JP2009103789A - Image forming device, and cleaning method for heating rotor or pressurizing member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device, a cleaning method for a heating rotor, and a leaning method for a pressurizing member, capable of removing effectively toner contamination deposited on a surface of the heating rotor or the pressurizing member, and capable of restraining a defective image from being generated. <P>SOLUTION: This image forming device is provided with: an image forming means for forming a toner image on a sheet material; and an image heater 200 for passing the sheet material to a heating nip part N formed of a fixing film 13 and a pressurizing roller 20 pressure-contacting with the fixing film 13, and for heating the toner image on the sheet material. The device has a cleaning mode for cleaning a surface of the fixing film 13, by passing the sheet material formed with a prescribed image pattern through the heating nip part N. In the image forming device, the image forming means forms the prescribed image pattern, by executing unframed printing of forming the image without providing a blank space area in a width-directional end part of the sheet material, in the cleaning mode. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as an electrophotographic copying machine and a printer, and a cleaning method for a heating rotator or a pressure member.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as an electrophotographic copying machine or printer, as a fixing means for fixing a toner image transferred on a sheet material, a fixing roller having excellent thermal efficiency and durability (a rotating body for heating) ) Having a fixing device having a method is widely known.

  On the other hand, by directly sliding the inside of the endless fixing film (heating rotating body) and the heating resistor, it is possible to shorten the rise time until the surface of the film member rises to a predetermined temperature. A film heating type fixing device is also known.

  According to the film heating type fixing device, since it is almost unnecessary to supply power to the fixing device during standby, it is possible to keep power consumption as low as possible. Such film heating type fixing devices are disclosed in Patent Documents 1 to 5.

  Further, in the fixing device having the heat roller method and the film heating method mentioned above, a pressure roller (elastic roller) is provided as a pressure member, and the pressure roller is in pressure contact with the fixing roller or the fixing film. Thus, a heating nip is formed.

  When the toner image is fixed on the sheet material, the toner image on the sheet material is heated and pressed by nipping and conveying the sheet material at the heating nip portion, and the toner image is thermally fixed on the sheet material. .

  However, there is toner that adheres to the surface of the fixing roller or the fixing film without being fixed on the sheet material when the toner image is fixed in the heating nip portion. Such toner is referred to as offset toner.

  Some of such offset toners are returned to the sheet material when the fixing roller or the fixing film makes one rotation and return to the heating nip portion, and are discharged together with the sheet material. However, some may remain on the surface of the fixing roller or the fixing film, or some may be transferred to the pressure roller between the sheet materials conveyed to the heating nip portion.

  On the other hand, in order to make it difficult to accumulate offset toner, a fixing roller and a fixing film whose surface is covered with a fluorine resin such as PFA or PTFE in a tube shape or a coat shape are known.

  On the other hand, in recent years, the spread of printers, copiers and the like has become widespread all over the world as prices have fallen. As a result of widespread use in areas where printers and the like have not been used so far, the types of sheet materials used vary widely, and their characteristics often vary from area to area. Among them, there is an area where a sheet material containing a large amount of heavy calcium carbonate as a filler is used in some areas.

In recent years, in order to improve the texture of the sheet material, the filling amount of calcium carbonate tends to increase due to high whiteness, excellent opacity, and low cost. However, paper powder containing calcium carbonate as a main component has a frictional charging characteristic such that it is strongly positively charged by friction with a fluororesin as compared with paper powder containing other fillers such as kaolin and talc.

  For this reason, if a sheet material containing a large amount of calcium carbonate passes through the heating nip portion, as described above, the surface of the fixing film or fixing roller whose surface is covered with a fluorine-based resin such as PFA or PTFE is statically discharged. It becomes easy to be electroadsorbed. Further, when paper dust adheres to the surface of the fixing roller or the fixing film in this way, the releasability of the surface of the fixing roller or the fixing film is significantly lowered.

  Once the releasability is lowered, the toner gradually starts to accumulate in the part where the releasability is lowered, and the toner is fixed and grows into toner stains. As the amount of accumulated toner stains increases, the toner stains are transferred to the sheet material, causing image defects. In addition, when the toner stains are sticky, there is a problem that a sheet material such as an OHP sheet is wound.

  On the other hand, various countermeasures have been conventionally taken with respect to cleaning means for removing toner stains accumulated on the surfaces of the fixing roller and the fixing film. Patent Document 6 discloses a method for cleaning dirt on a pressure roller by using a sheet material printed with solid black on one side and passing the fixing nip portion with the printing surface of the sheet material facing the pressure roller. Has been introduced.

Patent Document 7 discloses a method of automatically performing a cleaning mode at predetermined intervals. In the cleaning method introduced here, the sheet material (cleaning sheet) is stopped while being sandwiched between the heating nips, and heating, cooling, and step-by-step control of the sheet material to the next cleaning position are set as one step. By repeating this step a plurality of times, dirt around the pressure roller and the fixing film is sequentially transferred to the cleaning paper and removed.
JP-A-63-313182 Japanese Patent Laid-Open No. 2-157878 JP-A-4-44075 JP-A-4-204980 JP-A-8-6409 JP-A-2-160276 JP 2001-242730 A

  However, even if the conventional cleaning means is used, it is difficult to sufficiently remove paper dust or toner stains adhering to the surface of a heating rotating body such as a fixing roller and a fixing film.

  In cases where toner contamination accumulates on the surface of the rotating body for heating (here, the fixing film will be described as an example), first, paper powder containing a large amount of calcium carbonate adheres to the surface of the fixing film by passing the sheet material. Begin to. When the adhesion of paper dust increases and the releasability of the fixing film surface starts to decrease, the offset toner starts to accumulate as toner stains.

  If there is a toner image on the sheet material conveyed by subsequent printing, the paper powder adhering to the surface of the fixing film becomes the adhesive layer with the toner that melts at the time of heating and fixing in the image portion. Can be discharged together with the sheet material.

For example, since many toner images are generally transferred near the center of the sheet material, paper dust adhering to the surface of the fixing film that contacts the vicinity of the center of the sheet material is removed to the subsequent toner image. As a result, toner contamination is less likely to grow.

  On the other hand, compared with the vicinity of the central portion of the sheet material, the transferred toner image tends to decrease in the portion near the end portion in the width direction of the sheet material. When the transferred toner image is reduced, it is difficult to remove paper dust attached to the surface of the fixing film. Therefore, more paper dust adheres to the portion near the end in the width direction of the fixing film.

  In particular, in most cases, the toner image is not transferred to the margin area at the end in the width direction of the sheet material. Therefore, the margin area at the left and right end portions in the width direction of the sheet material on the surface of the fixing film. A lot of paper dust adheres to the contact portion (see FIG. 3). In particular, of the sheet material passed through the heating nip portion, the portion that contacts the left and right margins in the width direction of the sheet material having the maximum width is in contact with the toner image on the subsequent sheet material. There is little to do, so the most paper dust adheres.

  In addition, although the toner image is hardly transferred to the left and right end portions in the width direction of the sheet material, the margins at the end portions in the width direction on the sheet material are composed of regular and inverted toner transferred from the photosensitive drum. There is a small amount of fog.

  That is, the amount of paper dust accumulated in the fixing film is increased and the releasability is impaired, and such a small amount of fog toner gradually accumulates, so that the sheet material in the width direction is formed on the surface of the fixing film. Toner stains grow on the portions that come into contact with the left and right end portions. In particular, of the sheet material passed through the heating nip portion, toner contamination is remarkable in a portion that contacts the left and right margin regions in the width direction of the sheet material having the maximum width.

  As a solution to this problem, the toner adhesion is reduced by removing paper dust at the portion of the surface of the fixing film that contacts the left and right edges in the width direction before the toner stains accumulate. A method is conceivable.

  For example, the above-described conventional example discloses a configuration in which the toner stain on the surface of the fixing film is removed by preparing a cleaning paper on which solid black is printed and passing the cleaning paper again through the fixing nip portion. However, since there is a blank portion in the cleaning paper itself, the paper powder at the end of the fixing film cannot be effectively adsorbed and removed. In particular, it is difficult to remove the toner stains in the portion of the sheet material that passes through the heating nip portion that contacts the left and right margin regions in the width direction of the sheet material having the maximum width.

  In view of the above situation, the present invention provides an image forming apparatus capable of effectively removing toner stains adhering to the surface of a heating rotator or a pressure member and suppressing the occurrence of image defects, and a heating rotator. It is an object of the present invention to provide a body cleaning method and a pressure member cleaning method.

  In order to achieve the above object, according to the present invention, a heating nip formed by an image forming means for forming a toner image on a sheet material, a heating rotator, and a pressure member in pressure contact with the heating rotator. Image heating means for heating the toner image on the sheet material by passing the sheet material through the portion, and passing the sheet material on which a predetermined image pattern is formed through the heating nip portion, In the image forming apparatus having a cleaning mode for cleaning the surface of the heating rotator, the image forming unit forms an image without providing a blank area at the end in the width direction of the sheet material in the cleaning mode. The predetermined image pattern is formed by performing non-printing.

Further, the cleaning method for a heating rotator of the present invention is formed by an image forming means for forming a toner image on a sheet material, a heating rotator, and a pressure member in pressure contact with the heating rotator. An image heating means for heating a toner image on the sheet material by sandwiching the sheet material in a heating nip portion, wherein the image forming means is a cleaning method for cleaning the surface of the heating rotator of the image forming apparatus. By passing the sheet material on which the predetermined image pattern is formed by the sheet through the heating nip portion and attaching dirt on the surface of the heating rotating body to the image portion of the predetermined image pattern, the heating rotating body The surface of the substrate is cleaned.

  The pressure member cleaning method of the present invention is formed by an image forming means for forming a toner image on a sheet material, a heating rotator, and a pressure member in pressure contact with the heating rotator. In a cleaning method for cleaning the surface of the pressure member of an image forming apparatus, the image forming unit comprising: an image heating unit configured to sandwich a sheet material in a heating nip portion and heat a toner image on the sheet material; After the sheet material on which the image pattern is formed is passed through the heating nip portion, the surface of the sheet material on which the predetermined image pattern is formed is brought into contact with the surface of the pressure member during the next sheet passing. In this way, the surface of the pressure member is cleaned by passing the paper through the heating nip and attaching the dirt on the surface of the pressure member to the image portion of the predetermined image pattern. It is characterized in.

  According to the present invention, an image forming apparatus capable of effectively removing toner stains adhering to the surface of a heating rotator or a pressure member and suppressing the occurrence of an image defect, and a heating rotator cleaning method It is possible to provide a method for cleaning the pressure member.

  The best mode for carrying out the present invention will be exemplarily described in detail below based on the embodiments with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. Absent.

(First embodiment)
An image forming apparatus according to a first embodiment of the present invention will be described with reference to FIGS.

[Entire configuration of image forming apparatus]
FIG. 1 shows a schematic configuration of an image forming apparatus according to the present embodiment. As shown in FIG. 1, the image forming apparatus according to the present embodiment includes an image forming unit 100 (image forming unit) and a thermal fixing device 200 (image heating unit).

  The image forming unit 100 includes a photosensitive drum 1 (image carrier), a charging roller 2 (charging means), a laser scanner 3 (exposure means), a developing device 4 (developing means), and a transfer roller 5 (transfer means).

  The photosensitive drum 1 in the present embodiment is formed by providing a photosensitive material such as OPC, amorphous Se, or amorphous Si on a cylindrical substrate such as aluminum or nickel.

  When forming an image on a sheet material, first, the photosensitive drum 1 rotates in the direction of the arrow in FIG. A charging roller 2 provided in contact with the surface of the photosensitive drum 1 uniformly charges the surface of the photosensitive drum 1.

  The laser scanner 3 emits laser light L that is ON / OFF controlled based on image information to the uniformly charged surface of the photosensitive drum 1 to form an electrostatic latent image on the surface of the photosensitive drum 1. Thereafter, the developing device 4 supplies toner to the electrostatic latent image using a potential difference from the surface of the photosensitive drum 1, and develops the electrostatic latent image as a toner image on the surface of the photosensitive drum 1.

  As a developing method in the present embodiment, any of the jumping developing method, the two-component developing method, and the FEED developing method can be used. Further, image exposure and reversal development are often used in combination.

  The toner image developed on the surface of the photosensitive drum 1 is transferred to the sheet material P at the nip portion between the photosensitive drum 1 and the transfer roller 5. At this time, residual toner remaining on the surface of the photosensitive drum 1 without being transferred to the sheet material P is removed by the cleaning device 7. The timing at which the sheet material P is conveyed to the nip portion is controlled to a timing at which the toner image can be transferred to a desired position on the sheet material P by detecting the leading edge of the sheet material P by the top sensor 8. The

  The sheet material P on which the toner image is transferred at the nip portion between the photosensitive drum 1 and the transfer roller 5 is conveyed to the heat fixing device 200, where the toner image is permanently fixed.

  The sheet material P on which the toner image is permanently fixed is discharged from the heat fixing device 200 and is discharged to the outside of the apparatus main body via the discharge sensor 9. The discharge sensor 9 in the present embodiment is a sensor for detecting when the sheet material P causes a paper jam or the like between the top sensor 8 and the discharge sensor 9.

[Configuration of Heat Fixing Device]
With reference to FIG. 2, the structure of the heat fixing apparatus 200 in the present embodiment will be described. FIG. 2 shows a schematic configuration of the heat fixing apparatus 200 in the present embodiment. The heat fixing device 200 in the present embodiment is a film heating type fixing device.

  The heat fixing device 200 includes a fixing assembly 10 and a pressure roller 20 (pressure member). The pressure roller 20 is in pressure contact with the fixing assembly 10 to form a heating nip portion N, and the pressure roller 20 rotates in the direction of the arrow in the figure, so that the fixing assembly 10 is driven to rotate in the direction of the arrow in the figure. Configured as follows.

  The fixing assembly 10 includes a heater 11, a heat insulating holder 12, and a fixing film 13 (rotating body for heating). The heater 11 is held by the heat insulating holder 12 and is provided at a position that slides with the inner peripheral surface of the fixing film 13.

As the heater 11, a plate having a low heat capacity is used. In the present embodiment, an energization heat generating resistance layer such as Ag / Pd (silver palladium), RuO ₂ , Ta ₂ N is provided on the surface of an insulating ceramic substrate such as alumina or aluminum nitride along the longitudinal direction of the substrate. A printed version is used. In addition, a configuration in which a protective layer such as a glass layer that protects the energization heating resistance layer may be provided on the sliding surface with the inner peripheral surface of the fixing film 13 within a range that does not impair the thermal efficiency.

  The heat insulating holder 12 holds the heater 11 and is formed of a heat resistant resin such as a liquid crystal polymer, a phenol resin, PPS, or PEEK. In addition, the heater 11 is held and also has a function of guiding the rotation of the fixing film 13.

  For the fixing film 13 in the present embodiment, a heat resistant film having a layer thickness of 200 μm or less is used in order to enable quick start of the heat fixing device 200. In order to ensure durability, the layer thickness is desirably 20 μm or more. That is, in this embodiment, a fixing film having a layer thickness of 20 μm or more and 200 μm or less is used.

  In addition, the fixing film 13 in the present embodiment has a multilayer structure formed of a base layer and a surface layer. As the base layer, a heat-resistant resin such as polyimide, polyamideimide, or PEEK, or a pure metal such as SUS, Al, Ni, Cu, or Zn having heat resistance and high thermal conductivity, an alloy, or the like is used.

  As the surface layer, resins such as PTFE (polytetrafluoroethylene), PFA (tetrafluoroethylene perfluoroalkyl vinyl ether copolymer), and FEP (tetrafluoroethylene hexafluoropropylene copolymer) are used. Further, a resin such as ETFE (ethylene tetrafluoroethylene copolymer), CTFE (polychlorotrifluoroethylene), PVDF (polyvinylidene fluoride), or the like may be used. By configuring the surface layer of the fixing film 13 in this way, the releasability of the fixing film 13 is improved.

  The pressure roller 20 includes a metal core 21 made of SUS, SUM, Al or the like and an elastic layer 22 formed on the outside of the metal core 21.

  In the present embodiment, as the elastic layer 22, there is an elastic solid rubber layer formed of heat-resistant rubber such as silicone rubber or fluorine rubber, or an elastic sponge rubber layer formed by foaming silicone rubber in order to have a more heat insulating effect. Used. Moreover, the structure using the elastic foam rubber layer which disperse | distributed the hollow filler (microballoon etc.) in the silicone rubber layer, gave the gas part in hardened | cured material, and improved the heat insulation effect may be sufficient.

  Furthermore, the structure which forms release layers, such as a perfluoro alkoxy resin (PFA) and a polytetrafluoroethylene resin (PTFE), on the surface of the elastic layer 22 may be sufficient.

  The pressure roller 20 is pressed against the fixing film 13 by a spring (not shown) to obtain a heating nip portion N. A driving force that rotates in the direction of the arrow in FIG. 2 is obtained by a driving gear (not shown) provided at the end of the core 21. The driving force is transmitted from a motor (not shown) in accordance with a command from a CPU (not shown) that controls the control means. As the pressure roller rotates, the fixing film 13 is driven to rotate by the frictional force with the pressure roller 20.

  Further, in the present embodiment, by interposing a lubricant such as a fluorine-based or silicone-based heat resistant grease between the fixing film 13 and the heater 11, the frictional resistance is suppressed to a low level. The configuration allows smooth rotation.

  Further, the temperature control of the heater 11 is performed by controlling the duty ratio, wave number, etc. of the voltage applied by the CPU (not shown) to the energization heating resistor layer according to a signal from a temperature detection element such as a thermistor (not shown) provided on the back surface of the ceramic substrate. Is determined and appropriately controlled. According to this configuration, the temperature of the heating nip portion can be maintained at a desired fixing set temperature.

  A sheet material P holding an unfixed toner image is appropriately supplied to a heating and fixing apparatus 200 configured as described above by a feeding unit (not shown) at a predetermined timing, and is conveyed to a heating nip portion N. Heat fixing is performed. The sheet material P discharged from the heating nip portion N is guided by a discharge guide (not shown) and discharged.

[Description of cleaning mode]
In the heat fixing apparatus 200 configured as described above, when the sheet material is sandwiched in the heating nip portion N and heat fixing is performed, in particular, paper dust adheres to the surface of the end portion of the fixing film 13, and this portion Toner contamination has occurred.

  In addition, there was a case where such toner contamination was transferred from the fixing film 13 to the surface of the pressure roller 20, and toner contamination occurred at the end of the pressure roller 20. The end portions of the fixing film 13 or the pressure roller 20 are both end portions in the direction perpendicular to the conveying direction of the sheet material P in the heating nip portion N, and are in contact with the blank area in the width direction of the sheet material P. It shall refer to the part.

  Further, even in a portion that contacts the margin region in the width direction of the sheet material P, particularly in a portion that contacts the margin region in the width direction of the sheet material having the maximum width that is passed through the heating nip portion N, the toner contamination is remarkably increased. Had occurred.

  Therefore, the image forming apparatus according to the present embodiment is configured such that the end surface of the fixing film 13 can be periodically cleaned.

  Specifically, first, when the apparatus main body is switched from the normal printing mode to the cleaning mode, the image forming unit 100 creates a predetermined image pattern on the sheet material based on an image pattern preset in a storage unit (not shown). Form.

  A sheet material having a predetermined image pattern is sandwiched between the heating nips N to clean the end surface of the fixing film 13.

  In this embodiment, when a predetermined number of sheet materials are passed through the heat fixing device from a feeding tray on which a plurality of sheet materials are stacked, a control unit (not shown) automatically switches to the cleaning mode, It is assumed that the end surface of the fixing film 13 is cleaned.

  The sheet material on which a predetermined image pattern is formed in order to clean the end surface of the fixing film 13 will be referred to as a cleaning sheet and will be described below.

[How to create a cleaning sheet]
As shown in FIG. 4, in the present embodiment, a sheet material on which edgeless printing is applied to an end portion in a direction orthogonal to the conveyance direction of the sheet material is used as a cleaning sheet. Hereinafter, a method for creating such a cleaning sheet will be described.

  The cleaning sheet according to the present embodiment is characterized by providing a section in which charging is not performed temporarily (charging off) when the surface of the photosensitive drum 1 is uniformly charged by the charging roller 5. .

  If the photosensitive drum 1 continues to rotate for a predetermined time while the charging roller 5 is not charged, the surface of the photosensitive drum 1 has the same width as the longitudinal direction of the charging roller in the circumferential direction of the photosensitive drum 1. An uncharged section is formed over a predetermined length.

  FIGS. 5A and 5B show the state of the potential on the surface of the photosensitive drum 1 in the normal printing and the cleaning mode in the present embodiment.

  As shown in FIG. 5 (b), in the present embodiment, a charging off section is provided for a predetermined time in the cleaning mode. In the charging off section, the surface potential of the photosensitive drum 1 is 0 V, and this portion is a bright portion potential (portion where an image is formed).

  In this embodiment, since negatively charged toner is used, the dark portion potential of the photosensitive drum 1 is set to −600 v and the developing bias is set to −300 v. Further, the surface potential (bright portion potential) of the laser exposure portion during normal printing is set to −100 v (FIG. 5A).

  According to this configuration, an image is formed on the laser exposure portion during normal printing, and an image is formed on the charging off portion during the cleaning mode. However, in the configuration during normal printing, a margin area is set inside the widthwise end of the sheet material having the maximum width, and the laser irradiation width in the width direction of the sheet material is limited. No cleaning sheet can be generated.

  On the other hand, in the cleaning mode, the bright portion can be formed over the same width as the longitudinal direction of the charging roller 5, so that a toner image can be formed with a width wider than the laser irradiation width. Is possible.

  That is, it is possible to make the bright part potential wider than when bright part potential is formed by laser irradiation. Then, development is performed in this state, and the toner image is transferred from the photosensitive drum 1 to the sheet material, whereby a cleaning sheet having a borderless image as shown in FIG. 4 can be obtained. Therefore, the toner image can be brought into contact with a portion of the surface of the fixing film 13 that is in contact with the blank area in the width direction of the sheet material.

  Note that the toner that is not transferred onto the sheet material during borderless printing and that sticks to the surface of the transfer roller 5 from the sheet material is removed by a cleaning means (not shown) that is opposite to the transfer bias before and after paper passing. Or the like can be removed.

  In this embodiment, a cleaning sheet close to solid black is obtained. For example, by adjusting the developing bias, an adjustment is made so that an image having a halftone density is formed on the photosensitive drum 1, and the cleaning is performed using the halftone. The structure which forms a sheet | seat may be sufficient.

  Further, the length of the borderless image on the cleaning sheet (the length in the sheet conveying direction) is not limited to the length shown in FIG. 4, and may be longer or shorter. .

  However, when a solid image is formed from the vicinity of the front end of the sheet material in the conveyance direction, there is a possibility of winding around the fixing film 13 or the pressure roller 20 in the cleaning mode. It is desirable to form a solid white portion for the circumference.

[Comparison with conventional example]
After passing through every 500 sheets, the mode was switched to the cleaning mode, and the state of the end surface of the fixing film 13 was confirmed when the end surface of the fixing film 13 was cleaned by the cleaning sheet obtained in the above process.

  Further, as a comparison target of the image forming apparatus according to the present embodiment, a case where cleaning is not performed at all (Conventional Example 1) and a case where a cleaning sheet not subjected to borderless printing is used (Conventional Example 2). The experiment was performed under the same conditions. The result of this experiment is shown in FIG. FIG. 11 shows the number of sheets where the toner stain starts to adhere to the end surface of the fixing film, and the number of sheets where the toner stain accumulates and the stain appears as offset stain on the sheet material during printing.

As shown in FIG. 11, in the conventional example 2, although the cleaning sheet has some effect, the dirt on the end surface of the fixing film cannot be removed and remains, so the cleaning effect is small.

  On the other hand, in the present embodiment, the paper dust adhering to the end surface of the fixing film is effectively removed, so that it is possible to suppress the adhesion of toner stains. It is possible to prevent toner contamination from adhering to the material.

  As described above, according to the image forming apparatus according to the present embodiment, it is possible to provide an image forming apparatus that can effectively remove toner stains adhering to the fixing film 13 and suppress the occurrence of image defects. . Further, since the cleaning sheet can be generated by a simple process such as turning off the charging roller, the manufacturing cost can be reduced when the apparatus main body is provided with the cleaning mode.

  In the present embodiment, the created cleaning sheet is automatically passed periodically. However, the frequency of the periodic cleaning can be arbitrarily changed, and the user can arbitrarily select the cleaning mode. In such a case, it may be set so that cleaning is performed.

  If paper dust or toner stains adhere to the pressure roller 20 side, once the cleaning sheet is created, the cleaning sheet is set again in the feeding cassette. You may set so that it may contact a pressure roller.

  Further, when the cleaning sheet is passed through the heat fixing device 200, the cleaning sheet is stopped in a state where it is sandwiched between the heating nips N, and the heating, cooling, stepwise transport of the cleaning sheet to the next cleaning position is performed. May be repeated a plurality of times.

[Second Embodiment]
The image forming apparatus according to the second embodiment of the present invention differs from the image forming apparatus according to the first embodiment in [Cleaning sheet creation method]. Note that [the overall configuration of the image forming apparatus] and [the configuration of the heating and fixing apparatus] are not different from those of the first embodiment, and thus the description thereof is omitted. Here, the [generation method of the cleaning sheet] is omitted. Only explain.

[Cleaning sheet generation method]
In the first embodiment, when the surface of the photosensitive drum 1 is uniformly charged by the charging roller 5, a section in which charging is not temporarily performed (charging off) is provided to obtain a borderless image. It was. This is a particularly effective method when the laser irradiation width of the laser scanner 3 is limited and it is difficult to perform borderless printing (FIG. 6A).

  On the other hand, in the present embodiment, the setting frame of the non-printing area of the laser scanner 3 is canceled and the exposure by the laser scanner 3 is set to extend outside the maximum sheet passing width of the sheet material (FIG. 6B). ). According to this configuration, even when a sheet material having the maximum width is passed, the toner image can be developed to the end in the width direction, and the cleaning sheet on which borderless printing has been performed can be developed. Can be generated.

  Further, according to this configuration, since an arbitrary image pattern can be formed by the laser scanner 3, as shown in FIG. 7, a toner image is formed only at the end in the width direction of the sheet material, and the toner is formed at the center. It becomes possible to form a sheet material in which an image is not formed.

As described above, the toner stains adhering to the fixing film 13 are formed on the portion in contact with the blank area of the sheet material, that is, on the surface of the end of the fixing film 13, so that the cleaning sheet as shown in FIG. In this case, the fixing film 13 can be cleaned. In addition, it is possible to reliably clean the portion that contacts the marginal region in the width direction of the sheet material having the maximum width that is passed through the heating nip portion N.

  In this way, by creating a cleaning sheet having an image pattern capable of cleaning at least a portion in contact with the marginal region in the width direction of the sheet material passed through the heating nip portion N, consumption of excess toner is suppressed. It becomes possible.

  Actually, in the image forming apparatus according to the present embodiment, when the surface of the fixing film 13 is cleaned, paper dust and toner stains can be effectively removed, and even if the number of sheets to be passed increases. It has become possible to prevent toner contamination.

  In this embodiment, an image forming process is adopted in which the surface of the photosensitive drum 1 is uniformly charged and then developed on the electrostatic latent image formed by image exposure by exposure. An image forming process may be used in which background exposure is performed later and the portions other than the exposed portion are developed.

  When employing an image forming process that performs background exposure in this way, it is possible to obtain a desired cleaning sheet by uniformly charging the surface of the photosensitive drum and then not exposing the portion where the toner image is formed. become.

[Third Embodiment]
The third embodiment of the present invention relates to a method for cleaning the end surface of the fixing film 13 (rotating body for heating).

  When cleaning the end surface of the fixing film 13, first, borderless printing is performed to form an image without providing a blank area at the end in the width direction of the sheet material in the cleaning mode. Note that switching from the normal printing mode to the cleaning mode may be performed automatically by a CPU (not shown) based on the number of sheets to be passed, or may be a method that is arbitrarily selected by the user.

  Then, by passing the cleaning sheet on which the borderless image is formed to the heating nip portion N, the sheet material having the maximum width among the sheet materials to be passed through the heating nip portion N on the surface of the fixing film 13. Clean the part in contact with the margin area in the width direction.

  Note that the cleaning sheet generation method in the present embodiment is the same as the [cleaning sheet generation method] described in the first embodiment, and a description thereof will be omitted here.

  As described above, according to the method for cleaning the end surface of the fixing film according to the present embodiment, the toner contamination attached to the end surface of the fixing film 13 is effectively removed, and the occurrence of image defects is suppressed. It becomes possible.

  In this embodiment, the [cleaning sheet generation method] described in the first embodiment is used. However, the [cleaning sheet generation method] described in the second embodiment is used. Needless to say, the same effect can be obtained even if it is used.

[Fourth Embodiment]
The fourth embodiment of the present invention relates to a method for cleaning the end surface of the fixing film 13 (rotating body for heating).

The image forming apparatus includes a feeding unit including a feeding cassette, a multi-tray, and the like on which a plurality of sheet materials are stacked. Further, the feeding unit is provided with a width regulating plate (width regulating member) that comes into contact with both end faces in the width direction of the stacked sheet material and regulates the movement of the sheet material in the width direction. The width regulating plate includes a mechanism that freely slides in the width direction of the sheet material according to the size of the sheet material, and the user adjusts the width regulating plate according to the size of the sheet material.

  When switching from the normal printing mode to the cleaning mode, the user widens the width regulating plate to the most open state. The width regulating plate in the present embodiment can be opened further by 1 to 2 cm than the interval in the width direction of the sheet material having the maximum width. Note that switching from the normal printing mode to the cleaning mode may be performed automatically by a CPU (not shown) based on the number of sheets to be passed, or may be a method that is arbitrarily selected by the user.

  Then, one end surface in the width direction of the cleaning sheet is brought into contact with one of the width control plates in the most open state, and the cleaning sheet is offset (one end surface in the width direction of the cleaning sheet is the width control plate). The other end face is not in contact with the width regulating plate). This state is shown in FIG.

  When the cleaning sheet is conveyed to the image forming unit in a state of being aligned and a toner image is formed on the cleaning sheet, a toner image as shown in FIG. 9 is formed on the cleaning sheet. That is, borderless printing in which a toner image is formed only on the end surface of the cleaning sheet in the width direction that is not in contact with the width regulating plate is performed.

  In this manner, the cleaning sheet on which the toner image is formed at one end in the width direction is once discharged and set again in the feeding unit. At this time, the width regulating plate is returned to the normal printing position. In this state, the cleaning sheet is passed through the heating nip N.

  Then, since borderless printing is applied to one end in the width direction of the cleaning sheet, the portion of the surface of the fixing film 13 that contacts the blank area at one end in the width direction of the sheet material The cleaning sheet is cleaned (FIG. 10).

  After that, when the cleaning sheet is discharged again, the left and right sides in the width direction of the cleaning sheet are reversed and set in the feeding unit, and again passed through the heating nip, the surface of the end of the fixing film 13 that has not been cleaned Is cleaned.

  The cleaning mode is terminated by the above process. As a result, the portion of the surface of the fixing film 13 that comes into contact with the blank area at the end in the width direction of the sheet material passed through the heating nip portion is reliably cleaned, and the occurrence of toner contamination can be suppressed. Become.

  As described above, according to the method for cleaning the surface of the fixing film according to the present embodiment, the width regulating plate can be operated even when using an image forming unit that does not have a configuration capable of borderless printing. Thus, it becomes possible to obtain a cleaning sheet subjected to borderless printing. Then, by passing the cleaning sheet thus obtained through the heating nip portion, the end surface of the fixing film 13 can be reliably cleaned.

  Furthermore, by adjusting the interval between the width regulating plates, it is possible to clean the portion of the surface of the fixing film 13 that contacts the margin area in the width direction of the sheet material having the maximum width that is passed through the heating nip portion. It is.

As described above, toner contamination is most likely to occur on the surface of the fixing film 13 in contact with the marginal area in the width direction of the sheet material having the maximum width that is passed through the heating nip portion. According to the cleaning method of the end surface in the width direction of the fixing film according to the present embodiment, the toner image portion on the cleaning sheet is surely brought into contact with the portion where the toner stain occurs by adjusting the width regulating plate. It becomes possible to make it.

  In addition, according to the cleaning method according to the present embodiment, it is necessary for the user to adjust the width regulating plate and pass the cleaning sheet again. Accordingly, in order to facilitate the user's operation, there is provided a method that can easily notify a series of operations in the cleaning mode using an information processing device such as a personal computer connected to the image forming apparatus or an operation panel. Is desirable.

[Fifth Embodiment]
The fifth embodiment of the present invention relates to a method for cleaning the end surface of the fixing film 13 (rotating body for heating).

  FIG. 8 shows a state in which cleaning is performed by the cleaning method of the end surface of the fixing film 13 according to the present embodiment.

  The fixing film cleaning method according to the present embodiment is characterized in that the end surface of the fixing film 13 is cleaned by using a cleaning sheet that forms a blank area at the end in the width direction.

  When the mode is switched from the normal printing mode to the cleaning mode, a cleaning sheet in which a margin area is provided at the end in the width direction is generated. Then, the generated cleaning sheet is once discharged and set in the feeding unit again. Note that switching from the normal printing mode to the cleaning mode may be performed automatically by a CPU (not shown) based on the number of sheets to be passed, or may be a method that is arbitrarily selected by the user.

  When setting the sheet material on the feeding unit, the user widens the width regulating plate to the most open state. The width regulating plate in the present embodiment can be opened further by 1 to 2 cm than the interval in the width direction of the sheet material having the maximum width.

  Then, one end surface in the width direction of the cleaning sheet is brought into contact with one width regulating plate to bring the cleaning sheet into a state of being justified, and in that state, the sheet is passed through the heating nip portion.

  When paper is passed through the heating nip in this state, the toner image portion on the cleaning sheet can be brought into contact with the surface of one end of the fixing film 13. Therefore, it is possible to reliably clean one end surface of the fixing roller 13.

  When cleaning the surface of the other end of the fixing film 13, the cleaning sheet is brought into contact with the width regulating plate on the opposite side to the previous time and is offset, and the paper is passed through the heating nip as in the previous time. . Thereby, the surface of the other end portion that has not been cleaned in the previous cleaning operation can be cleaned.

  The cleaning mode is terminated by the above process. As a result, the portion of the surface of the fixing film 13 that comes into contact with the blank area at the end in the width direction of the sheet material passed through the heating nip portion is reliably cleaned, and the occurrence of toner contamination can be suppressed. Become.

  As described above, according to the method for cleaning the surface of the fixing film according to the present embodiment, the width regulating plate can be operated even when using an image forming unit that does not have a configuration capable of borderless printing. Thus, the end surface of the fixing film 13 can be reliably cleaned.

  Furthermore, by adjusting the interval between the width regulating plates, it is possible to clean the portion of the surface of the fixing film 13 that contacts the margin area in the width direction of the sheet material having the maximum width that is passed through the heating nip portion. It is.

  As described above, toner contamination is likely to occur on the surface of the fixing film 13 in contact with the marginal area in the width direction of the sheet material passed through the heating nip portion. According to the cleaning method of the end surface in the width direction of the fixing film according to the present embodiment, the toner image portion on the cleaning sheet is surely brought into contact with the portion where the toner stain occurs by adjusting the width regulating plate. It becomes possible to make it.

  In addition, according to the cleaning method according to the present embodiment, it is necessary for the user to adjust the width regulating plate and pass the cleaning sheet again. Accordingly, in order to facilitate the user's operation, there is provided a method that can easily notify a series of operations in the cleaning mode using an information processing device such as a personal computer connected to the image forming apparatus or an operation panel. Is desirable.

[Sixth Embodiment]
The sixth embodiment of the present invention relates to a method for cleaning the end surface of the pressure roller 20 (pressure member).

  The third to fifth embodiments described above relate to methods for cleaning the end surface of the fixing film 13. In the present embodiment, these cleaning methods are applied to clean the end surface of the pressure roller 20.

  When the end surface of the pressure roller 20 is cleaned, the surface on the cleaning sheet on which the toner image is formed may be brought into contact with the surface of the pressure roller 20. That is, the cleaning sheet on which a predetermined image pattern is formed may be set on the feeding unit so that the front and back are opposite to the case where the end surface of the fixing film 13 is cleaned.

  In this way, the end surface of the pressure roller 20 can be effectively cleaned. Therefore, it is possible to provide a cleaning method for the pressurizing member that can effectively remove toner stains adhering to the surface of the pressurizing member and suppress the occurrence of image defects.

[Other embodiments]
In the first to sixth embodiments, the fixing film 13 is used as the heating rotator. However, even a configuration in which a fixing roller is used instead of the fixing film 13 is better. That is, the present invention can be applied not only to a heat film heating method but also to a heat roller image heating device.

  In the first to sixth embodiments, the temperature of the heater 11 is adjusted and the sheet material conveyance speed is improved in order to further improve the cleaning effect of the end surface of the fixing roller or the pressure roller. The structure which adjusts may be sufficient.

  Only in the cleaning mode, the cleaning effect can be improved by raising the temperature of the heater 11 or slowing the conveying speed of the sheet material.

1 is a schematic configuration diagram of an image forming apparatus according to a first embodiment. 1 is a schematic configuration diagram of a heat fixing device according to a first embodiment. The figure which shows the position where toner dirt occurs Schematic diagram of a sheet material on which borderless printing is performed in the first embodiment Schematic diagram of printable area during normal printing and cleaning mode The figure which shows the structure of borderless printing in 1st Embodiment. Schematic diagram of the cleaning sheet generated in the second embodiment The figure explaining the cleaning method which concerns on 5th Embodiment The figure explaining the cleaning method which concerns on 4th Embodiment The figure explaining the cleaning method which concerns on 4th Embodiment Comparison results between the first embodiment and the conventional example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Charging roller 3 Laser scanner 4 Developer 10 Fixing assembly 13 Fixing film 100 Image forming unit 200 Heat fixing device

Claims (20)

Image forming means for forming a toner image on a sheet material;
An image heating means for passing a sheet material through a heating nip formed by a heating rotator and a pressure member pressed against the heating rotator and heating a toner image on the sheet material;
With
In the image forming apparatus having a cleaning mode for cleaning the surface of the heating rotating body by passing a sheet material on which a predetermined image pattern is formed through the heating nip portion,
The image forming unit includes:
Image formation characterized in that, in the cleaning mode, the predetermined image pattern is formed by performing borderless printing for forming an image without providing a blank area at the end in the width direction of the sheet material. apparatus. The predetermined image pattern is:
On the surface of the heating rotating body, at least an image portion of the predetermined image pattern is in a portion in contact with a margin region in the width direction of the sheet material having the maximum width among the sheet materials passed through the heating nip portion. The image forming apparatus according to claim 1, wherein the image forming apparatus is in contact with each other. The image forming unit includes:
An image carrier that is driven to rotate;
Charging means for uniformly charging the surface of the image carrier;
Developing means for supplying toner to the surface of the image carrier to form a toner image;
Transfer means for transferring a toner image formed on the surface of the image carrier onto a sheet material;
With
On the surface of the image carrier,
A section where no charging is performed by the charging unit is formed, toner is supplied to the section based on a potential difference between the surface potential of the section and the developing potential of the developing unit, and a toner image obtained thereby is transferred to the transfer unit. The image forming apparatus according to claim 1, wherein the borderless printing can be performed by transferring the image onto a sheet material by means. The image forming unit includes:
An image carrier that is driven to rotate;
Charging means for uniformly charging the surface of the image carrier;
Exposure means for exposing the surface of the image carrier to form an electrostatic latent image;
Developing means for supplying toner to the electrostatic latent image to form a toner image;
Transfer means for transferring a toner image formed on the surface of the image carrier onto a sheet material;
With
3. The borderless printing can be performed by exposing a portion of the surface of the image carrier that is in contact with an end portion in the width direction of the sheet material. 3. The image forming apparatus described. The image forming unit includes:
An image carrier that is driven to rotate;
Charging means for uniformly charging the surface of the image carrier;
Exposure means for exposing the surface of the image carrier;
Developing means for supplying toner to a portion not exposed by the exposure means to form a toner image;
Transfer means for transferring a toner image formed on the surface of the image carrier onto a sheet material;
With
3. The borderless printing can be performed by not exposing a portion of the surface of the image carrier that is in contact with an end portion in the width direction of the sheet material. 3. The image forming apparatus described. Image forming means for forming a toner image on a sheet material;
An image heating means for heating the toner image on the sheet material by sandwiching the sheet material in a heating nip formed by a heating rotator and a pressure member pressed against the heating rotator;
In the cleaning method for cleaning the surface of the heating rotating body of the image forming apparatus comprising:
By passing a sheet material on which a predetermined image pattern is formed by the image forming unit through the heating nip portion, and attaching dirt on the surface of the heating rotating body to an image portion of the predetermined image pattern, A cleaning method for a heating rotator, wherein the surface of the heating rotator is cleaned. In the image forming apparatus,
A width regulating member that regulates movement in the width direction of the sheet material in contact with the end surface in the width direction of the sheet material is provided,
When cleaning the surface of the heating rotor,
Increase the interval of the width regulating member than during normal printing,
Set the sheet material on which the toner image is formed between the width regulating members,
One end surface of the sheet material is brought into contact with one width regulating member, and the sheet material is shifted in the width direction,
By passing the sheet material through the heating nip portion in a state of being shifted in the width direction,
The portion of the sheet material on which the toner image is formed is a blank area in the width direction of the sheet material having the maximum width among the sheet materials passed through the heating nip portion on the surface of the heating rotator. The cleaning method for a heating rotator according to claim 6, wherein the surface of the heating rotator is cleaned in contact with a contact portion. The image forming means is
The heating rotating body according to claim 6, wherein the predetermined image pattern is formed by performing borderless printing for forming an image without providing a blank area at an end portion in the width direction of the sheet material. Cleaning method. The predetermined image pattern is:
On the surface of the heating rotating body, at least an image portion of the predetermined image pattern is in a portion in contact with a margin region in the width direction of the sheet material having the maximum width among the sheet materials passed through the heating nip portion. The heating rotating member cleaning method according to claim 6, wherein the heating rotating member is formed so as to be in contact with each other. The image forming unit includes:
An image carrier that is driven to rotate;
Charging means for uniformly charging the surface of the image carrier;
Developing means for supplying toner to the surface of the image carrier to form a toner image;
Transfer means for transferring a toner image formed on the surface of the image carrier onto a sheet material;
With
On the surface of the image carrier,
A section where no charging is performed by the charging unit is formed, toner is supplied to the section based on a potential difference between the surface potential of the section and the developing potential of the developing unit, and a toner image obtained thereby is transferred to the transfer unit. 10. The heating rotating member cleaning method according to claim 8 or 9, wherein the borderless printing is performed by transferring the sheet onto a sheet material. The image forming unit includes:
An image carrier that is driven to rotate;
Charging means for uniformly charging the surface of the image carrier;
Exposure means for exposing the surface of the image carrier to form an electrostatic latent image;
Developing means for supplying toner to the electrostatic latent image to form a toner image;
Transfer means for transferring a toner image formed on the surface of the image carrier onto a sheet material;
With
10. The heating rotator according to claim 8, wherein the borderless printing is performed by exposing a portion of the surface of the image carrier that is in contact with an end portion in a width direction of the sheet material. Cleaning method. The image forming unit includes:
An image carrier that is driven to rotate;
Charging means for uniformly charging the surface of the image carrier;
Exposure means for exposing the surface of the image carrier;
Developing means for supplying toner to a portion not exposed by the exposure means to form a toner image;
Transfer means for transferring a toner image formed on the surface of the image carrier onto a sheet material;
With
10. The heating rotator according to claim 8, wherein the borderless printing is performed by not exposing a portion of the surface of the image carrier that is in contact with an end portion in a width direction of the sheet material. Cleaning method. In the image forming apparatus,
A width regulating member that regulates movement in the width direction of the sheet material by contacting both ends in the width direction of the sheet material is provided,
When cleaning the surface of the heating rotor,
Increase the interval of the width regulating member than during normal printing,
One end surface of the sheet material is brought into contact with one width regulating member, and the sheet material is shifted in the width direction,
By forming a toner image by the image forming means in that state, an edgeless image is formed at the end of the sheet material on the side opposite to the one-sided position,
A sheet material on which an edgeless image is formed at the end of the sheet material on the opposite side to the one sided,
10. The method for cleaning a heating rotator according to claim 8 or 9, wherein the surface of the heating rotator is cleaned by passing the paper through the heating nip portion without being shifted to the next sheet. Image forming means for forming a toner image on a sheet material;
An image heating means for heating the toner image on the sheet material by sandwiching the sheet material in a heating nip formed by a heating rotator and a pressure member pressed against the heating rotator;
In the cleaning method for cleaning the surface of the pressure member of the image forming apparatus comprising:
After passing the sheet material on which a predetermined image pattern is formed by the image forming unit through the heating nip,
At the time of the next paper passing, the surface of the sheet material on which the predetermined image pattern is formed is passed through the heating nip portion so as to contact the surface of the pressure member,
A method of cleaning a pressure member, wherein the surface of the pressure member is cleaned by attaching dirt on the surface of the pressure member to an image portion of the predetermined image pattern. In the image forming apparatus,
A width regulating member that regulates movement in the width direction of the sheet material by contacting both ends in the width direction of the sheet material is provided,
When cleaning the surface of the pressure member,
Increase the interval of the width regulating member than during normal printing,
Set the sheet material on which the toner image is formed between the width regulating members,
One end surface of the sheet material is brought into contact with one width regulating member, and the sheet material is shifted in the width direction,
The pressure member cleaning method according to claim 14, wherein the sheet is passed through the heating nip portion to clean the surface of the pressure member. The image forming means is
The pressurizing member according to claim 14, wherein the predetermined image pattern is formed by performing borderless printing for forming an image without providing a blank area at an end portion in the width direction of the sheet material. Cleaning method. The image forming unit includes:
An image carrier that is driven to rotate;
Charging means for uniformly charging the surface of the image carrier;
Developing means for supplying toner to the surface of the image carrier to form a toner image;
Transfer means for transferring a toner image formed on the surface of the image carrier onto a sheet material;
With
On the surface of the image carrier,
A section where no charging is performed by the charging unit is formed, toner is supplied to the section based on a potential difference between the surface potential of the section and the developing potential of the developing unit, and a toner image obtained thereby is transferred to the transfer unit. The pressure member cleaning method according to claim 14 or 16, wherein the borderless printing is performed by transferring the sheet onto a sheet material by means. The image forming unit includes:
An image carrier that is driven to rotate;
Charging means for uniformly charging the surface of the image carrier;
Exposure means for exposing the surface of the image carrier to form an electrostatic latent image;
Developing means for supplying toner to the electrostatic latent image to form a toner image;
Transfer means for transferring a toner image formed on the surface of the image carrier onto a sheet material;
With
17. The borderless printing is performed by exposing a portion of the surface of the image carrier that is in contact with an end portion in a width direction of a sheet material onto which a toner image is transferred. Cleaning method of the pressure member. The image forming unit includes:
An image carrier that is driven to rotate;
Charging means for uniformly charging the surface of the image carrier;
Exposure means for exposing the surface of the image carrier;
Developing means for supplying toner to a portion not exposed by the exposure means to form a toner image;
Transfer means for transferring a toner image formed on the surface of the image carrier onto a sheet material;
With
17. The borderless printing is performed by not exposing a portion of the surface of the image carrier that is in contact with an end portion in a width direction of a sheet material onto which a toner image is transferred. Cleaning method of the pressure member. In the image forming apparatus,
A width regulating member that regulates movement in the width direction of the sheet material by contacting both ends in the width direction of the sheet material is provided,
When cleaning the surface of the pressure member,
Increase the interval of the width regulating member than during normal printing,
One end surface of the sheet material is brought into contact with one width regulating member, and the sheet material is shifted in the width direction,
By forming a toner image by the image forming means in that state, an edgeless image is formed at the end of the sheet material on the side opposite to the one-sided position,
A sheet material on which an edgeless image is formed at the end of the sheet material on the opposite side to the one sided,
17. The pressure member cleaning method according to claim 14, wherein the surface of the pressure member is cleaned by passing the paper through the heating nip portion without being shifted to the next time when the paper is passed.

Images