JP5286056B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus provided with a cleaning device for transferring an image onto a transfer paper surface via a transfer body and removing surface deposits such as residual toner attached to the surface of the transfer body.

  Conventionally, in an image forming apparatus such as a printer, a copier, a facsimile, or a multifunction machine equipped with these functionally, a toner image formed on the surface of a transfer body such as a photosensitive drum is transferred to an endless belt-like intermediate transfer. An image forming apparatus is known in which a toner image is secondarily transferred to the surface of a transfer paper after being first transferred to a body.

  Also known is an image forming apparatus that removes surface deposits (residual toner, transfer paper fiber scraps, etc.) remaining on the surface of the intermediate transfer member with a cleaning device (see, for example, Patent Document 1).

  At this time, particularly by using a brush as the cleaning member, the cleaning performance can be ensured regardless of the material of the intermediate transfer member.

  For example, in order to obtain high image quality, an endless elastic belt may be used for the intermediate transfer member. However, if the intermediate transfer member is an elastic member, it is difficult to use an elastic blade as a cleaning member.

  Further, in the cleaning method using a brush, it is known that the value of bias applied to the brush is optimized according to each process condition, and the cleaning performance is improved by increasing the number of rotations of the brush.

  For example, as shown in FIG. 5, the cleaning device has a secondary transfer roller 53 opposed to a drive roller 52 that rotates and moves an intermediate transfer belt (intermediate transfer body) 51 as a transfer body via the intermediate transfer belt 51. A large number of brush fibers (conductive) are disposed in the vicinity of the disposed secondary transfer portion and are in contact with the surface of the intermediate transfer belt 51 on the downstream side in the belt conveyance direction from the contact position of the secondary transfer roller 53. A cleaning brush 54 made of a cylindrical electrostatic fur brush or the like wound around a core metal, a recovery roller 55 for recovering residual toner removed by the cleaning brush 54, a counter contact with the surface of the recovery roller 55, and a recovery roller 55 A cleaning blade 56 that scrapes the collected residual toner, and waste toner (not shown) scraped by the cleaning blade 56 It recovered in a toner container.

  At this time, the cleaning device is a system that relatively does not give a torque fluctuation to the intermediate transfer belt 51, and in particular, in a brush cleaning mechanism that presses and separates the cleaning brush 54 from the intermediate transfer belt 51, Excellent response to speed fluctuations.

  On the other hand, with the recent reduction in the toner particle diameter, the brush cleaning mechanism has a problem that the cleaning blade 56 is easily worn out due to the problem of durable wear of the cleaning blade 56 and the occurrence of defective cleaning.

  Accordingly, in combination with the scraping effect due to the rigidity of the cleaning brush 54, a bias is applied to the cleaning brush 54 to electrically collect the toner, thereby improving the cleaning performance for the small particle size toner.

  The residual toner and the like collected by the cleaning brush 54 is rotated by contacting the cleaning brush 54 with a conductive collection roller 55 to which a bias can be applied. After the toner is transferred to the collection roller 55, the collection roller 55 and the counter are countered. A method of scraping with a cleaning blade 56 that is in contact is generally used.

  As described above, the cleaning device of the brush cleaning mechanism using the cleaning brush 54 is a system that is very effective for the cleaning property of the small particle size toner. However, due to the rigidity of the cleaning brush 54, the cleaning brush 54 and the intermediate transfer belt 51 are used. In the vicinity of the nip between the cleaning brush 54 and the collection roller 55, the toner scraped (collected) by the cleaning brush 54 tends to scatter.

  In particular, if toner scattering occurs in the vicinity of the nip portion between the cleaning brush 54 and the collection roller 55, it causes contamination in the machine, and problems such as image defects are likely to occur.

  This is because residual toner and the like collected by the rebound restoration (brush rigidity) of the cleaning brush 54 when the brush fibers (filaments) near the nip portion between the cleaning brush 54 and the collection roller 55 are separated from the surface of the collection roller 55. It is caused by being thrown away.

Therefore, in order to suppress this, there is a tendency to largely depend on the rigidity of the brush fiber of the cleaning brush 54 and the rotation speed of the cleaning brush 54.
JP 2007-188058 A

  However, factors such as the rotational speed of the cleaning brush 54 and the rigidity of the brush fibers of the cleaning brush 54 are in a trade-off relationship between toner scattering and cleaning performance, and the brush fibers of the cleaning brush 54 are used to suppress toner scattering. If the rigidity and the number of rotations are reduced, the cleaning performance is deteriorated.

  In view of the above circumstances, an object of the present invention is to provide an image forming apparatus that can improve cleaning performance and suppress toner scattering.

  The image forming apparatus of the present invention includes a conductive rotating brush that contacts a surface of an image carrier and collects surface deposits, and a surface that is biased to the conductive rotating brush and simultaneously collected by the conductive rotating brush. In the image forming apparatus including the collecting member for collecting deposits, a rotation direction nip length of the collecting member in a collecting nip portion where the conductive rotating brush and the collecting member are in contact with each other is set to It is characterized in that it is longer than the nip length in the rotational direction of the image carrier at the collection nip where it contacts the image carrier.

At this time, the collecting member is a collecting roller, and the radius of curvature of the collecting roller is larger than the radius of curvature of the image carrier in the collecting nip portion where the conductive rotating brush and the image carrier are in contact with each other. preferable.

  The collection member is an endless belt-like collection sleeve, and the rotational nip length of the slack portion of the collection sleeve that contacts the conductive rotary brush is such that the conductive rotary brush and the image carrier are in contact with each other. It is preferably longer than the nip length in the rotational direction of the image carrier at the collecting nip portion.

  The image forming apparatus of the present invention can improve cleaning performance and suppress toner scattering.

  Next, an image forming apparatus according to an embodiment of the present invention is applied to a printer and described with reference to the drawings.

  FIG. 1 is an explanatory diagram of a printer as an image forming apparatus according to an embodiment of the present invention, and FIG. 2 is an enlarged view of a main part of the image forming apparatus according to an embodiment of the present invention.

[Entire configuration of image forming apparatus]
As shown in FIG. 1, a printer 1 as an image forming apparatus according to an embodiment of the present invention is connected to a computer or the like (not shown), and has a full color or the like according to image data sent from the computer or the like. The image is transferred and fixed on transfer paper. The right side of the printer 1 is the front side operated by the operator.

  The printer 1 includes a photoreceptor 2 on which an electrostatic latent image is formed, a rotary developing device main body 3 as a developing unit, a laser unit 4 as an exposure device, and a toner container 5 containing replenishing toner. The toner supply member 6 supplies the replenishing toner contained in the toner container 5 to the rotary developing device main body 3, the intermediate transfer unit 7, the secondary transfer roller 8, and the fixing device 9.

[Configuration of Photoreceptor 2]
The photosensitive member 2 is rotatably provided in the center of the inside of the printer 1 and its rotation shaft is provided so as to extend in the width direction from the front side of the printer 1, that is, to extend in the depth direction in FIG. Yes. A charging device 10 for charging the surface of the photoconductor 2 is provided on the photoconductor 2. Further, a drum cleaning device 11 for cleaning toner and adhering matter remaining on the surface of the photoconductor 2 is provided on the side of the photoconductor 2.

[Configuration of Rotating Developing Device Body 3]
The rotary developing device main body 3 develops the electrostatic latent image formed on the photoconductor 2 with toner of each color, and is adjacent to the photoconductor 2 and its rotation center is substantially the same as the rotation center of the photoconductor 2. It is provided to be at the height position. The rotary developing device main body 3 has a cylindrical shape that is rotatable about an axis parallel to the rotation center axis of the photoreceptor 2 and is rotated by a drive system including a motor and gears (not shown). Further, in the present embodiment, the rotary developing device main body 3 is divided into four equal parts and corresponds to toners of six colors (for example, yellow (Y), magenta (M), cyan (C), and black (K)). Two developing devices 12 can be installed.

  Each developing device 12 has substantially the same configuration, and is provided with a developing roller 13 and the like that can be disposed facing the photosensitive member 2. In addition, each developing device 12 is disposed away from the toner container 5, thereby reducing the toner storage space of the rotary developing device main body 3 and reducing the size of the developing device 12. Further, the developing device 12 can be attached to and detached from the rotary developing device main body 3 respectively, and maintenance and replacement of the developing device 12 can be easily performed.

  Each of the developing devices 12 has a tip of the toner replenishing member 6 on the outer peripheral surface of the toner case 14 constituting the outer shape of the developing device 12 in order to replenish the replenishing toner from the toner container 5 into the developing device 12. A toner replenishing portion (not shown) made of an elastic material such as rubber having a slit or the like (not shown) is provided.

[Configuration of Laser Unit 4]
The laser unit 4 scans and exposes the photoconductor 2 based on image information sent from an external computer or the like, and is disposed above the photoconductor 2. The laser unit 4 is provided with known configurations such as a laser light source, a polygon mirror, and a polygon mirror driving motor (not shown). Further, a reflection mirror 15 is provided in front of the laser beam path of the laser unit 4. As a result, the laser beam P emitted from the laser unit 4 is bent by the reflection mirror 15 and applied to the surface of the photoreceptor 2.

[Configuration of Toner Container 5]
The toner container 5 stores replenishment toner corresponding to each developing device 12 of the rotary developing device main body 3, and is detachably installed in the printer 1 so as to be replaceable. Further, the toner container 5 is yellow (Y), magenta (M), cyan (C), black (from the one side surface of the printer 1 toward the other side surface (toward the depth direction in FIG. 1)). The four toner containers 5 containing the replenishment toners of the respective colors K) are independently arranged in parallel.

[Configuration of Toner Supply Member 6]
The toner replenishing member 6 is for supplying the toner of each color stored in the toner container 5 to the corresponding developing device 12, and between the laser unit 4 and the toner container 5 above the photoreceptor 2. Arranged in space. Further, the same number of toner replenishing members 6 as the toner containers 5 are arranged so as to be movable in the vertical direction. The toner replenishing members 6 face the respective developing devices 12 at positions shifted in the depth direction of the paper surface of FIG. 12 can be replenished.

[Configuration of Intermediate Transfer Unit 7]
The intermediate transfer unit 7 sequentially transfers the toner images of the respective colors formed on the photosensitive member 2 to an endless intermediate transfer belt 16 and is disposed below the photosensitive member 2 and the toner container 5.

  The intermediate transfer belt 16 is stretched between a driving roller 17 and driven rollers 18 and 19. Further, the portion of the intermediate transfer belt 16 that faces the photoconductor 2 is configured to contact the photoconductor 2 by the primary transfer roller 20. In this embodiment, the driven roller 18 has a function of a tension roller for maintaining the tension state of the intermediate transfer belt 16. Further, the intermediate transfer belt 16 is cleaned by a cleaning device 21 disposed below the rotary developing device main body 3.

  The drive roller 17 is disposed substantially directly below the contact portion between the photosensitive member 2 and the rotary developing device main body 3, and the center thereof is located further below the lowermost end of the rotary developing device main body 3. And it drives by the drive part containing the motor and gear which are not shown in figure.

  The driven roller 18 is disposed close to the bottom of the toner container 5 on the front side of the printer 1, and the height position thereof is substantially the same as that of the photoreceptor 2.

  The primary transfer roller 20 is provided below the photoconductor 2, whereby a predetermined range of the intermediate transfer belt 16 is in contact with the photoconductor 2.

[Configuration of Secondary Transfer Roller 8]
The secondary transfer roller 8 is for secondary transfer of the image transferred to the intermediate transfer belt 16 to the transfer paper that has been conveyed, and is disposed below the driving roller 17 so as to face the transfer sheet. The secondary transfer roller 8 is applied with a bias voltage for image transfer to the transfer paper by a voltage application unit (not shown).

[Configuration of Fixing Device 9]
The fixing device 9 heats and presses the toner (image) transferred onto the transfer paper from the front and back of the transfer paper in order to melt and fix the toner, and is disposed below the rotary developing device main body 3 and near the back of the printer 1. ing. The fixing device 9 includes a fixing roller 23 that is heated by heat generated by a heat source 22 such as a halogen heater, a pressure roller 24 that is in pressure contact with the fixing roller 23, and a transfer sheet that is immediately after toner fixing on the surface of the fixing roller 23 Separating member 25 to prevent.

[Configuration of transport route]
A paper feed cassette 26 for storing transfer paper (not shown) is provided at the bottom of the printer 1. Then, the transfer paper stored in the paper feed cassette 26 is taken out from the paper feed unit 27 and transported to a transport path 29 leading to the discharge port 28, and the image transfer / fixing process described above is performed in the transport process. The The paper feed cassette 26 can be pulled out from the front side of the printer 1 (the front side of the paper in FIG. 1) for replacement or replenishment of transfer paper.

  In addition, a manual feed tray 30 that can be tilted is provided on the side surface of the printer 1 (on the right side in FIG. 1), and transfer paper can be mounted on the manual feed tray 30. The transfer paper mounted on the manual feed tray 30 is taken out from the manual paper feed unit 31 and joined to the transport path 29, and the image transfer / fixing process described above is performed in the transport process.

  Further, on the upstream side of the secondary transfer roller 8 in the transport path 29, a resist for adjusting the timing between the leading edge of the transfer paper taken out from the paper feeding unit 27 or the manual paper feeding unit 31 and the intermediate transfer belt 16. A pair of rollers 32 is provided, and on the downstream side of the fixing device 9 in the conveyance path 29, the transfer paper that has been fixed for double-sided printing processing is reversely conveyed from the registration roller pair 32 to the upstream side of the conveyance path 29. An inversion path 33 is provided. At this time, after the transfer paper for reversing is once transported to the vicinity of the discharge port 28, the rear end of the transfer paper is transported downstream from the upstream port of the reversing path 33 in the transport path 29. When the switchback roller 34 is reversed, it is fed into the reverse path 33.

[Image forming operation]
In the above configuration, when the printer 1 is turned on, various parameters are initialized, and initial settings such as setting the temperature of the fixing device 9 are executed. When image data is input from a computer or the like connected to the printer 1 and an instruction to start printing is given, an image forming operation is executed as follows.

  During the image forming operation, the toner replenishing member 6 is moved away from the rotary developing device main body 3 to the upper retracted position.

  First, after the photosensitive member 2 is charged by the charging device 10, scanning exposure corresponding to image data is performed on the photosensitive member 2 by the laser unit 4, and an electrostatic latent image is formed on the photosensitive member 2.

  Next, the rotary developing device main body 3 is rotated so that the corresponding color developing device 12 is opposed to the photosensitive member 2. In this state, the electrostatic latent image on the photoreceptor 2 is developed with the corresponding color toner.

  The developed image is transferred to the intermediate transfer belt 16, and the above operation is sequentially repeated for each color, whereby a full-color image is formed on the intermediate transfer belt 16. Residual toner remaining on the photoreceptor 2 is cleaned by the drum cleaning device 11 and discarded in a waste toner container (not shown).

  On the other hand, the transfer paper positioned at the uppermost position of the paper feed cassette 26 taken out by the paper feed unit 27 is subjected to the secondary transfer after being matched with the image forming position on the intermediate transfer belt 16 by the registration roller pair 32. It is conveyed to the roller 8.

  Since the secondary transfer roller 8 is in contact with the intermediate transfer belt 16, the full color image formed on the intermediate transfer belt 16 is transferred onto the transfer paper by the transfer bias applied to the secondary transfer roller 8.

  The transferred transfer paper is guided to the fixing device 9, and the image is fixed on the transfer paper by heating and pressing by the fixing device 9.

  The fixed transfer sheet is discharged from the discharge port 28 via the switchback roller 34 in the case of single-sided printing. In the case of double-sided printing, the switchback roller 34 switches back to the reverse path 33 and returns to the upstream side of the conveyance path 29 from the registration roller pair 32, and then forms an image on the back side of the transfer paper. And then discharged from the discharge port 28.

  Residual toner remaining on the intermediate transfer belt 16 after the transfer is removed by a cleaning device 21 employing a bias cleaning method, and then discarded in a waste toner container (not shown).

[Cleaning device 21]
Hereinafter, a specific example of the cleaning device 21 of the present invention will be described.

  As shown in FIG. 2, the cleaning device 21 includes a housing 35 that opens toward the drive roller 17, and a number of brush fibers (conductive) that are disposed near the open end of the housing 35 and come into contact with the surface of the intermediate transfer belt 16. A cleaning brush 36 made of a cylindrical electrostatic fur brush or the like wound around a metal core, a recovery roller 37 for recovering residual toner removed by the cleaning brush 36, and a counter contact with the surface of the recovery roller 37 for recovery. A cleaning blade 38 that scrapes the residual toner collected by the roller 37 and a spiral 39 that transports the residual toner and the like scraped by the cleaning blade 38 to a waste toner container (not shown) are provided.

[Cleaning brush 36]
The cleaning brush 36 is formed into a roll shape by spirally winding and bonding a long woven fabric in which resinous brush fibers (filaments) such as 6 nylon are radially and densely planted. The cleaning brush 36 may apply a fluorine-based resin powder (for example, “Kyner 500” manufactured by Mitsubishi Yuka Co., Ltd.) as a lubricant to the brush fibers.

  Further, the cleaning brush 36 rotates in the direction opposite to the rotational movement direction of the intermediate transfer belt 16 (counter direction), and the linear velocity ratio at the contact portion is set to 1.1. At this time, the linear velocity ratio is preferably set within the range of 0.8 to 1.2. Further, the cleaning brush 36 is in contact with the surface of the intermediate transfer belt 16 with a predetermined biting amount, and is in contact with the collection roller 37 with a predetermined biting amount.

  Further, the cleaning brush 36 can be pressed against and separated from the intermediate transfer belt 16 by a cam (not shown) and a cam provided coaxially with the drive shaft of the drive roller 17. At this time, the cleaning brush 36 is always pressed against the intermediate transfer belt 16 by the bias of the spring, and the cleaning brush 36 can be pressed against and separated from the intermediate transfer belt 16 by rotating a cam when necessary. it can. Since the bearing of the cleaning brush 36 is rotatable with respect to the rotation shaft of the collection roller 37, the amount of biting of the cleaning brush 36 with respect to the collection roller 37 can always be made constant.

  The amount of biting of the cleaning brush 36 into the intermediate transfer belt 16 is defined as the maximum value at which the tip of the brush fiber of the cleaning brush 36 enters the intermediate transfer belt 16 when the intermediate transfer belt 16 does not exist. The amount of biting of the cleaning brush 36 relative to the roller 37 is the maximum value at which the tip of the brush fiber of the cleaning brush 36 enters the recovery roller 37 when the recovery roller 37 does not exist.

  In the present embodiment, the amount of biting of the cleaning brush 36 into the intermediate transfer belt 16 is set to 1 ± 0.2 mm, but there is no particular problem as long as it is less than half the brush fiber length of the cleaning brush 36. The preferable amount of brush biting is preferably set within a range of 30% or less of the brush fiber length. The setting of the amount of biting is the same in the recovery nip portion between the recovery roller 37 and the cleaning brush 36.

  Further, at the collection nip portion between the cleaning brush 36 and the intermediate transfer belt 16, the linear velocity ratio between the intermediate transfer belt 16 and the cleaning brush 36 may be in the range of 0.5 to 2.0 (counter direction). preferable.

  That is, if this linear velocity difference is too small, cleaning failure is likely to occur, and if it is too large, toner scattering is likely to occur. The relative position between the cleaning brush 36 and the intermediate transfer belt 16 may be variable or fixed. However, in a configuration that requires pressure contact and separation, the relative positions of the cleaning brush 36 and the intermediate transfer belt 16 are variable.

[Recovery roller 37]
The collection roller 37 is made of, for example, a stainless steel cylinder and rotates in a direction opposite to the rotation direction of the cleaning brush 36 (counter direction), and removes residual toner and the like adhering to each brush fiber of the cleaning brush 36 from the collection roller 37 side. Electrically recover.

  Further, one of the bearings (not shown) of the collection roller 37 is a conductive bearing, and a bias is applied to the collection roller 37 through this conductive bearing. On the other hand, the bearing (not shown) of the cleaning brush 36 is non-conductive so that the bias applied to the collection roller 37 can act as a cleaning bias without loss.

  In the present embodiment, the driving roller 17 has conductivity and serves as a cleaning counter electrode. The drive roller 17 is grounded.

  As a result, the cleaning current flows from the recovery roller 37 through the cleaning brush 36 to the drive roller 17 from the intermediate transfer belt 16. By optimizing the resistance of the cleaning brush 36, a necessary and sufficient electric field can be formed between the intermediate transfer belt 16, the cleaning brush 36, and the cleaning brush 36 and the collection roller 37.

  When a bias is applied to the shaft of the collection roller 37, a current path is formed in the order of the cleaning brush 36 → the intermediate transfer belt 16 → the drive roller 17.

  The cleaning brush 36 is supported by an arm (not shown) having a recovery roller 37 as a fulcrum, and is pressed against and separated from the intermediate transfer belt 16 as necessary (FIG. 2 shows that the cleaning brush 36 is the intermediate transfer belt 16). Is in pressure contact).

The radius of curvature of the collection roller 37 at the collection nip portion where the collection roller 37 and the cleaning brush 36 are in contact with each other is the radius of curvature of the intermediate transfer belt 16 at the collection nip portion where the cleaning brush 36 and the intermediate transfer belt 16 are in contact with each other. It is preferable to be larger than the radius of curvature .

In the present embodiment, the radius of curvature of the collection roller 37 is increased by making the outer diameter of the collection roller 37 larger than the outer diameter of the drive roller 17 (actually the thickness of the intermediate transfer belt 16 is added). The radius of curvature of the intermediate transfer belt 16 is larger. In the case of the recovery sleeve 41, which will be described later, by pressing the slack portion against the recovery nip portion of the recovery roller 37, it is possible to form a recovery nip portion having a large curvature radius with a light pressure.

  The resistance value of the collection roller 37 (and the collection sleeve 41 described later) preferably has a resistance layer with a surface resistivity of 1.0E + 8 to 1.0E + 12Ω / □, but a highly conductive metal roller Etc. (in the case of the recovery sleeve 41 described later, a nickel electroformed sleeve or the like) can also be used.

  Therefore, it is preferable that the resistance layer of the recovery roller 37 is a resistance layer having a surface resistivity of 1.0E + 8 to 1.0E + 12Ω / □ mainly composed of PTFE.

  At this time, the resistance layer mainly composed of PTFE can keep the surface friction coefficient low, and the driving torque can be set low even when the pressing force of the cleaning blade 38 is increased, and mechanical jitter is hardly generated. can do. Further, as the surface friction coefficient of the collection roller 37 is lower, slipping at the collection nip portion is less likely to occur. If the friction coefficient is 0.2 or less, it is possible to suppress an increase in torque and to prevent slipping through the recovery nip portion. Further, as the conductive agent, a conductive agent based on a metal oxide rather than carbon conductive is preferable. Furthermore, a filler or the like may be added in order to improve the surface wear resistance of the collection roller 37 and maintain high surface hardness.

  As a filler here, it is preferable to set it as the electroconductive filler which coat | covered the tin-oxide type electrically conductive agent on these surfaces as potassium titanate whisker, acicular titanium. The resistance value is preferably a resistance layer having a surface resistivity of 1.0E + 8 to 1.0E + 12Ω / □.

  The surface roughness (Ra) of the collection roller 37 is preferably 1.0 μm or less. That is, when the surface roughness (Ra) is 1.0 or more, the wear of the cleaning blade 38 is easily promoted, and slipping through the collection roller 37 is likely to occur.

[Recovery sleeve 41]
Incidentally, the collection roller 37 may be an endless belt-like collection sleeve 41 as shown in FIG.

  At this time, the recovery sleeve 41 is free (slack) in the vicinity of the cleaning brush 36 by being driven by a driving roller 42 that is arranged apart from the cleaning brush 36 and has an outer periphery shorter than the inner periphery of the recovery sleeve 41. ), And a part of the slack portion comes into contact with the cleaning brush 36. Further, on the back side of the drive roller 42 opposite to the side facing the cleaning brush 36, the back side of the recovery sleeve 41 is pressed against the drive roller 42 to define the slack direction of the recovery sleeve 41. The guide 43 is provided. The cleaning blade 38 is in contact with the surface of the recovery sleeve 41 at a portion pressed against the drive roller 42 by the guide 43.

  At this time, the guide 43 for pressing the recovery sleeve 41 against the drive roller 42 on the back side of the drive roller 42 in order to form the slack portion of the recovery sleeve 41 is the recovery sleeve at the portion pressed by the guide 43. It is preferable that the coefficient of friction with 41 is as low as possible and the surface roughness is as low as possible.

  The material of the recovery sleeve 41 is preferably a conductive resin sleeve, a nickel electroformed sleeve, or the like. The Young's modulus (E) of the recovery sleeve 41 is preferably formed of a material with E ≦ 100 MPa. As the conductive agent, not only carbon conductive but also metal oxide based conductive agents can be used. Further, in order to improve the wear resistance of the surface of the recovery sleeve 41 and maintain high surface hardness, a filler or the like may be added.

  As the filler here, potassium titanate whisker, acicular titanium, and a conductive filler obtained by coating a surface thereof with a soot oxide-based conductive agent are preferable. The resistance value is preferably a resistance layer having a surface resistivity of 1.0E + 8 to 1.0E + 12Ω / □.

  Further, the surface roughness (Ra) of the recovery sleeve 41 is preferably 1.0 μm or less. That is, when the surface roughness (Ra) is 1.0 or more, toner slips easily.

  The brush fibers of the cleaning brush 36 preferably have a thickness of 1 to 6 denier. The denier is a general unit of the thickness of a yarn, and when the length of a 9000 m yarn is 1 g, it is called 1 denier. The material of the brush fiber is preferably nylon such as 6-nylon or 12-nylon, or polyester or acrylic. In order to impart conductivity, it is preferable to add carbon black. Furthermore, it is preferable that the electrical resistance of the brush fiber is set such that the volume resistance value of the cleaning brush 36 is in a range of 1.0E + 5 to 1.0E + 9Ω. Moreover, it is preferable to add carbon black in order to impart conductivity.

  Hereinafter, specific experimental results of the present invention will be shown.

Example 1
Intermediate transfer belt 16
Conductive PVDF (film thickness 150μm)
Volume resistance 1E + 9Ω ・ cm
Surface resistance 1E + 10Ω / □
Cleaning brush 36 (cleaning brush that has undergone the brush aging process)
Brush material 6-Nylon (conductive fiber)
Brush outer diameter 14mm
Brush density 18,600 Filament / cm2
Brush thickness 6 denier recovery roller 37
Shaft outer diameter φ22mm
Shaft material SUS shaft Conductive layer material PTFE main component Conductive layer thickness 20μm
Surface resistivity 2.0E + 09Ω / □
As a result of performing the image forming process (printing) under the above-described conditions, as shown in FIG. 4, the toner scattering amount after printing 100,000 sheets was 0.05 g, and good results could be obtained.

(Example 2)
Intermediate transfer belt 16
Conductive PVDF (film thickness 150μm)
Volume resistance 1E + 9Ω ・ cm
Surface resistance 1E + 10Ω / □
Cleaning brush 36 (cleaning brush that has undergone the brush aging process)
Brush material 6-Nylon (conductive fiber)
Brush outer diameter 14mm
Brush density 18,600 Filament / cm2
Brush thickness 6 denier recovery sleeve 41
Sleeve outer diameter φ18mm
Sleeve material Polyamide 12 (nylon 12) and amorphous polyamide 12 (amorphous nylon 12) blended 4: 6 Sleeve thickness 150 μm
Drive roller 42
Conductive foam rubber roller (resistance value 1E + 05Ω or less)
Further, as a result of performing the image forming process (printing) under the above-described conditions, as shown in FIG. 4, the amount of scattered toner after printing 100,000 sheets was 0.02 g, and good results could be obtained. .

(Conventional example)
Intermediate transfer belt 51
Conductive PVDF (film thickness 150μm)
Volume resistance 1E + 9Ω ・ cm
Surface resistance 1E + 10Ω / □
Cleaning brush 54 (cleaning brush that has undergone the brush aging process)
Brush material 6-Nylon (conductive fiber)
Brush outer diameter 14mm
Brush density 18,600 Filament / cm2
Brush thickness 6 denier Collection roller 55
Shaft outer diameter φ16mm
Shaft material SUS shaft Conductive layer material PTFE main component Conductive layer thickness 20μm
Surface resistivity 2.0E + 09Ω / □
Further, as a result of performing the image forming process (printing) under the above-mentioned conditions, as shown in FIG. 4, the toner scattering amount after printing 100,000 sheets was an undesirable result of 0.20 g.

  As described above, in the image forming apparatus of the present invention, the brush fiber of the cleaning brush 36 contacts the collection roller 37 in order to suppress toner scattering in the vicinity of the collection nip portion between the cleaning brush 36 and the collection roller 37. By increasing the time during which the recovery is performed, the recovery time is increased and at the same time the recovery performance is improved. Further, the radius of curvature of the collection roller 37 is increased in order to keep the amount of deformation at the moment when the cleaning brush 36 moves away from the surface of the collection roller 37 small.

  Thereby, when the brush fibers are separated from each other at the collection nip portion between the cleaning brush 36 and the collection roller 37, it is possible to suppress the toner from being blown off due to rebound restoration (brush fiber rigidity) of the cleaning brush 36.

  In the above embodiment, the image forming apparatus of the present invention is applied to a full-color printer. However, the image forming apparatus may be a monochrome machine, a copier, a facsimile machine, or a multifunction machine equipped with these functions. The present invention can be applied to all forming apparatuses.

  At this time, the intermediate transfer belt 16 may be a simple transfer belt. The driving roller 17 may be a driven roller.

1 is an explanatory diagram of a printer as an image forming apparatus according to an embodiment of the present invention. FIG. 1 is an enlarged view of a main part of an image forming apparatus according to an embodiment of the present invention. It is an enlarged view of the other principal part of the image forming apparatus which concerns on one Embodiment of this invention. It is a comparison chart of the experimental result in the image forming apparatus concerning one embodiment of the present invention. It is explanatory drawing of the principal part which concerns on the conventional image forming apparatus.

Explanation of symbols

16: Intermediate transfer belt (image carrier)
36 ... Cleaning brush (conductive rotating brush)
37 ... Collection roller (collection member)
41 ... Recovery sleeve (recovery member)

Claims (2)

A conductive rotating brush that contacts the surface of the image carrier and collects surface deposits; and a recovery member that supplies bias to the conductive rotating brush and simultaneously collects surface deposits collected by the conductive rotating brush; A cleaning blade that contacts the surface of the recovery member and scrapes surface deposits recovered by the recovery member, and an image forming apparatus comprising:
The surface resistivity of the recovery member is 1.0E + 8 to 1.0E + 12Ω / □ and the surface roughness of the recovery member is 1.0 μm or less,
The collection member is a collection roller having PTFE as a main component and a surface friction coefficient of 0.2 or less, and a collection nip where the radius of curvature of the collection roller is in contact with the conductive rotating brush and the image carrier. Larger than the radius of curvature of the image carrier in the portion,
The nip length in the rotation direction of the collection roller at the collection nip portion where the conductive rotating brush and the collection roller are in contact with each other is that of the image carrier at the collection nip portion where the conductive rotation brush and the image carrier are in contact with each other. An image forming apparatus characterized by being longer than a nip length in a rotation direction. A conductive rotating brush that contacts the surface of the image carrier and collects surface deposits; and a recovery member that supplies bias to the conductive rotating brush and simultaneously collects surface deposits collected by the conductive rotating brush; A cleaning blade that contacts the surface of the recovery member and scrapes surface deposits recovered by the recovery member, and an image forming apparatus comprising:
The surface resistivity of the recovery member is 1.0E + 8 to 1.0E + 12Ω / □ and the surface roughness of the recovery member is 1.0 μm or less,
The collection member is a material obtained by blending polyamide and amorphous polyamide, and is an endless belt-like collection sleeve having a Young's modulus of 100 MPa or less, and rotation of a slack portion of the collection sleeve that contacts the conductive rotating brush direction nip length is long images forming device you characterized than the rotational direction nip length of the image bearing member in the collecting nip portion and the electrically conductive rotating brush and the image carrier are in contact.

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