JP2009217094A - Electrifying member cleaning device, process cartridge, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrifying member cleaning device which has excellent cleaning performance for the surface of an electrifying member such as an electrifying roll and suppresses hindrance of the rotation of the electrifying roll, even in a small-diameter electrifying roll. <P>SOLUTION: The electrifying member cleaning device includes a small movable piece member which is not fixed to a specific position, as a cleaning member for cleaning the surface of the electrifying member provided to an image forming apparatus. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a charging member cleaning device, a process cartridge, and an image forming apparatus.

  Conventionally, as a charging device of an image forming apparatus such as a copying machine or a printer adopting an electrophotographic method, a device using a corona discharge phenomenon such as a scorotron charger has been widely used, but a charging device using a corona discharge phenomenon is used. In this case, ozone or nitrogen oxides may be generated. In contrast, a contact charging method in which a charging member such as a conductive charging roll is directly brought into contact with the image carrier to charge the image carrier significantly reduces the generation of ozone, nitrogen oxides, etc., and improves the power efficiency. Recently, it has become mainstream because it is good.

  In such a contact charging type charging device, since the charging roll is in contact with the image carrier, there is a problem that the surface of the charging roll is likely to be contaminated with toner components or paper powder. The surface of the image carrier that repeats the image forming operation passes through a cleaning process for removing foreign matter such as residual toner after transfer on the downstream side of the transfer process, and then enters the charging process area. Even after passing through the process, particles smaller than the toner, such as a part of the toner and the external additive of the toner, remain on the image carrier without being cleaned, and adhere to the surface of the charging roll. The foreign matter adhering to the surface of the charging roll may cause unevenness in the surface resistance value of the charging roll, resulting in abnormal discharge or unstable discharge, which may deteriorate charging uniformity.

  As a technique for solving such a problem, a cleaning method has been proposed in which a plate-like brush or sponge is brought into contact with the surface of the charging roll as a cleaning member to scrape off the surface contamination of the charging roll. For example, Patent Documents 1 and 2 indicate that the surface roughness of the charging roll is made smaller than the toner diameter, and Patent Document 3 discloses that the ten-point average roughness of the surface of the charging roll is 3 μm or more. It is shown that it is 40 μm or less, and Patent Document 4 shows that the ten-point average roughness of the surface of the charging roll is 30 μm or less.

  However, in the techniques of Patent Documents 1 to 4, foreign matter gradually accumulates on the surface of the cleaning member in contact with the charging roll, and the cleaning performance deteriorates due to clogging. As a result, the charging roll becomes dirty. There are drawbacks, and there is a problem that the cleaning member fixed to the charging roll acts as a brake and obstructs the rotation of the charging roll. In recent years, in order to solve the problem, a roll type charging roll cleaner using a foam resin or foam rubber has been proposed.

  In a roll-type charging roll cleaner constituted by such a foam, when an adhering substance such as an external additive or a toner adhering to the charging roll is removed by a cleaning member, first, it is constituted by a foam. Foreign substances such as external additives are taken into the cells of the cleaning member. The foreign matter taken into the cell aggregates into a moderately sized aggregate. When the moderately sized aggregate is formed, the aggregate is discharged from the cell and is passed through the charging roll to form an image carrier. Since it is removed from the image carrier by a cleaning blade or the like, it is considered that foreign matters do not accumulate on the cleaning member, and that the cleaning performance is maintained by the cleaning member.

  In recent years, the image forming apparatus has been downsized and the diameter of the charging roll has been reduced, and accordingly, the diameter of the roll type charging roll cleaner has been reduced. Since it is difficult to reduce the diameter of the metal core material that supports the charging roll cleaner in order to ensure mounting rigidity, a method of reducing the thickness of the foam layer is used in reducing the diameter of the roll type charging roll cleaner. It has been taken. In order to ensure the cleaning property of the charging roll by the charging roll cleaner, it is necessary to bite the foam layer to a certain level or more with respect to the charging roll. However, since the thickness of the foam layer is thin, a higher load than before is required. It will be applied to the charging roll.

JP-A-8-166705 Japanese Patent Laid-Open No. 9-222776 JP 2005-24675 A Japanese Patent Laid-Open No. 11-143183

  The present invention includes a charging member cleaning device that has good cleaning performance on the surface of a charging member such as a charging roll, and that can inhibit inhibition of rotation of the charging roll even in a small-diameter charging roll, and the charging member cleaning device. A process cartridge and an image forming apparatus.

  The present invention is a charging member cleaning device including a movable small piece member that is not fixed at a specific position as a cleaning member for cleaning the surface of a charging member provided in an image forming apparatus.

  In the charging member cleaning device, it is preferable that a shape of the small piece member is at least one of a spherical shape, a cylindrical shape, and a polygonal column shape.

  In the charging member cleaning device, it is preferable that the small piece member includes at least one of resin, rubber, and inorganic material.

  In addition, the present invention is a process cartridge including an image holding member, a charging member that charges the surface of the image holding member, and the charging member cleaning device.

  The present invention also provides an image carrier, a charging member that charges the surface of the image carrier, the charging member cleaning device, a latent image forming unit that forms a latent image on the surface of the image carrier, An image forming apparatus comprising: a developing unit that develops a latent image formed on a surface of an image holding member with toner to form a toner image.

  According to the first aspect of the present invention, the surface of the charging member such as a charging roll has a better cleaning performance than the case where the present configuration is not provided, and the rotation of the charging roll is inhibited even in a small-diameter charging roll. It is possible to provide a charging member cleaning device capable of suppressing the above.

  According to the second aspect of the present invention, the surface of the charging member such as a charging roll has a better cleaning performance than the case where this configuration is not provided. It is possible to provide a charging member cleaning device capable of suppressing the inhibition.

  According to the third aspect of the present invention, the surface of the charging member such as a charging roll has a better cleaning performance than the case where this configuration is not provided. It is possible to provide a charging member cleaning device capable of suppressing the inhibition.

  According to the fourth aspect of the present invention, the surface of the charging member such as a charging roll has a better cleaning performance than the case where the present configuration is not provided, and the rotation of the charging roll is inhibited even in a small-diameter charging roll. It is possible to provide a process cartridge capable of suppressing the above.

  According to the fifth aspect of the present invention, the surface of the charging member such as a charging roll has a better cleaning performance than the case where this configuration is not provided, and the rotation of the charging roll is inhibited even in a small-diameter charging roll. It is possible to provide an image forming apparatus capable of suppressing the above.

  Embodiments of the present invention will be described below. This embodiment is an example for carrying out the present invention, and the present invention is not limited to this embodiment.

<Charging device>
FIG. 1A is a schematic configuration diagram illustrating an example of an image forming apparatus including a charging member cleaning device according to an embodiment of the present invention, and FIG. It is an enlarged view. The charging device 1 includes a charging roll 10 that is a rotating cylindrical charging member, and a charging roll cleaner 12 that is a charging member cleaning device for cleaning the surface of the charging roll 10. The charging roll 10 includes a conductive core member 14 and a charging layer 16 formed on the outer periphery of the conductive core member 14. The charging roll cleaner 12 includes a small piece member 18 that is not fixed at a specific position, and a housing 20 that is a housing member for housing the small piece member. The small piece member 18 is movable in the housing 20 that is a housing member. In addition, a voltage is applied to the charging roll 10 by a high voltage power source (not shown).

  As shown in FIG. 1, when the charging device 1 is installed in the image forming apparatus 5, the charging roll 10 is disposed beside the photosensitive drum 26 so as to be in contact with the photosensitive drum 26. The conductive core material 14 of the charging roll 10 is rotatably supported. A charging roll cleaner 12 is provided on the opposite side of the charging roll 10 from the photosensitive drum 26.

  The photosensitive drum 26 that is an image holding member is rotationally driven in the direction of arrow X by a motor (not shown), and the charging roll 10 is driven to rotate in the direction of arrow Y by the rotation of the photosensitive drum 26. The charging roll 10 is of a contact charging type that charges the surface of the photosensitive drum 26 while rotating in contact with the rotationally driven photosensitive drum 26.

  The charging roll cleaner 12 is disposed at a position where it does not interfere with other components other than the nip position between the charging roll 10 and the photosensitive drum 26 in contact therewith. The charging roll cleaner 12 includes a movable small piece member 18 that is not fixed at a specific position as a cleaning member for cleaning the surface of the charging roll 10. In the present embodiment, the small piece member 18 is accommodated in a housing 20 that covers at least a part of the cleaning portion of the charging roll 10. The small piece member 18 is accommodated so as to move in the housing 20 and contact the surface of the charging layer 16 of the charging roll 10. In order to prevent the small piece member 18 from entering the case 20 between the charging roll 10 and the case 20 and causing the biting between the charging roll 10 and the case 20, An outflow prevention plate 22 is provided on the rotation downstream side of the charging roll 10 as an outflow prevention means for preventing the member 18 from adhering to the surface of the charging roll 10 due to electrostatic adhesion and flowing out of the housing 20. May be.

  The charging roll cleaner 12 is arranged so that the small piece member 18 moves and contacts the surface of the charging roll 10, and the small piece member 18 moves and contacts the peripheral surface of the charging roll 10. When the small piece member 18 and the surface of the charging roll 10 are rubbed and the small piece member 18 electrostatically attached to the charging roll 10 is forcibly removed from the surface of the charging roll 10 by the outflow prevention plate 22, Deposits such as toner and toner external additives are cleaned. Further, by appropriately controlling the filling amount of the small piece member 18 into the housing 20, the small piece member 18 can be moved in the housing 20, so that the rotation of the charging roll 10 is hardly hindered. .

  Further, as shown in FIG. 1, when the charging roll 10 is positioned above or laterally of the photosensitive drum 26 in use, it is possible to apply the small piece member 18 to the surface of the charging roll 10 using gravity. However, when the charging roll 10 is positioned below the photosensitive drum 26 as shown in FIG. 2, the small piece member 18 cannot be applied to the surface of the charging roll 10 by gravity. By forcibly agitating the small piece member 18 using an agitation paddle 24 or the like as an agitation means for agitating 18, the surface of the charging roll 10 can be cleaned by bringing the small piece member 18 into contact with the surface of the charging roll 10. .

  The casing 20 that fills the small piece member 18 is made of, for example, resin, and may be a resin material that can be injection-molded.

  The shape of the small piece member 18 is not particularly limited as long as the surface of the charging roll 10 can be cleaned. However, from the viewpoint of cleaning performance, availability, etc., a spherical shape, a cylindrical shape and a triangular prism, a quadrangular column, a pentagonal column, a hexagonal column, etc. It is preferable that it is at least one of these polygonal columnar shapes.

  The material of the small piece member 18 is not particularly limited as long as the surface of the charging roll 10 can be cleaned, but preferably includes at least one of resin, rubber, glass, and inorganic materials such as metal. The small piece member 18 is preferably a resin, particularly a foamed resin from the viewpoint of noise and weight during use, and a foamable resin such as polyurethane, polyethylene, polystyrene, polyamide or polypropylene, nitrile rubber (NBR), ethylene- It can be selected from those made of rubber such as propylene-diene rubber (EPDM), styrene butadiene rubber (SBR), and silicone rubber. The small piece member 18 is not limited to one type, and a plurality of types can be used simultaneously.

  The diameter of the small piece member 18 is not particularly limited. However, from the viewpoint of space saving and as uniform contact as possible with the surface of the charging roll 10, for example, it is in the range of about 0.5 mm to 3 mm, particularly 1 mm or more. A range of φ2 mm or less is more preferable.

  The filling amount of the small piece member 18 in the housing 20 is not particularly limited as long as the small piece member 18 can be moved in the housing 20.

  As described above, by using the small piece member 18 as a cleaning member for cleaning the surface of the charging roll 10 and making the small piece member 18 movable without being fixed at a specific position, the charging roll 10 and the cleaning member. It is possible to keep the pressure of the small piece member 18 against the charging roll 10 low while securing the contact area. For this reason, even if the charging roll 10 has a small diameter while maintaining high cleaning properties, the rotational driving of the charging roll 10 is hardly hindered. Further, since the structure is relatively simple, an inexpensive charging member cleaning device can be obtained by selecting an inexpensive small piece member.

  The charging roll 10 will be described.

  In the charging roll 10, a conductive elastic layer, a surface layer, and the like are sequentially formed as a charging layer 16 on a conductive core 14.

  The diameter of the charging roll 10 is preferably φ8 mm or more and φ15 mm or less, more preferably φ9 mm or more and φ14 mm or less, and the thickness of the charging layer 16 is preferably 1.5 mm or more and 4 mm or less. When the diameter exceeds 15 mm, the number of times of contact with the external additive per place on the peripheral surface is reduced, and the number of discharges is reduced, which is excellent in terms of long-term stability against dirt and charging performance, but is disadvantageous from the viewpoint of miniaturization. If the diameter is less than 8 mm, the image forming apparatus can be downsized, which is advantageous. However, the number of times of contact with the external additive per location on the peripheral surface increases and the number of discharges increases, which is disadvantageous for long-term stability. It becomes.

  The charging roll 10 is not limited to the following configuration as long as it has a predetermined charging performance.

  As the material of the conductive core material 14, free-cutting steel, stainless steel or the like is used, and the material and the surface treatment method are appropriately selected according to the application such as slidability, and the material having no conductivity is plated. For example, the conductive treatment may be performed by general processing.

  The conductive elastic layer constituting the charging layer 16 of the charging roll 10 may be, for example, an elastic material such as elastic rubber, a conductive material such as carbon black or ionic conductive material that adjusts the resistance of the conductive elastic layer, or the like. Accordingly, materials that can be usually added to rubber, such as softeners, plasticizers, curing agents, vulcanizing agents, vulcanization accelerators, anti-aging agents, and fillers such as silica and calcium carbonate, may be added. It is formed by coating the peripheral surface of the conductive core material 14 with a mixture in which materials usually added to rubber are added. As a conductive agent for the purpose of adjusting the resistance value, a material in which a material that conducts electricity using at least one of electrons and ions as a charge carrier, such as carbon black or an ionic conductive agent blended in a matrix material, is dispersed. Can be used. The elastic material may be a foam.

  The elastic material constituting the conductive elastic layer is formed, for example, by dispersing a conductive agent in a rubber material. Rubber materials include isoprene rubber, chloroprene rubber, epichlorohydrin rubber, butyl rubber, urethane rubber, silicone rubber, fluorine rubber, styrene-butadiene rubber, butadiene rubber, nitrile rubber, ethylene propylene rubber, epichlorohydrin-ethylene oxide copolymer rubber, epichlorohydrin-ethylene oxide. -Allyl glycidyl ether copolymer rubber, ethylene-propylene-diene terpolymer rubber (EPDM), acrylonitrile-butadiene copolymer rubber, natural rubber and the like, and blended rubbers thereof. Among these, silicone rubber, ethylene propylene rubber, epichlorohydrin-ethylene oxide copolymer rubber, epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber, acrylonitrile-butadiene copolymer rubber, and blended rubbers thereof are preferably used. These rubber materials may be foamed or non-foamed.

  As the conductive agent, an electronic conductive agent or an ionic conductive agent is used. Examples of electronic conductive agents include carbon blacks such as ketjen black and acetylene black; pyrolytic carbon, graphite; various conductive metals or alloys such as aluminum, copper, nickel, stainless steel; tin oxide, indium oxide, titanium oxide Examples thereof include various conductive metal oxides such as tin oxide-antimony oxide solid solution and tin oxide-indium oxide solid solution; and the like. Examples of ionic conductive agents include perchlorates and chlorates such as tetraethylammonium and lauryltrimethylammonium; alkali metals such as lithium and magnesium, alkaline earth metal perchlorates and chlorates, etc. Can be mentioned.

  These conductive agents may be used alone or in combination of two or more. Further, the amount of addition is not particularly limited, but in the case of the electronic conductive agent, it is preferably in the range of 1 part by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the rubber material. In the case of an agent, it is preferably in the range of 0.1 to 5.0 parts by mass with respect to 100 parts by mass of the rubber material.

  The surface layer constituting the charging layer 16 is formed for the purpose of preventing contamination by foreign matters such as toner, and the surface layer material may be any of resin, rubber, etc. It is not limited. Polyester, polyimide, copolymer nylon, silicone resin, acrylic resin, polyvinyl butyral, ethylene tetrafluoroethylene copolymer, melamine resin, fluoro rubber, epoxy resin, polycarbonate, polyvinyl alcohol, cellulose, polyvinylidene chloride, polyvinyl chloride, polyethylene And ethylene vinyl acetate copolymer.

  Of these, polyvinylidene fluoride, a tetrafluoroethylene copolymer, polyester, polyimide, and copolymer nylon are preferably used from the viewpoint of preventing contamination by an external additive. The copolymer nylon includes one or more of 610 nylon, 11 nylon, and 12 nylon as polymerized units, and the other polymer units contained in the copolymer include 6 nylon. 66 nylon and the like. Here, the proportion of polymer units composed of 610 nylon, 11 nylon, and 12 nylon contained in the copolymer is preferably 10% by mass or more in total by mass ratio. When the polymerized unit is 10% by mass or more, it has excellent liquid preparation properties and film formability during coating of the surface layer, and particularly less wear of the resin layer and adhesion of foreign matter to the resin layer during repeated use, and durability of the roll Excellent properties and less change in properties due to the environment.

  The above polymer materials may be used alone or in combination of two or more. Further, the number average molecular weight of the polymer material is preferably in the range of 1,000 or more and 100,000 or less, and more preferably in the range of 10,000 or more and 50,000 or less.

  The surface layer can contain a conductive material to adjust the resistance value. The conductive material preferably has a particle size of 3 μm or less.

  In addition, as a conductive agent for adjusting the resistance value, at least one of electrons and ions such as carbon black, conductive metal oxide particles, or ionic conductive agent blended in the matrix material is used as a charge carrier. A material in which a material that conducts electricity is dispersed can be used.

  Specifically, carbon black as a conductive agent includes “Special Black 350”, “Special Black 100”, “Special Black 250”, “Special Black 5”, “Special Black 4” manufactured by Degussa, "Special Black 4A", "Special Black 550", "Special Black 6", "Color Black FW200", "Color Black FW2", "Color Black FW2V", "MONARCH1000" manufactured by Cabot, Cabot “MONARCH1300” manufactured by the company, “MONARCH1400” manufactured by Cabot, “MOGUL-L”, “REGAL400R”, and the like.

  The carbon black preferably has a pH of 4.0 or less. Compared to general carbon black, it has good dispersibility in the resin composition due to the effect of oxygen-containing functional groups present on the surface, and blending with carbon black having a pH of 4.0 or less improves charging uniformity. In addition, the fluctuation of the resistance value can be reduced.

  The conductive metal oxide particles, which are conductive particles for adjusting the resistance value, are conductive materials such as tin oxide, tin oxide doped with antimony, zinc oxide, anatase titanium oxide, and indium tin oxide (ITO). As long as it is a conductive agent using electrons as charge carriers, any particle can be used and is not particularly limited. These may be used alone or in combination of two or more. In addition, any particle size may be used as long as the effect of the present embodiment is not impaired, but from the viewpoint of resistance value adjustment and strength, tin oxide, antimony-doped tin oxide, and anatase-type titanium oxide are preferable. Furthermore, tin oxide and tin oxide doped with antimony are preferred.

  By performing resistance control with such a conductive material, the resistance value of the surface layer does not change depending on environmental conditions, and stable characteristics can be obtained.

  Further, a fluorine-based or silicone-based resin or the like is used for the surface layer. In particular, it is preferably configured to contain a fluorine-modified acrylate polymer. Moreover, you may add particle | grains in a surface layer. As a result, the surface layer becomes hydrophobic and acts to prevent the foreign matter from adhering to the charging roll 10. In addition, insulating particles such as alumina and silica are added to provide irregularities on the surface of the charging roll 10, thereby reducing the burden at the time of rubbing against the photosensitive drum 26 and charging roll 10 and the photosensitive drum. It is also possible to improve the mutual wear resistance.

<Process cartridge>
A process cartridge according to the present embodiment includes an image carrier, a charging member that charges the surface of the image carrier, and the charging member cleaning device. The process cartridge according to this embodiment includes a latent image forming unit that forms a latent image on the surface of the charged image carrier, and a toner that develops the latent image formed on the surface of the image carrier with toner as necessary. From the group consisting of developing means for forming an image, transfer means for transferring the toner image formed on the surface of the image carrier to the transfer target, and image carrier cleaning means for cleaning the surface of the image carrier after transfer You may provide at least 1 type selected.

  A schematic configuration of an example of the process cartridge according to the embodiment of the present invention is shown in FIG. 3, and the configuration will be described. The process cartridge 3 includes a photosensitive drum (electrophotographic photosensitive member) 26 as an image carrier on which an electrostatic latent image is formed, and a charging roll 10 that is a cylindrical charging member that contacts and charges the surface of the photosensitive drum 26. And a charging roll cleaner 12 as a charging member cleaning device for cleaning the surface of the charging roll 10, and development for forming a toner image by attaching toner to the electrostatic latent image formed on the surface of the photosensitive drum 26 A developing roll 52 as a unit and a cleaning blade 56 as an image carrier cleaning unit that contacts the surface of the photosensitive drum 26 and cleans toner remaining on the photosensitive drum 26 after transfer are integrally supported. And is detachable from the image forming apparatus. Exposure as latent image forming means for forming an electrostatic latent image on the surface of the photosensitive drum 26 around the photosensitive drum 26 by the charging roll 10, laser light, or reflected light of the original when mounted on the image forming apparatus. The apparatus 58, the developing roll 52, the transfer roll 54 as a transfer means for transferring the toner image on the surface of the photosensitive drum 26 to the recording paper 62 as the transfer target, and the cleaning blade 56 are arranged in this order. Yes. In FIG. 3, functional units normally required in other electrophotographic processes are omitted.

  The operation of the process cartridge 3 according to this embodiment will be described.

  First, the surface of the photosensitive drum 26 is uniformly charged to a high potential by supplying a voltage from a high voltage power source (not shown) to the charging roll 10 in contact with the surface of the photosensitive drum 26. At this time, the photosensitive drum 26 and the charging roll 10 rotate in the directions of the arrows in FIG. After charging, when image light (exposure) 60 corresponding to image information is irradiated onto the surface of the photosensitive drum 26 by the exposure device 58, the potential of the irradiated portion decreases. Since the image light 60 has a light amount distribution corresponding to the black / white of the image, a potential distribution corresponding to a recorded image, that is, an electrostatic latent image is formed on the surface of the photosensitive drum 26 by irradiation of the image light 60. When the portion where the electrostatic latent image is formed passes through the developing roll 52, toner adheres according to the level of the potential, and a toner image in which the electrostatic latent image is visualized is formed. The recording paper 62 is conveyed to a portion where the toner image is formed by a resist roll (not shown) at a predetermined timing, and overlaps the toner image on the surface of the photosensitive drum 26. After the toner image is transferred to the recording paper 62 by the transfer roll 54, the recording paper 62 is separated from the photosensitive drum 26. The separated recording paper 62 is transported through a transport path, and is heated and pressed and fixed by a fixing unit (not shown) as fixing means, and then discharged outside the apparatus.

  A charging roll cleaner 12 is installed on the charging roll 10 provided in the process cartridge 3. The charging roll cleaner 12 is arranged so that the small piece member 18 moves and contacts the surface of the charging roll 10 in the housing, and the small piece member 18 moves and contacts the peripheral surface of the charging roll 10, thereby 10. Deposits such as toner and toner external additives on the surface are cleaned.

  The photosensitive drum 26 has a function of forming at least an electrostatic latent image (electrostatic charge image). In the electrophotographic photosensitive member, an undercoat layer, a charge generation layer containing a charge generation material, and a charge transport layer containing a charge transport material are formed in this order on the outer peripheral surface of a cylindrical conductive substrate as necessary. It is a thing. The order of stacking the charge generation layer and the charge transport layer may be reversed. These are laminated photoconductors in which a charge generation material and a charge transport material are contained in separate layers (charge generation layer, charge transport layer), but both the charge generation material and the charge transport material are the same. A single-layer type photoreceptor included in the above layer may be used, and a laminated photoreceptor is preferable. Further, an intermediate layer may be provided between the undercoat layer and the photosensitive layer. In addition, other types of photosensitive layers such as an amorphous silicon photosensitive film may be used in addition to the organic photoreceptor.

  The exposure device 58 is not particularly limited. For example, a laser optical system, an LED array, or the like that can expose the surface of the photosensitive drum 26 with a light source such as a semiconductor laser beam, an LED beam, or a liquid crystal shutter beam in a desired image manner. Examples include optical system equipment.

  The developing means has a function of developing the electrostatic latent image formed on the photosensitive drum 26 with a one-component developer or a two-component developer containing an electrostatic charge image developing toner to form a toner image. Such a developing device is not particularly limited as long as it has the above-described function, and can be appropriately selected according to the purpose. Even a type in which the toner layer is in contact with the photosensitive drum 26 does not come into contact. A method may be used. For example, as shown in FIG. 3, a developing device having a function of attaching the electrostatic image developing toner to the photosensitive drum 26 using the developing roll 52, or a function of attaching the toner to the photosensitive drum 26 using a brush or the like. Examples of the developing device include a known developing device. A direct current voltage is normally used for the developer carrier, but an alternating voltage may be further superimposed.

  The transfer unit may be a type that directly transfers to paper or the like, or a type that transfers via an intermediate transfer member. For example, it is possible to use a transfer roll 54 and a transfer roll pressing device (not shown) using a conductive or semiconductive roll that directly transfers through a recording sheet 62 as shown in FIG. . Further, a recording paper 62 may be used in which a charge having a polarity opposite to that of the toner is applied to the recording paper 62 from the back side (the side opposite to the photosensitive member) of the recording paper 62 and the toner image is transferred to the recording paper 62 by electrostatic force. A direct current may be applied to the transfer roll 54 as a transfer current applied to the photosensitive drum 26, or an alternating current may be applied in a superimposed manner. The transfer roll 54 can be arbitrarily set depending on the width of the image area to be charged, the shape of the transfer charger, the opening width, the process speed (circumferential speed), and the like. Further, a single layer foam roll or the like is preferably used as the transfer roll 54 for cost reduction.

  The fixing unit as the fixing unit is not particularly limited as long as the toner image transferred onto the recording paper 62 is fixed by heating, pressing, or heating and pressing.

  Examples of the recording paper 62 that is a transfer target to which the toner image is transferred include plain paper, an OHP sheet, and the like used in electrophotographic copying machines and printers. In order to further improve the smoothness of the image surface after fixing, it is preferable that the surface of the transfer material is as smooth as possible. For example, coated paper whose surface of plain paper is coated with resin, art paper for printing, etc. It can be preferably used.

<Image forming apparatus>
An image forming apparatus according to the present embodiment includes an image carrier, a charging member that charges the surface of the image carrier, the charging member cleaning device, and a latent image forming unit that forms a latent image on the surface of the image carrier. And a developing means for developing the latent image formed on the surface of the image carrier with toner to form a toner image. The image forming apparatus according to the present embodiment includes a transfer unit that transfers a toner image formed on the surface of the image carrier to the transfer target, and an image carrier cleaning that cleans the surface of the image carrier after the transfer, as necessary. You may provide at least 1 type selected from the group which consists of means. The image forming apparatus according to the present embodiment may use the process cartridge.

  FIG. 4 shows a tandem full-color image forming apparatus 5 as an example of the image forming apparatus according to the present embodiment. Inside the image forming apparatus 5, an image forming unit having a photosensitive drum 26 and a developing device is arranged for each color of yellow (64Y), magenta (64M), cyan (64C), and black (64K). It has been. As the photosensitive drum 26, for example, a conductive cylinder whose surface is coated with a photosensitive layer including an organic photosensitive member is used, and a process speed of, for example, about 150 mm / sec in the direction of arrow X by a motor (not shown). Driven by rotation.

  The surface of the photoconductive drum 26 is charged to a predetermined potential by the charging roll 10 disposed in contact with the photoconductive drum 26, and then subjected to image exposure by a laser beam emitted from the exposure device 58. An electrostatic latent image corresponding to the above is formed.

  The electrostatic latent image formed on the photosensitive drum 26 is developed by developing units 66Y, 66M, 66C, and 66K for yellow (Y), magenta (M), cyan (C), and black (K). A toner image of a predetermined color is obtained.

  For example, when a full-color image is formed, the charging, exposure, and development processes are performed on the surface of the photosensitive drum 26 of each color by yellow (Y), magenta (M), cyan (C), and black (K). A toner image corresponding to each color of yellow (Y), magenta (M), cyan (C), and black (K) is formed on the surface of the photosensitive drum 26 of each color. .

  The yellow (Y), magenta (M), cyan (C), and black (K) toner images sequentially formed on the photosensitive drum 26 are sequentially printed on the recording paper 62 conveyed on the paper conveying belt 68. Are transferred by the transfer roll 54 of each color image forming unit.

  Further, the recording paper 62 onto which the toner image has been transferred is conveyed to the fixing device 70, and is heated and pressurized by the fixing device 70, so that the toner image is fixed on the recording paper 62. Thereafter, in the case of single-sided printing, the recording paper 62 on which the toner image is fixed is discharged as it is onto a discharge tray 74 provided on the upper portion of the image forming apparatus 5 by a discharge roll 72.

  On the other hand, in the case of duplex printing, the recording paper 62 on which the toner image is fixed on the first surface (front surface) by the fixing device 70 is not directly discharged onto the discharge tray 74 by the discharge roll 72 but is discharged as it is. With the rear end portion of the recording paper 62 being held in place, the discharge roll 72 is reversed, the conveyance path of the recording paper 62 is switched to the double-sided paper conveyance path 76, and the double-sided paper conveyance path 76 is arranged. With the conveying roll 78 provided, the recording sheet 62 is reversed and conveyed to the transfer position of the sheet conveying belt 68, and the toner image is transferred to the second surface (back surface) of the recording sheet 62. Then, the toner image on the second surface (back surface) of the recording paper 62 is fixed by the fixing device 70, and the recording paper 62 is discharged onto the discharge tray 74.

  The surface of the photoconductive drum 26 after the toner image transfer process is completed is changed by a cleaning blade 56 disposed obliquely above the photoconductive drum 26 every time the photoconductive drum 26 makes one rotation. Paper dust and the like are removed to prepare for the next image forming process.

  A charging roll cleaner 12 is installed on the charging roll 10 provided in the image forming apparatus 5. The charging roll cleaner 12 is arranged so that the small piece member moves and contacts the surface of the charging roll 10 in the housing, and the small piece member moves and contacts the peripheral surface of the charging roll 10, thereby Deposits such as toner and toner external additives are cleaned.

  The configuration other than the charging member cleaning device of the image forming apparatus according to the present embodiment is not limited thereto, and conventionally known configurations can be applied as the respective configurations of the electrophotographic image forming apparatus. That is, other than the charging member cleaning device, for example, a charging member, a latent image forming unit, a developing unit, a transfer unit, an image carrier cleaning unit, a discharging unit, a paper feeding unit, a conveying unit, an image control unit, etc. are necessary. According to the above, conventionally known ones are appropriately employed. These configurations are not particularly limited in the present embodiment.

  Further, the image forming apparatus according to the present embodiment is not limited to the above-described configuration, and for configurations other than the charging device, for example, an image forming device having only one photoconductor, and a toner image held on the image holding member in the middle. Conventionally known devices such as a color image forming apparatus that sequentially repeats primary transfer onto a transfer body are appropriately employed. These configurations are not particularly limited in the present embodiment.

<Toner and developer>
The developer used in this embodiment may be a two-component developer including a toner and a carrier, or may be a one-component developer used alone, such as a magnetic toner.

  The developer used in the present embodiment preferably contains spherical silica as an external additive. The reason for this is that silica has a refractive index of around 1.5, and even if the particle size is increased, the transparency is not lowered due to light scattering, and in particular, it does not affect the light transmittance during image preparation on the OHP surface. Can be mentioned.

  On the other hand, general fumed silica has a specific gravity of 2.2, and the maximum particle size of 50 nm may be a limit in production. In addition, although the particle size can be increased as an aggregate, uniform dispersion may be difficult, and the sealing effect may not be exhibited stably.

  Silica suitable as a material for the external additive contained for improving the cleaning property, particularly spherical monodispersed silica having a specific gravity of 1.3 or more and 1.9 or less can be obtained by a sol-gel method which is a wet method. Since the sol-gel method is a wet method and is a method of producing without firing, the specific gravity can be controlled lower than other methods such as a vapor phase oxidation method. Further, it is possible to further adjust the specific gravity by controlling the type of hydrophobic treatment agent or the amount of treatment in the hydrophobization treatment step. The particle size of the silica can be freely controlled by the hydrolysis of the sol-gel method, the mass ratio of alkoxysilane, ammonia, alcohol, water in the condensation polymerization step, the reaction temperature, the stirring rate, and the supply rate. Monodispersed and spherical silica can be formed by the sol-gel method.

  A specific method for producing silica is as follows.

  First, a silane compound such as tetramethoxysilane is dropped into a mixed solution of water and alcohol using ammonia water as a catalyst while applying temperature, and stirring is performed. Next, the produced silica sol suspension is centrifuged to separate it into wet silica gel, alcohol and aqueous ammonia. A solvent is added to wet silica gel to form a silica sol again, and a hydrophobizing agent is added to hydrophobize the silica surface. As the hydrophobic treatment, a general silane compound or the like can be used. Next, the target silica can be obtained by removing the solvent from the hydrophobized silica sol, drying, and sieve. Moreover, you may perform the process by the above-mentioned sol-gel method again obtained in this way.

  The toner is not particularly limited, and is a known toner that contains a binder resin and a colorant as main components and, if necessary, a release agent. As the toner, it is preferable to use a polymerized toner prepared by a polymerization method. Due to the irregular shape of the toner, the fluidity may not be sufficient even with the addition of a fluidity aid, and due to the mechanical shearing force during use, the particles on the toner surface move to the toner recesses over time. When the fluidity is lowered or the fluidity aid is buried in the toner, developability, transferability, cleaning property, etc. are deteriorated. Further, when the toner collected by cleaning is returned to the developing machine and used again, the image quality is likely to further deteriorate. If the flow aid is further increased in order to prevent these, contamination, filming, scratches and the like on the photoreceptor are generated.

  For this reason, as a means for intentionally enabling control of the toner shape and the surface structure, a toner production method by an emulsion polymerization aggregation method has been proposed. These are generally prepared by dispersion of resin particles by a polymerization method such as emulsion polymerization, on the other hand, by preparing a colorant particle dispersion in which a colorant is dispersed in a solvent, and mixing these, heating, pH control, The above-mentioned resin particles and colorant are aggregated to a desired particle size by adding a flocculant, and then the aggregated particles are stabilized at a desired particle size, and then heated to a temperature above the glass transition point of the resin particles. The toner is made by fusing.

  The toner particles obtained by the emulsion polymerization agglomeration method have extremely superior characteristics (particularly a narrow particle size distribution) compared to toner particles obtained by other polymerization methods represented by the conventional suspension polymerization method. If it is used as a toner, high quality image quality can be obtained over a long period of time. In addition, since the toner is prepared by the emulsion polymerization aggregation method, the aggregated particles are heated and fused to a temperature higher than the glass transition point (Tg) of the resin particles. To toner in a spherical particle state, various shapes of toner can be produced. Therefore, in the electrophotographic system used, the shape can be selected in a range from a so-called potato shape to a spherical shape.

  Hereinafter, although an example and a comparative example are given and the present invention is explained more concretely in detail, the present invention is not limited to the following examples.

(Examples 1 and 2)
A charging roll and a charging roll cleaner were prepared as follows.
<Charging roll 1>
After adding 3 parts by mass of ionic conductive agent PEL-100 (manufactured by Nippon Carlit Co., Ltd.) to 100 parts by mass of epichlorohydrin rubber and sufficiently kneading it, after extrusion molding, φ6mm SUM-Ni shaft (nickel plating on sulfur free cutting steel) After being molded and vulcanized with a press molding machine, it is processed to a desired outer diameter by polishing, and an end outer diameter φ8.95 mm and a central outer diameter φ9.00 mm are obtained. It processed so that it might become. Thereafter, the conductive elastic roll surface was coated with the following composition and film thickness by a dip coating method.

Dispersion A obtained by dispersing the following mixture in a bead mill is applied by dip coating on the surface of the conductive elastic roll, and then heated and dried at 160 ° C. for 30 minutes to form a surface layer having a thickness of 5 μm. Roll 1 was obtained.
Polymer material (fluorine varnish): Zeffle GK-500 (Daikin Kogyo Co., Ltd.) 100 parts by mass Conductivity imparting material (antimony-doped tin oxide): SN-100P (Ishihara Sangyo Co., Ltd.) 40 parts by mass Curing agent: Coronate 2507 ( 40 parts by mass Solvent: 200 parts by mass of 2-butanone
350 parts by weight of butyl acetate

<Charging roll 2>
After adding 3 parts by mass of ionic conductive agent PEL-100 (manufactured by Nippon Carlit Co., Ltd.) to 100 parts by mass of epichlorohydrin rubber and sufficiently kneading it, after extrusion molding, φ6mm SUM-Ni shaft (nickel plating on sulfur free cutting steel) After being molded and vulcanized with a press molding machine, it is processed to a desired outer diameter by polishing, and an end outer diameter φ8.95 mm and a central outer diameter φ9.00 mm are obtained. It processed so that it might become. Thereafter, the conductive elastic roll surface was coated with the following composition and film thickness by a dip coating method.

Dispersion B obtained by dispersing the following materials in a bead mill was diluted with methyl ethyl ketone (MEK), dip-coated on the surface of the conductive elastic roll, and then dried by heating at 180 ° C. for 30 minutes, thickness 7 μm Thus, a charging roll 2 was obtained.
Polymer material (saturated copolymer polyester resin solution): Byron 30SS (manufactured by Toyobo Co., Ltd.) 100 parts by mass Curing agent (amino resin solution): Superbecamine G-821-60 (manufactured by Dainippon Ink & Chemicals, Inc.) 26. 3 parts by mass Conductive agent (carbon black): MONARCH1000 (manufactured by Cabot) 10 parts by mass

<Charging roll cleaner>
As a small piece member, spherical polystyrene foam beads (φ2 mm) were filled in a case made of ABS resin. The amount of beads to be filled is the amount that fills about 90% of the space between the charging roll and the inner wall of the case when the charging roll is attached and pressed against the photoconductor, and the small piece member is not fixed at a specific position. It became possible to move with. In addition, an outflow prevention plate was provided on the downstream side of the rotation of the charging roll.

  The charging rolls 1 and 2 and the charging roll cleaner produced as described above were each incorporated in a process cartridge for an image forming apparatus (DELL C3110cn) and attached to a DELL C3110cn. In use, the charging roll was positioned obliquely above the photoreceptor, and a charging roll cleaner was installed on the opposite side of the charging roll from the photoreceptor. The continuous printing test was performed under a normal temperature and humidity environment (23 ° C., 55% RH). The results are shown in Table 1. This result is a substitute characteristic of the amount of deposits on the surface of the charging roll when running 8000 sheets, a metal bearing with a width of 5 mm is pressed against the charging roll at 100 gf, and a voltage of 100 V (DC) is applied while rotating the charging roll at 5 rpm. The volume resistance (log Ω) of the charging roll was measured using a microammeter (Advantest R8340) in an environment of 22 ° C./55% RH (measured at 60 points / circumference, 3 Average value of the measurement in minutes). In addition, the numerical value shown in Table 1 is the volume resistance difference (including the increase in energization of the charging roll body) of the charging roll between the number of running sheets 0 and after running.

(Comparative Examples 1 and 2)
A cylindrical elastic layer with an outer diameter of φ8 mm was formed on a shaft plated with Ni on a φ4 mm SUM24L, using urethane resin, to prepare a cleaning roll. Evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

  From this result, in Examples 1 and 2, it was possible to obtain the same or less charging roll cleaning performance as compared with the conventional roll type cleaning rolls in Comparative Examples 1 and 2. Thus, an inexpensive charging roll cleaning device that does not inhibit the rotation of a small-diameter charging roll could be obtained.

(A) It is a schematic block diagram which shows an example of an image forming apparatus provided with the charging member cleaning apparatus which concerns on embodiment of this invention. FIG. 4B is an enlarged view of the periphery of the charging device and the image carrier in the image forming apparatus including the charging member cleaning device according to the embodiment of the invention. It is a schematic block diagram which shows the other example of an image forming apparatus provided with the charging member cleaning apparatus which concerns on embodiment of this invention. It is a schematic structure figure showing an example of a process cartridge concerning an embodiment of the present invention. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an embodiment of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Charging device, 3 Process cartridge, 5 Image forming apparatus, 10 Charging roll, 12 Charging roll cleaner, 14 Conductive core material, 16 Charging layer, 18 Small piece member, 20 Case, 22 Outflow prevention plate, 24 Stirring paddle, 26 Photosensitive drum, 52 Developing roll, 54 Transfer roll, 56 Cleaning blade, 58 Exposure device, 60 Image light, 62 Recording paper, 64Y, 64M, 64C, 64K Image forming unit, 66Y, 66M, 66C, 66K Developer, 68 Paper transport belt, 70 fixing device, 72 discharge roll, 74 discharge tray, 76 paper transport path, 78 transport roll.

Claims (5)

  A charging member cleaning apparatus comprising a movable small piece member that is not fixed at a specific position as a cleaning member for cleaning a surface of a charging member provided in an image forming apparatus. The charging member cleaning device according to claim 1,
The charging member cleaning device, wherein the small piece member has at least one of a spherical shape, a cylindrical shape, and a polygonal columnar shape. The charging member cleaning device according to claim 1 or 2,
The charging member cleaning device according to claim 1, wherein the small piece member includes at least one of resin, rubber, and inorganic material.   A process cartridge comprising: an image holding member; a charging member that charges a surface of the image holding member; and the charging member cleaning device according to claim 1.   An image carrier, a charging member that charges the surface of the image carrier, the charging member cleaning device according to claim 1, and a latent image that forms a latent image on the surface of the image carrier. An image forming apparatus comprising: an image forming unit; and a developing unit that develops a latent image formed on the surface of the image carrier with toner to form a toner image.

Images