JP2008185860A - Fixing device, image forming apparatus, and cleaning method of separation pawl - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To transfer the attached toner adhering to a separation pawl for separating a sheet after toner image fixation from the outer peripheral surface of a fixing roller to the fixing roller with a simple configuration. <P>SOLUTION: A cleaning step of the separation pawl is carried out in parallel with a toner replenishing step in which continuous image formation is temporarily interrupted. The fixing roller is stopped (a fixing motor OFF) simultaneously with the start of the toner replenishing step and a first stopping step P1 (time S0 to S1) is carried out to melt the attached toner and to make the toner stick to the fixing roller. Next, the fixing roller is rotated backward and the first cleaning rotation step P2 (time S1 to S2) is performed so that the attached toner on a guide surface side of the separation pawl is made to transfer to the fixing roller. Next, the second stopping step P3 (time S2 to S3) and the second cleaning rotation step (time S4 to S4) are carried out, and thereby the attached toner on the back side of the separation pawl is made to transfer to the fixing roller. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fixing device, an image forming apparatus, and a separation claw cleaning method that prevent adhesion of toner on a separation claw that separates a sheet after a toner image is fixed from a fixing rotating body.

  2. Description of the Related Art A fixing device used in an image forming apparatus such as a copying machine or a printer is known that heat-fixes an unfixed toner image by heating and pressing.

  In this apparatus, a pressure roller is pressed against a heated fixing roller to form a fixing nip portion, and a sheet carrying an unfixed toner image is formed on the fixing nip portion. By inserting the toner image in a direction in contact with the toner, the unfixed toner image is heated and pressurized to be fixed on the surface of the sheet (toner image carrying surface). Since the sheet on which the toner image has been fixed tends to be brought into close contact with the outer peripheral surface of the fixing roller, the fixing claw tip is brought into contact with the outer peripheral surface of the fixing roller on the downstream side of the fixing nip portion. The sheet is inserted between the roller and the leading edge of the sheet, thereby separating the sheet from the outer peripheral surface of the fixing roller.

  In the above-described fixing, a small amount of toner that has not been fixed to the sheet at the time of fixing remains on the outer peripheral surface of the fixing roller, and this toner adheres to the separation claw. Toner adhering to the separation claw (hereinafter referred to as “adhering toner” as appropriate) gradually grows into a toner lump as the number of sheets on which images are formed (fixed number of sheets) increases. This toner lump may be peeled off from the separation claw due to vibration of the separation claw and transferred to the outer peripheral surface of the fixing roller. The transferred toner mass is melted by the fixing roller and contaminates the surface of the subsequent sheet, or once transferred to the pressure roller through the fixing nip portion and then contaminated the back surface of the sheet, An image defect will occur.

  For example, the following patent documents 1, 2, 3, and 4 describe the following contents as techniques for preventing such image defects.

  Patent Document 1: The surface temperature of the pressure roller is set higher than the surface temperature of the fixing roller, and the temperature of the separation claw is made higher than the surface temperature of the fixing roller by heat transmitted from the pressure roller to the separation claw. Then, the toner adhering to the separation claw is transferred to the fixing roller.

  Patent Document 2: The toner attached to the separation claw is melted by a dedicated heater for heating the separation claw so that the toner is returned to the fixing roller before a large amount of toner is accumulated.

  Patent Document 3: The separation claw is configured to take a first state in which its tip abuts on the outer peripheral surface of the fixing roller and a second state in which its antinode contacts with the outer peripheral surface of the fixing roller. Yes.

Patent Document 4: By setting the claw width of the separation claw to 1 mm or less, the toner lump attached to the separation claw is prevented from growing to 1 mm or more.
JP 2003-76204 A JP 2003-156967 A JP 2001-296768 A JP 2004-271760 A

  However, according to the above-mentioned Patent Document 1, the separation claw is heated to a temperature higher than that of the fixing roller by the radiant heat of the heated pressure roller. Therefore, temperature control such as the set temperature and heating timing of the fixing roller and the pressure roller can be performed. There is a problem that it becomes complicated.

  Further, according to Patent Document 2, there is a problem that a dedicated nail heater for heating the separation claw is required, and the configuration is complicated.

  Further, according to Patent Document 3, a separation claw moving mechanism for moving the separation claw is necessary, and there is a problem that the configuration is complicated accordingly.

  Further, according to Patent Document 4, since the separation claw has a claw width of 1 mm or less, sufficient strength cannot be ensured. For example, when a paper jam occurs in the separation claw, if the user forcibly pulls the sheet, the separation claw may be deformed.

  Therefore, the present invention is a simple configuration that does not require a dedicated configuration such as complicated temperature control, a claw heater or a separation claw movement mechanism, and it is possible to ensure sufficient strength of the separation claw, Moreover, it is an object of the present invention to provide a fixing device, an image forming apparatus, and a separation claw cleaning method capable of reliably cleaning the separation claw.

  According to the first aspect of the present invention, a fixing member is pressed against an outer peripheral surface of a fixing rotating body that is heated and rotated forward to form a fixing nip portion, and a sheet carrying an unfixed toner image is formed on the toner image carrying surface. Is inserted into the fixing nip portion so as to be in contact with the outer peripheral surface of the fixing rotator to fix the unfixed toner image on the sheet carrying surface, and the sheet on which the toner image has been fixed is fixed to the fixing rotation member. The present invention relates to a fixing device that separates from the outer peripheral surface of the fixing rotating body by bringing the tip of a separation claw into contact with the outer peripheral surface of the body. The fixing device according to the present invention includes: a driving unit that rotates the fixing rotator forward or backward; and a control unit that controls the driving unit to control the rotation operation of the fixing rotator. The control means has a cleaning mode in which the toner adhered to the separation claw after the sheet is separated from the outer peripheral surface of the fixing rotator is transferred to the outer peripheral surface of the fixing rotator. A first stop for stopping the fixing rotator and a first cleaning rotation for forward rotation or reverse rotation are then performed.

  According to a second aspect of the present invention, in the fixing device according to the first aspect, in the cleaning mode, the control unit stops the fixing rotator following the first stop and the first cleaning rotation. A second stop and then a second cleaning rotation for rotating the fixing rotator in a direction opposite to the first cleaning rotation are performed.

According to a third aspect of the present invention, in the fixing device according to the first or second aspect, an outer peripheral surface of the fixing rotator bites into the pressure member in the fixing nip portion.
It is characterized by that.

  According to a fourth aspect of the present invention, in the fixing device according to any one of the first to third aspects, the leading end of the separation claw is on an outer peripheral surface of the fixing rotator and in a rotation direction of the fixing rotator. It is characterized in that it is in contact with the counter direction.

  According to a fifth aspect of the present invention, in the fixing device according to the fourth aspect of the present invention, the fixing device includes a biasing member that abuts the distal end of the separation claw on the outer peripheral surface of the fixing rotating body in a biased state. Yes.

  According to a sixth aspect of the present invention, in the fixing device according to any one of the first to fifth aspects, the control unit performs the cleaning mode at a predetermined time interval.

  According to a seventh aspect of the present invention, in the fixing device according to any one of the first to fifth aspects, the control unit includes a preceding sheet and a sheet when the plurality of sheets are continuously fixed. The cleaning mode is performed between sheets between the subsequent sheets.

  According to an eighth aspect of the present invention, in the fixing device according to any one of the first to seventh aspects, the fixing rotator is a fixing drum formed in a drum shape.

  According to a ninth aspect of the present invention, in the fixing device according to any one of the first to seventh aspects, the fixing rotator is a fixing belt formed in a belt shape.

  The invention according to claim 10 relates to an image forming apparatus comprising: an image forming unit that forms an unfixed toner image on a toner image carrying surface of a sheet; and a fixing unit that fixes the unfixed toner image on a sheet carrying surface. . The image forming apparatus according to the present invention is characterized in that the fixing device according to any one of claims 1 to 9 is disposed in the fixing unit.

  According to an eleventh aspect of the present invention, a fixing member is pressed against an outer peripheral surface of a fixing rotator that is heated and rotated forward to form a fixing nip portion, and a sheet carrying an unfixed toner image is formed on the toner image carrying surface. Is inserted into the fixing nip portion so as to be in contact with the outer peripheral surface of the fixing rotator to fix the unfixed toner image on the sheet carrying surface, and the sheet on which the toner image has been fixed is fixed to the fixing rotation member. The present invention relates to a separation claw cleaning method in a fixing device that separates from the outer peripheral surface of the fixing rotating body by bringing a separation claw into contact with the outer peripheral surface of the body. The separation claw cleaning method according to the present invention includes a first stopping step of stopping the fixing rotator, and a first rotating step of rotating the fixing rotator forward or backward, following the first stopping step. And a cleaning rotation step.

  According to a twelfth aspect of the present invention, in the separation claw cleaning method according to the eleventh aspect, following the first cleaning rotation step, a second stop step of stopping the fixing rotator, and the second stop The process includes a second cleaning rotation step for rotating the fixing rotator in the direction opposite to the first cleaning rotation step.

  According to the first aspect of the present invention, after the sheet on which the fixing of the toner image has been completed is separated from the outer peripheral surface of the fixing rotating body, the first cleaning is performed by the control means, thereby attaching the sheet to the separation claw. The toner can be transferred to the outer peripheral surface of the fixing rotator.

  That is, when the first cleaning mode is started and the fixing rotator is stopped, the adhered toner adhering to the separation claw is melted by the heat of the fixing rotator, so that the contact area with the outer periphery of the fixing rotator Increases and adheres, and the adhesive strength increases. When the fixing rotator is rotated forward or backward in this state, a part of the adhered toner is transferred to the outer peripheral surface of the fixing rotator so as to be dragged to the outer peripheral surface of the fixing rotator. Here, of the two surfaces intersecting at the leading end of the separation claw, the surface that guides the leading end of the sheet at the time of separation, located on the upstream side along the positive rotation direction of the fixing rotating body, and the positive rotation In the first cleaning mode, when the surface positioned on the downstream side in the direction is the back surface, the toner adhering to the back surface of the separation claw is rotated when the fixing rotation body is rotated and then rotated forward. Can be transferred to the outer peripheral surface of the fixing rotator. On the other hand, when the toner is rotated in the reverse direction, the toner adhered on the guide surface side of the separation claw can be transferred to the outer peripheral surface of the fixing rotator. As described above, by executing the first cleaning mode at an appropriate time interval, which will be described later, the adhered toner can be removed from the separation claw before it grows and becomes a toner lump. An image defect that adheres to the sheet later via the fixing rotator can be prevented in advance. The toner transferred to the outer peripheral surface of the fixing rotator is directly attached to the surface of the succeeding sheet, or is temporarily transferred to the separation member via the fixing nip portion and attached to the back surface of the sheet from the separation member. be able to.

  According to the second aspect of the invention, by executing the second cleaning mode, it is possible to transfer the adhering toner adhering to both the guide surface and the back surface of the separation claw to the outer peripheral surface of the fixing rotator.

  According to the third aspect of the present invention, the tip of the separation claw is rubbed against the outer peripheral surface of the fixing rotator that is harder than the pressure member. The toner remaining on the surface is scraped by the separation claw and easily adheres to the separation claw, but this adhering toner can be reliably removed.

  According to the fourth aspect of the invention, since the separation claw is in contact with the counter rotation direction with respect to the normal rotation direction of the fixing rotator, the sheet after the toner image fixing is reliably separated from the outer peripheral surface of the fixing rotator. be able to.

  According to the invention of claim 5, since the tip of the separation claw is in contact with the outer peripheral surface of the fixing rotator while being urged by the urging member, the followability to the outer peripheral surface of the fixing rotator is high. Therefore, although the sheet can be reliably separated after the toner image is fixed, adhering toner is easily generated. In the invention according to the present claim, even when the toner adhering to the separation claw is likely to be generated as described above, the toner adhering can be surely removed.

  According to the sixth aspect of the present invention, the toner adhering to the separation claw can be transferred to the outer peripheral surface of the fixing rotator at a predetermined time interval. Here, the predetermined time interval can be set to, for example, the time before the toner adhering to the separation claw grows into a toner lump.

  According to the seventh aspect of the present invention, since the cleaning mode is performed between sheets between the preceding sheet and the succeeding sheet when the fixing is continuously performed on a plurality of sheets, for example, during continuous fixing (continuous In the middle of image formation), when toner is supplied to the developing device, the image formation is interrupted, and this can be used to perform the cleaning mode.

  According to the invention of claim 8, the fixing rotator is a drum-like fixing drum, and according to the invention of claim 9, the fixing rotator is a belt-like fixing belt. The present invention can be applied to the body, and the effects as in the first to eighth aspects can be obtained.

  According to the invention of claim 10, in the image forming apparatus, the effect as the fixing device of the above-described claims 1 to 9 can be exhibited as the image forming apparatus.

  According to the eleventh aspect of the present invention, when the fixing rotator is rotated forward after the fixing rotator is stopped by performing the first cleaning rotation step, the toner adhered to the back side of the separation claw is removed. The toner can be transferred to the outer peripheral surface of the fixing rotator, and in the case of reverse rotation, the toner adhered on the guide surface side of the separation claw can be transferred to the outer peripheral surface of the fixing rotator.

  According to the twelfth aspect of the present invention, by performing the second cleaning rotation step, it is possible to transfer the adhered toner on both the guide surface side and the back surface side of the separation claw to the outer peripheral surface of the fixing rotating body.

  Hereinafter, the best embodiment of the present invention will be described in detail with reference to the drawings. In addition, in each drawing, the member etc. which attached | subjected the same code | symbol are the same structures, The duplication description about these shall be abbreviate | omitted suitably. Moreover, in each drawing, members and the like that are not necessary for the description are omitted as appropriate.

<Embodiment 1>
The outline of the fixing device 37 according to the present invention and the image forming apparatus 1 including the same will be described with reference to FIGS. Examples of the image forming apparatus 1 include a copying machine, a printer, a facsimile machine, and a complex machine of these. In this embodiment, an image is formed using toner mainly composed of synthetic resin powder. An example of an electrophotographic four-color full-color printer to be formed will be described. Further, the image forming apparatus 1 shown in FIG. 1 employs a rotary development method and an intermediate transfer method.

  1 to 2 are schematic views of the entire configuration of the image forming apparatus as viewed from the front side. FIG. 2 is an enlarged view of the fixing device 37 viewed from the front side.

  As shown in FIG. 1, the image forming apparatus 1 includes a sheet feeding unit 10 that feeds and transports a sheet (recording medium such as copy paper, envelope, art paper, and transparent film) P, and the sheet feeding. An image forming unit 11 that forms a toner image (image) on the sheet P supplied from the unit 10; a fixing unit 12 that fixes the toner image on the sheet P; and a sheet discharge unit that discharges the sheet P on which the toner image is fixed. 13 is provided.

  In the sheet conveying unit 10, a sheet feeding cassette 14, a feeding roller 15, a feeding guide 16, a registration roller pair 17, and the like are disposed in order from the substantially upstream side along the sheet conveying direction. A plurality of sheets P are stored in the sheet feeding cassette 14 in a stacked state, and are conveyed along the conveyance guide 16 by the feeding roller 15 in order from the uppermost one, and by the registration roller pair 17, After the skew is corrected, the image is supplied to the image forming unit 11.

  The image forming unit 11 is provided with a photosensitive drum (drum-type electrophotographic photosensitive member) 20 that rotates in the direction of arrow R20, and is charged around the photosensitive drum 20 approximately in order along the rotational direction of the photosensitive drum 20. A roller 21, an exposure device 22, a developing device 23, a primary transfer roller 24, a drum cleaner 25, and the like are provided. In addition, an intermediate transfer belt 28 is provided around the primary transfer roller 24, the drive roller 26, and the tension roller 27 described above, and a secondary transfer roller 30 is provided so as to face the drive roller 26. ing. The developing device 23 described above develops with a rotatable rotary 31 and four-color developing devices mounted thereon, that is, yellow (Y), magenta (M), cyan (C), and black (K) toners. Developing units 32Y, 32M, 32C, and 32K are provided. Further, a portion of the intermediate transfer belt 28 positioned between the two primary transfer rollers 24 is in contact with the surface of the photosensitive drum 20 to form a primary transfer nip portion T1. Further, a secondary transfer nip portion T <b> 2 is formed between the intermediate transfer belt 28 and the secondary transfer roller 30. A belt cleaner 33 is disposed at a position corresponding to the drive roller 26.

  In the image forming unit 11, the photosensitive drum 20 is rotationally driven in the direction of the arrow 20 at a predetermined process speed (circumferential speed), and the surface (outer peripheral surface) is charged to a predetermined polarity and potential by the charging roller 21. The surface of the photosensitive drum 20 after charging is subjected to exposure L based on image information by the exposure device 22, and the charge of the exposed portion is removed to form an electrostatic latent image. This electrostatic latent image is developed by the developing device 23. In the developing device 23, a developing device 32Y for the first color (for example, yellow) that is used for development by the rotation of the rotary 31 is disposed at the developing position D facing the photosensitive drum 20, and attaches toner to the electrostatic latent image. To develop a yellow toner image. This toner image is primarily transferred by the primary transfer roller 24 onto the intermediate transfer belt 28 rotating in the direction of arrow R28 in the primary transfer portion T1. After the toner image has been transferred, the toner (primary transfer residual toner) remaining on the surface of the photosensitive drum 20 that has not been transferred to the intermediate transfer belt 28 is removed by the drum cleaner 25 to prepare for the next second color image formation. The series of image forming processes including the above-described charging, exposure, development, primary transfer, and cleaning is performed for the remaining three colors, that is, the second color (for example, magenta M), the third color (for example, cyan C), and the fourth color. (For example, black K) is repeated, so that toner images of four colors are superimposed on the intermediate transfer belt 28. These four color toner images are secondarily transferred collectively to the sheet P supplied from the sheet feeding unit 10 by the secondary transfer roller 30. The intermediate transfer belt 28 after the secondary transfer of the toner image is subjected to the next primary transfer after the toner remaining on the surface (secondary transfer residual toner) is removed by the belt cleaner 33.

  The fixing unit 12 includes a fixing device 37 having a fixing roller (fixing rotator) 35 heated by a heater 34 and a pressure roller (pressure member) 36 in pressure contact therewith. A fixing nip portion N is formed between the fixing roller 35 and the pressure roller 36. In the image forming unit 11 described above, the sheet P on which the toner image is transferred is heated and pressurized when passing through the fixing nip N, and the four color toner images are melted on the surface (toner image carrying surface). It is fixed. The fixing device 37 will be described in detail later.

  The sheet discharge unit 13 is provided with a pair of conveyance rollers 40 and 41, a pair of discharge rollers 42, a discharge tray 43, and the like. The sheet P on which the toner image is fixed is conveyed by a pair of conveying rollers 40 and 41, and is further discharged onto a sheet discharge tray 43 by a pair of discharge rollers 42. Thereby, the four-color full-color image formation on the surface of one sheet P is completed.

  FIG. 2 shows an enlarged view of the fixing device 37 viewed from the front side. The fixing device 37 includes a fixing roller 35 and a pressure roller 36. The fixing roller 35 is formed in a cylindrical shape, and is supported by a frame 45 of the image forming apparatus main body 44 so as to be rotatable about an axial center facing the front-rear direction. The fixing roller 35 is rotationally driven by a fixing motor (driving means) 46 in the forward rotation direction (the direction of the arrow R35: the rotation direction at the time of fixing the toner image) and the reverse rotation direction opposite thereto. The operation of the fixing motor 46, that is, the rotation direction, and the timing for starting and stopping the rotation are controlled by the control means 47. The pressure roller 36 is formed in a cylindrical shape, is disposed in parallel with the fixing roller 35, and is rotatably supported by the image forming apparatus main body 44. The pressure roller 36 is in contact with the fixing roller 35 from below, and a belt-like fixing nip portion N that is long in the front-rear direction is formed between the two rollers. In the present embodiment, since the outer peripheral surface (surface) 50 of the fixing roller 35 is formed to be harder than the outer peripheral surface (surface) 51 of the pressure roller 36, the fixing nip portion N is the outer peripheral surface of the fixing roller 35. 50 is formed so as to bite into the outer peripheral surface 51 side of the pressure roller 36. The pressure roller 36 is driven to rotate in the direction of arrow R36 (forward rotation direction) with the forward rotation of the fixing roller 35, and is driven to rotate in the direction opposite to the arrow R36 direction (reverse rotation direction) with the reverse rotation. It is supposed to be.

  The separation claw 52 and the separation mechanism 55 will be described with reference to FIGS. Among these, FIG. 3 is an enlarged view of the separation mechanism 55 as seen from the front side. FIG. 4 is an exploded perspective view of the separation mechanism 55 as viewed from the front side. FIG. 5 is an exploded perspective view of the separation mechanism 55 as viewed from the direction of arrow A (left side) in FIG. However, the separation claw unit 57 shows a state in which each member is disassembled in the front-rear direction. 6A, 6 </ b> B, and 6 </ b> C are views in which the housing 58, the disassembled state of the separation claw unit 57, and the support member 60 are viewed from above. FIG. 7 is a view of the state in which the separation claw unit 57 and the support member 60 are combined as seen from above.

  As shown in FIG. 2, the fixing device 37 has a separation claw 52 disposed immediately downstream of the fixing nip portion N along the sheet conveyance direction (arrow Kp direction). In this embodiment, as shown in FIG. 3, the separation claw 52 has the tip 54 with the X axis (the horizontal axis in FIGS. 2 and 3) and the Y axis (FIG. 2) with respect to the swing fulcrum 53. , A vertical axis in FIG. 3) and a Z axis (axis in the front and back direction in FIG. 2 and FIG. 3), and the entire tip 54 is the outer periphery of the fixing roller 35. It comes into contact with the surface 50 uniformly without any contact. For this reason, the effect of this invention appears especially notably. Hereinafter, these points will be described.

  First, the entire separation mechanism 55 having the separation claw 52 as a main component will be outlined.

  As shown in FIGS. 4 and 5, in this embodiment, the separation claw 52 is integrally incorporated in the holder member 56 to constitute a separation claw unit 57. Further, the separation claw unit 57 constitutes a separation mechanism 55 together with components such as the housing 58, the support member 60, and the compression coil spring (biasing member) 61. FIG. 4 is an exploded view of the separation mechanism 55 shown in FIG. That is, the entire separation mechanism 55 can be configured by combining the components shown in FIG. 3 in the substantially vertical direction as follows. The separation claw 52 is held by the holder member 56 to constitute the separation claw unit 57, the swinging fulcrum portion 53 of the separation claw unit 57 is engaged with the fulcrum receiving portion 62 of the housing 58 from below, and the support member 60 is further provided. Is engaged with the housing 58 from below. In addition, the supporting member 60 in the engaged state is indicated by a two-dot chain line in FIG. In this state, the support member 60 is fixedly engaged with the housing 58, whereas the separation claw unit 57 is rotatable with respect to the three axes described above with the swing fulcrum 53 as a reference. It becomes. In this state, the compression coil spring 61 is interposed between the upward boss 63 of the support member 60 and the downward boss 64 of the separation claw unit 57. As a result, the separation claw unit 57 is biased upward, the swinging fulcrum portion 53 of the separation claw 52 is pressed against the fulcrum receiving portion 62, and the tip 54 of the separation claw 52 is against the outer peripheral surface 50 of the fixing roller 35. It comes to contact.

  Next, each component constituting the separation mechanism 55 will be described. The separation mechanism 55 includes a housing 58, a separation claw unit 57 including a separation claw 52 and a holder member 56, and a support member 60.

  As shown in FIG. 5 and FIG. 6A, the lower surface side (back surface side) of the housing 58 is a stepped portion, and the stepwise front-rear direction (left-right direction in FIG. 5) and left-right direction (FIG. 6, a fulcrum receiving portion 62 formed of a quadrangular pyramid-shaped concave portion with which the swing fulcrum portion 53 of the separation claw 52 is engaged is formed. In addition, a pair of positioning recesses 66 into which the pair of positioning projections 65 of the support member 60 are fitted are formed on the front side and the rear side of the fulcrum receiving unit 62. Further, on the outer side in the front-rear direction of the positioning recess 66, a pair of hook portions 67 of the support member 60 are inserted from below, and hook engagement holes 68 that engage with the upper ends are vertically penetrated.

  The separation claw 52 is formed in a substantially “L” shape in a front view shown in FIGS. 3 and 4. The separation claw 52 has a substantially spherical rocking fulcrum 53 at the upper end, and the rocking fulcrum 53 is engaged with the fulcrum receiving part 62 of the housing 58 described above. Further, the lower end side of the separation claw 52 is formed in a wedge shape extending toward the fixing roller 35, and the front end 54 is in contact with the outer peripheral surface 50 of the fixing roller 35. As shown in FIG. 6B, the separation claw 52 is formed so that the width W in the front-rear direction near the tip 54 is wide. Here, the two surfaces forming the wedge shape in the separation claw 52 are positioned upstream of the fixing roller 35 along the normal rotation direction with respect to the front end 54 in FIG. If the surface that guides the tip is the guide surface 70 and the surface that is located downstream in the forward rotation direction is the back surface 71, the above-described tip 54 is a linear shape where the guide surface 70 and the back surface 71 intersect. It can be said that it is a part. As shown in FIG. 5 and FIG. 6, the separation claw 52 has a stepped portion 72 protruding outward on the front surface and the rear surface, respectively, and is a thick plate-like shape formed on the outer portion of the stepped portion 72. The press-fitting portion 73 is held (fixed) to the holder member 56 by being press-fitted into a press-fitting hole 76 of a front plate 74 and a rear plate 75 of the holder member 56 described later.

  The holder member 56 has a front plate 74 and a rear plate 75 facing the front side and the rear side across the separation claw 52 described above, and is a cylindrical holder that protrudes rearward from the inner surface of the front side plate 74. The small diameter insertion portion 78 at the tip of the width restricting portion 77 is combined by being fitted into the insertion hole 80 of the rear plate. The front side plate 74 and the rear side plate 75 are provided with press-fitting holes 76, and the press-fitting portion 73 of the separation claw 52 is press-fitted. On the inner surfaces of the front side plate 74 and the rear side plate 75 on the right end side, support shafts 81 project inwardly, and these support shafts 81 rotatably support a small diameter roller member 82. ing. As shown in FIG. 4, the roller members 82 have their lower ends protruding slightly downward from the lower ends of the front side plate 74 and the rear side plate 75, and are separated from the outer peripheral surface 50 of the fixing roller 35. The sheet P is conveyed smoothly. In addition, spring seats 83 project outward from the upper portions of the front side plate 74 and the rear side plate 75 on the right end side. On the lower surface of the spring seat portion 83, a boss 64 is engaged with which the upper end of the compression coil spring 61 is engaged. The separation claw 52 described above is held by the holder member 56 to constitute a separation claw unit 57 as a whole, and the separation claw unit 57 is a compression interposed between a support member 60 described below. The coil spring 61 is biased upward.

  As shown in FIG. 6C, the support member is formed in a “U” shape in a top view, and the above-described separation claw unit 57 is arranged inside this. As shown in FIGS. 4 and 5, the support member 60 has a pair of positioning projections 65 projecting upward on the front end side and the rear end side, and a pair of hook portions 67. Yes. The support member 60 is positioned in the front-rear and left-right directions by engaging the positioning protrusions 65 with the positioning recesses 66 of the housing 58 described above. Further, the hook portions 67 are engaged with the housing 58 to be positioned in the vertical direction and fixedly assembled to the housing 58. A pair of spring seats 84 are formed on the right end side of the lower part of the front end side and the rear end side of the support member 60, and a pair of bosses 63 project upward from these spring seat portions 84. It is installed. In this case, the lower end of the compression coil spring 61 described later is engaged. As shown in FIG. 7, an appropriate gap G is formed between the front and rear spring seats 84 of the support member 60 and the front plate 74 and the rear plate 75 of the separation claw unit 57. . The separation claw unit 57 is allowed to move in the front-rear direction within the gap G. That is, the support member 61 restricts the moving range so that the separation claw unit 57 does not move too much in the front-rear direction.

  A pair of compression coil springs 61 are used. As shown in FIGS. 4 and 5, the lower ends of the compression coil springs 61 are engaged with the pair of bosses 63 of the support member 61, and the upper ends of the compression coil springs 61 are separated by the separation claw unit 57. The pair of bosses 64 are engaged. As shown in FIG. 3, the compression coil spring 61 urges the separation claw unit 57 so as to cross the line connecting the oscillating fulcrum 53 and the tip 54 of the separation claw 52 from below to above. The fulcrum 53 is pressed against the fulcrum receiving part 62 of the housing 58, and the tip 54 of the separation claw 52 is urged counterclockwise in the figure with respect to the swinging fulcrum 53 (based on the Z axis). Thus, the fixing roller 35 is brought into contact with the outer peripheral surface 50. Further, as shown in FIG. 7, the pair of compression coil springs 61 urge the separation claw unit 57 outside the width W of the tip 54 of the separation claw 52, so The tip 54 of the separation claw 52 can be brought into contact with the outer peripheral surface 50 of the fixing roller 35 in a stable state with respect to the axis and the Y axis. As a result, the sheet that is in close contact with the outer peripheral surface 50 of the fixing roller 35 at the time of fixing the toner image can be inserted between the leading end and the outer peripheral surface 50 of the fixing roller 35 and reliably separated from the outer peripheral surface 50. it can.

  In this embodiment, since the separation mechanism 55 having the above-described configuration is employed, the tip 54 of the separation claw 52 is in contact with the outer peripheral surface 50 of the fixing roller 35 on the average over the entire width. For this reason, the separation claw 52 reliably scrapes off the toner remaining on the outer peripheral surface 50 of the fixing roller 35 without being fixed to the sheet P at the time of fixing the toner image. Cheap. The present invention is particularly effective for such a separation mechanism 55.

  In the present invention, the cleaning mode is executed by the control unit 47 after the sheet P on which the toner image has been fixed is separated from the outer peripheral surface 50 of the fixing roller 35. In this embodiment, the cleaning mode is performed in a state where the temperature of the fixing roller 35 is controlled to be maintained at the same fixing temperature as that at the time of fixing the toner image. In the cleaning mode, the rotation of the fixing roller is temporarily stopped, and then the toner is adhered to the separation claw on the outer peripheral surface of the fixing roller by rotating forward or backward.

  First, with reference to FIGS. 8A, 8 </ b> B, and 8 </ b> C, a mechanism for transferring the toner adhering to the separation claw 52 to the outer peripheral surface 50 of the fixing roller 35 will be described. As shown in FIG. 5A, it is assumed that the adhered toner t has already accumulated in the separation claw 52. Among the adhering toners, toner adhering to the vicinity of the tip 54 of the guide surface 70 of the separation claw 52 is appropriately distinguished as adhering toner t0 and toner adhering to the back surface 71 side as adhering toner t1. Further, it is assumed that the adhesion amount of the adhesion toners t0 and t1 does not reach the toner mass.

  The fixing roller 35 from which the sheet P after the toner image is fixed is maintained at the fixing temperature at the time of fixing. Here, the fixing temperature is a temperature that is equal to or higher than the glass transition temperature of the toner and can melt the toner. When the rotation of the fixing roller 35 is stopped in a state where the fixing temperature is maintained, a portion of the adhered toner that is in contact with the outer peripheral surface 50 of the fixing roller 35 and a portion in the vicinity thereof are melted by the heat of the fixing roller 35. Then, the contact force is increased by being brought into close contact with the outer peripheral surface 50. In particular, in the example shown in the figure, since the back surface 71 of the separation claw 52 is inclined downward toward the tip 54, the melted toner adheres to the outer peripheral surface 50 of the fixing roller 35 and the separation claw 52 by gravity. It tends to flow toward the tip 54 between the back surface 71. For this reason, the melted adhering toner tends to adhere to the outer peripheral surface 50. Even when the back surface 71 is horizontal or conversely the tip 54 side is inclined slightly upward, there is a phenomenon that the adhered toner melted is in close contact with the outer peripheral surface 50, although there is a difference in degree. In this state, as shown in (b), when the fixing roller 35 is rotated in the reverse direction (counterclockwise), the toner adhering t0 on the guide surface 70 side of the separation claw 52 is dragged by the outer peripheral surface 50. Transition to the side. The transferred toner t0 moves in the same direction as the fixing roller 35 rotates in the reverse direction, and is transferred to the outer peripheral surface 51 of the pressure roller 36 at the fixing nip N (see FIG. 2). On the other hand, after the fixing roller 35 is stopped and the adhered toner is melted, when the fixing roller 35 is rotated forward (in the direction of arrow R35: clockwise) as shown in FIG. The adhered toner t1 is transferred to the outer peripheral surface 50 side so as to be dragged to the outer peripheral surface 50. The transferred adhered toner t1 moves in the same direction as the fixing row 35 rotates forward, and is transferred to the outer peripheral surface 51 of the pressure roller 36 at the fixing nip N. As described above, when the fixing roller 35 is once stopped and then reversely rotated, the adhered toner t0 on the guide surface 70 side of the separation claw 52 can be removed. Can remove the adhering toner t1 on the back surface 71 side of the separation claw 52. Further, after the reverse rotation or the normal rotation, the rotation is stopped again. After that, when the rotation is the normal rotation or the reverse rotation opposite to the rotation direction before the stop, any of the guide surface 70 and the rear surface 71 of the separation claw 52 is detected. The adhered toners t0 and t1 can also be removed. Even when all of the adhered toner cannot be removed by reverse rotation or forward rotation after the fixing roller 35 is stopped, at least a part of the adhered toner can be removed. Further, the toner can be prevented from growing and becoming a toner lump.

  With reference to FIG. 9, a timing chart of the cleaning mode performed by the control means 47 is shown. In the figure, when the cleaning mode is executed after the sheet P on which the toner image has been fixed is separated from the fixing roller 35, that is, after the fixing roller 35 is temporarily stopped and reversely rotated after a predetermined time, it is again A cleaning mode (second cleaning mode) that stops and rotates forward after a predetermined time will be described. Also, in the same figure, in the cleaning mode, when the image forming operation needs to be interrupted once during the continuous image formation, for example, in the image forming apparatus 1 shown in FIG. An explanation will be given of a case where it becomes necessary to replenish yellow toner to the developing device 32Y when the amount becomes a predetermined amount or less.

  (A) in FIG. 9 is an image writing signal, that is, a signal for setting the timing of the exposure start by the exposure apparatus 22 shown in FIG. When writing an image, that is, when the exposure device 22 exposes the surface of the photosensitive drum 20 that has been uniformly charged by the charging roller 21, the exposure is started with the timing of this signal being turned ON. This image writing signal is a signal serving as a reference for the subsequent development process and transfer process in the image forming unit 11, the supply timing of the sheet P to the image forming unit 11 by the registration roller pair 17 of the sheet feeding unit 10, and the like. Note that the image writing signal is turned on at a predetermined time interval, and even if this signal is turned on, if the exposure device 22 is not turned on, the image writing is not performed. (B) shows ON / OFF of a sheet discharge switch (discharge SW: not shown). The sheet discharge switch is, for example, a switch that is disposed immediately downstream of the discharge roller pair 43 in FIG. 1 and detects that the discharge of the sheet P has been completed. This sheet discharge switch is once turned ON during the discharge operation of the sheet P after the toner image is fixed, and then turned OFF when the discharge operation is completed. The rotary motor (not shown) of (c) is a motor that rotates the rotary 31 of the developing device 23 in FIG. By turning on this rotary motor, the color developing device used for developing the electrostatic latent image on the photosensitive drum 20 is disposed at the developing position D facing the surface of the photosensitive drum 20, When the toner is insufficient and needs to be replenished, the developing unit is moved to a toner replenishment position (not shown). A main motor (not shown) of (d) is a motor that operates each process device in the image forming unit 11. For example, it is a motor that rotates the photosensitive drum 20 at a predetermined process speed (circumferential speed). A feed motor (not shown) of (e) is a motor that rotates each roller of the sheet feeding unit 10 in FIG. However, even if the feed motor is ON, the sheet P is not fed unless a paper feed signal is input to the feed roller 15. The fixing motor (f) is a motor that rotates the fixing roller. In the present embodiment, the fixing motor 46 (see FIG. 2) can rotate forward and backward, and the rotation direction and the timing of the rotation start and rotation stop are controlled by the control means 47.

  During a continuous image forming operation in which images are continuously formed on a plurality of sheets P, for example, a toner remaining amount detection sensor (not shown) arranged in the yellow developing device 32Y detects an insufficient amount of toner. In this case, the operation of the feeding roller 15 shown in FIG. Then, after it is confirmed that the sheet P currently being formed is discharged by the sheet discharge switch, a toner supply process is started (time S0). After the start of the toner supply process, after the first image writing signal G1 is received, the rotary motor is turned on, the rotary 31 is rotated (H1), and the yellow developing device 32Y is disposed at the toner supply position (not shown). Turn off the rotary motor. To the developing device 32Y disposed at the toner replenishing position, toner is replenished from a toner container (not shown) in which yellow replenishing toner is stored. When the toner supply is completed, the rotary motor is turned on (H2), and the rotary 31 is rotated to move to the home position. This completes the yellow toner replenishment step (time S5). Note that, during the toner replenishment process, the sheet P is not fed and conveyed and discharged, so the sheet discharge switch maintains the OFF state. Further, the main motor maintains the ON state and maintains the rotating state of the photosensitive drum 20. Further, the feed motor also keeps rotating, and waits so that the feeding of the sheet P can be started immediately when the sheet feeding signal is inputted.

  In the present embodiment, the cleaning mode starts (time S0) and ends (time S4) between the start and end of the toner replenishing step (between times S0 and S5), and the separation claw. The toner adhering to 52 is transferred to the outer peripheral surface 50 of the fixing roller 35.

  At the same time as entering the toner replenishing step, the cleaning mode is started. First, the fixing motor is turned off, and the fixing roller 35 that has been rotating forward until then is stopped (time S0: start of the first stopping step P1). In the cleaning mode, the operation is temporarily interrupted during the continuous image formation. Therefore, the fixing roller 35 is also used during the cleaning mode so that the fixing can be performed immediately when the continuous image formation is resumed. The temperature is maintained at a fixing temperature similar to that at the time of fixing. In the present embodiment, the fixing roller 35 is stopped for 10 seconds in the first stop process P1. As a result, as shown in FIG. 8A, the adhering toner adhering to the separation claw 52 is melted by the heat of the fixing roller 35 and brought into close contact with the outer peripheral surface 50 of the fixing roller 35 to increase the adhesive force. . After the first stop process P1 is continued for 10 seconds, the fixing motor is reversely rotated to rotate the fixing roller in reverse (time S1: start of the first cleaning rotation process P2). As a result, as shown in FIG. 8B, the adhered toner t <b> 0 on the guide surface 70 side of the separation claw 52 is transferred from the separation claw 52 to the outer peripheral surface 50 of the fixing roller 35. The transferred adhered toner t0 rotates with the reverse rotation of the fixing roller 35 and is transferred to the outer peripheral surface 51 of the pressure roller 36 at the fixing nip portion N. The attached toner t0 transferred to the outer peripheral surface 51 of the pressure roller 36 is attached to the back surface of the subsequent sheet P and removed when the continuous image formation is resumed. At this time, if the amount of toner adhering to the sheet is small, it will not stand out visually and will not greatly reduce the image quality. In order to remove the sheet adhering to the outer peripheral surface 51 of the pressure roller 36, a sheet on which image formation is not formed, that is, a cleaning-dedicated sheet may be passed through the fixing nip portion N.

  In the present embodiment, the reverse rotation of the fixing roller 35 (first cleaning rotation process P2) is 2 seconds. The two seconds are, for example, a time that the fixing roller 35 rotates three times. The fixing roller 35 is reversely rotated for 2 seconds and then stopped again (time S2: start of the second stopping step P3). By this second stopping step P3, the adhered toner t1 adhering to the back surface 71 side of the separation claw 52 is melted by the heat of the fixing roller 35 and is brought into close contact with the outer peripheral surface 50 of the fixing roller 35, thereby increasing the adhesive force. To do. After the second stop step P3 is continued for 10 seconds, the fixing motor is rotated forward to rotate the fixing roller 35 forward (time S3: start of the second cleaning rotation step P4). As a result, as shown in FIG. 8C, the adhered toner t <b> 1 on the back surface 71 side of the separation claw 52 is transferred from the separation claw 52 to the outer peripheral surface 50 of the fixing roller 35. The transferred adhering toner t1 rotates with the forward rotation of the fixing roller 35 and is transferred to the outer peripheral surface 50 of the pressure roller 35 at the fixing nip portion N. The adhered toner t1 is also adhered to the back surface of the succeeding sheet P and removed when the continuous image formation is resumed. At this time, if the amount of toner adhering to the sheet is small, it will not stand out visually and will not greatly reduce the image quality. When the second cleaning rotation process P4 is completed (time S4), the fixing motor is turned off to stop the fixing roller 35 and wait for the above-described toner supply process to be completed. When the toner supply process ends (time S5), the job is resumed. The rotary motor is turned on, the rotary 31 is rotated (H3), and the yellow developing device 32Y, which is the first color at the time of forming the four-color full-color image, is arranged at the development position D. At the same time, the fixing motor is turned on and the fixing roller 35 is rotated forward to prepare for fixing of the toner image.

  According to this embodiment, the control unit 47 controls the rotation of the fixing roller 35 to execute the cleaning mode, that is, the first stop process P1 for stopping the fixing roller 35, and the first rotating the fixing roller reversely. A simple process (control) is continuously performed, that is, a cleaning rotation process P2 of 1, a second stop process P3 of stopping the fixing roller 35 again, and a second cleaning rotation process P4 of rotating the fixing roller 35 forward. Thus, at least a part of the toner adhered to the guide surface 70 and the back surface 71 of the separation claw 52 can be transferred to the outer peripheral surface 50 of the fixing roller 35 and removed. By executing this cleaning mode before the toner adhering to the separation claw 52 grows into a toner mass, it is possible to prevent an image defect in which the toner mass contaminates the sheet P.

  In this embodiment, the cleaning mode is performed during the interruption period when the continuous image forming operation needs to be interrupted once during the continuous image formation. There is no need to secure. In the example shown in FIG. 9, if the cleaning mode requires more time than the toner replenishment step, the job may be restarted after the cleaning mode is completed. Even in this case, only the time required for executing the cleaning mode is equal to the time required for the cleaning mode minus the time required for the toner replenishment process.

  As described above, “when continuous image formation needs to be interrupted once during continuous image formation” includes, for example, calibration, belt refresh, drum refresh, charging feedback, belt cleaning brush refresh, and the like. Is mentioned. Here, calibration refers to the color tone of a color image due to a change in toner density accompanying the consumption of toner and a temperature rise in image formation when a two-component developer containing toner and carrier as main components is used. In order to suppress this change, an image for density adjustment is formed on the intermediate transfer belt 28 at regular time intervals. The belt refresh refers to cleaning the intermediate transfer belt 28 by the belt cleaner 33 at regular intervals in order to prevent contamination of the surface of the intermediate transfer belt 28 due to the external additive of the toner. The drum refresh is performed by polishing the surface of the photosensitive drum 20 or coating the toner at regular intervals in order to suppress image unevenness due to image flow in a high humidity environment or a change in surface sensitivity of the photosensitive drum 20. The cleaning operation is performed. Further, the charging feedback is a result of measuring a current flowing from the charging roller 21 to the photosensitive drum 20 at regular intervals in order to prevent a change in the charging area accompanying a change in temperature and humidity in the image forming apparatus main body. Is fed back to the charging voltage. Further, the belt cleaning brush refresh refers to scraping the brush surface with a blade at regular intervals in order to remove surface foreign matter from a brush (not shown) that cleans the intermediate transfer belt 28.

  By executing the cleaning mode in parallel with the above-described operation, it is not necessary to secure a separate time for executing the cleaning mode.

  In addition to the above, the timing of executing the cleaning mode includes, for example, every predetermined time interval, every predetermined number of sheets for image formation, etc. In this case, the time for executing the cleaning mode is set as the timing. It is necessary to secure them individually.

  In the above-described cleaning mode, the case where the fixing roller 35 is reversely rotated in the first cleaning rotation step P2 and the fixing roller 35 is normally rotated in the second cleaning rotation step P4 has been described. The fixing roller 35 may be rotated forward in the first cleaning rotation step P2, and the fixing roller 35 may be rotated reversely in the second cleaning rotation step P4.

  In the above example, the case where the cleaning mode includes the first stop process P1, the first cleaning rotation process P2, the second stop process P3, and the second cleaning rotation process P4 has been described as an example. For example, a cleaning mode (first cleaning mode) including the first stopping process P1 and the first cleaning rotation process P2 described above may be executed. In the first cleaning mode, one of the adhering toners adhering to the guide surface 70 and the back surface 71 of the separation claw 52 can be transferred to the outer peripheral surface 50 of the fixing roller 35. For example, if the fixing roller 35 is reversely rotated in the first cleaning rotation step P2, the adhered toner t0 on the guide surface 70 side of the separation claw 52 can be transferred. The adhered toner t1 on the back surface 71 side can be removed.

  In the above description, the first stop process P1 and the second stop process P3 are each set to 10 seconds, and the first cleaning rotation process P2 and the second cleaning rotation process P4 are each set to 2 seconds. These are merely examples, and for example, an experiment using an actual machine may be performed to set values suitable for the actual machine.

  In the above description, the front end 54 of the separation claw 52 can rotate about the X, Y, and Z axes around the swing fulcrum 53 so that the front end 54 is good on the outer peripheral surface 50 of the fixing roller 35. Although an example of following the above has been described, the present invention is not limited to this. For example, as shown in FIG. 10, the separation claw 52 is supported so as to be swingable with respect to a shaft 85 oriented in the front-rear direction, and the hook 85 provided at the upper end of the separation claw 52 is engaged with the image forming apparatus main body side. A tension spring 87 is interposed between the portion 86. A configuration in which the separation claw 52 is urged counterclockwise by the tension spring 87 and the tip 54 is brought into contact with the outer peripheral surface 50 of the fixing roller 35 may be employed. The present invention can achieve the same effect as described above for such a separation claw 52 as well.

  In the above example, the fixing rotator and the pressure member are both the drum-shaped fixing roller 35 and the pressure roller 36. However, of the fixing rotator and the pressure member, In principle, the present invention can be applied to the case where one is belt-shaped and the other is drum-shaped, or both are belt-shaped. Further, the pressure member may be in a block shape. However, in this case, the portion including the fixing nip portion N where the sheet P is rubbed needs to be configured so that the frictional force with the sheet P is low.

  In the above description, the case where the present invention is applied to the four-color full-color image forming apparatus 1 of the electrophotographic method, the rotary developing method, and the intermediate transfer method is described as an example. Any image forming apparatus that forms a toner image and fixes the toner image by heating and pressurizing with a fixing device can be applied to an image forming apparatus having an arbitrary configuration. For example, a so-called tandem is provided that includes four-color image forming stations each having a photosensitive drum, and sequentially transfers four-color toner images directly to a sheet carried on a transport belt by these image forming stations. The present invention can be applied to a four-color full-color image forming apparatus, a monochrome image forming apparatus, and an electrostatic recording image forming apparatus.

  Although the present invention has been described by taking as an example the case where the toner adhering to the separation claw is transferred to the fixing rotator and removed before growing into a toner lump, the present invention is, for example, a rotation corresponding to the fixing rotator. Body and a member corresponding to the separation claw disposed in contact with the rotating body, and a substance that can be melted by heat that adheres to the separation claw equivalent member is transferred from the separation claw equivalent member to the fixing rotation body equivalent member. It can be applied to general cases.

FIG. 2 is a diagram schematically showing a schematic configuration of the image forming apparatus according to the present invention provided with the fixing device according to the present invention as viewed from the front side. FIG. 3 is an enlarged view of the vicinity of the fixing device as viewed from the front side. It is an enlarged view of the separation mechanism seen from the front side. It is the disassembled perspective view which looked at the separation mechanism from the front side. It is the disassembled perspective view which looked at the isolation | separation mechanism from the arrow A direction (left side) in FIG. (A), (b), (c) is the figure which looked at the decomposition | disassembly state of the housing and the separation nail | claw unit, and the supporting member from the upper direction in this order. It is the figure which looked at the state which combined the separation claw unit and the support member from the upper part. (A), (b), (c) is a figure explaining the principle which transfers the adhesion toner adhering to a separation nail to the outer peripheral surface of a fixing roller. It is a timing chart explaining the 2nd cleaning mode. It is a front view explaining other composition of a separation claw.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Sheet feeding part, 11 ... Image forming part, 12 ... Fixing part, 35 ... Fixing roller (fixing rotating body), 36 ... Pressure roller (pressing member), 37 ... Fixing device, 46... Fixing motor (drive means) 47... Control means 50... Outer peripheral surface 52. Separation claw 54 54 Tip 61 61 Compression coil spring (biasing member) N. , P ... sheet, P1 ... first stop step, P2 ... first cleaning rotation step, P3 ... second stop step, P4 ... second cleaning rotation step, R35 ... when fixing Direction of rotation of the fixing roller (fixing rotator), t0, t1,.

Claims (12)

A fixing member is pressed against the outer peripheral surface of the fixing rotator that is heated and rotated forward to form a fixing nip portion, and the toner image carrying surface is the outer peripheral surface of the fixing rotator. The unfixed toner image is fixed on the sheet carrying surface by being inserted into the fixing nip portion so as to come into contact with the sheet, and the sheet after the toner image is fixed is separated on the outer peripheral surface of the fixing rotating member In the fixing device that separates from the outer peripheral surface of the fixing rotator by contacting the tip,
Drive means for rotating the fixing rotator forward or backward;
Control means for controlling the driving means to control the rotation operation of the fixing rotator,
The control means has a cleaning mode in which the toner adhered to the separation claw after the sheet is separated from the outer peripheral surface of the fixing rotator is transferred to the outer peripheral surface of the fixing rotator, and the cleaning mode A first stop for stopping the fixing rotator, and then a first cleaning rotation for the forward rotation or the reverse rotation.
A fixing device. In the cleaning mode, the control means is opposite to the first stop, the second stop for stopping the fixing rotator following the first cleaning rotation, and then the first cleaning rotation. Performing a second cleaning rotation to rotate the fixing rotator in a direction;
The fixing device according to claim 1. In the fixing nip portion, the outer peripheral surface of the fixing rotator bites into the pressure member.
The fixing device according to claim 1, wherein The tip of the separation claw is in contact with the outer peripheral surface of the fixing rotator in the counter direction with respect to the rotation direction of the fixing rotator.
The fixing device according to any one of claims 1 to 3, wherein An urging member that abuts the tip of the separation claw on the outer peripheral surface of the fixing rotating body in an urging state;
The fixing device according to claim 4. The control means performs the cleaning mode at predetermined time intervals.
The fixing device according to claim 1, wherein The control means performs the cleaning mode between a sheet between a preceding sheet and a sheet following the sheet when fixing is continuously performed on a plurality of sheets.
The fixing device according to claim 1, wherein The fixing rotator is a fixing drum formed in a drum shape.
The fixing device according to claim 1, wherein The fixing rotator is a fixing belt formed in a belt shape.
The fixing device according to claim 1, wherein An image forming apparatus comprising: an image forming unit that forms an unfixed toner image on a toner image carrying surface of a sheet; and a fixing unit that fixes the unfixed toner image on a sheet carrying surface.
The fixing device according to claim 1 is disposed in the fixing unit.
An image forming apparatus. A fixing member is pressed against the outer peripheral surface of the fixing rotator that is heated and rotated forward to form a fixing nip portion, and the toner image carrying surface is the outer peripheral surface of the fixing rotator. The unfixed toner image is fixed on the sheet carrying surface by being inserted into the fixing nip portion so as to come into contact with the sheet. In the fixing claw cleaning method in the fixing device that separates from the outer peripheral surface of the fixing rotator by contacting,
A first stop step of stopping the fixing rotator;
Following the first stopping step, a first cleaning rotation step of rotating the fixing rotator forward or backward.
A separation nail cleaning method characterized by the above. Following the first cleaning rotation step, a second stop step of stopping the fixing rotator;
Following the second stopping step, a second cleaning rotation step of rotating the fixing rotation body in a direction opposite to the first cleaning rotation step.
The method for cleaning a separation nail according to claim 11.

Images