JP2007212626A - Cleaning device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cleaning device which can be made compact and can suitably scrape a film-like substance and uncharged toner sticking on an image carrier, and an image forming apparatus. <P>SOLUTION: Transfer remaining toner with the minus polarity is removed in a first region comprising a plurality of naps of a brush roller applied with a plus bias to have a plus potential and transfer remaining toner having the plus polarity is removed in a second region comprising a plurality of naps applied with a minus bias to have a minus potential. Then the film-like substance and uncharged toner sticking on a photoreceptor are scraped off in a third area comprising of a plurality of insulating naps which are not electrically conductive. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

Conventionally, in an electrophotographic image forming apparatus, an image carrier that is a member to be cleaned, such as an image carrier or an intermediate transfer member, is not adhered to the surface after a toner image is transferred to a recording member or another image carrier. Necessary transfer residual toner is removed by a cleaning device.
As a cleaning member of this cleaning device, one using a cleaning blade is well known because it can generally be simplified in configuration and has excellent cleaning performance.

  Further, in order to meet the recent demand for higher image quality, an image forming apparatus using a nearly spherical toner (hereinafter referred to as “spherical toner”) formed by a polymerization method or the like is known. This spherical toner has characteristics such as higher transfer efficiency than conventional pulverized toner (unshaped toner), and is known to be able to meet the recent demand for higher image quality. However, after the spherical toner is dammed up by the cleaning blade, it rolls by the frictional force with the image carrier and easily passes through the cleaning blade, and the cleaning performance deteriorates.

  On the other hand, there is an electrostatic brush cleaning method as a cleaning method having a reliable cleaning property even when cleaning a small particle size toner or a spherical toner. This electrostatic brush cleaning type cleaning device has the following configuration. In other words, the configuration includes a conductive brush roller that contacts and rubs against the surface of the photosensitive member, a recovery roller that contacts the conductive brush roller, and a toner removal unit that includes a rubber blade that contacts the recovery roller. In the electrostatic brush cleaning type cleaning device, a voltage is applied to both the conductive brush roller or the conductive brush roller and the recovery roller, and the toner is removed from the photosensitive member by an electrostatic force in addition to the rubbing force. For this reason, the cleaning performance can be obtained even with respect to a small particle size toner or a spherical toner.

  In general, in an image forming apparatus, a toner having a polarity opposite to that of a developed toner is applied in a transfer process to transfer toner on the photoconductor. It is a mixture of the toner with the toner polarity, the toner charged with the opposite polarity, or the non-charged toner (see FIG. 9). As a cleaning device for cleaning the mixture of the bipolar and non-charged toners, a cleaning device as shown in FIG. 10 has been proposed. That is, the first conductive brush roller 171 to which a positive voltage is applied and the second conductive brush roller 172 to which a negative voltage is applied are arranged and cleaned for each polarity toner.

  However, two conductive brush rollers 171 and 172 are arranged opposite to the photosensitive member 1, and further, removal means 173 and 174 for removing toner adhering to the respective brushes are arranged in the image forming apparatus. It is difficult to achieve the problem of miniaturization. Therefore, Patent Document 1 proposes a cleaning device that includes a conductive brush roller that cleans toner for each polarity toner without increasing the size. The conductive brush roller of Patent Document 1 is divided into a first region in which a positive polarity bias is applied to a plurality of conductive brushes and a second region in which a negative polarity bias is applied. Then, the brush roller divided into the positive and negative areas is rotated so that each of the brush rollers comes into contact with the surface of the photoconductor, and cleaning is performed for each polar toner from the surface of the photoconductor. The uncharged toner is mechanically scraped off by the brush roller and removed from the surface of the photoreceptor. Accordingly, it is only necessary to arrange one brush roller so as to face the image carrier, and this is advantageous in terms of downsizing.

JP 2005-157374 A

  By the way, additives such as silica and zinc stearate contained in the toner may be released from the toner body due to mechanical stress during the image forming process. When the additive thus released is pressed against the surface of the image carrier for a long time by rubbing with the developer in the development region or rubbing with the brush, the additive adheres to the surface of the image carrier in a thin film form. Filming phenomenon occurs. When this filming phenomenon occurs, the adhesion force of the toner adhering to the image carrier is weakened, and problems such as a phenomenon called image flow occur. For this reason, the additive adhering to the film form with the said brush roller is shaved off, and the malfunction by the filming phenomenon is suppressed.

  However, as in the configuration of Patent Document 1, when a negative or positive voltage is applied to the conductive brush, the effect of scraping off the additive adhering to the film is reduced, and defects due to the filming phenomenon are sufficiently suppressed. There was a problem that could not be done. Therefore, the present applicant visually observed the behavior of the raising when the voltage was applied to the raising of the brush roller and when the voltage was not applied, and confirmed the following behavior. That is, when a voltage is applied to the raising, the conductive raising that is in contact with the photosensitive member bends upstream in the brush roller moving direction. When voltage is applied to the raised hair, the reason why the raised hair is bent is not clear, but as a result of applying voltage to the raised hair, an electric field is formed between the image carrier and the raised hair. It is considered that the raising is bent toward the upstream side in the brush roller moving direction. As described above, it is considered that as a result of the raising of the brush, the contact pressure between the photosensitive member and the raising is weakened, and the effect of scraping off the additive adhering to the film by the brush roller is reduced. In addition, as a result of the contact pressure between the photosensitive member and the raised brush being weakened, the uncharged toner cannot be scraped mechanically well, and the uncharged toner cannot be removed well from the surface of the photosensitive member.

  The present invention has been made in view of the above background, and an object of the present invention is to reduce the size of the apparatus and to scrape off the film-like substance and the uncharged toner adhering to the image carrier. It is an object of the present invention to provide a cleaning device and an image forming apparatus that can perform the above operation.

In order to achieve the above object, the invention of claim 1 has a plurality of conductive raised portions provided on a rotating shaft and rotates while abutting against an image carrier that moves on the surface. In the cleaning apparatus including a brush roller for cleaning the surface of the carrier, the brush roller applies a positive bias to the conductive brush to remove the negatively charged toner on the surface of the image carrier. An area, a second area where a negative polarity bias is applied to the conductive brush to remove the positively charged toner on the surface of the image carrier, and a scratch which mechanically removes substances adhering to the surface of the image carrier And a third region provided with a scraping member, which is configured not to conduct electricity to the scraping member.
According to a second aspect of the present invention, in the cleaning apparatus of the first aspect, the third region is a non-bias application region.
According to a third aspect of the present invention, in the cleaning device of the first aspect, the scraping member is an insulating member.
According to a fourth aspect of the present invention, in the cleaning device according to the third aspect, the third region is disposed between the first region and the second region.
The invention of claim 5 is the cleaning device according to any one of claims 1 to 4, wherein the scraping member is a plurality of raised hairs, and the rigidity of the raised hairs is larger than the rigidity of the conductive raised hairs. It is characterized by having comprised as follows.
According to a sixth aspect of the present invention, there is provided the cleaning apparatus according to any one of the first to fifth aspects, further comprising a removing means for removing a substance attached to the brush roller.
According to a seventh aspect of the present invention, in the cleaning device according to any one of the first to sixth aspects, the first area, the second area, and the second area while the surface of the image carrier passes through the area in contact with the brush roller. The three regions and the surface of the image carrier are configured to contact at least once.
In the cleaning device according to any one of claims 1 to 7, the ratio of the third area in the brush roller is higher than the ratio of the first area and the second area. It is characterized by.
According to a ninth aspect of the present invention, in the cleaning device according to any one of the first to seventh aspects, the ratio of the third area in the brush roller is lower than the ratio of the first area and the second area. It is characterized by.
According to a tenth aspect of the present invention, there is provided an image carrier, a charging device for charging the image carrier, a latent image forming device for forming an electrostatic latent image on the image carrier, and a static image on the image carrier. Image forming apparatus comprising: a developing device that causes toner to adhere to an electrostatic latent image to be visualized; a transfer device that transfers a toner image on the image carrier to a transfer material; and a cleaning device that cleans the image carrier. In the apparatus, the cleaning apparatus according to any one of claims 1 to 9 is adopted as the cleaning apparatus.
According to an eleventh aspect of the present invention, in the image forming apparatus according to the tenth aspect, the image bearing member is provided with a protective layer containing a filler (particulate matter).
According to a twelfth aspect of the present invention, in the image forming apparatus of the tenth or eleventh aspect, as a toner for forming a toner image on the image carrier, a shape factor SF-1 is in the range of 100 to 150. It is characterized by using.
According to a thirteenth aspect of the present invention, in the image forming apparatus according to any one of the tenth to twelfth aspects, the image carrier and at least the cleaning device are integrally configured, and the process cartridge is detachable from the apparatus main body. It is characterized by comprising.
According to a fourteenth aspect of the present invention, in the image forming apparatus according to the thirteenth aspect, a plurality of the process cartridges are provided.

  According to the first to fourteenth aspects of the present invention, the negatively charged toner on the surface of the image carrier is removed in the first area of the brush roller, and the positively charged toner is removed in the second area of the brush roller. Thus, the bipolar toner on the surface of the photoreceptor can be removed with one brush roller. Therefore, the apparatus can be reduced in size as compared with a configuration in which two brush rollers to which positive and negative voltages are respectively applied are arranged. Further, since no electricity is conducted to the scraping member provided in the third region, it is possible to suppress the formation of an electric field between the scraping member and the photosensitive member. Therefore, it is possible to suppress the scraping member from being bent to the upstream side in the brush roller moving direction due to the influence of the electric field, and it is possible to suppress the contact pressure between the scraping member and the image carrier. As a result, the scraping member can satisfactorily scrape off the toner additive attached to the surface of the image carrier in the form of a film and the uncharged toner on the image carrier. Accordingly, it is possible to satisfactorily remove the toner additive attached to the surface of the image carrier and the uncharged toner on the image carrier from the surface of the image carrier.

Hereinafter, an embodiment in which the present invention is applied to a printer which is an image forming apparatus will be described. FIG. 1 is an overall configuration diagram of a printer according to the present embodiment.
Around the photoconductor 1 as an image carrier, a charging device 2 that charges the surface of the photoconductor 1 with a charging roller or the like, and an exposure (not shown) that forms a latent image on the uniformly charged surface of the photoconductor 1 with a laser beam L. The toner image formed on the photosensitive member 1 by the transfer roller 12a and the developing device 6 as a developing unit that forms a toner image by attaching charged toner to the latent image on the photosensitive member 1 on the transfer sheet P A transfer device 5 for transferring the toner, a cleaning device 7 for removing the toner remaining on the photoreceptor drum 1 after the transfer, and a charge eliminating device 8 for removing the residual potential on the photoreceptor 1 are arranged in this order.

  In the printer having the above configuration, the photosensitive drum 1 whose surface is uniformly charged by the charging roller 2a of the charging device 2 is formed with an electrostatic latent image by an exposure device (not shown) and a toner image is formed by the developing device 6. The The toner image is transferred from the surface of the photosensitive drum 1 to the transfer paper P conveyed from the paper feed tray 3 by the transfer device 5.

  Below the transfer device 5, there is disposed a paper feed cassette 3 that accommodates a plurality of transfer sheets P as recording bodies. The paper feed cassette 3 rotates the paper feed roller 3a pressed against the uppermost transfer paper P at a predetermined timing, and feeds the transfer paper P to the paper feed conveyance path. In the paper feed conveyance path, the transferred transfer paper P passes through the plurality of conveyance roller pairs 13 and then is sandwiched between the rollers of the registration roller pair 14 and stopped. The registration roller pair 14 faces the transfer nip between the transfer roller 12a and the photoconductor 1 at a timing at which the sandwiched transfer paper P can be superimposed on the toner image formed on the photoconductor 1 as described above. Send it out. As a result, the toner image on the photosensitive member 1 and the transfer paper P sent out by the registration roller pair 14 are brought into close contact with each other at the transfer nip. Then, it is electrostatically transferred onto the transfer paper P due to the influence of the transfer voltage.

  A paper transport belt 12 is wound around the transfer roller 12a, and the paper transport belt 12 is stretched between the transfer roller 12a and the drive roller 12b, and moves endlessly counterclockwise in the drawing. Further, a fixing device 9 and a discharge roller pair 10 are sequentially disposed on the left side of the paper conveying belt 12. The transfer paper P on which the above-described toner image has been electrostatically transferred is fed onto the paper transport belt 12 and then enters the fixing device 9. The transfer paper P that has entered the fixing device 9 is subjected to heat treatment and pressure treatment. As a result, the toner is thermally melted under pressure and the toner image is fixed on the transfer paper P. Then, the transfer paper P is discharged out of the apparatus from the fixing device 9 through the paper discharge roller pair 10.

  The toner remaining on the photosensitive drum without being transferred is collected by the cleaning device 7. The photoreceptor 1 from which the residual toner has been removed is initialized by the charge eliminating lamp 8 and used for the next image forming process. Further, the toner that has been transferred onto the paper transport belt 12 is removed from the paper transport belt 12 by the belt cleaning device 15.

  In this embodiment, the photosensitive member 1, the developing device 6, the charging device 2, the cleaning device 7 and the like disposed around the photosensitive member 1 are configured as a process cartridge 100. The process cartridge 100 is detachable from the printer body. Therefore, when the life of a component housed in the process cartridge 100 is reached or maintenance is required, the process cartridge 100 may be replaced, which improves convenience.

  FIG. 2 is an enlarged configuration diagram showing the cleaning device 7. The cleaning device 7 includes a brush roller 71 in which countless raised hairs 71a are planted on the surface of a roller-shaped core member 71b serving as a rotating shaft, a removing unit including a collection roller 72 and a scraper member 73, and a conveying unit 74. is doing. The brush roller 71 is rotated in the clockwise direction in the figure by a driving means (not shown) so as to be moved in the direction opposite to the surface of the photoconductor 1 at the contact portion while the front end side of the brush roller 71 is in contact with the photoconductor 1. The transfer residual toner is captured by a plurality of raised brushes that rub against the surface of the photoreceptor 1. The collection roller 72 is disposed so that the brush roller 71 is sandwiched between the collection roller 72 and the photoreceptor 1. And the surface which contacts the brush 71a of the brush roller 71 is rotationally driven by the drive means which is not shown in figure clockwise so that it may move to the direction opposite to the raising 71a in a contact part. The plate-shaped scraper member 73 is disposed so that the edge at the tip thereof is brought into contact with the collection roller 72 with a predetermined pressure. Further, the conveying means 74 is disposed below the scraper member 73 in the direction of gravity.

  Next, the brush roller 71 will be described in detail. FIG. 3 is a diagram schematically showing the brush roller 71. As shown in the figure, the brushed 71a includes a region A that is a first region that is charged to a positive polarity, a region B that is a second region that is charged to a negative polarity, and a third region that is configured so that electricity is not conducted to the raised brush. And a region C. A first power source 701 that applies a negative voltage and a second power source 702 that applies a positive voltage are connected to the core member 71 b of the brush roller 71. The first power source 701 is connected to a portion corresponding to the region B of the core member 71b, and the second power source 702 is connected to a portion corresponding to the region A of the core member 71b. By applying a negative voltage from the first power source 701, the plurality of raised portions in the region B are charged to a negative polarity. Further, when a positive voltage is applied from the second power source 702, the plurality of raised portions in the region A are charged to positive polarity. The raising 71a arranged in the region A and the region B is a conductive raising, and the raising as a scraping member arranged in the region C is insulative, and electricity flows through the raising. There is no such thing. A region C composed of a plurality of insulating nappings is disposed between the region A and the region B. Since the region A and the region B are charged with different polarities, if the region A and the region B are adjacent to each other, the raising of the region A and the raising of the region B may come into contact with each other and leak. If the leakage occurs, the amount of charge of the raised portions in the areas A and B decreases, and the transfer residual toner cannot be adsorbed electrostatically, which may cause a cleaning failure. However, by providing the insulating region C between the region A and the region B as described above, it is possible to prevent leakage and suppress a reduction in the charge amount of the raised portions in the regions A and B. .

  When the raising of the region A and the region B to which the voltage is applied enters the nip region 26 where the surface of the photoreceptor is in contact with the brush roller, the raising is bent upstream in the direction of movement of the brush roller. The reason why the raised hair to which the voltage is applied is bent is not certain, but by applying a voltage to the raised hair, an electric field is formed between the photoconductor and the raised hair. It is considered that due to the influence of this electric field, a force that bends the raised hairs acts on the upstream side in the direction of movement of the brush roller. As a result, the raised areas in the regions A and B have an increased contact area with the photoconductor, and the transfer residual toner on the photoconductor can be electrostatically adsorbed satisfactorily to remove the transfer residual toner from the photoconductor. However, when the raising is bent, the contact pressure between the raising and the photosensitive member is lowered, and the toner additive attached to the surface of the photosensitive member in the form of a film cannot be scraped well. On the other hand, since the insulating raising in the region C does not conduct electricity, an electric field is not formed between the photosensitive member and the raising. Therefore, the raising in the region C does not bend to the upstream side in the brush roller moving direction due to the influence of the electric field. As a result, the raising of the region C suppresses a decrease in the contact pressure with the photosensitive member, and can favorably scrape off the toner additive and the uncharged toner adhered to the surface of the photosensitive member in the form of a film.

As a material for the raised 71a, fiber materials such as nylon, acrylic, polyester, and PET can be used. The raising | fluff of the area | region A and the area | region B is providing electroconductivity by decorating these fibers by using carbon fiber as a core material. Further, conductivity may be imparted to the raised hair by dispersing and mixing carbon fibers in these fibers. In the present embodiment, the volume resistivity of the conductive raised portions disposed in the region A and the region B is 10 ⁶ to 10 ⁹ [Ω · cm]. On the other hand, since the raised carbon provided in the region C does not contain the above carbon fever, the volume resistance value of the brush is high resistance of 10 ¹⁴ [Ω · cm] or more.

Further, it is preferable that the raised hairs disposed in the region C have higher rigidity than the raised hairs disposed in the region A and the region B. The raising in the areas A and B removes the toner remaining on the surface of the photosensitive member by electrostatically adsorbing it. Therefore, the larger the contact area with the photosensitive member when the raising is in contact with the photosensitive member, the more This is preferable because the transfer residual toner can be adsorbed electrostatically. Therefore, the raised brushes arranged in the region A and the region B have a low rigidity so that they are greatly bent when they come into contact with the photoconductor to increase the contact area with the photoconductor.
On the other hand, the raising in the region C mechanically scrapes and removes the toner additive attached to the film on the surface of the photosensitive member and the weakly charged toner on the photosensitive member. The contact pressure of the photosensitive member decreases, and the effect of mechanically scraping the weakly charged toner on the photoreceptor is weakened. Therefore, it is preferable that the raised hairs arranged in the region C have high rigidity so that the raised hairs do not bend easily even if they come into contact with the surface of the photoconductor so that the contact pressure with the photoconductor does not decrease.

  In addition, the areas A, B, and C of the brush roller are moved to the photosensitive member 1 at least once while the surface of the photosensitive member moves from the leading end position P to the trailing end position Q of the nip region 26 where the photosensitive member and the brush roller contact each other. The rotation speed of the brush roller 71 is set so as to be in sliding contact with.

Next, the collection roller 72 will be described in detail. FIG. 4 is a view showing the brush roller 71, the recovery roller 72, and the scraper member 73.
As shown in the figure, the collection roller 72 has an electrode part A ′, an electrode part B ′, and an insulating part C ′ on the surface thereof. The insulating part C ′ is arranged between the electrode part A ′ and the electrode part B ′ so that no leakage occurs between the electrode part A ′ and the electrode part B ′. A third power source 703 that applies a positive voltage to the electrode portion A ′ is connected to the electrode portion A ′. As a result, the electrode part A ′ is positively charged. A fourth power source 704 that applies a negative voltage to the electrode part B ′ is connected to the electrode part B ′. Thereby, the electrode part B ′ is negatively charged. The absolute value of the voltage applied to the electrode A ′ is set to be larger than the absolute value of the voltage applied to the region A of the brush roller 71. Further, the absolute value of the voltage applied to the electrode B ′ is set to be larger than the absolute value of the voltage applied to the region B of the brush roller 71. When the region A of the brush roller 71 passes through the region in contact with the collection roller 72, it contacts the electrode portion A ', and when the region B of the brush roller 71 passes through the region in contact with the collection roller 72, The rotation speed of the collection roller 72 is set so as to come into contact with the insulating portion C ′ when the region C of the brush roller 71 is in contact with the electrode unit B ′ and passes through the region of contact with the collection roller 72. The rotational speed of the collection roller 72 can be easily set mechanically by a combination of gears and the like. In order to improve the wear resistance of the scraper member 73, the surface of the collecting roller 72 is covered with fluorine, PVDF (polyvinylidene fluoride), PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer), or the like. May be.

  Next, the operation of the cleaning device 7 will be described in detail. When a print signal is input and an image forming operation is started, after the charging, writing, developing, and transferring steps, the transfer residual toner on the photosensitive member 1 is sent to a portion facing the cleaning device 7. This untransferred toner is a toner charged with a reverse polarity and charged with a reverse polarity or a mixture of uncharged toner in the transfer process. When the surface of the photosensitive member enters the tip position P of the nip region 26, it contacts one of the regions A, B, and C of the brush roller 71. For example, when the surface of the photosensitive member comes into contact with the region A at the tip position P of the nip region 26, the transfer residual toner charged to the negative polarity among the transfer residual toner on the surface of the photosensitive member is caused by the raising of the region A of the brush roller 71. It is electrostatically attracted and removed from the photoreceptor. As the surface of the photoconductor advances in the nip area, the area of the brush roller that contacts the photoconductor surface changes from area A to area C. When the area C of the brush roller 71 comes into contact with the surface of the photoconductor, the toner external additive attached to the surface of the photoconductor is scraped off and mechanically removed. Further, the weakly charged transfer residual toner on the surface of the photoconductor is also mechanically removed from the surface of the photoconductor by raising the region C of the brush roller 71. Further, as the surface of the photoreceptor 1 advances in the nip region, the region of the brush roller 71 that contacts the surface of the photoreceptor changes from region C to region B. When the area B of the brush roller 71 comes into contact, the transfer residual toner charged to the positive polarity on the surface of the photoconductor is electrostatically adsorbed to the raised hair and removed from the photoconductor. In this manner, at least once while the surface of the photoconductor passes through the nip region 26, the positive, negative, and non-charged transfer on the surface of the photoconductor is performed by contacting the regions A, B, and C of the brush roller 71. The residual toner is removed, and the toner additive adhering to the surface of the photoreceptor in the form of a film is removed.

  The negative transfer residual toner adhering to the region A of the brush roller 71 is electrostatically attracted to the electrode portion A ′ of the recovery roller 72 and removed from the brush roller 71. Further, the negative transfer residual toner adhering to the region B of the brush roller 71 is electrostatically attracted to the electrode portion B ′ of the recovery roller 72 and removed from the brush roller 71. Further, the uncharged transfer residual toner and the toner additive adhering to the region C of the brush roller 71 are shaken off from the brush roller 71 by the vibration at the time of contact with the recovery roller 72 and fall to the conveying means 74.

  The untransferred toner adhering to the collection roller 72 is blocked by the scraper member 73. When the electrode portion A ′ of the recovery roller 72 enters the area where the scraper member 73 blocks the transfer residual toner, the transfer residual toner of the positive polarity among the transfer residual toner blocked by the scraper member 73 is recovered by the repulsive force. Fly from the surface and leave the collection roller 72. Further, when the electrode portion B ′ of the recovery roller 72 enters the area where the scraper member 73 blocks the transfer residual toner, the positive transfer residual toner among the transfer residual toner blocked by the scraper member 73 is repulsive. Fly from the surface of the collection roller and leave the collection roller 72. In this way, the untransferred toner separated from the collection roller 72 falls to the conveying means 74.

  Transfer residual toner or the like that has dropped onto the conveying means 72 is appropriately discharged out of the cleaning device 7 by the conveying means 74.

  In this embodiment, the area of the brush roller is divided into 8 divisions as A, C, B, C, A, C, B, C. However, if at least the area is divided into an integral multiple of 4, A The insulating region C can be disposed between the region and the B region, and the insulating properties of the A region and the B region can be ensured. If the number of divisions is small, the rotational speed of the brush roller needs to be increased in order to make the surface of the photoreceptor contact with the brush roller A, B, C region while passing through the nip region. More specifically, when the region is a four-part brush roller of A, C, B, C, in order to make sure that the surface of the photosensitive member is in contact with the brush roller A, B, C region while passing through the nip region. This requires at least one rotation of the brush roller. On the other hand, in the case of an eight-division brush roller with areas A, C, B, C, A, C, B, and C, if the brush roller is rotated halfway while the photosensitive member surface passes through the nip area, the brush It can be reliably brought into contact with the roller areas A, B and C. As a result, when the number of divisions of the brush roller region is larger, the rotation speed of the brush roller can be reduced, and wear on the surface of the photoreceptor due to friction with the brush roller can be suppressed.

Next, the relationship between the number of divisions of the brush roller 71 and the cleaning property was examined. The result is shown in FIG. The horizontal axis in the figure is the absolute value of the voltage applied to the region A and the region B of the brush roller, and the vertical axis is the cleaning property (ID). The cleaning property (ID) is a value obtained as follows. The toner on the photoconductor after passing through the brush roller is transferred to a tape and attached to paper, and the reflection density is measured with a spectrocolorimeter (X-light manufactured by Amtec Corporation). On the other hand, this is a value (ID) obtained by subtracting the reflection density of only the tape from the reflection density of the tape on which only the tape is attached to the paper and the reflection density is measured with a spectrocolorimeter and the toner on the photoconductor is adhered. There is a correlation between the ID and the number of toners, and the ID value increases when the number of toners is large. Therefore, the cleaning property can be determined by the ID.
The specific conditions of the image forming apparatus at the time of investigation are as follows.
Photoconductor diameter: φ40 [mm]
Photoconductor linear velocity: 100 [mm / S]
Brush roller diameter: φ30 [mm]
Brush roller linear velocity: 300 [mm / S]
Brush bite amount: 1 [mm]
Toner: Spherical φ5 [μm]
Recovery roller absolute value applied voltage = brush roller absolute value applied voltage + 200 [V]

As shown in the figure, it can be seen that the cleaning performance is improved as the number of divisions of the brush roller region is increased. This is presumably because the number of contact between the surface of the photoreceptor and the region increases as the number of divisions of the brush roller region increases. More specifically, in the case of a brush roller with four divisions, the area A and the area B are in contact with the surface of the photoconductor only once (the area C is twice) while the brush roller rotates once. While the brush roller whose area is divided into eight is rotated once, the area A and the area B are in contact with the surface of the photoreceptor twice (area C is four times). The brush roller whose region is divided into 12 can make contact with the surface of the photoreceptor 3 times (region C is 6 times) in the region A and the region B during one rotation. Thus, it is considered that increasing the number of divisions of the region increases the number of contact times of the region and improves the cleaning performance.
Further, as can be seen from the figure, the cleaning performance improves as the absolute value of the voltage applied to the region A and the region B of the brush roller increases.

  In the present embodiment, the ratios of the areas A, B, and C of the brush roller are equally spaced, but the ratios may be changed as appropriate according to the characteristics of the apparatus and toner. For example, when the cleaning property is poor but the toner additive is difficult to film on the surface of the photoreceptor, the ratio of areas A and B is made larger than area C as shown in FIG. Use a brush roller with high removal capability. If the toner additive is easy to film on the surface of the photoreceptor, the area C is made larger than the areas A and B, and the brush roller has a high filming removal capability.

  Further, in this embodiment, the scraping member that scrapes the film-like toner additive in the region C is constituted by insulating brushing, but it is sufficient that electricity does not conduct to the scraping member. You may comprise by the shape of a flexible insulating member. Even if the region C is formed of a sheet-like insulating member, leakage between the brushes in the region A and the brushes in the region B can be suppressed. In addition, since the sheet-like insulating member does not conduct electricity, an electric field is not generated between the photosensitive member and the insulating member, and the sheet-like insulating member does not bend due to the influence of the electric field. Accordingly, a decrease in the contact pressure between the sheet-like insulating member and the photosensitive member is suppressed, and the toner additive attached to the surface of the photosensitive member at the tip of the sheet-like insulating member can be scraped off.

  Further, if no voltage is applied by setting the region C as a non-bias application region, electricity is not conducted to the raised portions disposed in the region C even if the raised portions disposed in the region C are conductive. Therefore, since an electric field is not formed between the photosensitive member surface and the raised portions in the region C, it is possible to suppress the raised portions in the region C from being bent due to the influence of the electric field. Therefore, it is possible to suppress a decrease in the contact pressure between the raising of the region C and the surface of the photosensitive member, and it is possible to scrape and remove the toner additive and the weakly charged toner adhered to the film shape in the region C. it can.

  Moreover, it can also be set as the structure which does not conduct electricity to the raising which is a scraping member by affixing an insulating sheet to the part of the area | region C of the core member 71b, and planting a plurality of raising on this insulating sheet. .

  Next, a modified example of the cleaning device 7 will be described. FIG. 7 shows a modification of the cleaning device 7. In the cleaning device 7 of this modification, the recovery roller 72 is a single electrode, and a power source 705 for applying a rectangular wave or SIN wave voltage is provided. The power source 705 applies a positive voltage to the collection roller 72 by the timing when the area A of the brush roller 71 passes through the contact area with the collection roller 72, and the area B passes through the contact area with the collection roller 72. A negative voltage is applied to the collection roller 71 by the timing. The absolute value of the voltage applied to the collection roller 72 is larger than the absolute value of the voltage applied to the brush roller.

At the timing when the area A of the brush roller passes through the contact area with the collection roller 72, the power supply device switches the voltage applied to the collection roller to the positive polarity, and the negative transfer residue electrostatically attracted to the brush in the area A The toner is electrostatically attracted to the collecting roller 72, and the negative transfer residual toner is collected from the brush roller. At this time, the positive transfer residual toner adhering to the collecting roller 72 flies from the surface of the collecting roller with a repulsive force, is separated from the collecting roller 72, and falls to the conveying means 74. In addition, the voltage applied to the collection roller 72 is switched to the negative polarity at the timing when the region B of the brush roller 71 passes through the contact area with the collection roller 72. The positive transfer residual toner electrostatically attracted to the brush in the region B is electrostatically attracted to the recovery roller 72, and the positive transfer residual toner is recovered from the brush roller. Further, the negative transfer residual toner collected by the collection roller 72 flies from the surface of the collection roller by a repulsive force, is separated from the collection roller 72, and falls to the conveying means 74. In this modified example, when the area C of the brush roller 71 passes through the contact area with the collection roller 72, no voltage is applied to the collection roller 72.
The cleaning device 7 of this modification can have one power source for applying a voltage to the collection roller 72, and the size of the device can be reduced. In addition, the degree of freedom of layout in the apparatus can be increased. Further, since the collecting roller 72 can be a single electrode, the collecting roller can be easily manufactured, and the cost can be reduced.

Next, a photoconductor preferably used in the image forming apparatus of this embodiment will be described.
The basic structure of the photoreceptor is composed of a conductive support, a latent image carrying layer, and a surface layer (protective layer). Further, the latent image bearing layer needs to be electrically insulative which can be charged, but a non-photoconductive dielectric layer or a photoconductive photosensitive layer can be used.

  The contact pressure between the photosensitive member 1 and the brush roller 71 of the cleaning device 7 is significantly smaller than that of the conventional blade cleaning method. However, when the brush roller 71 is rotated at a high speed, the surface of the photosensitive member is worn over time. Therefore, in order to ensure a long life, the durability can be improved by making the binder resin of the photoconductor protective layer into a crosslinked structure, or by strengthening it by having a charge transport site in the structure of the binder resin having a crosslinked structure. . Concerning the formation of the crosslinked structure of the binder resin, a reactive monomer having a plurality of crosslinkable functional groups in one molecule is used to cause a crosslinking reaction using light or thermal energy to form a three-dimensional network structure. To do. This network structure functions as a binder resin and exhibits high wear resistance. From the viewpoint of electrical stability, printing durability, and life, it is a very effective means to use a monomer having a charge transporting ability in whole or in part as the reactive monomer. By using such a monomer, a charge transporting site is formed in the network structure, and the function as a protective layer can be sufficiently expressed. The reactive monomer having charge transporting ability includes a compound containing at least one charge transporting component and a silicon atom having a hydrolyzable substituent in the same molecule, and a charge transporting component in the same molecule. A compound containing a hydroxyl group, a compound containing a charge transporting component and a carboxyl group in the same molecule, a compound containing a charge transporting component and an epoxy group in the same molecule, a charge transporting component in the same molecule And a compound containing an isocyanate group. These charge transport materials having a reactive group may be used alone or in combination of two or more. More preferably, a reactive monomer having a triarylamine structure is effectively used as the monomer having a charge transporting ability because of high electrical and chemical stability and high carrier mobility. In addition to this, monofunctional and bifunctional polymerizable monomers and polymerizable oligomers are used in combination for the purpose of viscosity adjustment during coating, stress relaxation of the cross-linked charge transport layer, low surface energy, and reduction of friction coefficient. be able to. As these polymerizable monomers and oligomers, known ones can be used.

  In addition, the hole transporting compound is polymerized or cross-linked using heat or light, but when the polymerization reaction is performed by heat, the polymerization reaction proceeds only with thermal energy or a polymerization initiator is required. However, in order to advance the reaction efficiently at a lower temperature, it is preferable to add an initiator. In the case of polymerization by light, it is preferable to use ultraviolet light as light, but the reaction rarely proceeds only by light energy, and a photopolymerization initiator is generally used in combination. The polymerization initiator in this case mainly absorbs ultraviolet rays having a wavelength of 400 [nm] or less, generates active species such as radicals and ions, and initiates polymerization. In the present invention, the aforementioned heat and photopolymerization initiator can be used in combination.

  The charge transport layer having a network structure formed in this manner has high wear resistance, but has a large volume shrinkage during the crosslinking reaction, and if it is too thick, it may cause cracks. In such a case, the protective layer may be a laminated structure, a low molecular dispersion polymer protective layer may be used for the lower layer (photosensitive layer side), and a protective layer having a crosslinked structure may be formed on the upper layer (surface side). good.

<Electrophotographic photoreceptor A>
In the electrophotographic photosensitive member 1, an electrophotographic photosensitive member A was prepared in the same manner as the electrophotographic photosensitive member 1, except that the protective layer coating solution, film thickness, and preparation conditions were changed as follows.
182 parts of methyltrimethoxysilane, 40 parts of dihydroxymethyltriphenylamine, 225 parts of 2-propanol, 106 parts of 2% acetic acid, and 1 part of aluminum trisacetylacetonate were mixed to prepare a coating solution for a protective layer. This coating solution was applied onto the charge transport layer and dried, and then heat-cured at 110 ° C. for 1 hour to form a protective layer having a thickness of 3 μm.

<Electrophotographic photoreceptor B>
In the electrophotographic photosensitive member 1, an electrophotographic photosensitive member B was prepared in the same manner as the electrophotographic photosensitive member 1, except that the protective layer coating solution, film thickness, and preparation conditions were changed as follows.
30 parts of a hole transporting compound (structural formula (I)), 0.6 part of an acrylic monomer (structural formula (II)) and a photopolymerization initiator (1-hydroxy-cyclohexyl-phenyl-ketone) are added to 50 parts of monochlorobenzene. Part / dichloromethane in a mixed solvent of 50 parts to prepare a coating material for the surface protective layer. This paint is applied on the previous charge transport layer by spray coating, and cured for 30 seconds with a light intensity of 500 [mW / cm ² ] using a metal halide lamp, thereby a surface protective layer having a thickness of 5 [μm]. Formed.

  In this embodiment, the example in which the drum-shaped photosensitive member 1 is used as the image carrier has been described. However, the present invention can be applied to an image carrier having another shape. For example, the present invention can be similarly applied to an apparatus using a belt-like photoreceptor that is stretched between two rollers and moves endlessly. In addition, the case where the photosensitive member 1 has a negative charging potential and a developing device that employs a reversal developing method using a two-component developer has been described. The present invention is not limited to those having a negative polarity, and can also be applied to those having a positive charging potential. Further, the present invention can be similarly applied to one using a one-component developer or one using a regular development system.

  Next, a toner that is preferably used in the image forming apparatus of the present embodiment will be described. In order to obtain a high-definition image, it is preferable that the particle size distribution of small particles is sharp. With a toner having a small particle size and a narrow particle size distribution, the toner charge amount distribution is uniform, a high-quality image with little background fogging can be obtained, and the transfer rate can be increased.

The toner shape factor SF-1 is preferably in the range of 100 to 150. Here, the shape factor SF-1 is a numerical value indicating the ratio of the roundness of the shape of the spherical material, and the square of the maximum length MXLNG of the elliptical shape formed by projecting the spherical material on a two-dimensional plane is defined as a graphic area AREA. Divided by and multiplied by 100π / 4.
That is, it is defined by the following equation (1).

When the value of SF-1 is 100, the shape of the toner becomes a true sphere, and becomes larger as the value of SF-1 increases. In general, when the shape of the toner is close to a sphere, the contact state between the toner and the toner or the toner and the photoconductor becomes point contact, so that the adsorption force between the toners is weakened and the fluidity is increased. The adsorption force between the toner and the photosensitive member is also weakened, and the transfer rate is increased.

  In addition, the toner used in this example is obtained by dissolving or dispersing a binder resin containing a modified polyester resin that can be urea-bonded in an organic solvent, and a toner composition containing a colorant. And a polyaddition reaction, and the toner obtained by removing the solvent of the dispersion, washing, and drying was used. In addition, as a method for increasing the average circularity and obtaining a so-called spherical toner, a known polymerization method such as an emulsion polymerization method, a suspension polymerization method, a dispersion polymerization method may be used in addition to the above-described manufacturing method. A toner obtained by spheroidizing treatment by heat treatment may be used.

  In this embodiment, the cleaning device of the present invention is applied to a monochrome image forming apparatus having one process cartridge, but the present invention is not limited to this. For example, the present invention can be applied to a color image forming apparatus in which four process cartridges 100Y, 100C, 100M, and 100K of magenta, cyan, yellow, and black are arranged side by side as shown in FIG.

  Further, the present invention can be applied to an intermediate transfer type image forming apparatus that transfers a toner image on a photosensitive member to an intermediate transfer member and transfers the toner image on the intermediate transfer member to a transfer sheet. At this time, the cleaning device of the present invention can be applied not only as a cleaning device for cleaning the transfer residual toner attached on the photosensitive member but also as an intermediate transfer member cleaning device for cleaning the transfer residual toner attached on the intermediate transfer belt. . As the intermediate transfer member, in addition to a belt-shaped intermediate transfer belt, a drum-shaped intermediate transfer drum or the like can be used. The electrical characteristics (volume resistivity, surface resistivity, etc.), thickness, structure (single layer, double layer, multiple layers), material, material, etc. of the intermediate transfer member are appropriate depending on the imaging conditions. Can be selected and employed.

(1)
As described above, according to the cleaning device of this embodiment, the negatively charged toner on the surface of the image carrier is removed in the region A which is the first region of the brush roller 71, and the positive electrode is used in the region B which is the second region of the brush roller 71. By removing the electrically charged toner, it is possible to remove the bipolar toner on the surface of the photoreceptor with a single brush roller. Therefore, the apparatus can be reduced in size as compared with a configuration in which two brush rollers to which positive and negative voltages are respectively applied are arranged. Further, since electricity is not conducted to the raised hairs which are scraping members provided in the C region which is the third region, it is possible to suppress the formation of an electric field between the raised hairs in the region C and the photosensitive member. Therefore, it is possible to suppress the raising of the region C from being bent to the upstream side in the brush roller moving direction due to the influence of the electric field, and it is possible to suppress the contact pressure between the raising of the region C and the photoconductor. As a result, the raised portions in the region C can mechanically scrape off the toner additive adhering to the surface of the photoreceptor in a film form and the uncharged toner on the photoreceptor. Therefore, it is possible to satisfactorily remove the toner additive adhering to the surface of the photoreceptor in the form of a film and the uncharged toner on the photoreceptor from the surface of the image carrier.
(2)
Further, by setting the C region as a non-bias application region, it is possible to prevent electricity from being conducted to the raised portions of the region C.
(3)
Further, even if the raising of the region C is made insulative, electricity can be prevented from being conducted to the raising of the region C.
(4)
Further, by arranging the region C where the insulating raising is disposed between the region A and the region B, it is possible to prevent leakage due to contact between the raising of the region A and the raising of the region B, Stable cleaning can be performed.
(5)
In addition, since the rigidity of the raised portions in the C region is larger than the rigidity of the conductive raised portions disposed in the A region and the B region, the raised portions in the C region are greatly bent when coming into contact with the photosensitive member. It can suppress that a contact pressure falls. Further, the raised portions in the regions A and B have lower rigidity than the raised portions in the region C. Therefore, when the raised portions in the region A or B come into contact with the photoconductor, they are greatly bent to increase the contact area between the photoconductor and the raised portions. be able to. Thereby, the transfer residual toner on the photoconductor can be electrostatically adsorbed satisfactorily.
(6)
Further, a collection roller is provided as a removing means for removing the toner adhering to the brush roller. Thus, the toner adhering to the brushed brush brush is removed and refreshed, so that the toner can be efficiently cleaned. Therefore, stable cleaning performance can be obtained over a long period of time.
(7)
In addition, while the surface of the photoconductor passes through the region in contact with the brush roller, the regions A to C and the surface of the photoconductor are brought into contact at least once. Therefore, the negatively charged toner, the positively charged toner, the weakly charged toner, and the film-like toner additive on the photoreceptor can be removed by the brush roller.
(8)
In addition, by making the ratio of the C area in the brush roller higher than the ratio of the A area and the B area, the cleaning property is good, but the toner additive is easy to film on the surface of the photoreceptor. Even in the apparatus, the transfer residual toner and the film-like toner additive can be removed satisfactorily.
(9)
Further, by making the ratio of the C area in the brush roller lower than the ratio of the A area and the B area, the cleaning property is poor, but the toner additive is difficult to film on the surface of the photoreceptor. Even in this apparatus, the transfer residual toner and the film-like toner additive can be satisfactorily removed.
(10)
Further, according to the image forming apparatus of the present embodiment, by using the cleaning device 7 having the features (1) to (9), the device can be reduced in size and good cleaning performance can be obtained. it can. Also, an abnormal image called image flow due to filming phenomenon on the surface of the photoreceptor can be suppressed.
(11)
Further, by using a photosensitive member on which a protective layer containing a filler (particulate matter) is formed, surface film abrasion of the photosensitive member can be reduced.
(12)
A toner having a shape factor SF-1 in the range of 100 to 150 is used as a toner for forming a toner image. As a result, the amount of cleaning input is reduced, the margin is improved, and a high-quality image is obtained. In addition, the life of the cleaning device can be extended.
(13)
In addition, since the photosensitive member and at least the cleaning device are integrally configured and a process cartridge that is detachable from the main body of the image forming apparatus is provided, user maintenance is high and abnormal images are unlikely to occur over a long period of time. An image forming apparatus is obtained.
(14)
In addition, a color image can be formed by providing a plurality of process cartridges.

1 is a schematic configuration diagram illustrating an image forming apparatus according to an exemplary embodiment. FIG. 3 is an explanatory diagram of a cleaning device used in the image forming apparatus. Explanatory drawing of the brush roller of the cleaning device. The principal part expanded block diagram of the cleaning apparatus. The figure which shows the relationship between cleaning property and the division | segmentation number of an area | region. The figure which shows the example which made the ratio which the area | region C in a brush roller occupies smaller than the ratio of the area | region A and the area | region B. FIG. The figure which shows the modification of a cleaning apparatus. 1 is a schematic configuration diagram of a tandem color image forming apparatus. FIG. 6 is a diagram showing a charge distribution of untransferred toner on a photoreceptor. The principal part block diagram of the conventional cleaning apparatus.

Explanation of symbols

1: Photoconductor 6: Developing device 7: Cleaning device 71: Brush roller 72: Collection roller 73: Scraper member 74: Conveying means 100: Process cartridge

Claims (14)

In a cleaning apparatus having a plurality of conductive raised portions provided on a rotating shaft and having a brush roller that rotates while contacting a surface-moving image carrier and cleans the surface of the image carrier ,
The brush roller applies a positive bias to the conductive napping to remove the negatively charged toner on the surface of the image carrier, and applies a negative bias to the conductive napping. A second region for removing the positively charged toner on the surface of the image carrier and a third region having a scraping member for mechanically removing the substance attached to the surface of the image carrier; A cleaning device configured not to conduct electricity to a member. The cleaning device according to claim 1.
A cleaning apparatus, wherein the third region is a non-bias application region. The cleaning device according to claim 1.
A cleaning device, wherein the scraping member is an insulating member. The cleaning device according to claim 3.
A cleaning apparatus, wherein the third region is disposed between the first region and the second region. In the cleaning apparatus in any one of Claims 1 thru | or 4,
The scraping member is a plurality of raised hairs, and the rigidity of the raised hairs is configured to be larger than the rigidity of the conductive raised hairs. In the cleaning apparatus in any one of Claims 1 thru | or 5,
A cleaning device comprising a removing means for removing a substance adhering to the brush roller. In the cleaning apparatus in any one of Claims 1 thru | or 6,
While the surface of the image carrier passes through the area in contact with the brush roller, the first area, the second area, and the third area are in contact with the surface of the image carrier at least once. A cleaning device characterized by. In the cleaning apparatus in any one of Claims 1 thru | or 7,
The cleaning apparatus characterized in that the ratio of the third area in the brush roller is higher than the ratio of the first area and the second area. In the cleaning apparatus in any one of Claims 1 thru | or 7,
The cleaning apparatus, wherein a ratio of the third area in the brush roller is lower than a ratio of the first area and the second area. An image carrier, a charging device for charging the image carrier, a latent image forming device for forming an electrostatic latent image on the image carrier, and a toner attached to the electrostatic latent image on the image carrier. In an image forming apparatus comprising: a developing device that visualizes; a transfer device that transfers a toner image on the image carrier to a transfer material; and a cleaning device that cleans the image carrier.
An image forming apparatus using the cleaning device according to claim 1 as the cleaning device. The image forming apparatus according to claim 10.
An image forming apparatus comprising a protective layer containing a filler (particulate matter) as the image carrier.   12. The image forming apparatus according to claim 10, wherein a toner having a shape factor SF-1 in the range of 100 to 150 is used as a toner for forming a toner image on the image carrier. apparatus. The image forming apparatus according to claim 10.
An image forming apparatus comprising: a process cartridge which is integrally configured with the image carrier and at least the cleaning device and is detachable from the apparatus main body. The image forming apparatus according to claim 13.
An image forming apparatus comprising a plurality of the process cartridges.

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