JP2019008032A - Cleaning device, fixing device, and image forming apparatus - Google Patents

Abstract

To provide a cleaning device that can prevent the occurrence of slack of a belt-like cleaning body, such as a cleaning web.SOLUTION: A fixing cleaning device comprises: a supply shaft being a send-off member that sends off a cleaning web being a belt-like cleaning body in contact with the surface of a fixing roller being a cleaning target body to which a toner being an image forming material used for image formation performed by an image forming unit being image forming means is attached, toward a web nip part being a contact part with the fixing roller; and a take-up shaft being a take-up member that is driven to rotate to take up the cleaning web in contact with the fixing roller. The fixing cleaning device includes a brake mechanism being take-up resistance providing means that provides take-up resistance for preventing the cleaning web taken-up by the take-up shaft from moving toward the take-up shaft, and includes a control unit that controls the brake mechanism on the basis of the image area ratio of an image formed by the image forming unit on a recording sheet being a recording medium.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a cleaning device, a fixing device, and an image forming apparatus.

As a conventional image forming apparatus, a fixing device that fixes a toner image on a recording medium on which a toner image is formed in an image forming unit, and a fixing member that a belt-like cleaning member such as a cleaning web is brought into contact with a fixing member of the fixing device. Some have a fixing cleaning device for cleaning. In this fixing cleaning device, the winding member is rotated by the driving means to wind up the belt-like cleaning body, whereby the belt-like cleaning body held by the delivery member is drawn out and directed from the delivery member toward the contact portion with the fixing member. Send out the belt-shaped cleaning body.
In Patent Document 1, as an image forming apparatus of this type, when the belt-like cleaning body is wound around the feeding member so that the feeding member holds the belt-like cleaning body, and the belt-like cleaning body is pulled out from the feeding member, the feeding member is provided. What rotates is described. The image forming apparatus of Patent Document 1 includes a rotation load mechanism that makes it difficult to rotate the delivery member.

In the image forming apparatus described in Patent Literature 1, when an image having a low image area ratio is continuous or an image having a low image area ratio is large as an image formed on a recording medium on which a toner image is fixed. In some cases, the belt-shaped cleaning body may be loosened.
When the belt-like cleaning body of the fixing cleaning device is loosened, the slackened belt-like cleaning body may be wound around the fixing member, and the wound belt-like cleaning body may interfere with the conveyance of the recording medium by the fixing member and may become a paper jam. is there.
The problem of slack in the belt-shaped cleaning body is not limited to the case where the object to be cleaned to be cleaned by the belt-shaped cleaning body is a fixing member, and an image of an image formed by an image forming unit with an image forming substance such as toner attached thereto. This is a problem that can occur if the amount of adhesion varies depending on the area ratio.

  In order to solve the above-described problems, the present invention is directed to a belt-like cleaning body that comes into contact with the surface of a body to be cleaned to which an image forming substance used for image formation of an image forming unit may be directed toward a contact portion with the body to be cleaned. And a winding member that winds up the belt-like cleaning member that has come into contact with the member to be cleaned by being rotationally driven, wherein the belt-like cleaning member wound around the winding member is the winding member. A winding resistance applying means for applying a winding resistance for preventing movement toward the taking member, and the winding resistance applying means based on an image area ratio of an image formed on the recording medium by the image forming means. It is characterized by comprising a control means for controlling.

  According to this invention, there exists the outstanding effect that it can suppress that slack generate | occur | produces in a strip | belt-shaped cleaning body.

6 is a flowchart of drive control of the fixing cleaning device according to the first exemplary embodiment. 1 is a schematic configuration diagram of a printer according to an embodiment. FIG. 2 is a schematic configuration diagram illustrating a configuration of a fixing device and a fixing cleaning device. Explanatory drawing about the force relationship which acts on the cleaning web which changes with the difference in an image area ratio. Explanatory drawing which shows the state which the slack produced in the cleaning web. The graph which shows transition of the roller diameter by the difference in an image area ratio about the cleaning web wound up by the winding shaft and became roller shape. The graph which shows the relationship between the frictional force which acts on a web nip part in the reverse direction to a winding direction, and an image area ratio. FIG. 3 is a schematic configuration diagram of a fixing device and a fixing cleaning device in a state in which a brake member is pressed against a cleaning web. 9 is a flowchart of drive control of the fixing cleaning device according to the second embodiment. 10 is a flowchart of drive control of the fixing cleaning device according to the third exemplary embodiment. Explanatory drawing about the change of the state of a winding shaft before and after the web winding operation | movement after paper passing operation | movement.

  Hereinafter, an embodiment of an image forming apparatus to which the present invention is applied will be described. The image forming apparatus according to the present embodiment is a color printer that can form a full color image by adopting an electrophotographic tandem method. The image forming apparatus is not limited to color but may be monochrome, and is not limited to a printer, and may be a copying machine, a facsimile machine, or the like.

  FIG. 2 is a schematic configuration diagram of a color printer (hereinafter referred to as “printer 100”) according to the present embodiment. First, the basic configuration and operation of the printer 100 will be described with reference to FIG. In the printer 100, a paper feed cassette 2 that stores recording paper P as a recording medium is disposed below the printer main body 1 serving as a base. The printer main body 1 also includes a control unit 90 that controls the operation of each device in the printer 100.

  In the central portion of the printer main body 1, four image forming units 8 (Y, C, M, and N) that are toner image forming means having drum-shaped photoreceptors 10 (Y, C, M, and K) that are image carriers. An image forming unit 80 provided with K) is provided. An intermediate transfer unit 7 having an intermediate transfer belt 3 as an intermediate transfer body, which is a flexible endless belt wound around a plurality of stretching rollers (4, 5, 6), is provided. Yes. Further, an exposure unit 15 that performs optical writing on the photoreceptor 10 and a fixing device 30 that fixes a toner image on the recording paper P are provided. The individual image forming units 8 (Y, C, M, K) and the intermediate transfer unit 7 are detachable from the printer main body 1.

The secondary transfer roller 20 of the secondary transfer device is disposed on the front surface, which is the outer surface of the loop of the intermediate transfer belt 3, at a position facing the secondary transfer counter roller 6 that is one of the stretching rollers. ing. A belt cleaning device 21 for cleaning the front surface of the intermediate transfer belt 3 is disposed at a position facing the cleaning facing roller 4 that is one of the stretching rollers.
The image forming unit 80 is disposed below the intermediate transfer belt 3, and four image forming units 8 (Y, C, M, K) are provided so as to face the tension surface below the intermediate transfer belt 3. Has been placed. The photoreceptors 10 (Y, C, M, K) of the individual image forming units 8 (Y, C, M, K) are in contact with the front surface of the intermediate transfer belt 3, respectively.
Around each photoconductor 10 (Y, C, M, K), a charging device 11 (Y, C, M, K), a developing device 12 (Y, C, M, K), and a photoconductor cleaning device 13 are provided. (Y, C, M, K) are arranged.

  Primary transfer rollers 14 (Y, C, M, K) as primary transfer means are provided at positions facing the photoconductors 10 (Y, C, M, K) with the intermediate transfer belt 3 interposed therebetween. The primary transfer rollers 14 (Y, C, M, K) primarily transfer the toner image formed on the photoreceptor 10 (Y, C, M, K) onto the intermediate transfer belt 3.

The developing device 12 (Y, C, M, K) of the image forming unit 8 (Y, C, M, K) includes yellow (Y), cyan (C), magenta (M), and black (K), respectively. Toner is stored. For the individual developing devices 12 (Y, C, M, K), when the amount of stored toner is reduced, the toner replenishing bottles 70 (Y, C, M, K) disposed at the top of the printer main body 1 are used. ) To supply replenishment toner.
The exposure unit 15 provided below the image forming unit 80 irradiates the surface of the photoconductor 10 (Y, C, M, K) with the light-modulated laser beam L, so that the photoconductor 10 (Y, C, A latent image for each color is formed on the surface of M, K).

  When the image forming operation is started, the photosensitive member 10 (Y, C, M, K) of the image forming unit 8 (Y, C, M, K) is rotationally driven in the clockwise direction in FIG. The The surface of the photoreceptor 10 (Y, C, M, K) is uniformly charged to a predetermined polarity by the charging device 11 (Y, C, M, K). The surface of the photoconductor 10 (Y, C, M, K) charged by the charging device 11 (Y, C, M, K) is irradiated with laser light L from the exposure unit 15, respectively. A latent image is formed. At this time, the image information used by the exposure unit 15 to expose each photoconductor 10 (Y, C, M, K) is a single color obtained by separating a desired full-color image into each color information of yellow, cyan, magenta, and black. Image information.

The latent image formed on the surface of the photoconductor 10 (Y, C, M, K) is developed by the developing device 12 (Y, C, M, K) as the photoconductor 10 (Y, C, M, K) rotates. ) Is visualized as a toner image by the toner of the developing device 12 (Y, C, M, K).
One of the three stretching rollers (4, 5, 6) around which the intermediate transfer belt 3 is wound is driven to rotate counterclockwise in FIG. It rotates in the counterclockwise direction indicated by the arrow “A” in FIG.

  A yellow toner image, a cyan toner image, a magenta toner image, and a black toner image formed on the surface of the photoreceptor 10 (Y, C, M, K) are primary on the surface of the intermediate transfer belt 3 that rotates in this way. The images are transferred so as to overlap one another by transfer rollers 14 (Y, C, M, K). As a result, a full color toner image is carried on the surface of the intermediate transfer belt 3.

  Residual toner adhering to the surface of the photoreceptor 10 (Y, C, M, K) after the toner image is transferred is transferred to the photoreceptor 10 (Y, C, M, K) by the photoreceptor cleaning device 13 (Y, C, M, K). C, M, K). Then, the surface of the photoreceptor 10 (Y, C, M, K) is neutralized by the neutralizing device, and the surface potential is initialized to prepare for the next image formation.

  The recording paper P fed from the paper feed cassette 2 is fed into the transport path. Then, the sheet feeding timing is measured by the registration roller pair 24 disposed upstream of the secondary transfer roller 20 in the sheet conveying direction, and the secondary transfer roller 6 and the secondary transfer roller 20 are opposed to each other. It is sent out to the transfer nip.

  A transfer voltage having a polarity opposite to the toner charging polarity of the toner image on the surface of the intermediate transfer belt 3 is applied to the secondary transfer roller 20, and the toner image on the surface of the intermediate transfer belt 3 is recorded in the secondary transfer nip. It is transferred onto the paper P at once. The recording paper P onto which the toner image has been transferred is conveyed to the fixing device 30, and when passing through the fixing device 30, heat and pressure are applied to fix the toner image. The recording paper P on which the toner image is fixed is discharged to a stacking tray 25 provided at the upper part of the printer main body 1 by the discharge roller pair 23 provided at the end of the conveyance path and provided at the upper part of the printer main body 1. The The toner remaining on the surface of the intermediate transfer belt 3 after the toner image is transferred to the recording paper P is removed from the surface of the intermediate transfer belt 3 by the belt cleaning device 21.

  The description so far relates to the image forming operation when a four-color full-color image is formed on the recording paper P. Any one of the image forming units 8 (Y, C, M, K) of the image forming unit 80 is described. One can be used to form a single color image or a two or three color image. When monochrome printing is performed using the printer 100 of the present embodiment, a toner image is formed only on the black photoconductor 10K of the black image forming unit 8K, transferred to the recording paper P, and then fixed by the fixing device 30. Just fix it.

  The printer 100 includes an image forming unit 80 that is an image forming unit that forms an image by applying toner that is an image forming material on a recording sheet P that is a recording medium, and a recording sheet on which a toner image that is an image is formed. And a fixing device 30 for fixing the toner image to P. Further, a fixing cleaning device 40 is provided as a cleaning means for cleaning the surface of the fixing roller 31 which is a member to be cleaned to which the toner can adhere in the fixing device 30.

FIG. 3 is a schematic configuration diagram showing the configuration of the fixing device 30 and the fixing cleaning device 40.
As shown in FIG. 3, the fixing device 30 includes a fixing roller 31 that is a fixing member, and a pressure roller 32 that is a pressure member that forms a fixing nip between the fixing roller 31 and the fixing roller 31. It has. The fixing cleaning device 40 may be arranged in the fixing device 30, or may be arranged in the printer 100 separately from the fixing device 30.

  The fixing roller 31 incorporates a heater 33 which is a heating unit, and is driven to rotate in the direction of the arrow “R2” (counterclockwise direction) in FIG. 3 by the driving unit. The pressure roller 32 is driven to rotate clockwise in FIG. 3 as the fixing roller 31 rotates. Further, around the fixing roller 31, a separation claw 34 that suppresses the winding of the recording paper P around the fixing roller 31, a temperature sensor 35 that detects the surface temperature of the fixing roller 31, and an entrance guide that guides the recording paper P. 36, an outlet guide 37, and the like are arranged. When the recording paper P carrying the toner image is fed into the fixing nip between the fixing roller 31 and the pressure roller 32, the toner image is fixed on the surface of the recording paper P under the action of heat and pressure. The

  When such a fixing operation is performed, since the toner image of the recording paper P contacts the fixing roller 31, the toner may transfer from the recording paper P to the surface of the fixing roller 31. If the amount of toner transferred to the surface of the fixing roller 31 is increased, the toner may be reattached to the surface of the recording paper P to contaminate the recording paper P and deteriorate the image quality. In contrast, in the fixing device 30, the toner transferred from the recording paper P to the surface of the fixing roller 31 is removed from the surface of the fixing roller 31 by the fixing cleaning device 40.

  The fixing cleaning device 40 employs a web cleaning system that uses a cleaning web 44 that is a belt-like cleaning body that cleans the surface of the fixing roller 31 by rubbing against the surface of the fixing roller 31 that is the object to be cleaned. As shown in FIG. 3, the fixing cleaning device 40 is a supply shaft 41 that is a feed member that winds and holds the cleaning web 44 so that the cleaning web 44 can be fed, and a take-up member that can wind the cleaning web 44. A winding shaft 43 is provided. One end of the cleaning web 44 is fixed to the winding shaft 43, and the other end of the cleaning web 44 is fixed to the supply shaft 41. Further, the fixing cleaning device 40 includes a pressing roller 42 that presses the cleaning web 44 fed from the supply shaft 41 against the fixing roller 31 to form a web nip portion.

  The winding shaft 43 to which one end of the cleaning web 44 is fixed winds up the cleaning web 44 that has come into contact with the fixing roller 31 at the web nip portion. The supply shaft 41 to which the other end of the cleaning web 44 is fixed holds the cleaning web 44 that is brought into contact with the fixing roller 31, and pulls the cleaning web 44 toward the web nip portion by pulling one end side of the cleaning web 44. .

  The supply shaft 41, the pressing roller 42, and the winding shaft 43 are rotatably supported by side plates provided at both front and back ends of the fixing device 30 or the fixing cleaning device 40 that are perpendicular to the paper surface of FIG. 3. . One end in the axial direction of the take-up shaft 43 is connected to a take-up motor 49 that is a take-up drive means via a gear or the like, and the control unit 90 drives the take-up motor 49, so that the take-up shaft 43 is driven. Is rotated in the direction of the arrow “R1” (counterclockwise direction) in FIG. The cleaning web 44 wound around the supply shaft 41 moves through the web nip portion at a predetermined timing by the rotational drive of the winding shaft 43 and is wound around the winding shaft 43.

  The fixing cleaning device 40 stops the rotation of the winding shaft 43 until the winding operation is performed, and the cleaning web 44 does not move. Therefore, in the web nip portion, the fixing roller is fixed by the same portion of the cleaning web 44. The residual toner on the surface of 31 is cleaned. Then, by rotating the winding shaft 43 in the winding direction at a predetermined timing, a new portion of the cleaning web 44 is gradually moved from the supply shaft 41 side to the web nip portion. In the fixing cleaning device 40 using such a web cleaning method, the portion of the cleaning web 44 that contacts the fixing roller 31 is renewed every time the winding operation is performed. For this reason, the fixing roller 31 can be cleaned until the cleaning web 44 is used up without significantly reducing the initial cleaning ability.

  In the printer 100 of this embodiment, the number of recording sheets P on which image formation has been performed by the control unit 90 is counted, and information on the number of recording sheets P that has passed through the fixing nip is recorded on the recording unit in the control unit 90. Further, the control unit 90 includes a calculation unit that calculates the image area ratio of the toner image on each recording paper P based on the image information of the toner image formed on each recording paper P, and calculates the calculated image area ratio. Is recorded in the recording unit.

  Then, the control unit 90 drives the winding motor 49 for a predetermined time set in advance at a predetermined interval of every predetermined number of sheets to pass, rotates the winding shaft 43, and winds the cleaning web 44. In this way, the printer 100 winds the cleaning web 44 at regular intervals regardless of image information such as the image area ratio of the toner image formed on the recording paper P.

  In the present embodiment, the reverse rotation preventing means such as a cam clutch is provided so that the winding shaft 43 can rotate only in the direction in which the cleaning web 44 is wound (counterclockwise direction indicated by arrow “R1” in FIG. 3). Prepare. As a result, even if a force in the direction of pulling out the cleaning web 44 from the take-up shaft 43 due to the cleaning web 44 being pulled by the fixing roller 31 at the web nip portion, the take-up shaft 43 is reversed in the take-up direction. It does not rotate in the direction.

  The cleaning web 44 can be made of an appropriately selected material such as cloth, paper, resin sheet, resin film, and metal foil. In the present embodiment, the cleaning web 44 slides on the surface of the fixing roller 31 to clean the surface and also has a function of applying oil to the surface. Therefore, the cleaning web 44 is composed of a material that can be impregnated with oil, for example, a non-woven fabric made by mixing fibers of aramid and PET. When the cleaning web 44 comes into sliding contact with the surface of the fixing roller 31, the oil impregnated in the cleaning web 44 is thinly and uniformly applied to the surface of the fixing roller 31. As the oil applied to the surface of the fixing roller 31, oil that makes it difficult for toner to transfer from the recording paper P to the surface of the fixing roller 31, improves the lubricity of the surface, and further suppresses the wear of the surface is used. It is done.

  In a web cleaning method used for cleaning a fixing member used in an electrophotographic image forming apparatus like the fixing cleaning device 40, a used portion of the cleaning web that has been in contact with the fixing member is wound up by a winding member. . At this time, when the loosening of the cleaning web wound around the winding member is loosened, the cleaning web is likely to be loosened (slack) for the following reason.

  That is, when a large amount of offset toner enters the web nip portion and adheres to the cleaning web due to a paper jam or the like, an excessive frictional force acts between the cleaning web and the fixing member at the web nip portion. Then, the cleaning web may be pulled by the surface movement of the fixing member. In addition, the poorly separated jammed paper may get caught in the web nip portion, and a load may be applied in the direction of pulling out the cleaning web. In these states, a force for pulling out the cleaning web from the winding member acts.

When a force that pulls out from the winding member acts on the cleaning web that has been loosened, the cleaning web is pulled out from the winding member, and the cleaning web is loosened.
If the cleaning web is slack, the slack portion of the cleaning web may wrap around the fixing member and cause a paper jam or an abnormal image.

As a configuration for suppressing the loosening of the winding, the supply load of the cleaning web is obtained by bringing the leaf spring directly into contact with the cleaning web wound around the supply member, or bringing the brake member into contact with the rotating shaft of the supply member. It is conceivable to have a brake mechanism that constantly increases However, the brake mechanism that constantly increases the supply load of the cleaning web cannot suppress fluctuations in the tension acting on the cleaning web taken up by the take-up member caused by fluctuations in the image area ratio (printing ratio) of the fixed toner image. . If the tension of the cleaning web taken up by the take-up member fluctuates, the above-described loosening of the web may occur when the tension is small.
Here, the fluctuation | variation of the tension | tensile_strength which acts on the cleaning web which a winding member winds up is demonstrated.

  FIG. 4 is an explanatory diagram of the force relationship acting on the cleaning web 44 that changes depending on the difference in the image area ratio of the toner image formed on the recording paper P. FIG. 4A is an explanatory diagram of a force relationship acting on the cleaning web 44 when the cleaning web 44 is wound up by the winding shaft 43 after fixing the toner image having a high image area ratio. FIG. 4B is an explanatory diagram of a force relationship acting on the cleaning web 44 when the cleaning web 44 is wound up after fixing a toner image having a low image area ratio.

  As shown in FIG. 4, forces “F1”, “F2”, and “F3” act on the cleaning web 44. “F1” is a force acting in the direction of winding the cleaning web 44 by the winding shaft 43. “F2” is a frictional force that acts in the direction opposite to the winding direction due to the friction between the cleaning web 44 pressed against the fixing roller 31 by the pressing roller 42 and the fixing roller 31. “F3” is a force acting on the supply shaft 41 in the direction opposite to the winding direction of the cleaning web 44. This “F3” is a reaction force against the force in the winding direction that rotates the supply shaft 41 by rotating the winding shaft 43 to pull out the cleaning web 44 wound around the supply shaft 41.

  In a state where the cleaning web 44 is stretched around the supply shaft 41, the pressing roller 42, and the winding shaft 43, the relationship “F1 = F2 + F3” is established. When the toner adheres to the cleaning web 44 at the web nip portion, the dynamic frictional force between the cleaning web 44 and the fixing roller 31 increases due to the toner, and the force “F2” increases.

  In the case of passing a sheet with a high image area ratio in which the toner adhesion amount to the fixing roller 31 is increased, “F2” becomes larger due to an increase in the dynamic frictional force. As a result, the resultant force “F2 + F3” (hereinafter referred to as “back tension”) of the force pulling in the direction opposite to the winding direction of the cleaning web 44 is increased. Then, as the force “F1” acting on the take-up shaft 43 that balances with the back tension is increased, as shown in FIG. 4A, the used cleaning web 44 to be taken up is strongly stretched. It becomes. By performing the winding operation in this state, the used cleaning web 44 is tightly wound around the winding shaft 43.

  On the other hand, when the sheet having a low image area ratio with a small amount of toner attached to the fixing roller 31 is used, the dynamic frictional force is small, so that the force “F2” is small and the back tension is small as compared with the high image area ratio. For this reason, the force “F1” acting on the take-up shaft 43 that balances with the back tension is also reduced, so that the used cleaning web to be taken up is not stretched strongly as shown in FIG. 4B. It becomes. When the winding operation is performed in this state, the used cleaning web 44 is loosely wound around the winding shaft 43.

FIG. 5 is an explanatory view showing a state in which the cleaning web 44 is slackened.
When the state in which the cleaning web 44 is loosely wound around the winding shaft 43 continues, the winding shaft 43 is loosened.

  In the web nip portion shown in FIG. 4, the surface movement direction of the fixing roller 31 is opposite to the movement direction of the cleaning web 44 during the winding operation. For this reason, when the fixing roller 31 is rotating, the force that the cleaning web 44 tries to move along with the surface movement of the fixing roller 31 due to the frictional force at the contact portion is the cleaning web wound around the winding shaft 43. Acts in the direction of pulling out 44. In such a configuration, when the frictional force between the cleaning web 44 and the fixing roller 31 increases due to a large amount of offset toner entering the web nip portion, the cleaning web 44 wound around the winding shaft 43 is used. The power to pull out is also increased. When the force for pulling out the cleaning web 44 wound around the winding shaft 43 is increased in a state where the winding shaft 43 is loosened, the cleaning web 44 loosely wound around the winding shaft 43 is pulled out. It is. When the cleaning web 44 is pulled out from the take-up shaft 43, the cleaning web 44 that has been pulled out passes through the web nip portion as the surface of the fixing roller 31 moves, and is indicated by “α” in FIG. This causes slack in the cleaning web 44 like a portion.

  Not only when a large amount of offset toner enters the web nip portion, but when a pulling force acts on the cleaning web 44 loosely wound around the winding shaft 43, the cleaning web 44 is slackened.

  FIG. 6 is a graph showing the transition of the roller diameter due to the difference in the image area ratio for the cleaning web 44 wound around the winding shaft 43 into a roller shape. The horizontal axis in FIG. 6 indicates the number of sheets to be passed, and the vertical axis is the roller diameter of the roller-shaped cleaning web 44 wound around the winding shaft 43. The solid line graph in FIG. 6 is a graph when the low image area rate is passed, and the broken line graph in FIG. 6 is a graph when the high image area rate is passed.

  When the sheet having a high image area ratio is passed, as described with reference to FIG. 4A, the frictional force “F2” acting on the cleaning web 44 in the direction opposite to the winding direction at the web nip portion becomes large. , The back tension increases. For this reason, the force “F1” acting on the take-up shaft 43 that balances with the back tension is increased, and the used cleaning web 44 to be taken up becomes tightly stretched, and the used cleaning web 44 is wound up. It is wound tightly on the take-off shaft 43. Therefore, the increase in the roller diameter of the cleaning web 44 on the winding shaft 43 after passing the sheet passing number “S” is moderate, and the outer diameter becomes “D1” in the example shown in FIG.

  On the other hand, in the low image area ratio paper passing, as described with reference to FIG. 4B, the frictional force “F2” acting on the cleaning web 44 in the direction opposite to the winding direction at the web nip portion is generated. The back tension is also reduced. For this reason, the force “F1” acting on the take-up shaft 43 that balances with the back tension is increased, and the used cleaning web 44 that is the object to be taken up is not stretched strongly. It is wound loosely around the take-up shaft 43. Therefore, the roller diameter of the cleaning web 44 on the take-up shaft 43 after passing the number of sheets “S” is abruptly increased, and the outer diameter becomes “D2” in the example shown in FIG.

  Even when the same number of sheets “S” is passed, the roller diameter of the cleaning web 44 on the take-up shaft 43 is enlarged corresponding to “D2-D1” in FIG. 6 due to the difference in the image area ratio. However, this indicates that loose winding has occurred. Since the cleaning web 44 is loosely wound around the winding shaft 43 as the roller diameter of the cleaning web 44 on the winding shaft 43 is increased, the cleaning web 44 is easily loosened.

  The following configuration is conceivable as a configuration that suppresses the occurrence of slack in the cleaning web 44 due to the low image area rate paper passing. That is, the integrated value of the image area ratio of the fixed toner image (hereinafter referred to as “integrated image area ratio”) is calculated, and the winding operation by the winding shaft 43 is performed until the predetermined integrated image area ratio is reached. A configuration not to perform is conceivable. However, in such a configuration, when the recording paper P on which a toner image with an extremely low image area ratio is formed is continuously passed, toner that is not counted in the cumulative image area ratio, which is so-called scumming toner, is web nip. Accumulated in the department. If the winding operation of the cleaning web 44 is not performed until the integrated image area ratio reaches a specified value, the toner accumulated in the web nip portion is dragged by the rotation of the fixing roller 31, and the fixing roller 31 moves in the web nip portion. Dragged downstream in the direction of surface movement. Then, it eventually slips through the web nip portion, reaches the fixing nip and adheres to the recording paper P, and there is a possibility that an abnormal image called a black spot is generated on the image.

  Therefore, there is a demand for a configuration that can both prevent the occurrence of paper jams and abnormal images due to the slack of the cleaning web 44 and the prevention of abnormal images due to toner slipping.

  FIG. 7 is a graph showing the relationship between the image area ratio and the force “F2”. FIG. 7A shows the difference in the relationship between the image area ratio and the force “F2” due to the difference in paper type, and FIG. 7B shows that the force “F2” is the reference value “R (F2)”. It is a graph which shows the range used as the image area ratio outside the regulation range which becomes lower than this.

The horizontal axes in FIGS. 7A and 7B indicate the image area ratio, and the image area ratio is higher on the right side in FIG. 7A and 7B indicates the frictional force “F2” that acts on the cleaning web 44 in the direction opposite to the winding direction at the web nip portion.
The fixing cleaning device 40 of the present embodiment winds the cleaning web 44 by rotating the winding shaft 43 for a predetermined time for each predetermined number of sheets passing. The value of “F2” on the vertical axis in FIG. 7 indicates that the recording shaft of one paper type is used and a predetermined number of sheets are passed under the condition that the image area ratio is constant, and then the winding shaft 43 is rotated. This is the value of the frictional force “F2” acting on the cleaning web 44 at the web nip when the winding operation is performed.

The graph “P (A)” in FIG. 7A is a graph showing the relationship between the image area ratio and the force “F2” in the recording paper “A” of an arbitrary paper type. Further, P (B) in FIG. 7A is a graph showing the relationship between the image area ratio and the force “F2” in the recording paper “B” of a paper type different from the recording paper “A”.
As shown in FIGS. 7A and 7B, the force “F2” varies depending on the image area ratio even when the paper type is the same, and the image area ratio is the same as shown in FIG. 7A. But it depends on the paper type.

  When the sheet having a low image area ratio is passed, since the offset toner to the cleaning target (fixing roller 31) is small and the toner input to the web nip is also small, "F2" is small as shown in FIG. As the image area ratio increases, the offset toner to the cleaning target increases, the toner input to the web nip also increases, and “F2” also increases as shown in FIG. However, when the image area ratio increases to some extent, “F2” decreases as shown in FIG. This is presumably because the offset toner to the member to be cleaned is reduced by the toners joining on the recording paper P.

  Here, the value of “F2” at which no winding looseness occurs at the winding shaft 43 is defined as an F2 reference value “R (F2)”. In this case, under any recording paper condition shown in FIG. 7B, the condition of the image area ratio in which “F2” is lower than the F2 reference value “R (F2)” is less than the reference value “R1” or the reference The condition exceeds the value “R2”.

  FIG. 7A shows that the reference value of the image area ratio in which “F2” is lower than the F2 reference value “R (F2)” differs depending on the paper type of the recording paper P. The recording paper “A” is a recording paper P that is less smooth than the recording paper “B”. When the recording paper P has low smoothness and the coupling between the toner and the recording paper P is weak, the toner offset with respect to the image area ratio is large and the toner input to the web nip portion also increases. The curve of “P (A)”. On the other hand, when the recording paper P has high smoothness and a strong bond between the toner and the recording paper P, the offset of the toner with respect to the image area ratio is small and the toner input to the web nip portion is also reduced. It becomes the curve of “P (B)” in the middle.

  As shown in FIG. 7A, the condition that the winding shaft 43 is loosened is less than the reference value “A1” or exceeds the reference value “A2” in the case of the recording paper “A”. In the case of recording paper “B”, the condition is less than the reference value “B1” or exceeds the reference value “B2”. As described above, the reference value of the image area ratio at which winding looseness varies depending on the paper type of the recording paper P.

  In paper passing in actual image formation, the image area ratio varies depending on the print page. Therefore, in this embodiment, as shown in FIG. 7B, the range of the image area ratio (the range of “β1” and “β2” in FIG. It is defined as “outer image area ratio”. Then, the brake operation of pressing the brake member against the cleaning web 44 depending on how much the recording paper P on which an image of “image area ratio out of the specified range” is formed is included in the print job or how long the recording paper P is included. Judge whether or not to execute.

  As shown in FIG. 3, the fixing cleaning device 40 of this embodiment includes a brake mechanism 50 that presses a brake member 54 against the cleaning web 44. The brake mechanism 50 includes a brake member 54 that swings about the brake rotation shaft 53 and that can contact and separate from the cleaning web 44, and an eccentric cam 51 that presses the brake member 54 against the cleaning web 44. Furthermore, the brake mechanism 50 includes a brake member contact / separation drive unit 52 that drives to change the rotational position of the eccentric cam 51 to bring the brake member 54 into and out of contact with the cleaning web 44.

  FIG. 3 shows a state where the pressing of the brake member 54 against the cleaning web 44 is released. FIG. 8 shows a state where the brake member 54 is moved from the state shown in FIG. 3 and the brake member 54 is pressed against the cleaning web 44.

  When the brake operation is executed from the state shown in FIG. 3, the control unit 90 controls the drive of the brake member contact / separation drive unit 52 to rotate the eccentric cam 51. Then, the brake member 54 is pressed against the pressure roller 42 so that the brake member 54 contacts the pressure roller 42 with the cleaning web 44 interposed therebetween, and the state shown in FIG. 8 is obtained. As a result, the cleaning web 44 is sandwiched between the pressing roller 42 and the brake member 54, and when the cleaning web 44 attempts to move, a frictional force acts on the cleaning web 44.

  As in Example 1 described later, the ratio of the number of sheets of recording paper P having an image area ratio outside the specified range to the number of sheets of recording paper P on which image formation has been performed after the previous winding operation is performed is as follows. When the percentage of the reference is exceeded, the brake operation is executed. Further, as in Example 2 described later, the brake operation is also executed when the number of continuous sheets of recording paper P having an image area ratio outside the specified range exceeds the reference number. The brake member 54 is pressed against the cleaning web 44 by executing the brake operation under a condition where the force “F2” may be insufficient. As a result, the back tension can be supplemented by the frictional force between the brake member 54 and the cleaning web 44, and the occurrence of loose winding can be prevented. Thereby, it is possible to prevent the cleaning web 44 from being slackened.

  On the other hand, when releasing the pressing of the brake member 54 against the cleaning web 44, the control unit 90 controls the drive of the brake member contacting / separating drive unit 52 from the state shown in FIG. The member 54 is separated from the cleaning web 44.

  As in Example 1 described later, when the ratio of the number of sheets of recording paper P having an image area ratio outside the range is equal to or less than the reference ratio, the pressing of the brake member 54 is released. Further, as in Example 2 described later, the pressing of the brake member 54 is also released when the number of continuous sheets of recording paper P having an image area ratio outside the specified range is equal to or less than the reference number. Under the condition that the force “F2” is not insufficient, a frictional force is not generated between the brake member 54 and the cleaning web 44, an increase in unnecessary back tension can be suppressed, and an increase in torque during the winding operation can be suppressed. .

  In the configuration of the brake mechanism 50 shown in FIGS. 3 and 8, the pressing amount of the brake member 54 against the cleaning web 44 can be arbitrarily changed by the rotation angle of the eccentric cam 51. Therefore, it is possible to control the pressing amount of the brake member 54 in a stepless manner in accordance with the ratio of the number of pages of the image area ratio outside the specified range and the number of consecutive pages of the image area ratio outside the specified range.

The brake mechanism 50 illustrated in FIGS. 3 and 8 is an example of a winding resistance applying unit that applies a winding resistance when the winding shaft 43 winds the cleaning web 44. The configuration for providing the winding resistance is not limited to the configuration in which the brake member 54 is brought into contact with the cleaning web 44. For example, a configuration may be adopted in which the back tension is increased by increasing the rotational resistance of the supply shaft 41 in contact with the supply shaft 41 and the winding resistance when the winding shaft 43 winds the cleaning web 44 is increased. .
In addition, the brake mechanism 50 that applies a frictional force to the cleaning web 44 may be configured using a solenoid or the like instead of the eccentric cam.

  In the brake mechanism 50 shown in FIGS. 3 and 8, the brake member 54 is in contact with the pressing roller 42 with the cleaning web 44 interposed therebetween. The brake member 54 may be configured to contact only the cleaning web 44. In this case, there is no backing on the cleaning web 44, and the cleaning web 44 escapes inward, so that the frictional force cannot be efficiently applied. As in the fixing cleaning device 40 of the present embodiment, the cleaning web 44 is sandwiched between the brake member 54 and the pressing roller 42 to efficiently apply a frictional force to the cleaning web 44 without newly placing a backing member. it can.

  The printer 100 according to the present embodiment includes a brake mechanism 50 that contacts and separates the brake member 54 from the cleaning web 44. Then, the control unit 90 controls the brake member contact / separation drive unit 52 of the brake mechanism 50 based on the image area ratio of the toner image formed by the image forming unit 80 that is an image forming unit. More specifically, the brake operation for bringing the brake member 54 into contact with the cleaning web 44 is executed when the ratio of the recording paper P having an image area ratio outside the specified range is large or continuous. By performing the winding operation while the brake member 54 is in contact with the cleaning web 44, the back tension can be compensated by the frictional force between the brake member 54 and the cleaning web 44, and the occurrence of loose winding is prevented. it can. Thereby, it is possible to prevent the cleaning web 44 from being slackened, and it is possible to prevent a paper jam caused by the slackness of the cleaning web 44.

Further, as described above, in the printer 100 of this embodiment, the control unit 90 drives the winding motor 49 at regular intervals, rotates the winding shaft 43, and winds the cleaning web 44. For this reason, it is possible to suppress the occurrence of an abnormal image due to the toner slipping through the web nip portion that may occur in the configuration in which the winding member is rotated based on the above-described integrated image area ratio.
In the printer 100 according to the present embodiment, since the braking operation is executed based on the image area ratio, it is possible to prevent the toner from slipping through the web nip portion and the web from slacking regardless of the fluctuation of the image area ratio.
When the winding motor 49 is driven at a constant interval, the fixing roller 31 that is the member to be cleaned may be rotated, or the rotation of the fixing roller 31 may be stopped.

[Example 1]
Next, a first example of control of the winding operation of the cleaning web 44 (hereinafter referred to as “Example 1”) will be described.
FIG. 1 is a flowchart of drive control of the fixing cleaning device 40 according to the first exemplary embodiment.
In the first embodiment, when the ratio of the recording sheet P whose image area ratio is out of a predetermined range with respect to the number of recording sheets P that have passed through the fixing nip exceeds the reference ratio, the control unit 90 performs the brake mechanism. 50 is controlled, and control for pressing the brake member 54 against the cleaning web 44 is executed.

  When the sheet feeding operation is started in the fixing device 30, an operation (web winding operation at the time of feeding) of winding the cleaning web 44 at a fixed interval (every predetermined number of sheets) is started. (Step “S11”). In the web winding operation during sheet passing, the supply shaft 41 is also rotated in accordance with the rotation of the winding shaft 43 that is rotationally driven, and the cleaning web 44 wound around the supply shaft 41 is fed toward the web nip portion.

  During the sheet passing operation, the recording unit in the control unit 90 counts the number of pages to be passed (step “S12”), and the calculation unit of the control unit 90 calculates the image area ratio of each page to be passed (step “step“ S12 ”). S13 "), and the number of pages with an image area ratio outside the specified range is counted.

  Next, it is confirmed whether or not the brake member 54 is pressed against the cleaning web 44 (step “S14”). In the control flow of the first embodiment, it is possible to have both a state where the brake member 54 is pressed against the cleaning web 44 and a state where the brake member 54 is not pressed at the time of step “S12” by repeated processing. For this reason, in step "S14", the pressing state of the brake member 54 is confirmed.

  If the brake member 54 is not pressed against the cleaning web 44 (“Y” in step “S14”), it is determined whether or not the ratio of the number of pages with an image area ratio outside the specified range exceeds a preset reference value. A determination is made (step “S15”). The ratio of the number of pages that has an image area ratio outside the specified range can be obtained from the count number of pages to be passed and the count number of pages that have an image area ratio outside the specified range.

When the brake member 54 is not pressed against the cleaning web 44 and the ratio of the number of pages that has an image area ratio outside the specified range exceeds the reference value (“Y” in step “S15”), the cleaning web 44 The brake member 54 is pressed (step “S16”).
When the ratio of the number of pages of the image area ratio outside the specified range exceeds the reference value, the back tension can be compensated by the frictional force between the brake member 54 and the cleaning web 44 by pressing the brake member 54 against the cleaning web 44. . Thereby, the slack of the cleaning web 44 can be prevented.
Then, after pressing the brake member 54 against the cleaning web 44, it is determined whether or not the print job is completed (step "S19").

  If the brake member 54 is not pressed against the cleaning web 44 and the ratio of the number of pages with an image area ratio outside the specified range is equal to or less than the reference value (“N” in step “S15”), printing is performed as it is. It is determined whether or not the job is finished (step “S19”).

On the other hand, if the brake member 54 has already been pressed against the cleaning web 44 (“N” in step “S14”), is the ratio of the number of pages that is an image area ratio outside the specified range equal to or less than a preset reference value? It is determined whether or not (step “S17”).
When the brake member 54 is pressed against the cleaning web 44 and the ratio of the number of pages with an image area ratio outside the specified range is equal to or less than the reference value (“Y” in step “S17”), the step “S18” Execute control. That is, the pressing of the brake member 54 to the cleaning web 44 is released.

When the ratio of the page number of the image area ratio outside the specified range is equal to or less than the reference value, the pressing of the brake member 54 to the cleaning web 44 is released. Thereby, frictional force between the brake member 54 and the cleaning web 44 is not generated, and an increase in torque due to an unnecessary increase in back tension can be prevented.
Then, after releasing the pressing of the brake member 54 to the cleaning web 44, it is determined whether or not the print job is completed (step “S19”).

  When the brake member 54 is pressed against the cleaning web 44 and the ratio of the number of pages with an image area ratio outside the specified range exceeds the reference value (“N” in step “S17”), the print job is left as it is. It is determined whether or not has been completed (step “S19”).

If it is determined in step “S19” that the print job remains (“N” in step “S19”), the process returns to step S12 and the process is repeated until the print job is completed. When the print job is finished (“Y” in step “S19”), the sheet passing operation is finished, and the web winding operation is also finished (step “S20”).
This series of processing is executed each time a sheet passing operation is performed, and the cleaning web 44 is prevented from slacking by performing until the life of the cleaning web 44 (the state in which the cleaning web 44 wound around the supply shaft 41 disappears). it can.

[Example 2]
Next, a second embodiment of control of the winding operation of the cleaning web 44 (hereinafter referred to as “embodiment 2”) will be described.
FIG. 9 is a flowchart of drive control of the fixing cleaning device 40 according to the second embodiment.
In the second embodiment, when the number of continuous sheets of recording paper P whose image area ratio is out of a predetermined range exceeds the reference number, the control unit 90 controls the brake mechanism 50 so that the brake member 54 is removed from the cleaning web. The control which presses to 44 is performed.

  When the sheet feeding operation is started in the fixing device 30, an operation (web winding operation at the time of feeding) of winding the cleaning web 44 at a fixed interval (every predetermined number of sheets) is started. (Step “S21”). In the web winding operation during sheet passing, the supply shaft 41 is also rotated in accordance with the rotation of the winding shaft 43 that is rotationally driven, and the cleaning web 44 wound around the supply shaft 41 is fed toward the web nip portion.

During the sheet passing operation, the image area ratio of each sheet passing page is calculated by the calculation section in the control section 90 (step “S22”), and the page in which the recording section in the control section 90 has an image area ratio outside the specified range. Is counted (step "S23").
Next, it is confirmed whether or not the brake member 54 is pressed against the cleaning web 44 (step “S24”). In the control flow of the second embodiment, it is possible to have both a state where the brake member 54 is pressed against the cleaning web 44 and a state where the brake member 54 is not pressed at the time of step “S22” due to the repeated processing. For this reason, in step “S24”, the pressing state of the brake member 54 is confirmed.

  If the brake member 54 is not pressed against the cleaning web 44 (“Y” in step “S24”), whether or not the continuous number of pages that have an image area ratio outside the specified range exceeds a preset reference value. A determination is made (step "S25").

When the brake member 54 is not pressed against the cleaning web 44 and the number of continuous pages having an image area ratio outside the specified range exceeds the reference value (“Y” in step “S25”), the cleaning web 44 is The brake member 54 is pressed (step “S26”).
When the continuous number of pages having an image area ratio outside the specified range exceeds the reference value, the back tension can be compensated by the frictional force between the brake member 54 and the cleaning web 44 by pressing the brake member 54 against the cleaning web 44. . Thereby, slack of the cleaning web 44 can be prevented.
Then, after pressing the brake member 54 against the cleaning web 44, it is determined whether or not the print job is completed (step "S29").

  When the brake member 54 is not pressed against the cleaning web 44 and the number of continuous pages having an image area ratio outside the specified range is equal to or less than the reference value (“N” in step “S25”), the printing is performed as it is. It is determined whether or not the job is finished (step “S29”).

On the other hand, if the brake member 54 has already been pressed against the cleaning web 44 (“N” in step “S24”), is the continuous number of pages with an image area ratio outside the specified range equal to or less than a preset reference value? It is determined whether or not (step “S27”).
When the brake member 54 is pressed against the cleaning web 44 and the continuation of the page having the image area ratio outside the specified range is equal to or less than the reference value (“Y” in step “S27”), the process proceeds to step “S28”. Execute control. That is, the pressing of the brake member 54 to the cleaning web 44 is released.

When the continuous number of pages having an image area ratio outside the specified range is equal to or less than the reference value, the pressing of the brake member 54 to the cleaning web 44 is released. Thereby, frictional force between the brake member 54 and the cleaning web 44 is not generated, and an increase in torque due to an unnecessary increase in back tension can be prevented.
Then, after releasing the pressing of the brake member 54 to the cleaning web 44, it is determined whether or not the print job is completed (step “S29”).

  When the brake member 54 is pressed against the cleaning web 44 and the continuous number of pages having an image area ratio outside the specified range exceeds the reference value (“N” in step “S27”), the print job is left as it is. It is determined whether or not the process has ended (step “S29”).

If it is determined in step “S29” that the print job remains (“N” in step “S29”), the process returns to step S22 and the process is repeated until the print job is completed. When the print job is finished (“Y” in step “S29”), the sheet passing operation is finished, and the web winding operation is also finished (step “S30”).
This series of processing is executed each time a sheet passing operation is performed, and the cleaning web 44 is prevented from slacking by performing until the life of the cleaning web 44 (the state in which the cleaning web 44 wound around the supply shaft 41 disappears). it can.

Example 3
Next, a third embodiment of control of the winding operation of the cleaning web 44 (hereinafter referred to as “Example 3”) will be described.
FIG. 10 is a flowchart of drive control of the fixing cleaning device 40 according to the third embodiment.
In the third embodiment, when the ratio of the recording paper P whose image area ratio is out of the predetermined range exceeds the reference ratio, or the continuous number of the recording paper P whose image area ratio is out of the predetermined range. When the number of sheets exceeds the reference number, control for pressing the brake member 54 against the cleaning web 44 is executed.

  When the sheet feeding operation is started in the fixing device 30, an operation (web winding operation at the time of feeding) of winding the cleaning web 44 at a fixed interval (every predetermined number of sheets) is started. (Step “S31”). In the web winding operation during sheet passing, the supply shaft 41 is also rotated in accordance with the rotation of the winding shaft 43 that is rotationally driven, and the cleaning web 44 wound around the supply shaft 41 is fed toward the web nip portion.

  During the sheet passing operation, the recording unit in the control unit 90 counts the number of pages to be passed (step “S32”), and the calculation unit of the control unit 90 calculates the image area rate of each sheet passing page (step “step“ S32 ”). S33 "), and the number of pages with an image area ratio outside the specified range is counted. Further, the recording unit in the control unit 90 counts the number of consecutive pages that have an image area ratio outside the specified range (step “S34”).

  Next, it is confirmed whether or not the brake member 54 is pressed against the cleaning web 44 (step “S35”). In the control flow of the third embodiment, it is possible to have both a state where the brake member 54 is pressed against the cleaning web 44 and a state where the brake member 54 is not pressed at the time of step “S32” due to repetitive processing. For this reason, in step "S35", the pressing state of the brake member 54 is confirmed.

If the brake member 54 is not pressed against the cleaning web 44 (“Y” in step “S35”), does the continuous number of pages with an image area ratio outside the specified range exceed a preset reference value (3)? It is determined whether or not (step “S36”). When the brake member 54 is not pressed against the cleaning web 44 and the continuous number of pages having an image area ratio outside the specified range exceeds the reference value (3) (“Y” in step “S36”), The control of step “S37” is executed. That is, the brake member 54 is pressed against the cleaning web 44.
Then, after pressing the brake member 54 against the cleaning web 44, it is determined whether or not the print job is completed (step "S42").

When the number of continuous pages having an image area ratio outside the specified range is equal to or less than the reference value (“N” in step “S36”), a reference in which the ratio of the number of pages having the image area ratio outside the specified range is set in advance. It is determined whether or not the value is exceeded (step "S38"). When the brake member 54 is not pressed against the cleaning web 44 and the ratio of the number of pages that has an image area ratio outside the specified range exceeds the reference value (1) (“Y” in step “S38”), The control of step “S37” is executed. That is, the brake member 54 is pressed against the cleaning web 44.
Then, after pressing the brake member 54 against the cleaning web 44, it is determined whether or not the print job is completed (step "S42").

When the number of consecutive pages that have an image area ratio outside the specified range is less than or equal to the reference value, and the ratio of the number of pages that have an image area ratio outside the specified range is also less than or equal to the reference value (“N” in step “S38”) As it is, it is determined whether or not the print job is finished (step "S42").
In the third embodiment, the cleaning web 44 is braked when the number of consecutive pages with an image area ratio outside the specified range exceeds the reference value, or when the ratio of the number of pages with the image area ratio outside the specified range exceeds the reference value. The member 54 is pressed. Thereby, the back tension can be supplemented by the frictional force between the brake member 54 and the cleaning web 44, and the cleaning web 44 can be prevented from slackening.

On the other hand, when the brake member 54 has already been pressed against the cleaning web 44 (“N” in step “S35”), the reference number (4) in which the continuous number of pages that have an image area ratio outside the specified range is set. ) It is determined whether or not (step “S39”).
When the continuation of the pages having the image area ratio outside the specified range is equal to or smaller than the reference value (“Y” in step “S39”), the reference value in which the ratio of the number of pages having the image area ratio outside the specified range is set in advance. (2) A determination is made as to whether or not it is below (step "S40").

When the number of continuous pages having an image area ratio outside the specified range is equal to or less than the reference value and the ratio of the number of pages having the image area ratio outside the specified range is also equal to or less than the reference value, the brake member 54 to the cleaning web 44 The pressing is released (step “S41”). Thereby, frictional force between the brake member 54 and the cleaning web 44 is not generated, and an increase in torque due to an unnecessary increase in back tension can be prevented.
Then, after releasing the pressing of the brake member 54 to the cleaning web 44, it is determined whether or not the print job is finished (step "S42").

  In addition, when the number of continuous pages having an image area ratio outside the specified range exceeds the reference value (“N” in step “39”), or the ratio of the number of pages having an image area ratio outside the specified range is the reference value. If it exceeds (N in Step “40”), the pressing of the brake member 54 is not released. That is, it is determined whether or not the print job is completed while maintaining the pressing of the brake member 54 against the cleaning web 44 (step "S42").

If it is determined in step “S42” that a print job remains (“N” in step “S42”), the process returns to step S32 and the process is repeated until the print job is completed. When the print job is finished (“Y” in step “S42”), the sheet passing operation is finished, and the web winding operation is also finished (step “S43”).
This series of processing is executed each time a sheet passing operation is performed, and the cleaning web 44 is prevented from slacking by performing until the life of the cleaning web 44 (the state in which the cleaning web 44 wound around the supply shaft 41 disappears). To do.

  FIG. 11 is an explanatory diagram of a change in the state of the winding shaft 43 before and after the web winding operation after the sheet passing operation. FIG. 11A is an explanatory diagram illustrating a state of the winding shaft 43 before the web winding operation after the sheet passing operation after the occurrence of winding loosening, and FIG. 11B illustrates the state after the occurrence of winding loosening. FIG. 5 is an explanatory diagram showing a state of the winding shaft 43 after the web winding operation after the sheet passing operation.

  Back tension is insufficient when the ratio of the number of pages of the image area ratio outside the specified range exceeds the preset reference value or the continuous number of pages of the image area ratio outside the specified range exceeds the preset reference value. It will be in the state. If printing is continued in this state and a winding operation is executed, the cleaning web 44 wound around the winding shaft 43 is wound in a state of insufficient back tension. As shown in the figure, there is a possibility that winding looseness occurs.

  When the state in which the loosening of the winding as shown in FIG. 11A continues occurs, the surface of the member to be cleaned (the fixing roller 31 in the present embodiment) is dragged to move the cleaning web 44 as shown in FIG. Looseness may occur. Further, when the recording paper P on which an image having a high image area ratio is formed after the loosening of the winding is passed and the dynamic frictional force at the web nip portion is increased, as shown in FIG. There is a possibility that the cleaning web 44 may be loosened.

  As shown in FIG. 8, the back tension can be supplemented by the frictional force between the brake member 54 and the cleaning web 44 by pressing the brake member 54 against the cleaning web 44. For this reason, the cleaning web 44 wound around the winding shaft 43 is tightly wound by executing the web winding operation after the sheet passing operation while the brake member 54 is pressed against the cleaning web 44. Thereby, as shown in FIG.11 (b), it will be in the state by which winding looseness was eliminated. Thereby, the slack of the cleaning web 44 can be prevented.

In the above-described embodiment, the case where the cleaning object that is cleaned by the cleaning means using the cleaning web is the fixing roller 31 as the fixing member has been described, but the cleaning object is not limited to the fixing member.
Any surface moving body to which an image forming substance can adhere, such as the intermediate transfer belt 3, the photosensitive member 10, and the conveying belt, and the amount of the image forming substance to be attached can vary depending on the image area ratio of the image to be formed. Applicable.

  In the above-described embodiment, the configuration in which the brake member 54 is pressed against the cleaning web 44 has been described as a configuration in which the winding resistance when the cleaning web 44 is wound by the winding shaft 43 is applied. The configuration for applying the winding resistance is not limited to the configuration in which the brake member 54 is pressed against the cleaning web 44. For example, a force that is required to feed the cleaning web from the feeding member may be increased, such as by providing a rotation resistance increasing member that increases the rotational resistance by contacting the supply shaft 41.

In the fixing cleaning device 40 of the present embodiment, “F3” acting on the supply shaft 41 side of the cleaning web 44 has the following value. That is, a value (N) obtained by dividing the torque (N · cm) required for rotating the supply shaft 41 by the radius (cm) of the roller-shaped cleaning web 44 wound around the supply shaft 41.
As the force constituting the force “F3”, in addition to the force acting by the torque described above, a resistance force for feeding the cleaning web 44 is added by providing a rotation resistance increasing means for increasing the rotation resistance of the supply shaft 41. It is good also as composition to do.

  In the web winding operation at the time of paper passing, by causing the resistance force of the cleaning web 44 to be fed from the supply shaft 41, the occurrence of loose winding during the web winding operation at the time of paper feeding can be suppressed. However, with a configuration in which a constant resistance is constantly applied, it is difficult to completely prevent the occurrence of winding looseness because it cannot cope with the fluctuation of the dynamic friction force between the cleaning web 44 and the fixing roller 31 due to the fluctuation of the image area ratio. It is. On the other hand, in the fixing cleaning device 40 of the present embodiment, the brake member 54 is pressed against the cleaning web 44 based on the image area ratio, so that the generated loosening can be eliminated, and the cleaning caused by the loosening is performed. The occurrence of slack in the web 44 can be prevented.

In the present embodiment, a pressing roller 42 that is a pressing member that presses the cleaning web 44 against the surface of the fixing roller 31 is provided. Accordingly, the cleaning web 44 can be brought into contact with the fixing roller 31 with an appropriate contact pressure, and the cleaning performance by the cleaning web 44 can be ensured.
The fixing cleaning device 40 included in the printer 100 according to the present embodiment is a web system that winds the cleaning web 44 at regular intervals. In a state in which the tension acting on the take-up shaft 43 caused by the change in the image area ratio occurs, the brake member 54 is pressed against the cleaning web 44 and the cleaning web 44 is taken up. Thereby, the cleaning web 44 wound around the winding shaft 43 is tightly wound, and it is possible to suppress the loosening of the cleaning web 44 or to eliminate the generated loosening. The state where the tension fluctuates means that the ratio of the number of pages with an image area ratio outside the specified range exceeds the reference value, or the number of continuous pages with an image area ratio outside the specified range exceeds the reference value. Etc.

  In the printer 100 of the present embodiment, winding resistance increase control for pressing the brake member 54 against the cleaning web 44 is executed as a configuration that prevents the loosening of the cleaning web 44 wound around the winding shaft 43 from occurring. The winding resistance increase control executed according to the image area ratio is not limited to this.

  The winding resistance increase control may be any control as long as the winding shaft 43 is rotationally driven in a state where the resistance when the cleaning web 44 moves toward the winding shaft 43 is increased. Examples of the configuration that increases the resistance of the cleaning web 44 moving toward the winding shaft 43 include the following configurations.

The pressing force applied to the fixing roller 31 by the pressing roller 42 is variable, and the pressing force is increased to increase the frictional force between the fixing roller 31 and the cleaning web 44 at the web nip portion, and the cleaning web 44 passes through the web nip portion. It is good also as a structure which increases resistance to do. By increasing the resistance passing through the web nip portion, the resistance when the cleaning web 44 moves toward the winding shaft 43 can be increased.
In addition, a pressure roller rotation regulating mechanism that regulates the rotation of the pressure roller 42 is provided, and the resistance that the cleaning web 44 wound around the pressure roller 42 moves toward the winding shaft 43 by regulating the rotation of the pressure roller 42 is provided. It is good also as a structure to increase.

  In the printer 100 of the present embodiment, the image area ratio calculating means for calculating the image area ratio of the image formed by the image forming means is the control unit 90. The configuration for calculating the image area ratio used for determining whether or not to perform the winding resistance increase control is not limited to the configuration provided in the printer 100. When outputting an image based on image information input from an external device, the external device calculates an image area ratio based on the image information, and transmits the image area ratio information to the control unit 90 of the printer 100 together with the image information. It is good also as a structure.

  What was demonstrated above is an example, and there exists an effect peculiar for every following aspect.

(Aspect A)
A belt-like cleaning body such as a cleaning web 44 that comes into contact with the surface of the body to be cleaned such as the fixing roller 31 to which an image forming substance such as toner used for image formation of the image forming unit such as the image forming unit 80 may adhere is to be cleaned. A feeding member such as a supply shaft 41 that feeds toward a contact portion (web nip portion or the like) of the paper and a winding member such as a winding shaft 43 that winds the belt-like cleaning body that is in contact with the object to be cleaned by being rotationally driven. In a cleaning device such as the fixing cleaning device 40, a winding resistance applying means such as a brake mechanism 50 that applies a winding resistance that prevents the belt-like cleaning body wound around the winding member from moving toward the winding member is provided. And a control unit such as a control unit 90 for controlling the winding resistance applying unit based on the image area ratio of the image formed on the recording medium such as the recording paper P by the image forming unit.
As a result of repeated extensive studies by the present inventors, when the image area ratio fluctuates and the amount of the image forming substance adhering to the object to be cleaned fluctuates, the winding of the belt-shaped cleaning element wound around the winding member becomes loose. It has been found that loosening may occur. This is considered to be due to the following reasons.
That is, when the image area ratio fluctuates and the amount of the image forming substance adhering to the object to be cleaned fluctuates, the amount of the image forming substance that reaches the contact portion (web nip part or the like) between the object to be cleaned and the belt-like cleaning object fluctuate. And when winding a strip | belt-shaped cleaning body around a winding member, the sliding load of the strip | belt-shaped cleaning body which slides with respect to a to-be-cleaned body in a contact part is fluctuate | varied. When the belt-like cleaning body is wound up in a state where the sliding load is large, the belt-like cleaning body can be wound up in a state where the belt-like cleaning body is strongly stretched between the contact portion and the winding member, and the belt-like cleaning body is tightly attached to the winding member. It is rolled up. On the other hand, when the belt-shaped cleaning body is wound in a state where the sliding load is small, the belt-shaped cleaning body is wound up in a state where the belt-shaped cleaning body is not strongly stretched between the contact portion and the winding member. It is considered that the winding member is loosely wound to cause loosening.
When winding looseness occurs, the surface to be cleaned moves, the belt-shaped cleaning body in the contact portion is brought along with the body to be cleaned, and when a force in the direction of pulling out the belt-shaped cleaning body wound around the winding member is applied, The belt-shaped cleaning body in which the winding is loosened is pulled out from the winding member, and the belt-shaped cleaning body is loosened.
On the other hand, in the aspect A, the control unit controls the winding resistance applying unit based on the image area ratio. Specifically, when the ratio of the recording medium on which an image with a low image area ratio is formed increases, the winding resistance decreases when the sliding load at the contact portion decreases and winding looseness may occur. The winding resistance applying means is controlled so as to increase. By increasing the winding resistance, the belt-shaped cleaning body can be wound tightly around the winding member, and the belt-shaped cleaning body can be tightly wound around the winding member to prevent loosening. Thereby, a strip | belt-shaped cleaning body is pulled out from the winding member in which winding looseness has arisen, and the problem that a slack generate | occur | produces in a strip | belt-shaped cleaning body can be suppressed.

(Aspect B)
In the aspect A, the control means such as the control unit 90 is based on the ratio of the recording medium whose image area ratio is out of the predetermined range with respect to the number of recording media such as the recording paper P on which the image such as the toner image is formed. When the ratio is exceeded, the winding resistance applied by the winding resistance applying means such as the brake mechanism 50 is increased (brake operation is performed).
According to this, as described in the first embodiment, it is possible to prevent the belt-like cleaning body such as the cleaning web 44 from being loosened and to prevent the belt-like cleaning body from loosening.

(Aspect C)
In the aspect B, the control means such as the control unit 90 is based on the ratio of the recording medium whose image area ratio is out of the predetermined range with respect to the number of recording media such as the recording paper P on which the image such as the toner image is formed. When the ratio is less than or equal to the ratio, the winding resistance applied by the winding resistance applying means such as the brake mechanism 50 is reduced (such as releasing the pressing of the brake member 54 against the cleaning web 44).
According to this, as described in the first embodiment, an increase in torque due to an unnecessary increase in back tension can be prevented.

(Aspect D)
In the aspect A, the control means such as the control unit 90 causes the brake mechanism 50 or the like to be wound when the continuous number of recording media such as the recording paper P whose image area ratio is outside the predetermined range exceeds the reference value. The winding resistance provided by the resistance applying means is increased (brake operation is performed).
According to this, as described in the second embodiment, it is possible to prevent the belt-like cleaning body such as the cleaning web 44 from being loosened and to prevent the belt-like cleaning body from loosening.

(Aspect E)
In the aspect D, the control means such as the control unit 90 causes the brake mechanism 50 or the like to be wound when the continuous number of recording media such as the recording paper P whose image area ratio is out of the predetermined range is equal to or less than the reference value. The winding resistance provided by the take-up resistance applying means is reduced (for example, the pressing of the brake member 54 against the cleaning web 44 is released).
According to this, as described in the second embodiment, an increase in torque due to an unnecessary increase in back tension can be prevented.

(Aspect F)
In any one of the aspects A to E, the winding resistance imparting means such as the brake mechanism 50 includes a brake member such as the brake member 54 disposed so as to be able to come into contact with and separate from the belt-shaped cleaning body such as the cleaning web 44. A winding resistance is imparted by bringing a brake member into contact with the belt-shaped cleaning body.
According to this, as explained about the above-mentioned embodiment, the composition which controls winding resistance with the frictional force between a beltlike cleaning object and a brake member is realizable.

(Aspect G)
In aspect F, a pressing member such as a pressing roller 42 that presses a belt-like cleaning body such as the cleaning web 44 against a member to be cleaned such as the fixing roller 31, and the belt-like cleaning body is formed by the pressing member and a brake member such as the brake member 54. By sandwiching, the brake member is brought into contact with the belt-shaped cleaning body.
According to this, as explained about the above-mentioned embodiment, a frictional force can be efficiently given to a beltlike cleaning object.

(Aspect H)
A fixing member such as a fixing roller 31 for fixing the image on the recording medium, and a fixing member for cleaning the surface of the fixing member. A fixing device such as the fixing device 30 provided with a member cleaning unit includes a cleaning device such as the fixing cleaning device 40 according to any one of modes A to G as a fixing member cleaning unit.
According to this, as described in the above embodiment, it is possible to prevent the occurrence of problems such as a paper jam in the vicinity of the fixing device due to the slack in the belt-like cleaning body such as the cleaning web 44.

(Aspect I)
In an image forming apparatus such as a printer 100 including a cleaning unit that cleans the surface of a member to be cleaned such as a fixing roller 31 to which an image forming substance such as toner used for image formation of an image forming unit such as an image forming unit 80 may adhere. A cleaning device such as the fixing cleaning device 40 according to any one of modes A to G is provided as a cleaning unit.
According to this, as described in the above embodiment, it is possible to prevent the occurrence of problems such as a paper jam caused by slack in the belt-shaped cleaning body such as the cleaning web 44.

DESCRIPTION OF SYMBOLS 1 Printer main body 2 Paper feed cassette 3 Intermediate transfer belt 4 Cleaning opposing roller 6 Secondary transfer opposing roller 7 Intermediate transfer unit 8 Image forming unit 8K Image forming unit 10 for black Photoconductor 10K Photoconductor 11 for black 11 Charging device 12 Developing device 13 Photoconductor cleaning device 14 Primary transfer roller 15 Exposure unit 20 Secondary transfer roller 21 Belt cleaning device 23 Discharge roller pair 24 Registration roller pair 25 Loading tray 30 Fixing device 31 Fixing roller 32 Pressure roller 33 Heater 34 Separation claw 35 Temperature sensor 36 Entrance guide 37 Exit guide 40 Fixing cleaning device 41 Supply shaft 42 Pressing roller 43 Winding shaft 44 Cleaning web 49 Winding motor 50 Brake mechanism 51 Eccentric cam 52 Brake member contact / separation drive unit 53 Brake rotation shaft 54 Brake member 0 toner supply bottle 80 imaging unit 90 controller 100 printer L laser beam P recording paper

Japanese Patent Laying-Open No. 2015-090428

Claims (9)

The belt-shaped cleaning body that contacts the surface of the body to be cleaned to which the image forming material used for image formation of the image forming means may adhere is sent to the contact portion with the body to be cleaned, and the feed member is rotated to drive the belt. In a cleaning device comprising a winding member that winds up the belt-shaped cleaning body that is in contact with the cleaning body,
A winding resistance applying means for applying a winding resistance that prevents the belt-shaped cleaning body wound around the winding member from moving toward the winding member;
A cleaning apparatus comprising: a control unit that controls the winding resistance applying unit based on an image area ratio of an image formed on a recording medium by the image forming unit. The cleaning device according to claim 1,
When the ratio of the recording medium in which the image area ratio is out of a predetermined range with respect to the number of recording media on which the image is formed exceeds a reference ratio, the winding resistance applying means A cleaning device characterized by increasing the winding resistance applied by the cleaning device. The cleaning device according to claim 2, wherein
The control means provides the winding resistance when the ratio of the recording medium in which the image area ratio is out of a predetermined range with respect to the number of the recording media on which the image is formed is equal to or less than a reference ratio. A cleaning device characterized in that the winding resistance provided by the means is reduced. In the cleaning device according to any one of claims 1 to 3,
The control means increases the winding resistance applied by the winding resistance applying means when the continuous number of the recording media whose image area ratio is out of a predetermined range exceeds a reference value. A cleaning device characterized. The cleaning apparatus according to claim 4.
The control means reduces the winding resistance provided by the winding resistance applying means when the continuous number of the recording media whose image area ratio is out of a predetermined range becomes a reference value or less. A cleaning device characterized by. In the cleaning device according to any one of claims 1 to 5,
The winding resistance applying means includes a brake member arranged so as to be able to contact and separate from the belt-shaped cleaning body,
The cleaning device, wherein the winding resistance is applied by bringing the brake member into contact with the belt-like cleaning body. The cleaning device according to claim 6.
A pressing member that presses the belt-shaped cleaning body against the body to be cleaned;
A cleaning device, wherein the belt member is brought into contact with the belt-like cleaning body by sandwiching the belt-like cleaning body between the pressing member and the brake member. A fixing member that moves the surface endlessly, contacts the recording medium on which the image is formed, and fixes the image on the recording medium;
In a fixing device comprising a fixing member cleaning means for cleaning the surface of the fixing member,
A fixing device comprising the cleaning device according to claim 1 as the fixing member cleaning unit. In an image forming apparatus including a cleaning unit that cleans the surface of an object to be cleaned to which an image forming material used for image formation of the image forming unit may adhere.
An image forming apparatus comprising the cleaning device according to claim 1 as the cleaning unit.

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