JP2007248910A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic image forming apparatus in which the ability to clean a photoreceptor and the transfer efficiency thereof are improved by applying an appropriate quantity of lubricant onto the surface of the photoreceptor according to the moved position of the surface of the photoreceptor. <P>SOLUTION: A lubricant is applied onto the surface of the photoreceptor 11 by a brush roller 52 before the surface reaches a cleaning blade 51 after passing the area opposite a transfer roller 15. In addition, the image forming apparatus includes a brush roller 63 that applies the lubricant onto a charging roller 61. The lubricant is applied onto the surface of the photoreceptor 11 via the charging roller 61 before the surface reaches the area opposite a developing device 14 after passing the cleaning blade 51. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrophotographic image forming apparatus.

  In an electrophotographic system employed in an image forming apparatus such as a copying machine or a laser printer, the surface of a photoconductor as an image carrier is charged by a charging device and then exposed by an exposure device to form an electrostatic latent image. Then, the electrostatic latent image is developed with a developing device to form a toner image. The toner image is electrostatically transferred to a recording sheet or the like as a transfer medium by a transfer device, and then the toner image transferred onto the recording paper is fixed by a fixing device to form an image on the recording paper. .

  By the way, in the electrophotographic image forming apparatus, a part of the toner image formed on the photoconductor is transferred to the recording paper in the transfer process, but the rest remains on the surface of the photoconductor after the transfer process. . If the toner remaining on the photoconductor is left unattended, the image quality is degraded. In particular, when a contact charging type charging device is used, the toner remaining on the photosensitive member is embedded in the surface of the photosensitive member by contact between the photosensitive member and the charging device (filming), and the image quality is significantly deteriorated. It will decline. In view of this, the electrophotographic image forming apparatus is provided with a cleaning device in order to remove the toner remaining on the photoreceptor. As a cleaning device, a device having a contact member (a blade, a brush, or the like) that comes into contact with the photosensitive member is often used.

  In addition, by applying a lubricant to the surface of the photoconductor, the friction coefficient of the surface of the photoconductor is reduced, and adhesion of toner to the surface of the photoconductor is reduced, and by applying the lubricant and scraping with a cleaning device, the photoconductor A technique for refreshing the surface and stabilizing the image quality has been proposed. For example, Patent Document 1 discloses a technique for detecting the background density on the surface of the photoconductor and controlling the amount of lubricant applied to the surface of the photoconductor according to the detection result.

In Patent Document 2, a lubricant is applied to the charging roller in order to improve the cleaning property of the charging roller and prevent occurrence of cleaning failure or filming in the image carrier, and the image is transferred from the charging roller. Techniques for transferring lubricant to the body are disclosed.
JP-A-8-202226 (published on August 9, 1996) Japanese Patent Laid-Open No. 6-342236 (released on December 13, 1994)

  However, in the technique in which the lubricant is applied immediately before the surface of the photosensitive member reaches the cleaning device as in Patent Document 1, a part of the lubricant on the photosensitive member adheres to the surface of the charging roller although it adheres to the surface of the charging roller. Since the amount of lubricant to be applied is small, contaminants such as toner, paper powder, and additives (silica, etc.) remaining on the photoreceptor without being removed by the cleaning device are likely to adhere to the surface of the charging roller. For this reason, there may be a case where charging failure occurs due to contaminants adhering to the charging roller, or the image quality is deteriorated by being embedded in the surface of the photosensitive member due to contact between the photosensitive member and the charging device.

  In the technique of Patent Document 2, the amount of lubricant adhering to the charging roller can be increased to improve the cleaning property of the charging roller. However, only the amount of lubricant transferred from the charging roller to the photoreceptor is sufficient. In some cases, it is not possible to sufficiently obtain an effect of preventing unnecessary toner from adhering to the surface. Further, the frictional force between the contact member (cleaning blade or the like) provided on the cleaning device and the photosensitive member may not be sufficiently reduced.

  Note that the lubricant applied to the charging roller and the photoconductor is increased by increasing the amount of lubricant applied to the photoconductor in the technique of Patent Document 1 or by increasing the amount of lubricant applied to the charging roller in the technique of Patent Document 2. It is conceivable to increase the coating amount. However, in any of the above cases, it is difficult to keep the amount of lubricant applied to both the photoconductor and the charging roller at an optimum amount for reducing the friction coefficient of the photoconductor and the charging roller to an appropriate value. is there. For this reason, when the lubricant application amount is too small, the effect of preventing unnecessary toner adhesion cannot be sufficiently obtained, and when the lubricant application amount is too large, the toner adhesion amount increases. . There is also a problem that the amount of lubricant consumed increases.

  In addition, it is known that by applying an appropriate amount of lubricant to the surface of the photoreceptor before the development process and the transfer process, the surface energy of the photoreceptor can be reduced to improve the transfer efficiency. In the techniques of Patent Documents 1 and 2, it is difficult to appropriately set the amount of lubricant on the surface of the photoconductor when the surface of the photoconductor reaches the facing portion of the developing device and the transfer device. For this reason, in the techniques of Patent Documents 1 and 2, transfer efficiency cannot be improved by optimizing the amount of lubricant.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide an appropriate amount corresponding to the moving position of the surface of the image carrier on the surface of the image carrier in an electrophotographic image forming apparatus. This is to improve the cleaning property and transfer efficiency of the photoreceptor.

  In order to solve the above-described problems, an image forming apparatus according to the present invention includes a rotating image carrier and a charging unit that charges the image carrier disposed around the image carrier along the rotation direction. A latent image forming unit that forms an electrostatic latent image on the charged image carrier, a developing unit that develops the electrostatic latent image formed on the image carrier with a developer, and the image carrier. In the image forming apparatus comprising a transfer means for transferring an image developed on the body to a recording material and a cleaning means for cleaning the surface of the image carrier after the transfer, the image carrier after the transfer and before the cleaning And a second application unit for applying the lubricant to the surface of the image carrier after the cleaning and before the development.

  According to the above configuration, the lubricant is applied to the surface of the image carrier after the transfer by the transfer unit and before the cleaning by the cleaning unit. Thus, an appropriate amount of lubricant for preventing toner adhesion to the image carrier and improving the cleaning performance of the image carrier can be applied to the image carrier. Further, a lubricant is applied to the surface of the image carrier after the cleaning by the cleaning means by the second application means and before the development by the developing means. As a result, an appropriate amount of lubricant is applied to the image carrier to prevent the occurrence of poor cleaning and filming in the image carrier and to reduce the surface energy of the image carrier and improve the transfer efficiency. Can do. In addition, since an appropriate amount of lubricant for obtaining the above-described effects can be applied by the first application means and the second application means, compared to the conventional configuration in which the lubricant is applied by a single application means, Lubricant consumption can be reduced.

  The charging means is a contact charging type charging means provided with a contact charging member that contacts the image carrier and charges the image carrier, and the second coating means lubricates the contact charging member. A lubricant may be applied to the image carrier via the contact charging member by applying an agent.

  According to the above configuration, the second application unit applies the lubricant to the contact charging member, thereby applying the lubricant to the image carrier via the contact charging member. Thereby, the quantity of the lubricant applied to the contact charging member can be appropriately set, and the adhesion of contaminants to the contact charging member can be suppressed.

  The lubricant application amount to the contact charging member by the second application unit may be larger than the lubricant application amount to the image carrier by the first application unit.

  According to the above configuration, the amount of lubricant applied to the contact charging member by the second application unit is larger than the amount of lubricant applied to the image carrier by the first application unit. Can be prevented from adhering to the contact charging member.

Further, the amount of lubricant applied to the contact charging member by the second application unit is 0.05 μg / cm ² or more and 0.08 μg / cm ² or less, and the amount of lubricant applied to the image carrier by the first application unit is May be 0.01 μg / cm ² or more and 0.06 μg / cm ² or less.

  According to the above configuration, the effect of preventing the adhesion of toner to the image carrier and the contact charging member, the effect of improving the cleaning property, and the effect of improving the transfer efficiency of the image carrier can be efficiently realized with less lubricant.

  The charging unit may include a contact charging member that contacts the image carrier and charges the image carrier, and a rotation driving unit that rotationally drives the contact charging member.

  According to the above configuration, unlike the configuration in which the contact charging member is driven and rotated by the image carrier, the contact charging member is rotationally driven by the rotation driving means. Therefore, even if the coefficient of friction on the surface of the image carrier is reduced by applying a lubricant to the image carrier, the contact charging member does not rotate poorly due to slip, and the contact charging member can be rotated stably. Therefore, uneven charging due to rotation failure of the contact charging member can be prevented.

  In addition, a driving unit that rotationally drives the first coating unit is provided, and the driving unit moves the surface of the first coating unit at the contact portion between the first coating unit and the image carrier. The first application unit may be rotationally driven so as to move in a direction opposite to the direction.

  According to the above configuration, the driving means moves the first application means so that the surface of the first application means moves in a direction opposite to the moving direction of the surface of the image carrier at the contact portion between the first application means and the image carrier. The coating means is driven to rotate. That is, the first application unit rotates against the image carrier. Accordingly, it is possible to remove the contaminants attached to the surface of the image carrier by the first application unit, and to disperse the contaminants attached to the surface of the image carrier to improve the removal efficiency of the contaminants by the cleaning unit. it can. For example, in the case of an image forming apparatus using a two-component developer, the carrier adhering to the image carrier can be removed by the first application unit, and the carrier is caught by the cleaning unit and the image carrier is damaged. It can be prevented from occurring. Even when a small-diameter toner adheres to the image carrier, the toner can be dispersed on the image carrier to improve the toner removal efficiency by the cleaning means.

  The first application unit may be a rotary brush that includes a large number of linear members and applies a lubricant by bringing the tips of the linear members into contact with the surface of the image carrier.

  According to the above configuration, since the first application unit is a rotating brush, it is possible to prevent an excessive pressure contact force from being applied to the image carrier, and to extend the life of the image carrier and the first application unit. Can do. In addition, the contaminants adhering to the surface of the image carrier are efficiently dispersed to improve the removal efficiency of the contaminants by the cleaning means, and, for example, a relatively large contaminant such as a carrier is appropriately removed from the surface of the image carrier. Can be removed.

  The charging unit includes a contact charging member that contacts the image carrier and charges the image carrier, and a second cleaning unit that removes contaminants attached to the contact charging member. May be.

  According to the above configuration, since the contaminants attached to the contact charging member can be removed by the second cleaning means, the image bearing member and the contact charging member are damaged by the contaminants attached to the contact charging member, or uneven charging is performed. Can be prevented.

  In addition, the second cleaning unit is a contact cleaning unit that contacts the contact charging member to remove contaminants, or a cleaning voltage is applied to the contact charging member so that the contact charging member and the image carrier are in contact with each other. An electrostatic cleaning unit that moves a contaminant attached to the contact charging member due to a potential difference to the image carrier, or a combination of the contact cleaning unit and the electrostatic cleaning unit may be used.

  By providing the contact cleaning unit or the electrostatic cleaning unit, it is possible to remove contaminants attached to the contact charging member. Further, when both the contact cleaning unit and the electrostatic cleaning unit are provided, the contaminants attached to the contact charging member can be more appropriately removed.

  As described above, the image forming apparatus of the present invention includes the first application unit that applies the lubricant to the surface of the image carrier after the transfer and before the cleaning, and the image carrier after the cleaning and before the development. Second application means for applying a lubricant to the surface.

  Therefore, an appropriate amount of lubricant for preventing toner adhesion to the image carrier and improving the cleanability of the image carrier can be applied to the image carrier by the first application unit. In addition, the second application means prevents the occurrence of cleaning defects or filming in the image carrier, and also reduces the surface energy of the image carrier and improves the transfer efficiency to provide an appropriate amount of lubricant. Can be applied to the body. In addition, the amount of lubricant consumed can be reduced as compared with the conventional configuration in which the lubricant is applied by a single application means.

  An embodiment of the present invention will be described. FIG. 2 is an explanatory diagram showing a schematic configuration inside the image forming apparatus 1 according to the present embodiment. The image forming apparatus 1 is an electrophotographic color image forming apparatus, and records, for example, based on image data transmitted from the outside via a network, image data read by an image reading apparatus (not shown), or the like. A multicolor or single color image is formed on paper.

  As shown in FIG. 2, the image forming apparatus 1 includes a visible image forming unit 10, a recording paper transport unit 30, a fixing device 40, and a supply tray 20.

  The visible image forming unit 10 includes four visible image forming units 10Y, 10M, 10C, and 10B corresponding to the colors of yellow (Y), magenta (M), cyan (C), and black (B). It is installed side by side. That is, the visible image forming unit 10 includes four visible image forming units 10Y, 10M, 10C, and 10B. The visible image forming unit 10Y forms an image using yellow (Y) toner, and the visible image is formed. The forming unit 10M forms an image using magenta (M) toner, the visible image forming unit 10C forms an image using cyan (C) toner, and the visible image forming unit 10B is black (B). An image is formed using the toner. Specifically, four sets of visible image forming units 10Y, 10M, 10C, and 10B are arranged along the conveyance path for conveying the recording paper from the supply tray 20 to the fixing device 40, and are conveyed. Each color toner is transferred onto a recording sheet.

  The visible image forming units 10Y, 10M, 10C, and 10B have substantially the same configuration. That is, a photoconductor (photoconductor drum, image carrier) 11, a charging device 12, a laser beam irradiation means 13, a developing device 14, a transfer roller 15, and a cleaner unit 16 are provided for each.

  The charging device 12 uniformly charges the surface of the photoconductor 11 to a predetermined potential. In this embodiment, the charging device 12 uses a contact charging type charging device that charges the surface of the photoconductor 11 by contacting the charging roller. Yes. The details of the charging device 12 will be described later.

  The laser beam irradiation means 13 exposes the surface of the photoconductor 11 charged by the charging device 12 according to image data, and forms an electrostatic latent image on the surface of the photoconductor 11. The developing device 14 develops the electrostatic latent image formed on the surface of the photoconductor 11 with toner to form a toner image. The transfer roller 15 is applied with a bias voltage having a polarity opposite to that of the toner, and transfers the toner image formed on the photoconductor 11 onto the recording paper conveyed by the recording paper conveying means 30.

  The cleaner unit 16 removes and collects toner remaining on the surface of the photoconductor 11 after the transfer process by the transfer roller 15. The details of the cleaner unit 16 will be described later.

  With the above configuration, in each visible image forming unit, the surface of the photoconductor 11 is charged by the charging device 12, and the charged surface of the photoconductor 11 is exposed by the laser light irradiation means 13 to form an electrostatic latent image. Then, the electrostatic latent image is developed by the developing device 14, and the developed toner image is transferred to the recording paper by the transfer roller 15. The toner image remaining on the surface of the photoconductor 11 after the transfer is removed and collected by the cleaner unit 16. Then, the transfer of the toner image onto the recording paper is sequentially performed in the visible image forming unit of each color, whereby the toner images of the respective colors are transferred onto the recording paper in a multiple manner.

  The recording paper conveying means 30 includes a driving roller 31, an idling roller 32, and a conveying belt 33, and conveys the recording paper so that the toner image is transferred to the recording paper by each visible image forming unit. The driving roller 31 and the idling roller 32 stretch an endless conveying belt 33, and the conveying belt 33 rotates when the driving roller 31 is rotationally driven at a predetermined peripheral speed. . Further, the outer surface of the transport belt 33 is charged to a predetermined potential, and transports the recording paper while electrostatically attracting it.

  The recording paper transported by the recording paper transporting means 30 and passed through each visible image forming unit and having the toner image (unfixed toner image) transferred thereon is peeled off from the transport belt 33 by the curvature of the driving roller 31 and is then fixed. 40. The fixing device 40 applies appropriate heat and pressure to the recording paper, dissolves the toner transferred onto the recording paper and fixes it on the recording paper, and discharges the recording paper to a paper discharge tray (not shown).

  Next, the configuration of the cleaner unit 16 and the charging device 12 will be described with reference to FIG. FIG. 1 is a cross-sectional view showing the configuration of the visible image forming units 10Y, 10M, 10C, and 10B.

  First, the cleaner unit 16 will be described. As shown in FIG. 1, the cleaner unit 16 includes a blade (cleaning blade) 51, a brush roller 52, a flicker 53, a toner conveying screw 55, a sealing material 56, a lubricant 57, and an urging member 58 inside the case 54 or Prepared around.

  The blade 51 is for collecting toner remaining on the surface of the photoconductor 11 and is formed of a long rubber member whose longitudinal direction is the axial direction of the photoconductor 11. The blade 51 is arranged such that one long side is attached to the downstream side in the rotation direction of the photoconductor 11 in the opening provided in the case 54, and the other long side edge (corner) is in contact with the surface of the photoconductor 11. Has been.

  The blade 51 dams off the transfer residual toner remaining on the surface of the photoconductor 11 after the toner image is transferred, and scrapes it off while performing a stick-slip operation. The stick-slip operation is based on the operation in which the contact portion of the blade 51 with the photosensitive member 11 moves in the rotational direction of the photosensitive member 11 according to the movement of the surface of the photosensitive member 11 and the elastic force of the blade 51 itself. The movement of returning to the position is repeated, and the edge of the blade 51 slides on the surface of the photoconductor 11.

  As a rubber member used for the blade 51, for example, a member made of urethane rubber, silicone rubber, chloroprene rubber, butadiene rubber or the like is used. In this embodiment, the blade 51 has a rebound resilience of 10% to 45% (more preferably 10% to 40%) and a Young's modulus of 5 MPa to 11 MPa (more preferably 5 MPa to 10 MPa). Is used. Further, the blade 51 is provided so that the contact angle (cleaning angle) θ with respect to the photoconductor 11 is 6 ° ≦ θ ≦ 25 °. Here, the contact angle θ is an angle formed by the surface of the photoreceptor 11 on which the edge 51a of the blade 51 slides and the surface of the blade 51 on the photoreceptor 11 side.

The brush roller 52 is a cylindrical brush having substantially the same length (width) as that of the photoconductor 11, and the shaft of the photoconductor 11 and the mutual shaft is arranged so that the tip of the brush hair hits the surface of the photoconductor 11. Are arranged in parallel. Specifically, in the present embodiment, a conductive nylon brush having a thickness of 2 denier (electric resistance value: 7.5 Ω · cm) on a stainless steel shaft having a diameter of 6 mm has a density of 6 × 10 ⁴ / inch ² . A brush roller 52 arranged so that the outer diameter of the brush is 16 mm toward the diameter direction of the stainless steel shaft was used.

Further, the brush roller 52 is rotationally driven in the same direction as the rotation direction of the photosensitive member 11 by driving means (not shown) such as a motor and a gear. Therefore, the brush roller 52 and the photoconductor 11 slide in opposite directions at the contact portion. Accordingly, the brush roller 52 scrapes off the lubricant 57 disposed on the upstream side in the rotation direction of the brush with respect to the contact portion with the photoconductor 11 and supplies the scraped lubricant to the surface of the photoconductor 11. In the present embodiment, the rotational speed of the brush roller 52 is set so that the amount of lubricant applied to the surface of the photoconductor 11 by the brush roller 52 is 0.01 μg / cm ² or more and 0.06 μg / cm ² or less. Has been. The lubricant scraped off by the brush roller 52 is supplied as fine particles to the surface of the photoreceptor 11.

  Thus, by applying fine particles of the lubricant 57 to the surface of the photoconductor 11, the friction coefficient between the blade 51 and the surface of the photoconductor 11 can be reduced, and the toner on the surface of the photoconductor 11 can be reduced. The adhesion force is weakened, and the toner can be efficiently removed by the blade 51.

  Further, the brush roller 52 also acts to disperse the toner adhering to the surface of the photoconductor 11 by coming into contact with the photoconductor 11, so that the removal by the blade 51 is efficiently performed. When a two-component developer composed of toner and carrier is used, the carrier in the developing device adheres to the photoconductor 11 (so-called carrier rise), and is caught by the blade 51 and causes a line-like scratch on the photoconductor 11. In some cases, since the carrier can be removed from the surface of the photoconductor 11 when the brush roller 52 comes into contact with the photoconductor 11, it is possible to prevent the above-described damage. Further, the brush roller 52 is disposed at a position where the toner scraped off and scraped off by the blade 51 can be collected, and the toner scraped off by the blade 51 is scraped off by the brush tip to remove the toner 11 surface. It is also mechanically removed from the case 54 and collected in the case 54.

  The flicker 53 is a rectangular plate-like member having substantially the same width as the brush roller 52, and its longitudinal direction is parallel to the axis of the brush roller 52, and one long side (edge) is the brush roller. 52 so as to be in uniform contact with 52. When the brush roller 52 rotates, the tip of the hair of the brush roller 52 is caught by the flicker 53, and the hair is curved in a bow shape. When the brush roller 52 further rotates in this state, the tip of the hair is released from the flicker 53, and the hair quickly tries to return to the original shape (linear shape) by the elastic force. Thereafter, the hair of the brush roller 52 quickly stops when it becomes the original shape (linear shape). However, the toner attached to the hair tries to continue to move according to the law of inertia, so it is detached from the hair and dropped. I will do it. As a result, the toner adhering to the brush roller 52 falls into the case 54 by contacting the flicker 53.

  The material of the flicker 53 is not particularly limited, but a material having a small friction coefficient (dynamic friction coefficient) with respect to the brush roller 52 is preferably used in order to suppress wear of the brush roller 52 and deformation of the hair. For example, polyethylene terephthalate resin, polyethylene terephthalate-containing polycarbonate resin, polyether ether ketone resin, polyoxymethylene resin, ultrahigh molecular weight polyethylene resin, resin coated with diamond-like carbon, coating with fluorine-containing resin The applied metal or the like can be used.

  The lubricant (solid lubricant) 57 is applied to the surface of the photoconductor 11 by the brush roller 52, and has a rectangular parallelepiped shape having a length (width) substantially the same as the length of the photoconductor 11 in the longitudinal direction. It has become. The lubricant 57 is urged toward the brush roller 52 by an urging member 58 made of a spring or the like, and the brush roller 52 surely scrapes the lubricant 57 regardless of the remaining amount of the lubricant 57 and is photosensitive. The body 11 can be made. Further, the lubricant 57 can be replaced when it is worn out and the remaining amount is reduced.

  In this embodiment, zinc stearate (zinc stearate) is used as the lubricant 57. However, the lubricant 57 is not limited to this, and for example, other fatty acid metal salts known as metal soaps or fluororesins may be used. In addition to zinc stearate, fatty acid metal salts include barium stearate, lead stearate, iron stearate, nickel stearate, cobalt stearate, copper stearate, strontium stearate, calcium stearate, cadmium stearate, magnesium stearate. , Zinc oleate, manganese oleate, iron oleate, cobalt oleate, lead oleate, magnesium oleate, copper oleate, zinc palmitate, cobalt palmitate, copper palmitate, magnesium palmitate, aluminum palmitate, palmitate Calcium acid, lead caprylate, lead caproate, zinc linolenate, cobalt linolenate, calcium linolenate, zinc ricolinonenate, cadmium ricolinoneate and the like. The water contained in the lubricant 57 affects the charging ability and the like on the photoconductor 11, so that it is preferable to use the lubricant 57 having a hygroscopicity of 0.5% or less. Furthermore, in the lubricant 57, porous powder such as porous glass or zeolite may be mixed in order to remove discharge products.

  The toner conveying screw 55 is disposed on the bottom side of the case 54 and sends the collected toner to a waste toner box (not shown) outside the case 54. A seal material 56 is attached to the upstream side of the opening of the case 54 in the rotation direction of the photoconductor 11 so as to prevent the toner collected in the case 54 from leaking out of the case 54.

  Next, the configuration of the charging device 12 will be described. As shown in FIG. 1, the charging device 12 includes a charging roller 61, a cleaning member 62, a brush roller 63, a lubricant 64, and an urging member 65.

  The charging roller 61 has a length approximately the same as the axial length of the photoconductor 11 and is arranged so that the shaft of the photoconductor 11 is parallel to the surface of the photoconductor 11 so as to be in contact with the surface of the photoconductor 11. The surface of the photoconductor 11 is uniformly charged by power supplied from (not shown). Further, the charging roller 61 is rotationally driven in a direction opposite to the rotational direction of the photoconductor 11 by a rotational driving means (not shown) such as a motor or a gear, so that the two move in the same direction at the contact portion. It has become.

  The charging roller 61 has a conductive support as a base, an elastic layer formed on the outer peripheral surface thereof, and a resistance layer formed on the elastic layer. As the conductive support, for example, a round bar made of a metal material such as iron, copper, stainless steel, aluminum, or nickel can be used. In addition, in order to provide rust prevention and scratch resistance, these metal surfaces may be plated. However, it is necessary not to impair the conductivity.

  The elastic layer has appropriate conductivity and elasticity in order to supply power to the photosensitive member 11 as a member to be charged and to ensure good uniform adhesion of the charging roller 61 to the photosensitive member 11. Specifically, examples of the elastic layer include natural rubber, ethylene propylene rubber (EPDM), styrene butadiene rubber (SBR), silicone rubber, urethane rubber, epichlorohydrin rubber, isoprene rubber (IR), butadiene rubber (BR), Synthetic rubber such as nitrile butadiene rubber (NBR) and chloroprene rubber (CR), or an elastic material such as polyamide resin, polyurethane resin, silicone resin, etc. has an electronic conduction mechanism such as carbon black, graphite, conductive metal oxide, etc. What added suitably the electrically conductive agent etc. which have ion conduction mechanisms, such as a electrically conductive agent and an alkali metal salt, a quaternary ammonium salt, can be used. In order to ensure uniform adhesion between the charging roller 61 and the photosensitive member 11, the elastic layer is polished so that the central portion is thickest and becomes thinner from the central portion toward both ends (so-called so-called). (Crown shape) is preferable.

  The resistance layer is formed in contact with the elastic layer and prevents bleeding out of the surface of the charging roller 61 such as softening oil or plasticizer contained in the elastic layer and adjusts the electric resistance of the entire charging roller 61. Provided for. As the resistance layer, a conductive or semiconductive material is used. For example, epichlorohydrin rubber, NBR, polyolefin-based thermoplastic elastomer, urethane-based thermoplastic elastomer, polystyrene-based thermoplastic elastomer, fluororubber-based thermoplastic elastomer, polyester-based thermoplastic elastomer, polyamide-based thermoplastic elastomer, polybutadiene-based thermoplastic elastomer, A conductive agent having an electronic conduction mechanism (for example, a material composed of ethylene vinyl acetate thermoplastic elastomer, polyvinyl chloride thermoplastic elastomer, chlorinated polyethylene thermoplastic elastomer, etc., or a mixed material or copolymer thereof) Conductive carbon, graphite, conductive metal oxides, copper, aluminum, nickel, iron powder, etc.) and conductive agents with an ionic conduction mechanism (for example, alkali metal salts, ammonium salts, etc.) are suitable. Use have been added. In this case, in order to obtain a desired electric resistance, two or more kinds of the above various conductive agents may be used in combination. However, in consideration of environmental fluctuations and contamination of the photoconductor 11, it is preferable to use a conductive agent having an electronic conduction mechanism.

  The cleaning member 62 is disposed so as to be in contact with the surface of the charging roller 61, and is for removing toner, paper dust, and the like attached to the surface of the charging roller 61. As the cleaning member 62, for example, felt, sponge, mylar sheet or the like can be used.

  The brush roller 63 is a cylindrical brush having substantially the same length (width) as the charging roller 61, and the shaft of the charging roller 61 and the shaft of the charging roller 61 are arranged so that the tip of the brush hair hits the surface of the charging roller 61. Are arranged in parallel. In the present embodiment, the brush roller 63 having the same configuration as the brush roller 52 described above is used.

Further, the brush roller 63 is rotationally driven in a direction opposite to the rotation direction of the charging roller 61 by a rotational driving means (not shown) such as a motor or a gear. Therefore, the charging roller 61 and the photoconductor 11 are moved in the same direction at the contact portion. As a result, the brush roller 63 scrapes off the lubricant 64 disposed upstream of the contact portion with the charging roller 61 in the rotation direction of the brush, and supplies the scraped lubricant to the surface of the charging roller 61. In the present embodiment, the amount of lubricant applied to the surface of the charging roller 61 by the brush roller 63 is 0.05 μg / cm ² or more and 0.08 μg / cm ² or less, and the surface of the photoconductor 11 by the brush roller 52 is applied. The rotational speed of the brush roller 63 is set so as to be larger than the amount of lubricant applied. The lubricant scraped off by the brush roller 63 is supplied to the surface of the charging roller 61 as fine particles.

  The lubricant (solid lubricant) 64 is applied to the surface of the charging roller 61 by the brush roller 63 and has a rectangular parallelepiped shape having a length (width) substantially the same as the length of the charging roller 61 in the longitudinal direction. It has become. The lubricant 64 is biased toward the brush roller 63 by a biasing member 65 such as a spring fixed at one end to the frame of the image forming apparatus 1 or a case covering the charging device 12. Regardless of the amount, the brush roller 63 can reliably scrape the lubricant 64 and supply it to the charging roller 61. Further, the lubricant 64 can be replaced when it is worn out and the remaining amount is reduced.

  As the lubricant 64, a fatty acid metal salt, a fluororesin, or the like can be used in the same manner as the lubricant 57 described above. The lubricant 57 and the lubricant 64 may be made of the same material or different materials.

  As described above, in the image forming apparatus according to the present embodiment, the surface of the photoconductor 11 passes through the portion facing the transfer roller 15 and before reaching the contact portion with the cleaning blade 51. The first application means (brush roller 52) for applying the lubricant 57 to the photosensitive member 11 and the second application for applying the lubricant to the photosensitive member 11 after passing through the cleaning blade 51 and before reaching the portion facing the developing device 14 Means (brush roller 63). In this embodiment, the brush roller 63 as the second application unit applies the lubricant to the photoconductor 11 via the charging roller 61.

  As a result, an appropriate amount of lubricant capable of preventing toner adhesion to the photoconductor 11 and improving cleaning performance can be applied to the photoconductor 11 by the first application unit. Furthermore, the second application means prevents the occurrence of cleaning failure or filming in the photoconductor 11, and reduces the surface energy of the photoconductor 11 to improve the transfer efficiency, thereby providing an appropriate amount of lubricant. Can be applied. In addition, since an appropriate amount of lubricant for obtaining the above-described effects can be applied by the first application means and the second application means, the total amount of lubricant consumption is reduced as compared with the configuration in which the application is performed by a single application means. it can.

  In this embodiment, the lubricant 64 is applied to the charging roller 61 by the brush roller 63 so that the lubricant is applied from the charging roller 61 to the photoconductor 11.

  Therefore, the brush roller 52 applies an appropriate amount of lubricant that can prevent toner adhesion to the photoconductor 11 and improve the cleaning property of the photoconductor 11 to the photoconductor 11, and the brush roller 63 uses the charging roller 61. Thus, it is possible to apply an appropriate amount of lubricant to the charging roller 61 in order to improve the cleaning performance, prevent the occurrence of cleaning failure and filming in the photoconductor 11, and improve transfer efficiency.

  In this embodiment, the amount of lubricant applied to the charging roller 61 by the brush roller 63 is larger than the amount of lubricant applied to the photoconductor 11 by the brush roller 52. If the linear pressure of the blade 51 provided in the cleaner unit 16 against the photoconductor 11 is excessively increased, there arises a problem that the photoconductor 11 is damaged or the blade 51 is reversed. For this reason, since it is necessary to limit the above-mentioned linear pressure, some of the contaminants such as toner and paper powder adhering to the photoreceptor 11 inevitably pass through the blade 51. These contaminants that have passed through the blade 51 come into contact with the charging roller 61, but when the amount of lubricant applied to the charging roller 61 is made larger than the amount of lubricant applied to the photoconductor 11, the contamination is transferred to the charging roller 61. Can suppress the adhesion of pollutants. As a result, it is possible to prevent problems such as scratches on the photosensitive member 11 and the charging roller 61 due to contaminants attached to the charging roller 61 and prevent the life of the photosensitive member 11 and the charging roller 61 from being reduced.

In this embodiment, the amount of lubricant applied to the surface of the photoconductor 11 by the brush roller 52 is set to 0.01 μg / cm ² or more and 0.06 μg / cm ² or less, and the surface of the charging roller 61 by the brush roller 63 is applied. The amount of lubricant applied is set to be 0.05 μg / cm ² or more and 0.08 μg / cm ² or less and larger than the amount of lubricant applied to the surface of the photoreceptor 11 by the brush roller 52. Thereby, the effect of improving the cleaning property of the photoconductor 11 and the charging roller 61, the effect of preventing toner adhesion, and the effect of improving the transfer efficiency can be suitably obtained.

  In the present embodiment, the lubricant is applied to the charging roller 61 by the brush roller 63, and the lubricant is transferred from the charging roller 61 to the photoconductor 11. However, the present invention is not limited to this. After the surface of 11 passes through the portion facing the transfer roller 15 and before reaching the contact portion with the blade 51, the first application means for applying the lubricant 57, and after passing through the blade 51, the developing device 14 And a second coating unit that coats the photoconductor 11 with a lubricant before reaching the opposite portion. For example, the second application unit may be provided so that the lubricant is applied to the surface of the photoconductor 11 at a position after the surface of the photoconductor 11 passes through the blade 51 and before reaching the contact portion with the charging roller 61. . Further, the charging device 12 is not limited to the configuration including the charging roller 61. For example, a belt-shaped or blade-shaped member that contacts the photoconductor 11 may be used, or a non-contact charging device such as corotron or scorotron may be used. However, the present invention is more effective when a contact charging type charging device is used.

  In the present embodiment, the rotation direction of the brush roller 52 is set so as to move in the opposite direction to the photoconductor 11 at the contact portion with the photoconductor 11. Thereby, the toner adhering to the surface of the photoreceptor 11 is scattered by the brush roller 52, and the removal by the blade 51 can be efficiently performed. Further, when a two-component developer is used, the carrier adhering to the photoconductor 11 (the carrier has risen) can be removed by the brush roller 52, and the carrier is caught by the blade and the photoconductor 11 is damaged. Can be prevented.

  In the present embodiment, the charging roller 61 is driven independently from the rotational drive of the photoconductor 11 by a rotational drive means such as a motor or a gear. That is, it is not driven and rotated by the photoconductor 11, but is rotated by the rotation driving means. Therefore, even if the surface friction coefficient of the photoconductor 11 and the charging roller 61 is reduced due to the application of the lubricant, it is possible to prevent the charging roller 61 from rotating poorly due to slip and to prevent uneven charging.

In the present embodiment, the hair density of the brush rollers 52 and 63 is 6 × 10 ⁴ / inch ² , but the present invention is not limited to this. However, the hair density is preferably set to 1 × 10 ⁴ / inch ² or more. As a result, uneven application of the lubricant to the photosensitive member 11 or the charging roller 61 is reduced, and uneven density is not seen even in the low density portion of the toner image transferred onto the recording paper. Further, it is more preferable that the number is set to 2 × 10 ⁴ lines / inch ² or more. In this case, the unevenness of application of the lubricant to the photoreceptor 11 or the charging roller 61 is extremely reduced, and the toner transferred onto the recording paper. In the low density portion of the image, density unevenness is hardly seen. However, if the hair density exceeds 5 × 10 ⁵ strands / inch ² , the function as a brush is deteriorated and the manufacture becomes difficult. Therefore, the hair density is 5 × 10 ⁵ strands / inch ² or less. It is preferable to set. In addition, it is more preferable to set the hair density to 1 × 10 ⁵ / inch ² in order to reliably prevent the function of the brush from being lowered and to facilitate the production.

  In the present embodiment, the brush rollers 52 and 63 have a thickness of 2 deniers, but are not limited thereto. However, it is preferable to use hair having a thickness of 1 to 10 denier. If the hair is thinner than 1 denier, the scraping property of the lubricant is insufficient, and thick hair exceeding 10 denier is not preferable because it causes damage to the surface of the photoreceptor 11 or the surface of the charging roller 61 and wear. Further, in order to sufficiently secure the shaving property of the lubricant, it is more preferable to use a lubricant having a thickness of 2 denier or more.

  Moreover, in this embodiment, although conductive nylon was used as the hair of the brush roller 52, it is not restricted to this. However, the brush roller 52 is charged by frictional charging with the flicker 53 and the toner repelled from the brush roller 52 by the brush roller 52 coming into contact with the flicker 53 is reattached to the brush roller 52 by electrostatic attraction. In order to prevent this, it is preferable to use a material having a small electric resistance value and to ground the brush roller 52 (ground). As a result, the charge of the charged toner or the charge generated by friction with the flicker 53 is released to the ground, and the brush roller 52 can be prevented from being charged. Examples of the conductive material used for the brush roller 52 include nylon or acrylic resin in which carbon black is dispersed. A similar brush roller 63 can be used.

  In the present embodiment, the resilience of the blade 51 is set to 10% to 45% (more preferably 10% to 40%). As the rebound resilience of the blade 51 becomes smaller, the cleaning property can be improved with a lower linear pressure (pressure per unit length acting between the blade 51 and the photoconductor 11). This is because, as the rebound resilience is reduced, the edge portion of the blade 51 pressed against the photosensitive member 11 is easily crushed and the stick-slip behavior becomes smoother. In other words, when the resilience is low, the edge portion is crushed even at a low linear pressure, and the blade 51 and the photoconductor 11 come into contact with each other over a wide range, resulting in a low-vibration stick-slip behavior. However, it cannot pass through a wide contact portion, is blocked, and has good cleaning properties.

  Further, the fine particles of the lubricant 57 applied (supplied) to the surface of the photoconductor 11 by the brush roller 52 gather at or near the portion where the brush hair of the brush roller 52 is in contact. For this reason, the surface of the photoconductor 11 is made non-uniform, and the chargeability of the surface of the photoconductor 11 is lowered. In particular, when combined with the contact charging method, charge leakage is caused. When the impact resilience is 45% or less, the distribution of fine particles on the surface of the photoconductor 11 can be made uniform in the portion where the edge portion of the blade 51 is crushed, but when it exceeds 45%, the edge portion is less crushed. It becomes difficult to correct this non-uniformity. For these reasons, the resilience of the blade 51 is preferably 45% or less, and more preferably 40% or less.

  Further, when the impact resilience is lower than 10%, although the friction coefficient between the photoconductor 11 and the blade 51 is reduced by the lubricant 57, the photoconductor 11 is easily worn by contact with an excessive range. On the other hand, if it is lower than 10%, the restoring force of the blade 51 is too low to recover the deformation, and the phenomenon that the toner slips through in a short period of use is likely to occur.

  In the present embodiment, since the rebound resilience of the blade 51 is in the above range, the charging device 12 can be used in the contact charging system without accelerating the wear of the photoconductor 11 or accelerating the functional deterioration of the blade 51. Even in this case, the charging characteristics of the photoconductor 11 can be improved without causing charge leakage due to charge concentration.

  In the present embodiment, the Young's modulus of the blade 51 is 5 MPa or more and 11 MPa or less (more preferably 5 MPa or more and 10 MPa or less). By making the Young's modulus within the above range, the blade 51 can be made hard and has a strong elastic force, and even if it is a small particle size toner without corners, it can be reliably dammed and removed without slipping out. The life of the photoconductor 11 is not impaired.

  In the present embodiment, the contact angle of the blade 51 with respect to the photoconductor 11 is set to 6 ° ≦ θ ≦ 25 °. As the contact angle θ is smaller, the degree of freedom of movement in the sliding direction of the tip portion (edge 51a portion) of the blade 51 that contacts the photosensitive member 11 increases, which is advantageous for stick-slip motion and is smooth. Can realize stick-slip movement. However, if the contact angle θ is too large, the friction of the blade 51 and the surface of the photoconductor 11 becomes too large, and an increase in the torque of the photoconductor 11 or the turning-up phenomenon of the blade 51 occurs under other conditions. Or the edge 51a of the blade 51 is likely to be damaged. Therefore, in the present embodiment, the contact angle θ is in the above range. As a result, the stick-slip motion can be realized without problems and the occurrence of the above-mentioned problems can be avoided.

  In the present embodiment, the rotational speeds of the brush rollers 52 and 63 are set so that the amount of lubricant applied to the photoconductor 11 or the charging roller 61 falls within a predetermined range. Here, the application amount of the lubricant does not depend only on the rotational speed of the brush rollers 52 and 63, but the material of the lubricants 57 and 64, the type of the brush rollers 52 and 63 (shape, thickness of hair, bristle Density, hair material, etc.). Therefore, after setting the number of rotations of the brush rollers 52 and 63, the material of the lubricants 57 and 64, the type of the brush rollers 52 and 63, etc. can be selected so that the amount of lubricant applied can be within a predetermined range. Good. That is, each of the rotational speed of the brush rollers 52 and 63, the material of the lubricants 57 and 64, the type of the brush rollers 52 and 63, and the like so that an appropriate amount of lubricant can be applied to the photoreceptor 11 or the charging roller 61. Conditions may be set as appropriate.

  Further, in this embodiment, the lubricant is applied by the brush rollers 52 and 63, but the present invention is not limited to this, and any application means that can appropriately set the amount of the lubricant applied may be used. For example, a lubricant may be applied to the photoreceptor 11 or the charging roller 61 with a cloth or a sponge.

  In the present embodiment, the contaminant attached to the surface of the charging roller 61 is removed by the cleaning member 62 that contacts the charging roller 61, but the present invention is not limited to this. For example, by adopting an electrostatic cleaning method and applying a cleaning voltage from a power source (not shown) to the charging roller 61, contaminants attached to the charging roller 61 due to a potential difference between the charging roller 61 and the photoconductor 11. May be returned to the surface of the photoconductor 11. Specifically, in this embodiment, the charging roller 61 surface potential during image formation is set to -1.3 kV and the photoreceptor 11 surface potential is set to -600 V, but in a period during which image formation is not performed. By applying a cleaning AC bias voltage (for example, ± 500 V) to the charging roller 61, the contaminants attached to the charging roller 61 can be returned to the surface of the photoconductor 11.

  Further, cleaning by the cleaning member 62 that contacts the charging roller 61 and electrostatic cleaning may be used in combination. As a result, the contaminants attached to the charging roller 61, in particular, external additives such as silica having a strong adhesive force can be efficiently cleaned, and the life of the charging roller 61 can be extended.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims. That is, embodiments obtained by combining technical means appropriately changed within the scope of the claims are also included in the technical scope of the present invention.

  The present invention can be applied to an electrophotographic image forming apparatus.

1 is a cross-sectional view illustrating a configuration of a visible image forming unit provided in an image forming apparatus according to an embodiment of the present invention. 1 is an explanatory diagram illustrating a schematic configuration of an image forming apparatus according to an embodiment of the present invention.

Explanation of symbols

1 Image forming apparatus 10, 10Y, 10M, 10C, 10B Visible image forming unit 11 Photosensitive member (image carrier)
12 Charging device (charging means)
13 Laser beam irradiation means (latent image forming means)
14 Developing device (Developing means)
15 Transfer roller (transfer means)
16 Cleaner unit (cleaning means)
51 Cleaning blade 51a Edge 52 Brush roller (first coating means, rotating brush)
53 Flicker 54 Case 55 Toner conveying screw 56 Sealing material 57 Lubricant 58 Energizing member 61 Charging roller (contact charging member)
62 Cleaning member (second cleaning means, contact cleaning means)
63 Brush roller (second application means)
64 Lubricant 65 Biasing member θ Contact angle

Claims (9)

A rotating image carrier, a charging unit arranged around the image carrier along the rotation direction for charging the image carrier, and forming an electrostatic latent image on the charged image carrier Latent image forming means, developing means for developing the electrostatic latent image formed on the image carrier with a developer, transfer means for transferring the image developed on the image carrier to a recording material, In the image forming apparatus provided with a cleaning unit for cleaning the surface of the image carrier after the transfer,
First application means for applying a lubricant to the surface of the image carrier after the transfer and before the cleaning;
An image forming apparatus comprising: a second application unit that applies a lubricant to the surface of the image carrier after the cleaning and before the development. The charging unit is a contact charging type charging unit including a contact charging member that contacts the image carrier and charges the image carrier.
2. The image formation according to claim 1, wherein the second application unit applies a lubricant to the contact charging member to apply the lubricant to the image carrier through the contact charging member. apparatus.   3. The image forming apparatus according to claim 2, wherein the amount of lubricant applied to the contact charging member by the second application unit is larger than the amount of lubricant applied to the image carrier by the first application unit. The amount of lubricant applied to the contact charging member by the second application means is 0.05 μg / cm ² or more and 0.08 μg / cm ² or less,
4. The image forming apparatus according to claim 3, wherein the amount of lubricant applied to the image carrier by the first application unit is 0.01 μg / cm ² or more and 0.06 μg / cm ² or less.   2. The charging device according to claim 1, wherein the charging unit includes a contact charging member that contacts the image carrier and charges the image carrier, and a rotation driving unit that rotationally drives the contact charging member. The image forming apparatus described. Drive means for rotationally driving the first application means;
The driving unit rotates the first coating unit so that the surface of the first coating unit moves in a direction opposite to the moving direction of the surface of the image carrier at a contact portion between the first coating unit and the image carrier. The image forming apparatus according to claim 1, wherein the image forming apparatus is driven.   7. The rotary brush according to claim 6, wherein the first applying means is a rotating brush that includes a large number of linear members and applies a lubricant by bringing the tips of the linear members into contact with the surface of the image carrier. Image forming apparatus.   The charging unit includes a contact charging member that contacts the image carrier and charges the image carrier, and a second cleaning unit that removes contaminants attached to the contact charging member. The image forming apparatus according to claim 1. The second cleaning means includes
Contact cleaning means that contacts the contact charging member to remove contaminants, or contamination that adheres to the contact charging member due to a potential difference between the contact charging member and the image carrier by applying a cleaning voltage to the contact charging member. 9. The image forming apparatus according to claim 8, wherein the electrostatic cleaning unit moves the substance to the image carrier, or the contact cleaning unit and the electrostatic cleaning unit are used in combination.

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