the pressing roller  22  are rotated in the direction indicated by arrows R 21  and R 22 , that is, in the directions for feeding the recording paper is by the nip N, at a predetermined peripheral speed. 
     The halogen heaters  21   d  and  22   d  of the fixing roller  21  and the pressing roller  22  generate heat by receiving electric power supply from voltage source portions  103 ,  104  ( FIG. 3 ). By the generated heat, the fixing roller  21  and the pressing roller  22  are heated from the inside so that the surface temperatures rise. 
     To the fixing roller  21  and the pressing roller  22 , thermistors (temperature detecting means)  21   e  and  22   e  for detecting that the surface temperatures of the respective rollers are contacted. The thermistor  21   e  is contacted to the fixing roller  21  at the position upstream of the fixing nip N and downstream of a position of an external heating belt unit  30  which will be described hereinafter, with respect to the peripheral movement of the fixing roller. 
     Temperature information a detected by the thermistors  21   e  and  22   e  is supplied to the temperature adjustment circuit portions  105  and  106  of the control circuit portion  101 . The temperature adjustment circuit portion  105  controls the electric power supply to the halogen heater  21   d  from the voltage source portion  103  so that the surface temperature of the fixing roller  21  detected by the thermistor  21   e  converges to a predetermined temperature (approx. 165 degree C. in this embodiment). The temperature adjustment circuit portion  106  controls the electric power supply to the halogen heater  22   d  from the voltage source portion  104  so that the surface temperature of the pressing roller  22  detected by the thermister  22   e  converges to a predetermined temperature (approx. 140 degree C. in this embodiment). 
     The fixing roller  21  and the pressing roller  22  are rotated, and the surface temperatures thereof are raised to and maintained at the respective predetermined temperatures. In this state, a recording paper carrying an unfixed toner image T is introduced into the fixing device  20  from the image forming station. Designated by reference numeral  24  is a recording paper guiding plate in the entrance side. 
     The recording paper P is introduced into and fed through the nip N with the unfixed toner image carrying side contacted to the fixing roller  21  during which the unfixed toner image T is fixed into a fixed image by the heat and pressure in the nip N. That is, the fixing roller  21  (first rotatable member) is on the side contacting to the toner image T on the recording paper. The recording paper P having passed through the nip N is separated from the fixing roller  21  and is discharged out of the fixing device  20  along the recording paper guiding plate  25  at the exit side. 
     (2) External Heating Belt Unit: 
     The external heating belt unit  30  externally heats the fixing roller  21 . Using the external heating type, a printing productivity (print number per unit time) particularly on large basis weight sheets such as rough paper, emboss paper or coated paper can be increased. 
     The external heating belt unit  30  in this embodiment comprises first and second supporting rollers  31 ,  32 , respective halogen heaters  31   a ,  32   a  therein, and an endless external heating belt  33  extended around the rollers  31 ,  32 . The first and second supporting rollers  31 ,  32  are rotatable and support the external heating belt  33  at the inner surface so as to press-contact the external heating belt  33  to the fixing roller  21 . The external heating belt  33  is closely contacted to the outer surface of the fixing roller  21  along the roller curvature, that is, over a wide range with respect to the widthwise direction, between the first and second supporting rollers  31 ,  32 . 
     The external heating belt  33  is rotated by the rotation of the fixing roller  21 . The first and second supporting rollers  31 ,  32  are rotated by the rotation of the external heating belt  33 . The first and second supporting rollers  31 ,  32  are internally heated by the halogen heaters  31   a ,  32   a , respectively, which are supplied with electric power supply from the voltage source portions  107 ,  108 . The heat is transferred to the external heating belt  33  through the first and second supporting rollers  31 ,  32  and then to the surface of the fixing roller  21 , so that the decrease of the surface temperature of the fixing roller is prevented. 
     The temperature of the external heating belt  33  is detected by a thermistor  31   b  contacted to the surface of the belt at the position of the first supporting roller  31 . In addition, the temperature of the belt is detected by a thermistor  32   b  contacted to the belt surface at the second supporting roller  32 . 
     Temperature information detected by the thermistors  31   b  and  32   b  is supplied to the temperature adjustment circuit portions  109  and  110  of the control circuit portion  101 . The temperature adjustment circuit portion  109  controls the electric power supply to the halogen heater  31   a  from the voltage source portion  107  so that the surface temperature of the external heating belt  33  detected by the thermistor  31   b  converges to a predetermined target temperature. The temperature adjustment circuit portion  110  controls the electric power supply to the halogen heater  32   a  from the voltage source portion  108  so that the surface temperature of the external heating belt  33  detected by the thermistor  32   b  converges to a predetermined target temperature. 
     The target temperature of the external heating belt  33  is higher than the target temperature of the fixing roller  21  by the predetermined degree. With this structure, against the drop of the surface temperature of the fixing roller  21  caused by the contact to the recording paper in the fixing nip N, the heat can be applied to the fixing roller  21  from the external heating belt  33  with high responsivity (thermal responsivity). 
     (3) Image Fixing Roller Cleaning Mechanism 
     A fixing roller cleaning mechanism  40  comprises a collection roller (cleaning roller)  41  for collecting offset toner which has been offset from the recording paper P onto the fixing roller  21  in the fixing nip N. 
     In this embodiment, the collection roller  41  is a metal roller of SUS303 having an outer diameter φ20 mm. The collection roller  41  is contacted to the fixing roller  21  and is extended substantially in parallel with the fixing roller  21  at a position above the fixing roller  21  and upstream of the position of the external heating belt unit  30  with respect to the peripheral moving direction of the fixing roller. The roller  41  is rotatably supported by ball bearings (unshown) between the side plates of the fixing device casing  23  at the opposite end portions of the roller  41 . 
     The collection roller  41  is rotated by the rotation of the fixing roller  21 , and the offset toner (another deposited matter on the surface of the fixing roller, such as paper dust) is deposited, transferred and collected from the surface of the fixing roller onto the surface of the collection roller  41 . The collection roller  41  is always in contact with the fixing roller  21  for the purpose of collecting the deposited matter on the surface of the fixing roller  21 , in addition to the period of the image forming operation of the image forming apparatus. The toner collected on the surface of the collection roller  41  is removed by a cleaning web (cleaning sheet)  48  of the web unit (cleaning device)  42 . 
     Referring to  FIG. 1  and  FIG. 4 , the structures of the web unit  42  in this embodiment will be described. The web unit  42  comprises a unit casing (chassis)  43 . It further comprises a wound roller  45 , a web roller (pressing roller)  46  and a winding-up roller  47  supported between opposing side plates of the casing  43 . The cleaning web  48  is a long non-endless non-woven fabric wound on the wound roller  45 . 
     The wound roller  45  is rotatably supported between the opposing side plates of the casing  43 . The cleaning web  48  is extended around the web roller  46 , and a leading end portion of the cleaning web  48  is fixed on the winding-up roller  47 . 
     The web roller  46  is an elastic roller contacted to the upper surface of the collection roller  41  to be cleaned, through the cleaning web  48 . As will be described hereinafter, the web roller comprises a core metal  46   a  (shaft), a sponge layer provided on a peripheral surface of the core metal (elastic layer  46   b ), a wire  46   c  of metal spirally extended (wound) on the sponge layer  46   b , and a coating layer (toner parting layer) coating the peripheral surface of the sponge layer  46   b  including the wire  46   c . The elastic layer is a porous sponge layer, taking the heat insulation property into account. 
     The opposite end portions of the core metal (shaft)  46   a  of the web roller  46  are engaged with round elongated holes  43   a  of the opposing side plates of the casing  43 , respectively. By this, the web roller  46  is rotatably supported between the side plates so as to be slidable along the elongated holes  43   a.    
     The direction of the sliding is perpendicular to the nip between the web roller  46  and the collection roller  41  (the direction connecting the center of the core metal of the web roller  46  and the center of the collection roller  41 ). The opposite end portions of the core metal  46   a  are urged toward bottom end portions of the elongated hole  43   a  by urging springs  49  provided on the side plates. 
     One end portion side of the winding-up roller  47  is connected with a driving portion (motor)  111  for winding up the cleaning web  48 . By the driving portion  111  controlled by the control circuit portion  101 , the winding-up roller  47  is rotated in the winding-up direction. By this, the cleaning web  48  is gradually moved in the direction indicated by an arrow b and wound up on the roller  47  by the way of the web roller  46  from the wound roller  45 . 
     More specifically, the control circuit portion  101  intermittently rotates the winding-up roller  47  by the driving portion  111  at predetermined control timing by a predetermined angle of rotation, thus intermittently and gradually winding up the cleaning web  48  from the wound roller  45  to the winding-up roller  47 . The web roller  46  rotates together with the winding-up movement of the cleaning web  48 . 
     The web unit  42  is supported swingably about a rotation shaft  50  between the side plates of the fixing device casing  23 . The web unit  42  is movable about the rotation shaft  50  between a first position A (part (a) of  FIG. 4 ) and a second position B (part (b) of  FIG. 4 ), by controlling an angle of rotation of a contacting and spacing cam  51 . In the first position A of the web unit  42 , the cleaning web  48  is in contact with the collection roller  41  (contact state of the cleaning web  48 ). In the second position B, the cleaning web  48  is spaced from the collection roller  41  (non-contact state of the cleaning web  48 ). 
     In this embodiment, the cam shaft  52  is moved by a driving portion  112  controlled by the control circuit portion  101 , so that a high portion of a cam profile of the contacting and spacing cam  50  is kept in a position facing horizontally as shown in part (a) of  FIG. 4 . In this position, the web unit  42  rotates in the counterclockwise direction in  FIG. 4  by the weight thereof about the rotation shaft  50 , and the web roller  46  urges the cleaning web  48  to the collection roller  41  while comprising the urging spring  49  (first position A). 
     In this embodiment, in the state that the cleaning web  48  is contacted to the collection roller  41 , the web roller  46  urges the cleaning web  48  to the collection roller  41  at an urging force of 40 N by the urging spring  49 . 
     When the contacting and spacing cam  50  takes the position by the driving portion  112 , as shown in part (b) of  FIG. 4 , the high portion of the cam profile faces horizontally. In this position, the web unit  42  is lifted by the contacting and spacing cam  50  about the rotation shaft  49  in the clockwise direction in  FIG. 4  so that the web roller  46  is spaced from the collection roller  41  (second position B). In this spaced state of the cleaning web  48 , the opposite end portions of the core metal of the web roller  46  are placed at the bottom end portion of the round elongated holes  43   a , respectively. 
     In the state that the cleaning web  48  is spaced from the collection roller  41 , no urging force is applied to the collection roller  41  from the web unit  42 , and therefore, the collection roller  41  is contacted to the fixing roller  21  at an urging force of approx. 10 N (weight) in this embodiment. In the contact state of the cleaning web  48  shown in part (a) of  FIG. 4 , the collection roller  41  urged toward the fixing roller  21  by approx. 50 N which is a sum of approx. 10 N of the weight and approx. 40 N through the contact of the web roller  46 . In this state, the collection roller  41  is driven by the rotation of the fixing roller  21 . 
     As shown in part (a) of  FIGS. 1 and 4 , by rotating the fixing roller  21  while the cleaning web  48  is kept in contact with the collection roller  41  by the web roller  46 , The collection roller  41  is rotated to clean the fixing roller  21 . By doing so, the cleaning web  48  removes the toner from the collection roller  41 . 
     The cleaning web  48  contacting the collection roller  41  is gradually wound up in the direction of arrow b, so that a fresh part of the web is brought into contact with the collection roller  41  before the web is saturated with the toner. That is, the contact surface of the cleaning web  48  relative to the collection roller  41  is renewed by the movement of the cleaning web  48 . 
     The cleaning web  48  wound on the roller  45  is consumed gradually by being wound up on the roller  47 . Therefore, it is desirable that when a small amount of unused part of the web is still on the wound roller  45 , the use is prompted so that the user can replace the cleaning web  48  or prepare for the replacement. 
     This is because of various cases in which the web cannot be replaced immediately. For example, when a large amount of prints have to be produced in one job, it is not desirable to stop the process only because of the shortage of the web  48 . Therefore, the above-described prompt is desirable. 
     Under the circumstances, in order to detect the remaining amount of the web  48 , a cut-away portion  48   a  is provided in the cleaning web at a position which is away from the end of the web  48  by a predetermined distance. When the cut-away portion  48   a  appears as a result of consumption of the cleaning web  48  from the wound roller  45  to the winding-up roller  47 , the cut-away portion  48   a  is detected by a sensor  113 . 
     The sensor  113  is provided between the wound roller  45  and the web roller  46 . The sensor  113  may be a micro-switch having an actuator for detecting the cut-away portion  48   a  by falling into the cut-away portion  48   a , or a photo-coupler having an optical path which is opened by the cut-away portion  48   a , for example. 
     When the control circuit portion  101  receives a cut-away portion detection signal from the sensor  113 , it causes a display portion  120   a  of an operating portion  120  of the image forming apparatus  100  or a display portion of the host apparatus  200  to display the information of the small remaining amount of the cleaning web  48 . In response to this event, the user replenishes the cleaning web  48  or prepares the replenishment. 
     (4) Countermeasure for Agglomeration Mass on the Collection Roller: 
     As described in the foregoing, the collection roller  41  collects the offset toner from the fixing roller  21 , using the cleaning web  48 . During the collection, the toner which has not been removed by the cleaning web  48  gradually accumulates on the surface layer of the collection roller  41 . The accumulated toner is solidified into agglomerated masses  80  on the surface layer of the collection roller  41 , as shown in  FIG. 6 . 
     The toner once solidified on the surface layer of the collection roller  41  is not easily removed by an ordinary cleaning operation of the cleaning web  48 . The presence of the agglomerated mass deteriorates the cleaning effect of the collection roller  41  even to such an extent that the collection roller  41  has to be changed. 
     The agglomerated mass tends to be produced more if the amount of the offset toner collected on the collection roller  41  from the fixing roller  21  is more. The amount of the offset toner is large when the temperature of the fixing roller  21  is higher or lower than the proper value, and recently, the images are frequently formed on various kind of paper with a constant temperature control, which necessitates processing with non-optimum temperature control for the respective kinds of paper. Under the circumstances, the amount of the offset toner becomes relatively large, and therefore, the web unit  42  is desired to have a high cleaning property in the cleaning of the collection roller  41 . 
     As a counter measurement for the formation of the agglomerated mass by enhancing the cleaning property of the web unit  42 , it is preferable to provide the peripheral surface of the elastic layer of the web roller with the wire as disclosed in above-mentioned Japanese Laid-open Patent Application 2002-189373. 
       FIG. 10  shows a specific structure with reference numerals common to this embodiment for the elements having the same functions. In this web roller  46 , a high stiffness metal (SUS303) is penetrated through the center of the shaft  46   a  in other to suppress flexure thereof when it is contacted to the collection roller  41 . In order to enhance the cleaning power, it is preferable to make wide the nip width relative to the collection roller  41 , and in view of this, a heat resistive and easily deformable elastic layer (sponge layer)  46   b , more particularly, silicone sponge is provided on the shaft  46   a  into a roller shape having a diameter of φ30 mm. However, the coating layer  46   d  is not coated. 
     The wire  46   c  of metal (SUS304) having a diameter of φ1.0 mm is extended spirally on the surface of the elastic layer along the axial direction by one-full turn, and the opposite end portions  46   c L,  46   c R of the wire  46   c  are fixed on the shaft  46   a , respectively. The wire  46   c  has a hardness higher than that of the elastic layer. 
     The web roller  46  is urged toward the collection roller  41  to press-contact with the cleaning web  48  to the collection roller  41 , by which the elastic layer  46   b  is elastically deformed, and the wire  46   c  is press-contacted to the surface of the collection roller  41  restoring force of the elastic member behind the wire  46   c . Therefore, the pressure applied by the cleaning web  48  to the collection roller  41  is locally increased. 
     In other words, when the nip is formed between the collection roller  41  and the cleaning web  48 , the nip pressure is raised locally at the position where the wire  46   c  exists. Therefore, at the timing of the wire  46   c  press-contacting the web  48  to the collection roller  41  during the rotation of the web roller  46  by the winding-up movement of the web  48 , the pressure of the press-contact between the cleaning web  48  and the collection roller  41  is increased locally. 
     By doing so, the deposited matter such as solidified toner and/or externally added material on the collection roller  41  can be effectively removed by the cleaning web  48 , and therefore, the agglomerated mass on the collection roller  41  can be effectively suppressed. 
     On the other hand, as described hereinbefore, the cleaning web  48  is provided with the cut-away portion  48   a  at the position away from the end of the web  48  for the opposite of the remaining length detection. Therefore, when the cut-away portion  48   a  is detected by the sensor  113 , there exists a fresh part of the web on the wound roller  45 . 
     Therefore, even after the sensor  113  detects the cut-away portion  48   a , the fixing device  20  is still openable for a while. During such a period, the cut-away portion  48   a  of the web  48  passes through the nip between the collection roller  41  and the web roller  46 . 
     In such a case, that is, in the case of the structure of the web roller  46  shown in  FIG. 10 , the hard wire  46   c  on the surface of the web roller  46  directly contacts the collection roller  41  through the cut-away portion  48   a  of the web  48 . Then, the collection roller  41  may be damaged, which may lead to damage to the fixing roller. 
     In addition, when the toner soaking into the cleaning web is transferred onto the sponge layer (elastic layer) of the web roller, it may be hardened with an intentional result of non-uniform distribution of the pressure between the web roller and the cleaning roller along the longitudinal direction. 
     In addition, the wire  46   c  is fixed only at the end portions thereof, and therefore, the wire  46   c  may easily move on the surface of the roller, in the longitudinal in central portions of the web roller  46 . Particularly, when the wire  46   c  is in the nip between the collection roller  41  and the web roller  46 , the wire  46   c  is easily deviated by the driving force from the collection roller  41 . Despite the fact that the wire is additionally provided for the purpose of local high-pressure portion in the nip, the deviation of the wire in the nip results in no such high pressure, and therefore, the cleaning property is deteriorated even to such an extent that the gradually increasing agglomerated mass becomes unable to be removed. 
     In view of the foregoing, according to this embodiment, the web roller  46  is a structure as shown in part (a) of  FIG. 7 . As is different from the conventional web roller  46  shown in  FIG. 10 , a coating layer (toner parting layer)  46   d  is provided on the outer peripheral surface of the elastic layer including the wire  46   c , in this embodiment. As a result, transition of the toner onto the sponge layer of the web roller can be suppressed. In addition, the above-described deviation of the wire  46   c  can be prevented. Further, even in such a case that the cleaning web is torn, the wire does not directly contact to the cleaning roller, and therefore, the deterioration of the collection roller  41  can be avoided. 
     In this embodiment, the coating layer (toner parting layer)  46   d  of fluorine resin material coats the sponge layer (elastic layer) including the wire. Specifically, the coating layer  46   d  is a PFA tube having a thickness of 100 μm. The PFA exhibits good toner parting property and good slidability. Furthermore, even when directly contacting the collection roller  41 , the wire does not damage the collection roller  41 . The PFA tube  46   d  has a thermal contraction property (thermal contraction property resin material tube). Therefore, a certain degree of pressure is always applied to the wire  46   c  so that the positional deviation of the wire  46   c  on the surface of the elastic layer can be suppressed. 
     Part (b) of  FIG. 7  is a schematic enlarged cross-sectional view of part (a) of  FIG. 7 . An outer configuration of the web roller  46  in the cross-section is such that the part where the wire  46   c  exists protrudes as compared with the part where the wire  46   c does not exist. However, in the configuration shown in part (c) of  FIG. 7 , the part where the wire  46   c  exists does not protrude. 
     In either of these cases, the wire  46   c  is effective to press-contact with the web  48  to the surface of the collection roller  41  by the restoring force of the elastic member provided behind the rear side of the wire  46   c  in this state that the elastic layer  46   b  is elastically deformed. Therefore, the pressure applied by the cleaning web  48  to the collection roller  41  can be locally increased. 
     According to this embodiment, a local high pressure portion can be provided in the nip by the wire  46   c  without the deviation of the wire  46   c , so that the production of the agglomerated mass  80  of the toner on the collection roller  41  can be suppressed. 
     In addition, even when the cut-away portion  48   a  of the web  48  passes through the nip between the collection roller  41  and the web roller  46 , the wire  46   c  of the web roller  46  does not directly contact the collection roller  41  because of the existence of the PFA tube  46   d  therebetween. Thus, the direct contact of the wire  46   c  to the collection roller  41  can be prevented. Therefore, the damage to the collection roller  41  can be prevented, and the image defect attributable to the fixing roller damage and the image defect attributable to the defective cleaning can be avoided. 
     As described in the foregoing, according to this embodiment, the cleaning property can be enhanced, and therefore, the frequency of exchange of parts is reduced. In addition, the surface property of the fixing member can be maintained, and therefore, the quality of the prints can be enhanced with stabilized continuous printing operation. 
     [Embodiment 2] 
     In the description of Embodiment 2, the structures are similar to those of Embodiment 1 unless particular mentioning is made, and a part of the structure of the web roller is different from that of Embodiment 1. 
     In order to further suppress the deviation of the wire  46   c  on the surface of the elastic layer  46   b  of the web roller  46 , an adhesive material  46   e  is soaked into between the elastic layer  46   b  and wire  46   c  and the PFA tube  46   d.    
     As shown in parts (a) and (b) of  FIG. 8 , a bonding material layer  46   e  is provided between the elastic layer  46   b  and the coating layer  46   d , and the wire  46   c  is in the bonding material layer  46   e . By the provision of the bonding material layer, the deviation of the wire  46   c  on the surface of the elastic layer  46   b  can be further suppressed. 
     [Embodiment 3] 
     In the description of Embodiment 3, the structures are similar to those of Embodiment 1 unless particular mentioning is made, and a part of the structure of the web roller is different from that of Embodiment 1. 
     As shown in  FIG. 9 , in this embodiment, two or more wires  46   c  (two in  FIG. 9 ) are provided on the surface of the elastic layer  46   b  and extended spirally along the roller axial direction 
     The wire  46   c  may be extended not spirally, and for example, one or more wires  46   c  may extend linearly along the generatrix direction of the roller with a space or spaces in the circumferential direction of the roller. Furthermore, the wire  46   c  is not limited to linear shape, but may be bent into a waveform or the like. 
     [Embodiment 4] 
     In the description of Embodiment 4, the structures are similar to those of Embodiment 1 unless particular mentioning is made, and a part of the structure of the web roller is different from that of Embodiment 1. 
     This embodiment is directed to the problem which will be described below. 
     In the foregoing embodiments, the end portions  46   c L,  46   c R of the wire  46   c  are fixed on the core metal  46   a , and therefore, the pressure distribution at the end portions may change significantly depending on the position of the fixing, with the possible result of unstable pressure distribution. An outer diameter of the web roller  46  is φ30 mm, and the portion where the wire  46   a  exists protrudes by 0.5-0.8 mm. In this case, if the wire end portions  46   c L,  46   c R are fixed on the core metal  46   a , the pressure at the end portion is all applied to the wire end portion  46   c L,  46   c R with the possible result of excessive stress in the web  48 , which may lead to tearing of the web  48 . 
     As shown in  FIG. 11 , in view of this, in this embodiment, the end portions  46   c L,  46   c R of the wire  46   c  are made slidable relative to the core metal  46   a.    
     In the example of  FIG. 11 , the end portion  46   c L,  46   c R of the wire  46   c  is bent toward the core metal  46   a  (along the end surface corresponding to the sponge layer) and is inserted into a hole  46   f  having a diameter larger than the diameter of the wire  46   c  and extending in the radial direction of the core metal  46   a . A portion  46   c   1  projected out of the hole  46   f  is bent into a retaining portion, at each of the new portions. By doing so, the end portions  46   c L and  46   c R of the wire  46   c  are slidably engaged with the core metal  46   a.    
     In other words, the wire  46   c  spirally extends on the surface of the elastic layer  46   b  along with the axial direction of the roller, and the end portions  46   c L and  46   c R are engaged with the core metal  46   a  so as to be movable in the diametrical direction of the core metal  46   a.    
     More specifically, the core metal  46   a  is provided with a hole  46   f  of φ2 mm extending in the radial direction, at each of the axial end portions, and the wire  46   c  is bent into an end portion  46   c L,  46   c R which is penetrated through the hole  46   f , and the end of the end portion  46   c L,  46   c R is bent into a L shape to prevent disengagement of the wire  46   c . The diameter of the wire  46   c  is φ1.0 mm, and in the diameter of the hole  46   f  of the core metal  46   a  is φ2.0 mm, and therefore, the wire  46   c  is easily slidable in the radial direction of the roller. 
     The sliding direction c ( FIG. 12 ) is toward the axis of the web roller  46 . When the web roller  46  urges the web  68  to the collection roller  41  (part (a) →part (b) of  FIG. 12 ), the end portion  46   c L,  46   c R slides in the hole  46   f . In  FIG. 1 , cleaning web  68  is omitted for better understanding. By the sliding of the bent end portions  46   c L,  46   c R of the wire  46  with the formation of the elastic layer, extreme pressure rises at the wire end portions can be avoided. 
     With this structure, the possible tearing of the web  48  can be prevented, and therefore, the damage to the collection roller  41 , the deterioration of the cleaning property, the image defect which are attributable to the tearing of the web  48  can be prevented. 
     As described in the foregoing, according to this embodiment, the cleaning property can be enhanced, and therefore, the frequency of exchange of parts is reduced. In addition, the surface property of the fixing member can be maintained, and therefore, the quality of the prints can be enhanced with stabilized continuous printing operation. 
     [Embodiment 5] 
     In the description of Embodiment 5, the structures are similar to those of Embodiment 1 unless particular mentioning is made, and a part of the structure of the web roller is different from that of Embodiment 1. 
     In this embodiment, the method of fixing the wire is different from that of Embodiment 4. 
       FIG. 13  shows the slidable engagement of the end portion  46   c L,  46   c R of the wire  46  wherein the core metal  46   a , according to this embodiment. End portion  46   c L,  46   c R of the wire  46  is bent toward the core metal  46   a , and is further bent into a loop  46   c   2  defining an elongated hole around the core metal  46   a , so that the end portion  46   c L,  46   c R of the wire  46  is slidably engaged with the core metal  46   a . With this structure, it is not necessary that the hole  46   f  is formed through the core metal  46   a.    
     In other words, the wire  46   c  spirally extends on the surface of the elastic layer  46   b  along with the axial direction of the roller, and the end portions  46   c L and  46   c R are engaged with the core metal  46   a  so as to be movable in the diametrical direction of the core metal  46   a.    
     The structure for slidably engaging the end portion  46   c L,  46   c R of the wire  46  with the core metal  46   a  is not limited to Embodiment 4 and 5, but may be another which can be selected by a person skilled in the art. 
     In the Embodiments 4 and 5, two or more wires  46   c  can be spirally extended along the roller axial direction on the surface of the elastic layer  46   b.    
     The wire  46   c  may be extended not spirally, and for example, one or more wires  46   c  may extend linearly along the generatrix direction of the roller with a space or spaces in the circumferential direction of the roller. Furthermore, the wire  46   c  is not limited to linear shape, but may be bent into a waveform or the like. 
     [Others] 
     1) In the foregoing description of the embodiments, the member to be cleaned has been a collection roller  41 , but may be another rotatable member used in an electrophotographic image forming apparatus. 
     2) The image heating apparatus is not limited to a fixing device described in the foregoing. It may be a device for temporary fixing a toner image formed on a sheet, or a glossiness improving device for improving the glossiness of a toner image by heating an already fixed toner image. 
     The electrophotographic image forming apparatus is not limited to a printer, but it may be a copying machine, a facsimile machine or a multifunction machine having and the functions of them, or the like. In addition, it is not limited to a color image forming apparatus, but may be a monochromatic image forming apparatus. 
     While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions. 
     This application claims priority from Japanese Patent Applications Nos. 027558/2014 and 027559/2014 filed Feb. 17, 2014 and Feb. 17, 2014, respectively, which are hereby incorporated by reference.