JP2010039272A - Belt cleaning device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a belt cleaning device that satisfactorily exhibits cleaning performance and suppresses the deformation of a cleaning member and a belt caused by a creep phenomenon. <P>SOLUTION: The belt cleaning device includes: the belt cleaning member 23 for cleaning the belt 10 by coming into contact with the peripheral face of an endless belt 10 extended by a plurality of rollers including a drive roller; and a pressing means 24 for pressing the belt cleaning member 23 from the internal circumferential side of the belt 10. The device further includes a pressing force varying means 28 for changing the pressing force of the pressing means 24 to the belt cleaning member 23. While the belt cleaning member 23 and the belt 10 are kept in contact with each other, the pressing force of the pressing means 24 is varied by the pressing force varying means 28. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a belt cleaning device that removes deposits adhering to the surface of a belt, and an image forming apparatus including the belt cleaning device.

  As an image forming apparatus using an electrophotographic image forming process such as a copying machine, a facsimile machine, a printer, etc., toner images of different colors carried on the surfaces of a plurality of photosensitive members are primarily transferred to an intermediate transfer belt, and the intermediate 2. Description of the Related Art An indirect transfer type image forming apparatus is known in which a toner image transferred to a transfer body is secondarily transferred collectively to a recording medium such as paper.

  In this type of image forming apparatus, a part of toner remains on the intermediate transfer belt after the secondary transfer. For this reason, the image forming apparatus is provided with a belt cleaning device having a cleaning blade or the like for removing residual toner on the intermediate transfer belt.

  FIG. 13 is an enlarged view of a peripheral portion of the cleaning blade 200 included in the belt cleaning device. As shown in FIG. 13, the tip of the cleaning blade 200 is in contact with the surface of the intermediate transfer belt 300. Further, the tip of the cleaning blade 200 is supported from the back side of the intermediate transfer belt 300 by the backup roller 400. The intermediate transfer belt 300 travels in the direction of the arrow in the figure, and at that time, toner, dust, and the like adhering to the intermediate transfer belt 300 are scraped off and removed by the tip of the cleaning blade 200.

  When the contact pressure of the cleaning blade 200 with respect to the intermediate transfer belt 300 increases, the cleaning blade 200 deforms as indicated by the dotted line in the figure, and the cleaning angle formed between the front end surface 200a of the cleaning blade 200 and the surface of the intermediate transfer belt 300. (Contact angle) changes from θ1 to θ2. In order for the cleaning blade 200 to exhibit good cleaning properties, it is necessary to set the cleaning angle and contact pressure of the cleaning blade 200 to an appropriate state.

  Further, as shown in FIG. 14, there is a conventional belt cleaning device configured such that the tip of the cleaning blade 200 is supported by a tension roller 500 that applies tension to the intermediate transfer belt 300. This belt cleaning device moves the cleaning blade 200 following the movement of the tension roller 500 in order to maintain the cleaning angle and contact pressure of the cleaning blade 200 in an appropriate state (Patent Documents 1, 2 or 3).

  By the way, when the contact pressure of the cleaning blade with respect to the intermediate transfer belt is set to be large, the cleaning property is improved. However, if the cleaning blade is kept in strong pressure contact with the intermediate transfer belt, the cleaning blade is deformed by a creep phenomenon. When the cleaning blade is deformed by the creep phenomenon, the cleaning angle and the contact pressure are changed, and as a result, the cleaning performance is deteriorated. Further, since the cleaning blade is in strong pressure contact with the intermediate transfer belt, the intermediate transfer belt may be deformed by a creep phenomenon.

  For this reason, some conventional image forming apparatuses are configured such that the cleaning blade is separated from the intermediate transfer belt and waits in a non-contact state in order to suppress deformation due to the creep phenomenon of the cleaning blade and the intermediate transfer belt. (For example, see Patent Documents 3, 4, 5 or 6).

Accordingly, the pressure contact of the cleaning blade with the intermediate transfer belt can be released, and an excessive load is not applied to the cleaning blade and the intermediate transfer belt, and deformation due to a creep phenomenon is suppressed.
JP 2006-106465 A JP 2005-70509 A JP-A-3-220571 Japanese Patent No. 3796999 Japanese Patent No. 3050691 JP 2007-279092 A

  However, in the above-described conventional belt cleaning device, when the pressure contact of the cleaning blade to the intermediate transfer belt is released, the cleaning blade is not in contact with the intermediate transfer belt. May collapse. When the removed matter adhering to the cleaning blade partially collapses, there is a difference in cleaning properties between the portion of the cleaning blade where the removed matter adheres and the portion where it does not adhere, and uniform cleaning properties cannot be exhibited. In addition, when the cleaning blade separated from the intermediate transfer belt is brought into contact with the intermediate transfer belt, there is a possibility that the removed material or the like dropped between the intermediate transfer belt and the intermediate blade is caught between the cleaning blade and the intermediate transfer belt. If the removed material or the like is caught between the cleaning blade and the intermediate transfer belt, the toner on the intermediate transfer belt slips out from the portion where the removed material of the cleaning blade is caught, resulting in a problem that the cleaning property deteriorates.

  Further, the cleaning performance of the cleaning blade is affected by the magnitude of the electrostatic force of the toner layer on the intermediate transfer belt. For this reason, when the electrostatic force of the toner layer on the intermediate transfer belt changes with time, it is necessary to adjust the cleaning angle and contact pressure of the cleaning blade accordingly. However, the above patent document does not disclose means for adjusting the cleaning performance of the cleaning blade.

  In view of such circumstances, the present invention intends to provide a belt cleaning device and an image forming apparatus that can exhibit good cleaning properties and suppress deformation of the cleaning blade and the intermediate transfer belt due to a creep phenomenon.

  According to the first aspect of the present invention, there is provided a belt cleaning member that contacts an outer peripheral surface of an endless belt stretched by a plurality of rollers including a driving roller to clean the belt, and the belt from the inner peripheral surface side of the belt. A belt cleaning apparatus including a pressing unit that presses the cleaning member, the belt cleaning device including a pressing force variable unit that changes a pressing force of the pressing unit against the belt cleaning member, and maintains the state in which the belt cleaning member and the belt are in contact with each other. However, the pressing force of the pressing means is changed by the pressing force variable means.

  By changing the pressing force of the pressing means by the pressing force variable means, the contact pressure of the belt cleaning member with respect to the belt can be changed. For this reason, when the belt cleaning member is not used, it is possible to prevent the belt cleaning member and the belt from being subjected to an excessive load by reducing and reducing the contact pressure of the belt cleaning member.

  It is also possible to adjust the contact pressure and cleaning angle of the belt cleaning member with respect to the belt to an appropriate state by changing the pressing force of the pressing means. Thereby, a good cleaning property can be exhibited.

  Further, when the pressing force of the pressing means is changed, the belt cleaning member can maintain a state in contact with the belt. For this reason, there is no possibility that a part of the removed matter adhering to the belt cleaning member collapses and falls onto the belt, or the removed matter is caught between the belt cleaning member and the belt.

  According to a second aspect of the present invention, in the cleaning device according to the first aspect, the pressing means is disposed to face the belt cleaning member via the belt and approaches / separates the belt cleaning member. And a biasing means for biasing the backup roller to the belt cleaning member, and the biasing force of the biasing means is changed within a predetermined range by the pressing force variable means. In addition, the belt cleaning member is disposed so as to come into contact with the belt in a state where the urging force of the urging means is set to the minimum urging force within the predetermined range.

  By changing the urging force of the urging means by the pressing force varying means, the pressing force of the backup roller against the belt cleaning member can be changed. As the pressing force of the backup roller changes, the contact pressure of the belt cleaning member with respect to the belt changes. In addition, when the urging force of the urging means is set to the minimum urging force within a predetermined range, the belt cleaning member and the belt are in contact with each other because the belt cleaning member is disposed in contact with the belt. It is possible to change the urging force of the urging means while maintaining the above.

  According to a third aspect of the present invention, in the belt cleaning device according to the second aspect, the bearing for supporting both ends of the rotation shaft of the backup roller is urged to the belt cleaning member by the urging means. It is.

  Since the bearing of the backup roller is pressed by the biasing means, the biasing force can be stably applied to the backup roller. As a result, it is possible to suppress the occurrence of variations in the contact pressure of the belt cleaning member with respect to the belt, and to exhibit stable cleaning properties.

  According to a fourth aspect of the present invention, in the belt cleaning device according to the third aspect, a compression coil spring is provided as the urging means for urging the bearing, and the degree of compression of the compression coil spring is changed by the pressing force varying means. It is comprised so that it may make it.

  It is possible to change the urging force of the compression coil spring by changing the degree of compression of the compression coil spring by the pressing force varying means.

  According to a fifth aspect of the present invention, in the belt cleaning apparatus according to the second aspect of the present invention, the belt cleaning device includes a swinging member disposed so as to be swingable in a direction approaching and separating from the belt cleaning member. The backup roller is rotatably attached to one end portion that swings, and the urging means is disposed on the other end side opposite to the one end portion of the oscillating member. The moving member is biased so as to swing in a direction approaching the belt cleaning member.

  The biasing means can be disposed at a position away from the backup roller. For this reason, it is possible to avoid the crowding of parts near the backup roller, and it is possible to increase the design margin.

  According to a sixth aspect of the present invention, in the belt cleaning device according to the fifth aspect, a torsion coil spring is provided as the urging means for urging the swing member, and the torsion degree of the torsion coil spring by the pressing force varying means. Is configured to change.

  It is possible to change the urging force of the torsion coil spring by changing the degree of torsion of the torsion coil spring by the pressing force varying means.

  A seventh aspect of the present invention is the belt cleaning device according to the second aspect, wherein a plurality of the urging means are arranged in parallel in the axial direction of the backup roller, and the backup roller is moved to the belt cleaning member by the plurality of urging means. It is comprised so that it may bias.

  By urging the backup roller by the plurality of urging means, the backup roller can be uniformly pressed in the axial direction against the belt cleaning member. Thereby, the contact pressure of the belt cleaning member with respect to the belt can be made uniform, and good cleaning properties can be stably exhibited.

  According to an eighth aspect of the present invention, in the belt cleaning device according to the seventh aspect, the plurality of urging means are configured to urge the backup roller via a rotatable support roller.

  Thereby, it is possible to apply a biasing force to the backup roller while maintaining a smooth rotation of the backup roller.

  According to a ninth aspect of the present invention, in the belt cleaning device according to any one of the second to eighth aspects, a range in which the backup roller is displaceable is determined based on a contact pressure of the belt cleaning member and the backup roller. It is set inside the belt when it is stretched in a state where it is not subjected to a pressing force from the belt.

  By setting the range in which the backup roller can be displaced as described above, it is possible to prevent the belt from loosening due to the displacement of the backup roller. Thereby, it becomes possible to maintain the cleaning property of the belt cleaning member well.

  A tenth aspect of the present invention is the belt cleaning apparatus according to any one of the first to eighth aspects, wherein tension is applied to the belt by the pressing means.

  When the drive roller is rotated and the belt travels around, a braking force that prevents the belt from traveling is generated at the contact position between the belt cleaning member and the belt. Therefore, the belt tension is loosened on the opposite side (upstream side) of the belt traveling direction from the contact position between the belt cleaning member and the belt. This loosening of the belt tension can be suppressed by applying tension to the belt by the pressing means. Thereby, fluctuations in belt tension can be suppressed, and the cleaning performance of the belt cleaning member is stabilized.

  An eleventh aspect of the present invention is the belt cleaning device according to any one of the first to tenth aspects, wherein the pressing force varying means can be manually operated.

  Thereby, the user etc. can change the pressing force of a pressing means by operating a pressing force variable means as needed.

  According to a twelfth aspect of the present invention, in the belt cleaning device according to any one of the first to eleventh aspects, a control unit that controls the pressing force varying unit based on a preset condition is provided.

  The pressing force variable means can be automatically controlled by the control means, and the operation burden on the user or the like can be reduced.

  According to a thirteenth aspect of the present invention, in the belt cleaning apparatus according to the twelfth aspect, the pressing means is controlled at the predetermined timing before the belt cleaning is started by controlling the pressing force varying means by the control means. The pressure is increased so that the contact pressure of the belt cleaning member with respect to the belt becomes a preset contact pressure for cleaning, and the pressing force of the pressing means is reduced at a predetermined timing after the cleaning of the belt. Thus, the contact pressure of the belt cleaning member with respect to the belt is set to a preset contact pressure for standby.

  As a result, when the belt cleaning member is not used, the contact pressure of the belt cleaning member can be automatically reduced by the control means so that the belt cleaning member and the belt are not excessively loaded. can do.

  According to a fourteenth aspect of the present invention, in the belt cleaning apparatus according to the twelfth or thirteenth aspect, the control unit includes a determination unit that determines whether the cleaning by the belt cleaning member is sufficient, and the determination unit If it is determined that the cleaning is insufficient, the pressing force of the pressing means is increased by controlling the pressing force variable means.

  As a result, the contact pressure of the belt cleaning member is automatically increased based on the determination by the determination unit, and the contact pressure and the cleaning angle of the belt cleaning member can be adjusted to an appropriate state.

  According to a fifteenth aspect of the present invention, an endless belt stretched by a plurality of rollers including a driving roller, a belt cleaning member that contacts the outer peripheral surface of the belt and cleans the belt, and an inner peripheral surface of the belt In the image forming apparatus including a pressing unit that presses the belt cleaning member from the side, the image forming apparatus includes a pressing force varying unit that changes a pressing force of the pressing unit against the belt cleaning member. The pressing force of the pressing means is changed by the pressing force varying means while maintaining the belt in contact with each other.

  The image forming apparatus of the fifteenth aspect can exhibit the same operation and effect as the belt cleaning apparatus of the first aspect.

  According to a sixteenth aspect of the present invention, in the image forming apparatus according to the fifteenth aspect, a unit in which at least the belt, the pressing unit, and the pressing force varying unit are integrally configured is detachable from the image forming apparatus main body. In the image forming apparatus, the pressing force varying means includes an interference portion provided in the image forming apparatus main body and a displaceable moving member provided on the pressing means side, and the unit is used as the image forming apparatus. When the movable member is mounted on the main body, the moving member interferes with the interference member and is displaced to increase the pressing force of the pressing means, and the contact pressure of the belt cleaning member with respect to the belt is set in advance. It is comprised so that it may become the contact pressure of.

  Accordingly, when the unit is mounted on the image forming apparatus main body, the user or the like does not need to perform an operation for setting the contact pressure of the belt cleaning member with respect to the belt. Therefore, it is possible to reduce the operation burden on the user and the like, and it is possible to prevent the occurrence of defective cleaning due to forgetting to perform the setting operation of the contact pressure. Further, when the unit is not attached to the main body of the image forming apparatus, the contact pressure of the belt cleaning member with respect to the belt can be reduced and kept small, so that an unnecessary load is not applied to the belt cleaning member and the belt. be able to.

  According to the belt cleaning device and the image forming apparatus including the belt cleaning device of the present invention, the contact pressure of the belt cleaning member with respect to the belt can be changed. For this reason, when the belt cleaning device is not used, it is possible to prevent the belt cleaning member and the belt from being subjected to an excessive load by reducing the contact pressure of the belt cleaning member to be small. As a result, the belt cleaning member and the belt can be prevented from being deformed due to the creep phenomenon, and the life of these members can be extended.

  It is also possible to adjust the contact pressure and cleaning angle of the belt cleaning member to the belt to an appropriate state. Thereby, a good cleaning property can be exhibited.

  Further, when the pressing force of the pressing means is changed, particularly when the pressing force is reduced, the belt cleaning member can maintain a state in contact with the belt. For this reason, it is possible to prevent a part of the removed matter adhering to the belt cleaning member from collapsing, and it is possible to prevent variations in cleaning properties caused by the partial collapse of the removed article. In addition, since there is no possibility that the removed material bites between the belt cleaning member and the belt, it is possible to exhibit good cleaning properties.

  FIG. 1 is a schematic configuration diagram showing an embodiment of an image forming apparatus according to the present invention. The image forming apparatus of the present invention shown in FIG. 1 includes four process units 1Y, 1C, 1M, and 1Bk. Each of the process units 1Y, 1C, 1M, and 1Bk is configured to be detachable from the image forming apparatus main body 100.

  The process units 1Y, 1C, 1M, and 1Bk have the same configuration except that they contain toners of different colors of yellow, cyan, magenta, and black corresponding to the color separation components of the color image. Therefore, the configuration of one process unit 1Y will be described as an example.

  The process unit 1Y includes a photosensitive member 2 as an electrostatic latent image carrier, a charging roller 3 as a charging unit that charges the surface of the photosensitive member 2, and a developing unit that forms a toner image on the surface of the photosensitive member 2. A developing device 4 and a photosensitive member cleaning blade 5 as a cleaning means for cleaning the surface of the photosensitive member 2 are provided.

  Above each of the process units 1Y, 1C, 1M, and 1Bk, an exposure device 7 is disposed as an exposure unit that exposes the surface of the photoreceptor 2. An intermediate transfer unit 6 is disposed below each process unit 1Y, 1C, 1M, 1Bk. The intermediate transfer unit 6 has an intermediate transfer belt 10 constituted by an endless belt. The intermediate transfer belt 10 is stretched around a driving roller 8 and a driven roller 9 and is configured to be able to run around in the direction of the arrow in the figure. The driven roller 9 functions as a tension roller for applying a predetermined tension to the intermediate transfer belt 10.

  On the inner peripheral surface of the intermediate transfer belt 10, four primary transfer rollers 11Y, 11C, 11M, and 11Bk as primary transfer units are disposed to face the four photoconductors 2. The four photoconductors 2 are in pressure contact with the outer peripheral surface of the intermediate transfer belt 10, and a primary transfer nip is formed at each pressure contact portion.

  A secondary transfer roller 12 as a secondary transfer unit is disposed at a position facing the driving roller 8 that stretches the intermediate transfer belt 10. The secondary transfer roller 12 is in pressure contact with the outer peripheral surface of the intermediate transfer belt 10 and forms a secondary transfer nip at the pressure contact portion.

  The intermediate transfer unit 6 includes a belt cleaning device 21 for cleaning the surface of the intermediate transfer belt 10. A waste toner container 22 for storing waste toner is disposed below the intermediate transfer unit 6. A waste toner transfer hose (not shown) extending from the belt cleaning device 21 is connected to the entrance of the waste toner container 22.

  A recording medium storage unit 13 that stores a recording medium S such as paper or an OHP sheet is disposed below the image forming apparatus main body 100. The recording medium accommodating portion 13 is provided with a supply roller 14 for carrying out the recording medium S and the like.

  In the image forming apparatus main body 100, a conveyance path R for guiding the recording medium S upward from the recording medium accommodating portion 13 is disposed. A pair of registration rollers 15a and 15b are disposed on the upstream side (downward in the drawing) of the transport path R with respect to the secondary transfer nip formed by the drive roller 8 and the secondary transfer roller 12. In addition, the fixing device 16 is disposed downstream of the secondary transfer nip in the conveyance direction of the conveyance path R (upward in the drawing). The fixing device 16 includes a heating roller 17 and a pressure roller 18. The heating roller 17 and the pressure roller 18 are in pressure contact with each other, and a fixing nip is formed at the pressure contact portion.

  A pair of discharge rollers 19 a and 19 b are disposed at the downstream end of the transport path R in the transport direction. In addition, a stock unit 20 on which the recording medium S is loaded is formed with the upper surface of the image forming apparatus main body 100 being recessed inward.

  As shown in FIG. 2, a front cover 100a provided at the front portion (right side in the figure) of the image forming apparatus main body 100 is configured to be openable and closable around a fulcrum 100b. The intermediate transfer unit 6 is configured to be detachable from the image forming apparatus main body 100 in the horizontal direction. As shown by a two-dot chain line in FIG. 2, the intermediate cover unit 6 is moved to the right in the figure by swinging the front cover 100a forward and retracting the secondary transfer roller 12 from the front of the drive roller 8. Can be removed.

  FIG. 3 is an enlarged view of a peripheral portion of the belt cleaning device 21 included in the intermediate transfer unit 6. Hereinafter, based on FIG. 3, 1st Embodiment of the belt cleaning apparatus 21 which concerns on this invention is described.

  The belt cleaning device 21 has a belt cleaning blade (belt cleaning member) 23 for cleaning the surface (outer peripheral surface) of the intermediate transfer belt 10. The tip of the belt cleaning blade 23 is disposed in contact with the outer peripheral surface of the intermediate transfer belt 10. In the embodiment of the present invention, the belt cleaning blade 23 is brought into contact with the intermediate transfer belt 10 in the counter direction from the viewpoint of achieving good cleaning properties. However, the cleaning blade 23 is attached to the intermediate transfer belt 10. On the other hand, you may make it contact in the trailing direction.

  Further, the belt cleaning device 21 includes a pressing unit 24 that presses the belt cleaning blade 23 from the inside of the intermediate transfer belt 10. The pressing unit 24 includes a backup roller 25 and a compression coil spring 26 as an urging unit.

  The backup roller 25 is disposed to face the belt cleaning blade 23 with the intermediate transfer belt 10 interposed therebetween. Both ends of the rotation shaft of the backup roller 25 are supported by bearings 27, and the bearings 27 are configured to be displaceable in directions toward and away from the belt cleaning blade 23. The compression coil spring 26 urges the backup roller 25 to the belt cleaning blade 23 via a bearing 27. As a result, the backup roller 25 presses the belt cleaning blade 23 via the intermediate transfer belt 10.

  Further, the belt cleaning device 21 has a pressing force variable means 28 for changing the degree of compression of the compression coil spring 26. Specifically, the pressing force varying means 28 includes a movable member 29 that can be displaced and an operation member 30 that displaces the movable member 29.

  The moving member 29 is attached to the lower end portion of the compression coil spring 26 and is disposed on the upper surface of the operation member 30. The operation member 30 is configured to be manually movable in the horizontal direction (the left-right direction in the figure). On the upper surface of the operation member 30, a sliding surface 30a is formed by connecting surfaces having different heights with inclined surfaces. As the operating member 30 is moved in the horizontal direction, the moving member 29 slides on the sliding surface 30a and moves in the vertical direction (vertical direction in the figure). That is, the moving member 29 is configured to be able to reciprocate in the compression direction and the extension direction of the compression coil spring 26.

  Further, the sliding surface 30a of the operation member 30 shown in FIG. 3 is configured by connecting two surfaces having different heights with an inclined surface, but the sliding surface 30a has three surfaces having different heights from each other. It is also possible to form by connecting more than the surfaces and connecting them with inclined surfaces.

  FIG. 4 shows a second embodiment of the belt cleaning device 21 according to the present invention. 4, the same reference numerals as those in FIG. 3 denote the same members as in FIG. The belt cleaning device 21 shown in FIG. 4 includes a solenoid 33 as a drive unit that horizontally moves the operation member 30 and a control unit 32 that includes a CPU or the like for controlling the drive of the solenoid 33.

  The control means 32 automatically controls the driving of the solenoid 33 based on preset conditions. Specifically, the control means 32 is configured to drive the solenoid 33 at a predetermined timing before the start of cleaning by the belt cleaning blade 23 and at a predetermined timing after the end of cleaning. The control unit 32 is provided with a determination unit (not shown) for determining whether or not the cleaning by the belt cleaning blade 23 is sufficient, and the control unit 32 drives the solenoid 33 based on the determination result of the determination unit. You may comprise so that it may control. The condition for the control means 32 to drive the solenoid 33 is not limited to the above-described condition. The control means 32 can drive the solenoid 33 based on other conditions, or the control means 32 can be configured to control the solenoid 33 in response to an instruction from a user or the like.

  FIG. 5 shows a third embodiment of the belt cleaning device 21 according to the present invention. The belt cleaning device 21 shown in FIG. 5 also has a belt cleaning blade 23 for cleaning the surface of the intermediate transfer belt 10 and a pressing unit that presses the belt cleaning blade 23 from the inside of the intermediate transfer belt 10, as in the above embodiment. 24. The pressing means 24 includes a backup roller 25, a torsion coil spring 35 as an urging means, and a longitudinal swing member 34 for transmitting the urging force of the torsion coil spring 35 to the backup roller 25.

  The swing member 34 is configured to be swingable in a direction in which one end thereof approaches and separates from the belt cleaning blade 23 around the support shaft 36. A bearing 27 that supports both ends of the rotating shaft of the backup roller 25 is attached to one end of the swinging member 34 that swings. A torsion coil spring 35 is attached to a support shaft 36 disposed on the other end side opposite to the one end portion where the swing member 34 swings. The torsion coil spring 35 urges the swinging end of the swinging member 34 in a direction approaching the belt cleaning blade 23, and the backup roller 25 is pressed against the belt cleaning blade 23.

  Further, the belt cleaning device 21 includes a pressing force variable means 28 for changing the degree of twist of the torsion coil spring 35. Specifically, the pressing force varying means 28 includes a moving member 37 and an operation member 31 that displaces the moving member 37.

  The moving member 37 is attached to one end of the torsion coil spring 35. The operation member 31 is configured to be manually movable in the horizontal direction (left-right direction in the figure). A protrusion 31 a is provided on the upper surface of the operation member 31, and the protrusion 31 a is disposed so as to contact the moving member 37. As the operating member 31 is moved horizontally, the moving member 37 is configured to move in a direction in which the torsion coil spring 35 is twisted and a direction in which the twist is released. Further, when the operating member 31 moves the moving member 37 in the twisting direction of the torsion coil spring 35, the moving member 37 after the movement receives a biasing force of the torsion coil spring 35 and is not returned. A holding mechanism is provided (not shown).

  Further, in this case, the operation member 31 is configured to be manually moved, but a control unit that controls the operation member 31 based on preset conditions may be provided (not shown).

  In the belt cleaning apparatus shown in FIGS. 3 to 5, the moving members 29 and 37 and the operating members 30 and 31 are configured as separate members. However, the operating unit is integrated with the moving members 29 and 37. It is also possible to dispose the moving members 29 and 37 by directly and manually operating the operation section.

  FIG. 6 shows a fourth embodiment of the belt cleaning device 21 according to the present invention. In FIG. 6, the right side is the front of the image forming apparatus main body 100, and the direction of the arrow A in the figure is the mounting direction of the intermediate transfer unit 6 with respect to the image forming apparatus main body 100. In FIG. 6, the same reference numerals as those in FIG. 3 or FIG. 4 denote the same members as in FIG. 3 or FIG.

  In the belt cleaning device 21 shown in FIG. 6, the pressing force varying means 28 for changing the urging force of the compression coil spring 26 includes a moving member 38 attached to the lower end portion of the compression coil spring 26, and the interior of the image forming apparatus main body 100. It is comprised by the interference part 39 provided in the flame | frame. The interference unit 39 has a guide surface 39 a that is inclined upward in the mounting direction A of the intermediate transfer unit 6. When the intermediate transfer unit 6 is mounted on the image forming apparatus main body 100, the moving member 38 is configured to abut against the guide surface 39a.

  FIG. 7 shows a fifth embodiment of the belt cleaning device 21 according to the present invention. In FIG. 7, the right side is the front of the image forming apparatus main body 100, and the direction of the arrow A in the figure is the mounting direction of the intermediate transfer unit 6 with respect to the image forming apparatus main body 100. In FIG. 7, the same reference numerals as those in FIG. 5 denote the same members as in FIG.

  In the belt cleaning device 21 shown in FIG. 7, as the pressing force varying means 28 for changing the urging force of the torsion coil spring 35, the moving member 40 attached to one end of the torsion coil spring 35 and the inside of the image forming apparatus main body 100 are used. It is comprised by the protrusion-shaped interference part 41 provided in the flame | frame. When the intermediate transfer unit 6 is mounted on the image forming apparatus main body 100, the moving member 40 is configured to contact the interference unit 41.

FIG. 8 shows a sixth embodiment of the belt cleaning device 21 according to the present invention.
As shown in FIG. 8, the backup roller 25 is supported by four support rollers 42 that are rotatably held by a holder 43. The four support rollers 42 extend in the same direction as the axial direction of the backup roller 25, and are arranged in parallel in the axial direction of the backup roller 25. An upper end portion of a compression coil spring 44 as an urging means is disposed in contact with the lower surface of each holder 43. The holders 43 are biased upward by the compression coil springs 44, whereby the support rollers 42 are pressed against the backup roller 25. Further, the number of the compression coil springs 26 is not limited to four as long as it is plural. Further, the backup roller 25 may be supported by one support roller that is long in the axial direction. In FIG. 8, the intermediate transfer belt 10, the belt cleaning blade 23, the pressing force varying means 28 for changing the urging force of each compression coil spring 44, and the like are omitted.

  Further, as shown in FIG. 9, the belt cleaning device 21 of the present invention is in a state where the belt cleaning blade 23 is in contact with the intermediate transfer belt 10 even if the pressing force of the backup roller 25 against the belt cleaning blade 23 is changed. Is configured to maintain. That is, as shown by the dotted line in FIG. 9, even when the urging force of the urging means (not shown) with respect to the backup roller 25 is minimized within a predetermined range, the tip of the cleaning blade 23 is at the intermediate transfer belt. 10 is contacted.

The basic operation of the image forming apparatus will be described below with reference to FIG.
In the process unit 1Y, the photosensitive member 2 is rotated in the direction of the arrow in the figure, and the surface of the photosensitive member 2 is charged to a uniform high potential by the charging roller 3. Next, a laser beam is irradiated from the exposure device 7 to the surface of the photoconductor 2 based on the image data, and the potential of the irradiated portion is lowered to form an electrostatic latent image. The toner charged by the developing device 4 is electrostatically transferred to the portion of the electrostatic latent image formed on the surface of the photoreceptor 2 to form a yellow toner image (visualization).

  The primary transfer roller 11Y is applied with a constant voltage or a constant current controlled voltage having a polarity opposite to the charging polarity of the toner. As a result, a transfer electric field is formed in the primary transfer nip between the primary transfer roller 11Y and the photoreceptor 2. Then, in the primary transfer nip, the toner image on the rotating photoconductor 2 is primarily transferred to the intermediate transfer belt 10 running in the direction of the arrow in the figure.

  In each of the other process units 1C, 1M, and 1Bk, a toner image is similarly formed on the photoreceptor 2, and the four color toner images are primarily transferred to the intermediate transfer belt 10 so as to overlap each other.

  Further, the surface of the photoreceptor 2 after the primary transfer process is cleaned by the photoreceptor cleaning blade 5 to remove residual toner. Further, the residual charge remaining on the surface of the photoreceptor 2 is neutralized by a neutralizing lamp (not shown).

  On the other hand, the recording medium S accommodated in the recording medium accommodating portion 13 is sent out to the conveyance path R by rotating the supply roller 14. The sent recording medium S is temporarily stopped by the registration rollers 15a and 15b.

  Further, a voltage having a polarity opposite to the charging polarity of the toner is applied to the secondary transfer roller 12 to form a transfer electric field in the secondary transfer nip. Alternatively, a similar transfer electric field may be formed by applying a voltage having the same polarity as the charging polarity of the toner to the driving roller 8 facing the secondary transfer roller 12. Thereafter, the driving of the registration rollers 15a and 15b is resumed, and the recording medium S is sent to the secondary transfer nip in synchronism with the toner image on the intermediate transfer belt 10. Then, the toner image on the intermediate transfer belt 10 is secondarily transferred collectively onto the recording medium S by a transfer electric field formed in the secondary transfer nip. Further, after the secondary transfer, the toner remaining on the surface of the intermediate transfer belt 10 is removed by the belt cleaning device 21, and the removed toner is collected in the waste toner container 22.

  The recording medium S to which the toner image has been transferred is conveyed to the fixing device 16. The recording medium S sent to the fixing device 16 is sandwiched between the heating roller 17 and the pressure roller 18 and heated and pressurized, and the toner image is fixed on the recording medium S. Thereafter, the recording medium S is discharged to the stock unit 20 by the discharge rollers 19a and 19b.

  Next, a method of changing the contact pressure of the belt cleaning blade 23 (hereinafter simply referred to as “cleaning blade”) with respect to the intermediate transfer belt 10 in the belt cleaning device 21 of each embodiment according to the present invention will be described.

First, the belt cleaning device 21 according to the first embodiment shown in FIG. 3 will be described.
As shown in FIG. 3, the moving member 29 is disposed at a low position on the sliding surface 30 a of the operation member 30. In this state, the compression coil spring 26 biases the backup roller 25, and the backup roller 25 is pressed toward the cleaning blade 23.

  When the operating member 30 is operated and moved to the right side of the figure, the moving member 29 slides on the sliding surface 30a of the operating member 30 and is disposed at a high position on the sliding surface 30a (see FIG. (See dotted line 3). As a result, the compression coil spring 26 is further compressed to increase the urging force. As a result, the pressing force of the backup roller 25 against the cleaning blade 23 increases, so that the contact pressure of the cleaning blade 23 with respect to the intermediate transfer belt 10 increases.

  On the other hand, when the operating member 30 is moved to the left side in the drawing and returned to the original position, the moving member 29 slides on the sliding surface 30a of the operating member 30 and is disposed at a low position on the sliding surface 30a. Thereby, the compression coil spring 26 is extended and the urging force is reduced. As a result, the pressing force of the backup roller 25 against the cleaning blade 23 decreases, so that the contact pressure of the cleaning blade 23 with respect to the intermediate transfer belt 10 decreases.

Next, the case of the belt cleaning device 21 of the second embodiment shown in FIG. 4 will be described.
In this embodiment, the control means 32 controls the drive of the solenoid 33 at a predetermined timing before the cleaning by the cleaning blade 23 and at a predetermined timing after the cleaning ends. Hereinafter, this control method will be described.

  When the predetermined timing is reached before the cleaning is started by the cleaning blade 23, the control means 32 drives the solenoid 33 to move the operation member 30 to the right side in the figure. As the operating member 30 moves, the moving member 29 moves to a higher position on the sliding surface 30a of the operating member 30 and the urging force of the compression coil spring 26 increases as in FIG. As a result, the contact pressure of the cleaning blade 23 increases to a preset contact pressure for cleaning. Thereafter, the intermediate transfer belt 10 is cleaned by the cleaning blade 23 having a contact pressure for cleaning.

  After the cleaning of the intermediate transfer belt 10 is completed by the cleaning blade 23, the control means 32 drives the solenoid 33 at a predetermined timing to move the operation member 30 to the left side in the drawing. As a result, similarly to FIG. 3, the moving member 29 is returned to a lower position on the sliding surface 30 a of the operating member 30, and the urging force of the compression coil spring 26 is reduced. As a result, the contact pressure of the cleaning blade 23 is reduced to a standby contact pressure. Thereafter, the contact pressure of the cleaning blade 23 is similarly switched every time a predetermined timing before cleaning and a predetermined timing after cleaning are reached.

  A case will be described in which the control unit 32 includes a determination unit that determines whether or not the cleaning is sufficient. The determination unit is configured to determine whether the intermediate transfer belt is sufficiently cleaned based on information such as the density of the image transferred to the recording medium and transfer efficiency. When the determination unit determines that the cleaning is insufficient, the control unit 32 drives the solenoid 33 to move the operation member 30 to the right side in the figure. As a result, as described above, the contact pressure of the cleaning blade 23 increases and the pressing force of the backup roller 25 increases. Thereby, the contact pressure and the cleaning angle of the cleaning blade 23 can be adjusted to an appropriate state, and the cleaning performance can be improved.

The case of the belt cleaning device 21 of the third embodiment shown in FIG. 5 will be described.
First, when the operating member 31 is moved from the state indicated by the solid line to the right side of the figure, the moving member 37 is pressed to the right side of the figure along with the movement of the operating member 31 and the torsion coil spring 35 is twisted. (See the dotted line in the figure). As a result, the urging force of the torsion coil spring 35 against the swing member 34 increases, and the pressing force of the backup roller 25 against the cleaning blade 23 increases. As a result, the contact pressure of the cleaning blade 23 with respect to the intermediate transfer belt 10 increases.

  On the other hand, when the operating member 31 is moved to the left side in the drawing and returned to the original position, the moving member 37 moves in a direction to release the twist of the torsion coil spring 35. As a result, the urging force of the torsion coil spring 35 against the swing member 34 is reduced, and the pressing force of the backup roller 25 against the cleaning blade 23 is reduced. As a result, the contact pressure of the cleaning blade 23 with respect to the intermediate transfer belt 10 is also reduced.

The operation of the belt cleaning device 21 of the fourth embodiment shown in FIG. 6 will be described.
As shown in FIG. 6, the intermediate transfer unit 6 in which the intermediate transfer belt 10 and the belt cleaning device 21 are integrated is inserted into the image forming apparatus main body 100 from the direction of arrow A in the figure and attached. At this time, the moving member 38 interferes with the guide surface 39 a of the interference unit 39 provided in the image forming apparatus main body 100. As the intermediate transfer unit 6 is inserted, the moving member 38 slides on the guide surface 39a and moves upward in the drawing. As a result, the compression coil spring 26 is compressed to increase the urging force, and the pressing force of the backup roller 25 against the cleaning blade 23 increases. As a result, the contact pressure of the cleaning blade 23 against the intermediate transfer belt 10 increases, and the contact pressure of the cleaning blade 23 becomes a preset contact pressure for cleaning.

  Further, the intermediate transfer unit 6 attached to the image forming apparatus main body 100 can be removed from the image forming apparatus main body 100 by moving the intermediate transfer unit 6 in the direction opposite to the direction of the arrow A. When the intermediate transfer unit 6 is moved in the direction opposite to the direction of the arrow A, the moving member 38 slides on the guide surface 39a and moves downward. As a result, the compression coil spring 26 extends to reduce the urging force, and the pressing force of the backup roller 25 against the cleaning blade 23 is reduced. As a result, the contact pressure of the cleaning blade 23 with respect to the intermediate transfer belt 10 is reduced.

  The belt cleaning device 21 of the fifth embodiment shown in FIG. 7 also has an intermediate transfer unit 6 in which the intermediate transfer belt 10 and the belt cleaning device 21 are integrated in the image forming apparatus main body 100 as shown in FIG. Insert from the direction of arrow A and attach. At this time, the moving member 40 attached to the torsion coil spring 35 comes into contact with the interference portion 41 provided in the image forming apparatus main body 100, so that the moving member 37 is pressed in the twisting direction (right side in the drawing) of the torsion coil spring 35. Is done. As a result, the degree of torsion of the torsion coil spring 35 increases and the biasing force increases, and the pressing force of the backup roller 25 against the cleaning blade 23 increases. As a result, the contact pressure of the cleaning blade 23 against the intermediate transfer belt 10 increases, and the contact pressure of the cleaning blade 23 becomes a preset contact pressure for cleaning.

  Further, when the intermediate transfer unit 6 is removed from the image forming apparatus main body 100, if the intermediate transfer unit 6 is moved in the direction opposite to the direction of the arrow A, the pressure on the moving member 40 by the interference unit 41 is released. As a result, the twisting force on the torsion coil spring 35 is weakened, the biasing force of the torsion coil spring 35 is reduced, and the pressing force of the backup roller 25 on the cleaning blade 23 is reduced. As a result, the contact pressure of the cleaning blade 23 with respect to the intermediate transfer belt 10 is also reduced.

  As described above, the image forming apparatus according to the present invention can reduce the contact pressure of the cleaning blade 23 with respect to the intermediate transfer belt 10 when the belt cleaning device 21 is not used. As a result, it is possible to prevent the cleaning blade 23 and the intermediate transfer belt 10 from being deformed by a creep phenomenon, and it is possible to extend the life of the cleaning blade 23 and the intermediate transfer belt 10. In particular, when the belt cleaning device is not used for a long period of time such as when the image forming apparatus is stored or transported, it is effective to suppress deformation of the cleaning blade 23 and the intermediate transfer belt 10 due to a creep phenomenon.

  As shown in FIG. 9, when the pressing force of the backup roller 25 is increased or decreased, the tip of the cleaning blade 23 is always in contact with the intermediate transfer belt 10. In particular, as shown by the dotted line in FIG. 9, even if the pressing force of the backup roller 25 is reduced, the tip of the cleaning blade 23 is separated from the intermediate transfer belt 10 and is not in a non-contact state. For this reason, it can prevent that the removal thing adhering to the front-end | tip of the cleaning blade 23 collapses, and can prevent the dispersion | variation in the cleaning property which arises by partial collapse of a removal thing. In addition, since there is no possibility that the removed material bites between the cleaning blade 23 and the intermediate transfer belt 10, it is possible to exhibit good cleaning properties.

  The backup roller 25 may be in a non-contact state with respect to the intermediate transfer belt 10 as long as the cleaning blade 23 can be kept in contact with the intermediate transfer belt 10.

  Further, the belt cleaning device 21 shown in FIG. 3 can increase or decrease the contact pressure of the cleaning blade 23 against the intermediate transfer belt 10 as necessary by manually operating the operation member 30. Further, since the belt cleaning device 21 shown in FIG. 3 directly urges the bearing 27 of the backup roller 25 by the compression coil spring 26, the pressing force can be stably applied to the backup roller 25. For this reason, it is possible to suppress the occurrence of variations in the contact pressure of the cleaning blade 23 with respect to the intermediate transfer belt 10 and to exhibit stable cleaning properties.

  The belt cleaning device 21 shown in FIG. 4 can automatically change the contact pressure of the cleaning blade 23 by the control means 32. Therefore, it is possible to reduce the operation load on the user and the like, and it is possible to efficiently execute various operations such as an image forming operation and an adjustment operation of the cleaning performance in the image forming apparatus. Further, since the belt cleaning device 21 also directly biases the bearing 27 of the backup roller 25 by the compression coil spring 26, the pressing force can be stably applied to the backup roller 25.

  The belt cleaning device 21 shown in FIG. 5 can also increase or decrease the contact pressure of the cleaning blade 23 against the intermediate transfer belt 10 as needed by manually operating the operation member 30. Further, in this embodiment, the backup roller 25 and the torsion coil spring 35 are disposed via the swing member 34. Thereby, the torsion coil spring 35 can be disposed at a position away from the backup roller 25. For this reason, it is possible to avoid the parts from being crowded in the vicinity of the backup roller 25 and to increase the design margin.

  6 and 7, when the intermediate transfer unit 6 is mounted on the image forming apparatus main body 100, the contact pressure of the cleaning blade 23 is caused by the interference between the moving members 38 and 40 and the interference portions 39 and 41. Can be a preset contact pressure for cleaning. As a result, it is possible to reduce the burden of the setting operation of the contact pressure of the cleaning blade 23 by the user or the like, and it is possible to prevent the occurrence of defective cleaning due to forgetting to perform the setting operation. When the intermediate transfer unit 6 is not attached to the image forming apparatus main body 100, the contact pressure of the cleaning blade 23 can be reduced, and the cleaning blade 23 and the intermediate transfer belt 10 are deformed by a creep phenomenon. Can be suppressed.

  The belt cleaning device 21 shown in FIGS. 6 and 7 is the same as the belt cleaning device 21 shown in FIGS. 3 to 5 in a portion where the same structure as the belt cleaning device 21 shown in FIGS. It is possible to exert the action / effect.

  In the belt cleaning device 21 of the sixth embodiment shown in FIG. 8, the backup roller 25 is pressed by four compression coil springs 44. For this reason, the backup roller 25 can be uniformly pressed over the axial direction. Thereby, the contact pressure of the cleaning blade 23 can be made uniform, and good cleaning properties can be stably exhibited. Further, since the backup roller 25 is supported by the rotatable support roller 42, it is possible to smoothly maintain the travel of the intermediate transfer belt 10 (not shown).

  In the belt cleaning device according to the present invention, the cleaning blade 23 is supported by the backup roller 25 different from the tension roller (the driven roller 9 in FIG. 1) for applying tension to the intermediate transfer belt 10. In this respect, it differs from the belt cleaning device (see Patent Document 1, 2 or 3) configured to support the tip of the cleaning blade by the tension roller shown in FIG. In the belt cleaning apparatus shown in FIG. 14, when the pressing force of the tension roller is changed in order to increase or decrease the contact pressure of the cleaning blade with respect to the intermediate transfer belt, the tension of the intermediate transfer belt fluctuates, resulting in image quality and belt cleaning performance. There is a risk of adverse effects. On the other hand, in the belt cleaning device of the present invention, even if the pressing force of the backup roller 25 is changed in order to increase or decrease the contact pressure of the cleaning blade 23, the tension of the intermediate transfer belt 10 is optimal by the tension roller. Maintained. For this reason, the belt cleaning apparatus of the present invention can stably maintain image quality and belt cleaning performance as compared with the belt cleaning apparatus shown in FIG.

  Further, as shown in FIG. 10, when the intermediate transfer belt 10 travels in the direction of the arrow, a braking force that prevents the intermediate transfer belt 10 from traveling is generated at the contact position between the cleaning blade 23 and the intermediate transfer belt 10. Therefore, the tension of the intermediate transfer belt 10 is loosened in a range H on the opposite side (upstream side) of the traveling direction of the intermediate transfer belt 10 from the contact position of the cleaning blade 23 and the intermediate transfer belt 10. The looseness of the tension of the intermediate transfer belt 10 causes a problem that the cleaning performance of the cleaning blade 23 becomes unstable. Therefore, by adding a function of applying tension to the intermediate transfer belt 10 to the backup roller 25, it is possible to suppress the loosening of the tension. Thereby, the tension fluctuation of the tension of the intermediate transfer belt 10 can be suppressed, and the cleaning performance of the cleaning blade 23 is stabilized. However, as described above, since the tension roller is provided separately from the backup roller 25 in the present invention, the tension applied to the intermediate transfer belt 10 by the backup roller 25 here is only auxiliary. . In order to prevent the backup roller 25 from actively applying tension to the intermediate transfer belt 10, as shown in FIG. 10, a contact portion 45 is provided on the bearing 27 and the like of the backup roller 25, and this contact portion. The displacement of the backup roller 25 may be regulated by abutting 45 on a regulating member 46 provided on the image forming apparatus main body or the like.

  Further, as shown in FIG. 11, the range in which the backup roller 25 can be displaced is located inside the intermediate transfer belt 10 that is stretched in a state where it does not receive the contact pressure from the cleaning blade 23 and the pressing force from the backup roller 25. By setting, loosening of the intermediate transfer belt 10 due to the displacement of the backup roller 25 can be prevented.

  That is, when the backup roller 25 is arranged as shown in FIG. 11, when the pressing force of the backup roller 25 is reduced as shown in FIG. 12A, the intermediate transfer belt 10 receives a force in the tensioning direction. . On the other hand, when the displacement range of the backup roller 25 is set to protrude outside the intermediate transfer belt 10 shown in FIG. 11, the pressing force of the backup roller 25 is set as shown in FIG. When reduced, the intermediate transfer belt 10 receives a force in a loosening direction. When the looseness of the intermediate transfer belt 10 cannot be absorbed by a tension roller or the like, the intermediate transfer belt 10 remains loose, and there is a possibility that problems may occur in the image forming operation and the cleaning performance of the cleaning blade 23. However, the above-mentioned problem can be prevented by setting the displacement range of the backup roller 25 to the inside of the intermediate transfer belt 10 shown in FIG.

  The embodiments of the belt cleaning device and the image forming apparatus having the belt cleaning device according to the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention. Of course, it is possible to add these changes. For example, the configuration of the present invention can be applied to a belt cleaning device that cleans the surface of a photosensitive belt carrying a toner image. In FIG. 1, the belt cleaning apparatus of the present invention is mounted on a so-called tandem type indirect transfer type color image forming apparatus. However, a so-called revolver type color image forming apparatus sequentially forms toner images of respective colors on one photoconductor. The present invention can also be applied to an image forming apparatus. Further, even when the belt cleaning device of the present invention is applied to an image forming device of a direct transfer system that directly transfers a toner image formed on a photosensitive member to a recording medium, the same effect as the above-described embodiment of the present invention is achieved. Can be obtained.

1 is a schematic diagram illustrating an overall configuration of an image forming apparatus of the present invention. FIG. 4 is a diagram illustrating an opening / closing operation of a front cover of the image forming apparatus. It is a figure which shows 1st Embodiment of the belt cleaning apparatus which concerns on this invention. It is a figure which shows 2nd Embodiment of the belt cleaning apparatus which concerns on this invention. It is a figure which shows 3rd Embodiment of the belt cleaning apparatus which concerns on this invention. It is a figure which shows 4th Embodiment of the belt cleaning apparatus which concerns on this invention. It is a figure which shows 5th Embodiment of the belt cleaning apparatus which concerns on this invention. It is a figure which shows 6th Embodiment of the belt cleaning apparatus which concerns on this invention. FIG. 6 is an enlarged view showing a contact state of a belt cleaning blade with an intermediate transfer belt. FIG. 4 is a diagram for explaining a means for suppressing looseness of an intermediate transfer belt. It is a figure for demonstrating the range which can displace a backup roller. FIG. 7 is an enlarged view for explaining a difference in tension variation acting on the intermediate transfer belt due to the displacement of the backup roller, in which (A) shows a state in which the intermediate transfer belt is stretched, and (B) shows the intermediate transfer belt It is a figure which shows the state loosened. FIG. 6 is an enlarged view for explaining a contact pressure and a cleaning angle of a cleaning blade with respect to an intermediate transfer belt. It is an enlarged view which shows a mode that the cleaning blade of the conventional belt cleaning apparatus moves following the movement of a tension roller.

Explanation of symbols

DESCRIPTION OF SYMBOLS 21 Belt cleaning apparatus 23 Belt cleaning blade 24 Pressing means 25 Backup roller 26 Compression coil spring 27 Bearing 28 Pressing force variable means 29 Moving member 30 Operating member 31 Operating member 32 Control means 34 Oscillating member 35 Torsion coil spring 37 Moving member 38 Moving Member 39 Interference part 40 Moving member 41 Interference part 42 Support roller 44 Compression coil spring 100 Image forming apparatus main body

Claims (16)

A belt cleaning member that contacts an outer peripheral surface of an endless belt stretched by a plurality of rollers including a driving roller to clean the belt, and a pressing unit that presses the belt cleaning member from the inner peripheral surface side of the belt In a belt cleaning device comprising:
A pressing force variable means for changing a pressing force of the pressing means against the belt cleaning member, and the pressing force of the pressing means by the pressing force variable means while maintaining the state where the belt cleaning member and the belt are in contact with each other; A belt cleaning device configured to change the angle. The pressing means is disposed opposite to the belt cleaning member via the belt and is displaceable in a direction approaching and separating from the belt cleaning member, and the backup roller is moved to the belt cleaning member. A biasing means for biasing the member;
The urging force of the urging means is configured to change within a predetermined range by the pressing force varying means, and the urging force of the urging means is set to the minimum urging force within the predetermined range. The belt cleaning apparatus according to claim 1, wherein the belt cleaning member is disposed in contact with the belt.   The belt cleaning device according to claim 2, wherein the urging unit urges a bearing that supports both ends of the rotation shaft of the backup roller to the belt cleaning member.   4. The belt cleaning device according to claim 3, wherein a compression coil spring is provided as the biasing means for biasing the bearing, and the degree of compression of the compression coil spring is changed by the pressing force varying means.   And a swinging member disposed so as to be swingable in a direction approaching and separating from the belt cleaning member. The backup roller is rotatably attached to one swinging end of the swinging member, and the swinging member is rotated. The urging means is disposed on the other end side opposite to the one end of the moving member, and the urging means oscillates the oscillating member in a direction approaching the belt cleaning member. The belt cleaning device according to claim 2, wherein the belt cleaning device is urged to.   6. The belt cleaning device according to claim 5, wherein a torsion coil spring is provided as the urging means for urging the swing member, and the degree of twist of the torsion coil spring is changed by the pressing force varying means.   The belt cleaning device according to claim 2, wherein a plurality of the urging units are arranged in the axial direction of the backup roller, and the backup roller is urged toward the belt cleaning member by the plurality of urging units.   The belt cleaning device according to claim 7, wherein the plurality of urging units are configured to urge the backup roller via a rotatable support roller.   The range in which the backup roller can be displaced is set inside the belt when the belt is stretched in a state where it does not receive contact pressure from the belt cleaning member and pressing force from the backup roller. The belt cleaning device according to any one of 1 to 8.   The belt cleaning apparatus according to claim 1, wherein tension is applied to the belt by the pressing unit.   The belt cleaning device according to claim 1, wherein the pressing force varying means is configured to be manually operable.   The belt cleaning device according to claim 1, further comprising a control unit that controls the pressing force varying unit based on a preset condition.   By controlling the pressing force variable means by the control means, the pressing force of the pressing means is increased at a predetermined timing before the cleaning of the belt is started, and the contact pressure of the belt cleaning member with respect to the belt is previously set. The set contact pressure for cleaning is set, and at a predetermined timing after cleaning of the belt, the pressing force of the pressing means is reduced, and the contact pressure of the belt cleaning member with respect to the belt is set in advance. The belt cleaning device according to claim 12, wherein the belt cleaning device is configured to have a contact pressure of 10 μm.   The control unit includes a determination unit that determines whether or not the cleaning by the belt cleaning member is sufficient. When the determination unit determines that the cleaning is insufficient, the control unit controls the pressing force variable unit. The belt cleaning device according to claim 12 or 13, wherein the pressing force of the pressing means is increased by doing so. An endless belt stretched by a plurality of rollers including a driving roller, a belt cleaning member that contacts the outer peripheral surface of the belt to clean the belt, and the belt cleaning member from the inner peripheral surface side of the belt In the image forming apparatus provided with pressing means for pressing,
A pressing force variable means for changing a pressing force of the pressing means against the belt cleaning member by the pressing means, and the pressing force changing means maintains the state in which the belt cleaning member and the belt are in contact with each other; An image forming apparatus characterized in that the pressing force of the means is changed. An image forming apparatus in which at least the unit including the belt, the pressing unit, and the pressing force varying unit is configured to be detachable from the image forming apparatus main body.
The pressing force varying means has an interference portion provided in the image forming apparatus main body and a displaceable moving member provided on the pressing means side, and when the unit is attached to the image forming apparatus main body, The moving member is displaced by interfering with the interference member to increase the pressing force of the pressing means so that the contact pressure of the belt cleaning member to the belt becomes a preset cleaning contact pressure. The image forming apparatus according to claim 15.

Images