JP5120067B2 - Cleaning device and image forming apparatus - Google Patents

Description

  The present invention relates to a cleaning device for removing toner remaining on an image carrier and an image forming apparatus having the cleaning device.

  Conventionally, in the field of electrophotography, as a cleaning device for toner remaining on an image carrier, cleaning is performed using a brush corresponding to the use of a device that removes with a rubber blade or a small particle size toner such as polymerized toner. Things are known.

The belt-shaped conductive brush includes a conductive recovery member that captures toner with a belt-shaped conductive brush and collects the captured toner by a potential difference from the belt-shaped conductive brush. There is known a cleaning device in which the curvature of the contact portion with the image carrier is smaller than the curvature of the contact portion with the conductive recovery member (see, for example, Patent Document 1).
JP 2007-155960 A

  In the case of a cleaning device that uses a brush, as the cleaning operation continues, toner or paper dust collected by the brush gradually accumulates at the base of the brush, and this accumulated toner or paper dust, etc. There is a problem that the cleaning performance is deteriorated because it is not easily recovered.

  The cleaning device described in Patent Document 1 increases the curvature of the contact portion with the recovery member to increase the spread of the brush tip, lower the density of the brush tip, and pull out the toner that has entered the base of the brush. It tries to be easy. However, since the density on the base side of the brush is not changed, there is a problem that a great improvement in cleaning performance cannot be expected.

  SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to obtain a cleaning apparatus and an image forming apparatus with improved cleaning performance by improving the recovery efficiency of toner that has entered the base side of a brush.

  The above object is achieved by the invention described below.

(1) A cleaning device that is formed on an endless belt and has a brush that collects toner remaining on an image carrier that carries a toner image, and a collection unit that collects the toner collected by the brush. The belt is formed of a base material that can be stretched and stretched by at least two rollers. Among the rollers, the peripheral speed of the roller disposed on the collection unit side is set to be higher than that of the other roller. A cleaning device that is driven at high speed .

(2) Of the rollers, the root of the brush on the roller disposed on the collecting portion side is driven by driving the peripheral speed of the roller disposed on the collecting portion side at a higher speed than the other roller. The density on the side is made lower than the density when the cleaning device is stopped, and the density of the bristles of the brush on the other roller is made lower than the density when the cleaning device is stopped. The cleaning device according to (1), wherein the cleaning device is made high.

Belt lengths sites in the recovery section is opposed position when the (3) before Symbol cleaning device is operating, to a belt length part between the rollers when the cleaning device is stopped, 1 The cleaning device according to (1) or (2) , wherein the cleaning device is stretched by 2 times or more and 1.4 times or less .

( 4 ) An image carrier that carries a toner image, the cleaning device according to any one of (1) to (3), and a fixing device that fixes a toner image transferred from the image carrier to a sheet material. An image forming apparatus comprising:

  According to the present invention, it is possible to improve the recovery efficiency of the toner that has entered the base side of the brush, and to obtain a cleaning device and an image forming apparatus with good cleaning performance.

  Hereinafter, the present invention will be described in detail with reference to embodiments, but the present invention is not limited thereto.

  FIG. 1 is a schematic diagram showing a configuration of a digital color copying machine which is an example of an image forming apparatus according to the present embodiment.

  The image forming apparatus shown in FIG. 1 has an automatic document feeder 1 at the top of the apparatus main body, and includes an image reading device 2, an image forming unit 3, a belt unit unit 4, a paper feeding unit 5, a fixing device T, a reverse discharge unit. A paper / refeed unit 6 and an ADU 7 serving as a reverse conveying unit are provided.

  The automatic document feeder 1 feeds documents one by one, conveys them to an image reading position, and discharges the document after image reading to a predetermined location. The automatic document feeder 1 includes a document placing table 101, a document separating unit 103, a document conveying unit 105, a document discharging unit 107, a document discharging table 109, and rollers for reversing the front and back surfaces of a document in the duplex image forming mode. A pair of document reversing means 111 is provided.

  A plurality of documents (not shown) placed on the document placing table 101 are separated one by one by the document separating means 103 and conveyed toward the image reading position via the document conveying section 105. The document reading position is provided at a lower portion of the document conveying unit 105, where an image of the document is read through the slit 201 constituting the image reading device 2, and the read document is a document discharge unit 107. Is discharged onto the document discharge tray 109.

  In the double-sided image forming mode, a document that is transported after one side is read is transported by the document reversing unit 111 in the direction indicated by a two-dot chain line arrow. Then, after the driving of the document reversing means 111 is stopped in a state where the trailing end in the advancing direction is bitten, the image is again guided to the image reading position via the document conveying unit 105 by the reverse rotation, and then The original is discharged onto the original discharge table 109 by the original discharge means 107.

  The above process is repeated for the number of documents placed on the document placing table 101.

  The image reading apparatus 2 includes a first mirror unit 205, a second mirror 217, and a third mirror 219 that are integrated with a slit 201, a document irradiation lamp 213, and a first mirror 215 that reflects reflected light of the document. The second mirror unit 207 is provided. Further, an imaging lens 209 that forms an image of reflected light from the third mirror 219 on the imaging device, and a linear imaging device 211 that obtains image information by photoelectrically converting the light image formed by the imaging lens 209. have. For example, a CCD (Charge Coupled Device) is used as the image sensor 211.

  The image information obtained by the image reading device 2 is subjected to appropriate image processing and then temporarily stored in a memory in the control means S.

  In a mode in which the document fed by the automatic document feeder 1 is read by the image reading device 2, the first mirror unit 205 and the second mirror unit 207 are fixed at positions as shown in the figure. The image information for each color read by the image reading device 2 is sequentially extracted from the memory, and is input as an electric signal to the exposure optical system for each color, which is an electrostatic charge latent image forming unit.

  The image forming unit 3 forms four sets of image forming units (hereinafter referred to as image forming units) of yellow (Y), magenta (M), cyan (C), and black (BK) that form a toner image corresponding to the color separation image. 30.

  Each of the image forming units 30 includes a photosensitive drum 310 as a first image carrier having a photosensitive layer provided on a drum-shaped metal substrate, a charger 320, an exposure optical system 330 as image writing means, and a developing device 8. The transfer unit 340 and the photosensitive drum cleaning unit 350 are main components.

  The developing device 8 contains, for example, a two-component developer including a magnetic carrier (hereinafter simply referred to as a carrier) and a non-magnetic toner (hereinafter simply referred to as a toner). Further, the developing device 8 includes a developer carrying member (hereinafter referred to as a developing sleeve or simply a sleeve) having a rotatable and non-magnetic cylindrical shape including a plurality of magnets (magnetic poles) fixed in position along the circumferential direction. And a toner density detecting means (not shown).

  The exposure optical system 330 is an exposure unit composed of a laser optical system.

  The transfer unit 340 includes a roller facing a part of the circumferential surface of the photosensitive drum 310 via the intermediate transfer belt 401, and has a configuration called an ordinary transfer electrode including an electrode formed of a discharge wire. You can also

  Since the mechanical configuration of the four sets of image forming units 30 described above is basically the same, the reference numerals are given only for one set of units, and the other units are omitted.

  Each of the image forming units 30 extends along one plane (stretched surface) A of the intermediate transfer belt 401 that is a long loop-shaped image carrier that constitutes the belt unit 4 and that is long in the vertical direction. From the top, yellow, magenta, cyan, and black are arranged in this order.

  The intermediate transfer belt 401, support rollers 405, 406, 407, a backup roller 410, and the like that suspend the intermediate transfer belt 401 rotatably constitute the belt unit 4. The backup roller 410 constitutes a secondary transfer unit with a transfer roller 510 disposed so as to rotate while pressing the backup roller 410 with the intermediate transfer belt 401 interposed therebetween.

  Image formation by the configuration of the image forming unit 30 and the belt unit 4 is performed as follows.

  With the start of the image forming process, the surface of the photosensitive drum 310 that rotates counterclockwise is charged to a predetermined polarity (here, negative polarity) by the charger 320.

  Next, the exposure optical system 330 performs exposure corresponding to the first color signal, that is, the yellow (Y) image signal, and a latent image corresponding to the (Y) image is formed on the photosensitive drum 310. . The latent image is reversed and developed into a (Y) toner image by contact or non-contact development processing with a developer in the developing device 8, and then transferred onto the intermediate transfer belt 401 by the action of the transfer unit 340. The

  Image formation with other color signals that is sequentially started after a predetermined time from the start of image formation with the first color signal is performed for each of magenta (M), cyan (C), and black (BK) by the same process as described above. This is done by the image forming unit.

  Each toner image on the photosensitive drum formed by each image forming unit is sequentially transferred so as to overlap with an image area where the toner image of (Y) is overlapped, and is superimposed on the intermediate transfer belt 401. A toner image is formed. On the other hand, the surface of the photoconductive drum 310 after the transfer process is completed is cleaned by the photoconductive drum cleaning unit 350, and preparations for new image formation are made.

  Next, the color toner image formed on the intermediate transfer belt 401 is transferred onto a sheet material that is a transfer material (generally, a rectangular paper cut into a predetermined size such as plain paper), and the apparatus The other components of the apparatus will be briefly described in connection with the process until the sheet is discharged outside.

  At an appropriate timing corresponding to the image formation on the intermediate transfer belt 401, the sheet material P is fed by the sheet feeding roller 503 (513, 523) positioned in the feeding section 501 (511, 521) of the sheet feeding section 5. .

  Next, the separation roller 506, a plurality of conveyance roller pairs R1 to R7 provided on the paper feed path, and the conveyance roller 550 are directed toward the registration roller 551 provided in front of the transfer portion (transfer area). Be transported.

  After the leading edge of the sheet material P comes into contact with the registration roller 551, the sheet material P is fed again at a timing overlapping with the color toner image area on the intermediate transfer belt 401 by resuming the rotation of the registration roller 551. The sheet material P is pressed and nipped together with the intermediate transfer belt 401 by the backup roller 410 and the transfer roller 510 in the secondary transfer portion, and the color toner image on the intermediate transfer belt 401 is transferred onto the sheet material P during this time.

  The sheet material P to which the toner image has been transferred is separated from the intermediate transfer belt 401 and conveyed toward the fixing device T by a conveyance belt (not shown).

  The fixing device T includes a fixing roller T1 including a fixing heater and a pressure roller T2 that rotates while being in pressure contact with the fixing roller, and the color toner forming the image is melted by heating and pressing with both rollers. Then, it is fixed on the sheet material P.

  After completion of the fixing process by the fixing device T, the sheet material P is conveyed by a paper discharge roller 603 provided downstream thereof and discharged onto a paper discharge tray provided outside the apparatus main body.

  On the other hand, the surface of the intermediate transfer belt 401 after the completion of the secondary transfer is cleaned by a cleaning device 40 described later, and preparations for carrying a new toner image are made.

  The sheet material P after the fixing process is discharged with the upper and lower surfaces reversed depending on the rotation position of the passage switching member 601 or discharged as it is. For example, in the reverse discharge of the sheet material P, after the sheet material P sent out from the fixing device T is guided downward along the right side of the path switching member 601 and the rear end is sandwiched by the roller 602, Rotate, reverse rotation. Next, the paper passes through the left side of the switching member 601, reaches the paper discharge roller 603, and is discharged by the paper discharge roller.

  When forming an image on both sides of the sheet material P, the sheet material P after the fixing process on which an image is formed on one side is guided downward along the right side of the switching member 601, and the rear end of the sheet material P is a roller pair. Stop in the state of being pinched at 605. Next, the roller pair 605 is rotated in the reverse direction, is raised along the guide plate G, is guided to the ADU 7 having a plurality of roller pairs 701, 703, and 705, and the sheet material P is reversed. The image forming process for the second surface of the sheet material P is basically the same as described above, and any of the aforementioned discharge paths after being sent out from the fixing device T is selected.

  In the drawing, P1, P2, and P3 are paper storage devices that can store a predetermined amount of sheet material P, and are configured to be drawn out toward the front side of the drawing.

  Next, the configuration of the cleaning device according to the present embodiment will be described.

  FIG. 2 is an enlarged view of a main part illustrating a part of the cleaning device 40 and the intermediate transfer belt 401 according to the present embodiment.

  The cleaning device 40 shown in the figure has an endless structure in which a first roller 41 disposed opposite to a support roller 405 that suspends an intermediate transfer belt 401, a second roller 42 disposed opposite to a collection roller 44, and a brush 43b are formed. A belt 43 is formed. The belt 43 is formed of a conductive and expandable base material, and the brush 43b is formed of conductive polyester. Hereinafter, the endless belt 43 on which the brush 43b is formed is referred to as a brush belt BB.

  As illustrated, the brush belt BB is stretched by a first roller 41 and a second roller 42, and the first roller 41 rotates in a direction opposite to the rotation of the support roller 405. The collection roller 44 rotates in the direction opposite to the rotation of the second roller 42. 45 is a scraper and 46 is a screw.

  The collection roller 44 is made of stainless steel and has a surface roughness Rz of 0.1 μm. Further, the scraper 45 is made of stainless steel having a thickness t of 0.05 mm, for example, and is in counter contact with the recovery roller 44 so that the toner recovered by the recovery roller 44 is mechanically scraped off. The collecting roller 44 is applied with a voltage having a polarity opposite to that of the toner.

On the other hand, the support roller 405 for suspending the intermediate transfer belt 401 is grounded, and the toner remaining on the intermediate transfer belt 401 is electrostatically attracted to the brush 43b. The intermediate transfer belt 401 is made of, for example, polyimide, and has a volume resistance of 10 ⁹ Ω and a surface resistance of 10 ¹¹ Ω. Reference numerals 47 and 48 denote rubber blades which are members for cleaning the first roller 41 and the second roller 42.

  The first roller 41 is driven by using the second roller 42 as a driving roller, or the peripheral speed of the second roller 42 is driven higher than the peripheral speed of the first roller 41 while driving the second roller 42 and the first roller 41 together. By doing so, the brush belt BB in the region facing the collection roller 44 on the second roller 42 can be further extended by using its stretchability. As a result, the density of the brush base side of the brush belt BB in the region facing the recovery roller 44 can be reduced, and the recovery efficiency of the toner that has entered the base side can be improved. Further, since the brush belt BB in the region facing the intermediate transfer belt 401 on the first roller 41 is restrained from being stretched, the density of the brush tip in the region facing the intermediate transfer belt 401 can be increased. Efficiency can be improved.

  The stretchable base material referred to in the present application refers to a material having a Young's modulus of 0.1 GPa or less. Such a stretchable base material can be obtained, for example, by using natural rubber, synthetic rubber or polyurethane as a base material, or knitting rayon or polyester fiber.

  There are various methods for creating the brush belt BB. Three examples are given below.

  (A) A brush is knitted directly on the stretchable base material as described above. In this case, the direction in which the brush is knitted is desirably knitted perpendicular to the belt rotation direction (direction in which the brush is to be expanded and contracted). This is because if the brush is knitted in the belt rotation direction, the base material may be prevented from expanding and contracting.

  (B) A base fabric in which a brush is implanted is attached to a base material that can be expanded and contracted as described above. In this case, it is desirable to cut the base fabric on which the brush is planted into a strip shape and paste the base fabric so that the short side direction is the rotational direction.

  (C) A brush is electrostatically implanted on the belt. In this case, it is desirable to use an adhesive having elasticity that can expand and contract as an adhesive for bonding the brush and the base material.

  Examples will be described below.

  In the cleaning device as shown in FIG. 2, the brush belt BB created by the method (a) is used, the first roller 41 is a driving roller and the second roller is a driven roller. Create a roller with different peripheral speed ratio by driving the second roller 42, a roller with different recovery voltage applied, and a roller with a different friction coefficient, and check the efficiency of collection and recovery efficiency and cleaning. The experiment was conducted.

  The following ten examples were used in the experiment. The specifications of each example are described below.

Example 1
Belt base material: Conductive polyurethane Belt base material Young's modulus: 0.06 GPa
Belt thickness: 500 μm
Brush material: Conductive polyester (raw yarn resistance 10 ⁹ Ω)
Brush wire diameter: about 2 denier Brush hair length: 5mm
Recovery roller biting amount: 1 mm
Recovery roller applied voltage: 1.5 kV
First roller radius: 10 mm
First roller friction coefficient: 0.35
Second roller radius: 10 mm
Second roller friction coefficient: 0.35
Belt tension: 54N
Peripheral speed ratio: First roller: driving roller, second roller: driven roller, the arrangement shown in FIG.

(Example 2)
Peripheral speed ratio (both the first and second rollers are driven): 3: 1 (second roller: first roller)
Others are the same as in the first embodiment.

(Example 3)
Peripheral speed ratio (both the first and second rollers are driven): 2: 1 (second roller: first roller)
Others are the same as in the first embodiment.

Example 4
Peripheral speed ratio (both the first and second rollers are driven): 1.5: 1 (second roller: first roller)
Others are the same as in the first embodiment.

(Example 5)
Recovery roller applied voltage: 2 kV
Others are the same as in the second embodiment.

(Example 6)
Recovery roller applied voltage: 2 kV
Others are the same as in the third embodiment.

(Example 7)
Recovery roller applied voltage: 1 kV
Others are the same as in the second embodiment.

(Example 8)
Recovery roller applied voltage: 1 kV
Others are the same as in the third embodiment.

Example 9
Young's modulus of belt substrate: 0.05 GPa
First roller friction coefficient: 0.45
Second roller friction coefficient: 0.45
Others are the same as in the third embodiment.

(Example 10)
Young's modulus of belt substrate: 0.07 GPa
First roller friction coefficient: 0.25
Second roller friction coefficient: 0.25
Others are the same as in the third embodiment.

  Hereinafter, a comparative example will be described.

  FIG. 3 is an enlarged view of a main part showing a part of the cleaning device 40 and the intermediate transfer belt 401 used in Comparative Example 1 and Comparative Examples 3 to 5 in an enlarged manner.

  As shown in FIG. 3, the overall schematic configuration is the same as that shown in FIG. 2, and a conductive polyester having a high Young's modulus is used for the belt 43.

  FIG. 4 is an enlarged view of a main part showing a part of the cleaning device and the intermediate transfer belt used in Comparative Example 2.

  As shown in FIG. 4, the cleaning device 40 used in Comparative Example 2 includes a first roller 41 disposed opposite to a support roller 405 that suspends the intermediate transfer belt 401, and a second roller disposed opposite to a collection roller 44. 42, and a brush belt BB composed of an endless belt 43 on which a brush 43b is formed. The diameter of the first roller is larger than that of the second roller, and the belt 43 is made of conductive polyester having a high Young's modulus.

  3 and 4, the first roller 41, the second roller 42, the collection roller 44, and the support roller 405 rotate as indicated by the arrows in the drawing. 45 is a scraper and 46 is a screw.

  The collection roller 44 is made of stainless steel and has a surface roughness Rz of 0.1 μm. Further, the scraper 45 is made of stainless steel having a thickness t of 0.05 mm, for example, and is in counter contact with the recovery roller 44 so that the toner recovered by the recovery roller 44 is mechanically scraped off. The collecting roller 44 is applied with a voltage having a polarity opposite to that of the toner.

  On the other hand, the support roller 405 for suspending the intermediate transfer belt 401 is grounded, and the toner remaining on the intermediate transfer belt 401 is electrostatically attracted to the brush 43b.

  The comparative examples used in the experiment are the following five types. The specifications of each comparative example are described below.

(Comparative Example 1)
Belt substrate: Conductive polyester Belt substrate Young's modulus: 1.8 GPa
Belt thickness: 500 μm
Brush material: Conductive polyester (raw yarn resistance 10 ⁹ Ω)
Brush wire diameter: about 2 denier Brush hair length: 5mm
Recovery roller biting amount: 1 mm
Recovery roller applied voltage: 1.5 kV
First roller radius: 10 mm
First roller friction coefficient: 0.35
Second roller radius: 10 mm
Second roller friction coefficient: 0.35
Belt tension: 54N
Peripheral speed ratio: First roller: driving roller, second roller: driven roller, and the arrangement shown in FIG.

(Comparative Example 2)
Second roller radius: 5 mm
And the arrangement shown in FIG. Others are the same as in Comparative Example 1.

(Comparative Example 3)
Peripheral speed ratio (both the first and second rollers are driven): 2: 1 (second roller: first roller)
And the arrangement shown in FIG. Others are the same as in Comparative Example 1.

(Comparative Example 4)
Recovery roller applied voltage: 2 kV
And the arrangement shown in FIG. Others are the same as in Comparative Example 3.

(Comparative Example 5)
Recovery roller applied voltage: 1 kV
And the arrangement shown in FIG. Others are the same as in Comparative Example 3.

  For the 10 types of the brush belts BB of the above-mentioned specifications and the comparative example 5 types, the toner collection efficiency from the intermediate transfer belt 401, the collection efficiency of the collection roller, and the flat portion between the rollers on the surface of the belt 43 The elongation percentage with respect to the state was measured.

  Specifically, bizhub PRO C500 manufactured by Konica Minolta Co. was used.

  First, a state in which the collection roller of the cleaning device is removed is created. Next, a test chart image is prepared on the intermediate transfer belt using cyan toner, and the intermediate transfer belt is conveyed without transferring the toner image to the sheet material, and collected by the brush belt. Measure the mass of The toner mass collected is obtained from the mass increase amount at this time, and the toner collection efficiency is calculated.

  Next, the recovery roller is attached and the toner adhered to the brush belt is recovered by the recovery roller, and the mass of the brush belt after the toner recovery by the recovery roller is measured. Thus, the collected toner mass is obtained, and the collection efficiency on the collecting roller side is obtained from the toner mass collected by the brush belt from the intermediate transfer belt and the collected toner mass.

  Further, the elongation rate was obtained by measuring the interval between the scales with each interval being marked on the belt. The friction coefficient was measured using Shinto Kagaku Co., Ltd., portable tribometer, Muse TYPE: 94i-II.

  Further, as a judgment on the matching of the cleaning performance, an image pattern with a printing rate of 20% was continuously printed at 10,000, and it was confirmed whether or not residual toner on the intermediate transfer belt slipped out and whether or not slipping occurred on the paper surface. The occurrence of slip-through on the paper surface means that toner that could not be collected from the intermediate transfer belt is transferred at the time of the next printing.

The judgment criteria in this judgment are:
(◎): No slippage occurred on the intermediate transfer belt or on the paper (no problem)
(○): Slight slippage occurs on the intermediate transfer belt.
No slippage on paper (no problem in practical use)
(×): Slip-on occurred on the intermediate transfer belt and on the paper surface (problem)
It was.

  Table 1 below shows the specifications and experimental results.

  As shown in Table 1, the results of the determination of the union of the cleaning devices of Examples 1 to 10 in which the belt is formed of a stretchable base material were determined as having no problem or practically no problem.

  In Examples 2, 3 and 5 to 9, the peripheral speed of the second roller arranged on the collection unit side is driven at a higher speed than the first roller on the intermediate transfer belt side, so that the base material has a low Young's modulus. The formed brush belt is stretched 1.2 times or more at the position facing the collecting roller on the second roller side, the density of the brush root is lowered, and toner and paper dust clogged not only at the brush tip but also at the root are removed. It is assumed that it can be recovered with high efficiency.

  Further, in Examples 1, 4, and 10, since the elongation at the position facing the collection roller on the second roller side is slightly less than 1.05 to 1.1 times, the collection efficiency is slightly lowered, and the middle Although a slight slip occurs on the transfer belt, it does not reach a level where the slip occurs on the paper surface, and it is assumed that the level has no practical problem.

  Accordingly, it is desirable that the brush belt BB at the position where the recovery roller 44 is opposed is extended by 1.2 times or more with respect to the linear portion between the first roller 41 and the second roller 42 when stopped. I understand that.

  On the other hand, Comparative Examples 1 to 5 using a stretchable and minimal belt having a high Young's modulus do not have a large change in the density of the brush root, and therefore, the collection efficiency and the recovery efficiency are low, and on the intermediate transfer belt and on the paper surface. It is assumed that slipping through occurs.

  As described above, the toner that has entered the base of the brush is formed by forming the belt with a stretchable base material, and selecting and setting the tension between the rollers, the friction coefficient of the rollers, and the peripheral speed ratio of the rollers as appropriate. The recovery efficiency can be improved, and a cleaning device with good cleaning performance can be obtained.

  In the above embodiment, the cleaning device for cleaning the intermediate transfer belt has been described. However, the present invention is not limited to this, and it is needless to say that the present invention can also be applied to the case where the photosensitive drum is an image carrier. .

  Further, although the recovery unit has been described as using the recovery roller, the present invention is not limited to this, and recovery from the brush belt may be performed using air suction or the like. Also in this case, the same effect can be obtained by reducing the density of the brush base in the recovery unit, and a cleaning device with high recovery efficiency can be obtained.

1 is a schematic diagram illustrating a configuration of a digital color copier that is an example of an image forming apparatus according to an exemplary embodiment. FIG. 3 is an enlarged view of a main part illustrating a part of the cleaning device and the intermediate transfer belt according to the present embodiment. FIG. 6 is an enlarged view of a main part showing a part of the cleaning device and the intermediate transfer belt used in Comparative Example 1 and Comparative Examples 3 to 5; FIG. 9 is an enlarged view of a main part showing a part of the cleaning device and the intermediate transfer belt used in Comparative Example 2;

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Automatic document feeder 2 Image reading part 3 Image forming part 4 Belt unit part 5 Paper feed part 6 Reverse discharge / re-feed part 40 Cleaning device 41 1st roller 42 2nd roller 43 Belt 43b Brush 44 Recovery roller 45 Scraper 46 screw 405 support roller 401 intermediate transfer belt BB brush belt T fixing device

Claims (4)

In a cleaning device having a brush that is formed on an endless belt and collects toner remaining on an image carrier that carries a toner image, and a collection unit that collects toner collected by the brush,
The belt is formed of a stretchable base material, and is stretched by at least two rollers.
A cleaning device that drives a peripheral speed of a roller disposed on the collecting unit side at a higher speed than the other roller . The density of the base side of the brush on the roller arranged on the side of the collecting unit by driving the peripheral speed of the roller arranged on the side of the collecting unit at a higher speed than the other roller among the rollers. Lower than the density when the cleaning device is stopped, and the density of the bristles of the brush on the other roller is made higher than the density when the cleaning device is stopped. The cleaning device according to claim 1. Belt lengths sites in the recovery section is opposed position when the previous SL cleaning device is operating, to a belt length part between the rollers when the cleaning device is stopped, 1.2 above, a cleaning device according to claim 1 or 2, characterized in that stretched 1.4 times or less. An image bearing member for bearing a toner image, a cleaning device according to any one of claims 1 to 3, further comprising a fixing device for fixing the toner image transferred to the sheet material from said image bearing member An image forming apparatus.

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