JP2009217204A - Core material for charging member cleaner, charging member cleaner, process cartridge, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a core material of a charging member cleaner, capable of efficiently removing extraneous matters on a surface of a charging member, and accordingly capable of extending the service life of the charging member. <P>SOLUTION: In the core material for the charging member cleaner used for cleaning the surface of the charging member of an image forming apparatus while being kept in contact with the surface of the charging member, the area of a cross-section perpendicular to the lengthwise axial center is, at least in a cleaning area, smaller than the area of a circumcircle whose center is located at the center of the cross-section. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

  In recent years, a charging roll has been mainly used as a charging member of an image forming apparatus such as a printer or a copying machine. The charging roll has an advantage in that the amount of ozone generation is small compared to a charging device using a corona discharge phenomenon. However, the function of the charging roll may be deteriorated when toner, external additives, or the like adhere to the surface. Therefore, in recent years, a roll-shaped charging member cleaning member having a cleaning portion such as an elastic foam layer is frequently used as a means for achieving a longer life of the charging roll as a means for removing deposits attached to the surface of the charging roll. (For example, see Patent Document 1). This is a method in which the elastic foam layer of the charging member cleaning member is evenly applied to the circumferential direction of the charging roll.

JP 2006-330613 A

  The present invention includes a charging member cleaning member core, a charging member cleaning member, and a charging member cleaning member that can efficiently remove deposits on the surface of the charging member and extend the life of the charging member. A process cartridge and an image forming apparatus.

  The present invention provides a charging member cleaning member that contacts and cleans the surface of a charging member provided in an image forming apparatus. The charging member cleaning member core is smaller than the area of a circumscribed circle centering on the center.

  Moreover, it is preferable that the outer periphery of the cross section and the outer periphery of the circumscribed circle are in contact with each other at 1 point or more and 6 points or less in at least a cleaning region of the charging member cleaning member core material.

  In the charging member cleaning member core material, the ratio of the shortest distance from the center of the cross section to the outer periphery with respect to the radius of the circumscribed circle is preferably in the range of 40% to 95%.

  Moreover, this invention is a charging member cleaning member which has the said core material for charging member cleaning members, and the cleaning part formed in the outer periphery of the said core material.

  In the charging member cleaning member, it is preferable that the cleaning portion is a cylindrical elastic foam layer.

  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 member.

  The present invention also provides an image carrier, a charging member that charges the surface of the image carrier, the charging member cleaning member, 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, as compared with the case where the present configuration is not provided, the charge on the surface of the charging member can be efficiently removed, and the charging member capable of extending the life of the charging member. A core material for a member cleaning member can be provided.

  According to claim 2 of the present invention, it is possible to more efficiently remove the deposits on the surface of the charging member and to extend the life of the charging member as compared with the case where the present configuration is not provided. A core for a charging member cleaning member can be provided.

  According to the third aspect of the present invention, it is possible to more efficiently remove deposits on the surface of the charging member and to extend the life of the charging member as compared with the case where the present configuration is not provided. A core for a charging member cleaning member can be provided.

  According to claim 4 of the present invention, compared to the case where the present configuration is not provided, the deposit on the surface of the charging member can be efficiently removed, and the charging member capable of extending the life of the charging member. A member cleaning member can be provided.

  According to claim 5 of the present invention, it is possible to more effectively remove deposits on the surface of the charging member, and to extend the life of the charging member, compared to the case where this configuration is not provided. A charging member cleaning member can be provided.

  According to the sixth aspect of the present invention, it is possible to efficiently remove deposits on the surface of the charging member and to extend the life of the charging member as compared with the case where the present configuration is not provided. A process cartridge capable of obtaining good image quality can be provided.

  According to claim 7 of the present invention, it is possible to efficiently remove deposits on the surface of the charging member and to extend the life of the charging member as compared with the case where the present configuration is not provided. Thus, it is possible to provide an image forming apparatus capable of obtaining good image quality.

  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.

  FIG. 1 is a side view showing a schematic configuration of an example of a charging device using a charging member cleaning member having a core for a charging member cleaning member according to the present embodiment. FIG. 2 is a front view showing a schematic configuration of an example of the charging device according to the present embodiment. A charging device 1 shown in FIG. 1 is a charging member that charges the surface of an image carrier provided in an image forming apparatus, and is a cylindrical charging member that rotates about an axis. And a cleaning roll 12 which is a charging member cleaning member 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 cleaning roll 12 includes a core material 18 and a cylindrical elastic layer 20 that is a cleaning portion formed on the outer periphery of the core material 18.

  In the charging device 1, the charging roll 10 is placed on the surface of the photosensitive member 22 by an elastic member such as a coil spring 24 (see FIG. 2) installed at both ends of the conductive core member 14 with respect to the photosensitive member 22 that is an image holding member. Pressed to follow the photoreceptor 22. On the other hand, the cleaning roll 12 is held by a bearing 26 (see FIG. 2) at a bearing distance between the conductive core 14 of the charging roll 10 and the core 18 of the cleaning roll 12, and the cleaning roll 12 has a predetermined nip amount. Then, the charging roll 10 is driven. The charging roll 10 and the cleaning roll 12 may be driven by the photosensitive member 22 and the charging roll 10, respectively, or may be driven separately.

  In the charging member cleaning member core material according to this embodiment, at least in the cleaning region, the area of the cross section perpendicular to the longitudinal axis center is smaller than the area of the circumscribed circle centering on the center of the cross section. Examples of the core material are shown in FIGS. As shown in FIGS. 3 to 5, in the core material 18, the area of the cross section 28 perpendicular to the longitudinal axis center is smaller than the area of the circumscribed circle 32 centering on the center 30 of the cross section 28. As a result, the cleaning pressure by the cleaning roll 12 can be increased or decreased with respect to the circumferential direction of the charging roll 10, and the cleaning performance is improved.

  The cross section of the conventional core material has a circular shape, and the cross section of the elastic layer is also circular. In this case, since the cleaning roll and the charging roll are fixed at a constant distance and the thickness of the elastic layer is constant, only a constant force is applied to the circumferential direction of the charging roll when the cleaning roll is rotated. It is almost impossible to increase or decrease the pressure. For this reason, removal of deposits on the surface of the charging roll is not sufficient, and the charging roll is contaminated during long-term use, resulting in poor charging and poor image quality. In the present embodiment, by making the cross section of the core member 18 a non-circular shape so that the cleaning pressure can be increased or decreased, the cleaning pressure can be varied to improve the cleaning performance.

  In addition, it may be possible to increase or decrease the cleaning pressure by cutting the outer surface of the cylindrical elastic layer or attaching a sheet, but the cleaning pressure is too strong and the charging roll vibrates. Will be transmitted and uneven charging will occur.

  According to the charging member cleaning member having the non-circular core 18, it is possible to efficiently remove deposits such as toner and external additives on the surface of the charging roll 10, and almost to the surface of the photoreceptor 22. Uniform charging is performed, the occurrence of defects due to poor charging on the image quality is suppressed, and image quality defects can be prevented. Further, the life of the charging member can be extended.

  The shape of the cross section 28 of the core material 18 is not particularly limited as long as the area of the cross section 28 is smaller than the area of the circumscribed circle 32. That is, the shape of the cross section 28 may be any shape as long as it is not circular (having a constant radius). Examples of the shape of the cross section 28 include a polygon such as a triangle, a quadrangle, a pentagon, and a hexagon, an ellipse, and a star.

  Here, the cleaning region refers to a region where the charging layer 16 of the charging roll 10 and the elastic layer 20 of the cleaning roll 12 are in contact with each other.

  In the present embodiment, it is preferable that at least in the cleaning region, the outer periphery of the cross section 28 and the outer periphery of the circumscribed circle 32 are in contact with each other at 1 point or more and 6 points or less. If the outer periphery of the cross section 28 and the outer periphery of the circumscribed circle 32 are in contact with each other in excess of six points, it is difficult to increase or decrease the cleaning pressure, and the cleaning effect may be reduced.

  In the example in which the cross section 28 in FIG. 3 is elliptical, the outer periphery of the cross section 28 and the outer periphery of the circumscribed circle 32 are in contact at two points. In the example in which the cross section 28 in FIG. In the example where the cross section 28 in FIG. 5 is a star shape, the outer periphery of the cross section 28 and the outer periphery of the circumscribed circle 32 are in contact at four points.

  The ratio of the shortest distance Q from the center 30 of the cross-section 28 to the outer periphery with respect to the radius R of the circumscribed circle 32 ((Q / R) × 100 [%]) is preferably in the range of 40% to 95%. The range of 50% to 80% is more preferable from the viewpoint of the cleaning effect. If the ratio is less than 40%, the cleaning pressure may be too strong and weak, and vibration may be transmitted to the charging roll 10 to cause uneven charging. If the ratio exceeds 95%, it is difficult to increase or decrease the cleaning pressure, and the cleaning effect may be reduced.

  In the present embodiment, the average nip amount between the charging roll 10 and the cleaning roll 12 is usually in the range of 0.2 mm to 3 mm. If the average nip amount is less than 0.2 mm, the film may not be driven and a filming mechanism may be required. If the average nip amount exceeds 3 mm, the brake action may be activated and not driven. The average nip amount is a value obtained from the interaxial distance between the center of the conductive core 14 of the charging roll 10 and the center of the core 18 of the cleaning roll 12 and the radii of both members. As an example, if the distance between the axes is 10 mm, the radius of the charging roll 10 is 7 mm, and the radius of the cleaning roll 12 is 5 mm, the average nip amount is 2 mm.

  As the material of the core 18 of the cleaning roll 12, metals such as free-cutting steel and stainless steel, resin, etc. are used, and the material and surface treatment method are appropriately selected according to applications such as slidability and have conductivity. The material not to be processed may be processed by a general process such as a plating process and subjected to a conductive process, or may be used as it is. Further, since the charging roll 10 is brought into contact with the charging roll 10 with an appropriate nip pressure via the elastic layer 20, a material having a strength that does not bend at the time of nip or a shaft diameter having sufficient rigidity with respect to the shaft length may be selected. preferable.

  The elastic layer 20 is preferably a cylindrical elastic foam layer configured to include a foam having a porous three-dimensional structure. By using the foam, it is easy to increase or decrease the cleaning pressure, but vibration is hardly transmitted to the charging roll 10 and uneven charging is less likely to occur. Examples of foams include foamable resins such as polyurethane, polyethylene, polyamide or polypropylene, nitrile rubber (NBR), ethylene-propylene-diene terpolymer rubber (EPDM), styrene-butadiene rubber (SBR), silicone rubber, and the like. Is selected from those made of. The elastic layer 20 efficiently cleans foreign matters by driven sliding friction with the charging roll 10, and at the same time, the surface of the charging roll 10 is not scratched by rubbing of the elastic layer 20. In order to prevent the occurrence of cracks, at least one of polyurethane, nitrile rubber, ethylene-propylene-diene terpolymer rubber, styrene-butadiene rubber, and silicone rubber, which is resistant to tearing and pulling, is more preferably used. Is particularly preferably used.

  The polyurethane is not particularly limited, and polyols such as polyester polyol, polyether polyester and acrylic polyol, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4-diphenylmethane diisocyanate, tolidine diisocyanate, It only needs to be accompanied by a reaction of an isocyanate such as 1,6-hexamethylene diisocyanate, and a chain extender such as 1,4-butanediol or trimethylolpropane is preferably mixed. In general, foaming is performed using a foaming agent such as water, azodicarbonamide, azo compounds such as azobisisobutyronitrile. Furthermore, you may add auxiliary agents, such as a foaming aid, a foam stabilizer, a catalyst, as needed.

  The charging member cleaning member according to the present embodiment is obtained by, for example, integrating the foam thus produced into the core member 18 as shown in FIGS. Can be processed.

  As the cleaning portion formed on the outer periphery of the core material 18, a brush method using a brush-like material including fibers extending from the core material in addition to the cylindrical elastic layer 20 may be used. In the case of the brush system, it is difficult to increase or decrease the cleaning pressure. Therefore, a roll system using a cylindrical elastic layer is preferable.

  Next, 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 5 mm to 15 mm, more preferably 7 mm to 14 mm, and the thickness of the charging layer 16 is 1.5 mm to 4 mm. When the diameter exceeds 15 mm, the number of times of contact with foreign matter per place on the peripheral surface is reduced, and the number of discharges is reduced. Therefore, although it is excellent in long-term stability against dirt and charging performance, it is disadvantageous from the viewpoint of miniaturization. If the diameter is less than 8 mm, the image forming apparatus can be reduced in size, which is advantageous. However, the number of times of contact with foreign matter per peripheral surface increases and the number of discharges increases, which is disadvantageous for long-term stability. Become.

  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 And fine powders such as various conductive metal oxides such as tin oxide-antimony oxide solid solution and tin oxide-indium oxide solid solution; 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, and the material of the surface layer may be any of resin, rubber, etc. and is particularly limited. is not. 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. Further, insulating particles such as alumina and silica are added to give unevenness to the surface of the charging roll 10, thereby reducing the burden at the time of rubbing against the photosensitive member 22, so that the charging roll 10 and the photosensitive member 22 are mutually connected. It is also possible to improve the wear resistance.

<Process cartridge>
The 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 member. 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. 6, and the configuration will be described. The process cartridge 3 includes a photosensitive member (electrophotographic photosensitive member) 24 as an image holding member on which an electrostatic latent image is formed, a cylindrical charging roll 10 as a charging member that contacts and charges the surface of the photosensitive member 22, A toner image is formed by attaching toner to a cleaning roller 12 as a charging member cleaning member that contacts the charging roller 10 and cleans the surface of the charging roller 10, and an electrostatic latent image formed on the surface of the photosensitive member 22. A developing roll 52 as a developing unit and a cleaning blade 56 as an image carrier cleaning unit that contacts the surface of the photoconductor 22 and cleans toner remaining on the photoconductor 22 after transfer are integrally supported. It is detachable from the image forming apparatus. When mounted on the image forming apparatus, an exposure device 58 as a latent image forming means for forming an electrostatic latent image on the surface of the photosensitive member 22 around the photosensitive member 22 by the charging roll 10, laser light, or reflected light of the document. Further, a developing roll 52, a transfer roll 54 as a transfer means for transferring a toner image on the surface of the photosensitive member 22 to a recording sheet 62 as a transfer target, and a cleaning blade 56 are arranged in this order. As described above, in the cleaning roll 12, at least in the cleaning region, the area of the cross section perpendicular to the axial center in the longitudinal direction is smaller than the area of the circumscribed circle centering on the center of the cross section. In FIG. 6, the description of functional units normally required in other electrophotographic processes is omitted.

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

  First, the surface of the photoconductor 22 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 photoconductor 22. At this time, the photosensitive member 22 and the charging roll 10 rotate in the directions of arrows in FIG. After charging, when image light (exposure) 60 corresponding to image information is irradiated onto the surface of the photosensitive member 22 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 the recorded image, that is, an electrostatic latent image is formed on the surface of the photoconductor 22 by the 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 with the toner image on the surface of the photoreceptor 22. After the toner image is transferred to the recording paper 62 by the transfer roll 54, the recording paper 62 is separated from the photoreceptor 22. 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 cleaning roll 12 is installed on the charging roll 10 provided in the process cartridge 3, and a voltage is applied to the bearing 26 from a high-voltage power supply, and the cleaning roll 12 has the same polarity as the charging roll 10, thereby removing foreign matter. Since it can move without accumulating on the surfaces of the cleaning roll 12 and the charging roll 10 and can be collected by the cleaning blade 56, foreign matters such as toner adhering to the charging member can be stably removed over a long period of time. Further, by applying a strength to the cleaning pressure of the cleaning roll 12, it is possible to efficiently remove deposits that adhere and adhere to the surface of the charging roll 10. For this reason, dirt is not accumulated on the charging roll 10 over a long period of time, and the uniform charging performance is excellent, and stable charging performance can be maintained.

  The photoreceptor 22 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. Further, a protective layer may be provided on 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 that can expose a light source such as semiconductor laser light, LED light, and liquid crystal shutter light on the surface of the photosensitive member 22 in a desired image-like manner, and optical such as an LED array. System equipment.

  The developing unit has a function of developing the electrostatic latent image formed on the photosensitive member 22 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 functions, and can be appropriately selected according to the purpose. Even if the toner layer is in contact with the photosensitive member 22, it is not in contact with the developing device. It may be. For example, as shown in FIG. 6, a developer having a function of attaching toner for developing an electrostatic charge image to the photoreceptor 22 using the developing roll 52, or a development having a function of attaching the toner to the photoreceptor 22 using a brush or the like. And a known developing device.

  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. 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>
The 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 member, 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. 7 shows a schematic configuration of an example of the image forming apparatus according to the present embodiment, and the configuration will be described. The image forming apparatus 5 includes a photosensitive member 22 as an image carrier on which an electrostatic latent image is formed, a cylindrical charging roll 10 as a charging member that contacts and charges the surface of the photosensitive member 22, and a contact with the charging roll 10. Then, a cleaning roll 12 as a charging member cleaning member for cleaning the surface of the charging roll 10 and exposure as a latent image forming means for forming an electrostatic latent image on the surface of the photosensitive member 22 by laser light or reflected light of the original. The apparatus 58, a developing roll 52 as a developing unit that forms a toner image by attaching toner to the electrostatic latent image formed on the surface of the photosensitive member 22, and the toner image on the surface of the photosensitive member 22 are transferred members. A transfer roll 54 serving as a transfer unit that performs transfer processing on the recording paper 62, and a cleaner as an image carrier cleaning unit that contacts the surface of the photoconductor 22 and cleans toner remaining on the photoconductor 22 after transfer. And a Guburedo 56. In the image forming apparatus 5, a charging roll 10, an exposure device 58, a developing roll 52, a transfer roll 54, and a cleaning blade 56 are arranged in this order around the photoreceptor 22. As described above, in the cleaning roll 12, at least in the cleaning region, the area of the cross section perpendicular to the axial center in the longitudinal direction is smaller than the area of the circumscribed circle centering on the center of the cross section. In FIG. 7, functional units normally required in other electrophotographic processes are not shown. Each configuration of the image forming apparatus 5 and operations during image formation are the same as those of the process cartridge 3 of FIG.

The charging roll 10 provided in the image forming apparatus 5 is provided with a cleaning roll 12, a voltage is applied to the bearing 26 from the high-voltage power supply 63, and the cleaning roll 12 has the same polarity as the charging roll 10, Since foreign matters can be transferred without accumulating on the surfaces of the cleaning roll 12 and the charging roll 10 and can be collected by the cleaning blade 56, foreign matters such as toner adhering to the charging member can be stably removed over a long period of time. . Further, by applying a strength to the cleaning pressure of the cleaning roll 12, it is possible to efficiently remove deposits that adhere and adhere to the surface of the charging roll 10. For this reason, dirt is not accumulated on the charging roll 10 over a long period of time, and the uniform charging performance is excellent, and stable charging performance can be maintained.

  FIG. 8 shows a tandem full-color image forming apparatus 7 as another example of the image forming apparatus according to the present embodiment. In the image forming apparatus 7, an image forming unit having a photoreceptor 22 and a developing device is arranged for each color of yellow (64Y), magenta (64M), cyan (64C), and black (64K). ing. As the photoconductor 22, for example, a conductive cylinder whose surface is coated with a photoconductor layer including an organic photoconductor is used. The photoconductor 22 is rotated by a motor (not shown) in the arrow X direction at a process speed of, for example, about 150 mm / sec. Driven.

  The surface of the photosensitive member 22 is charged to a predetermined potential by the charging roll 10 disposed in contact with the photosensitive member 22, and then subjected to image exposure by a laser beam emitted from the exposure device 58, and according to image information. An electrostatic latent image is formed.

  The electrostatic latent image formed on the photosensitive member 22 is developed by yellow (Y), magenta (M), cyan (C), and black (K) developing devices 66Y, 66M, 66C, and 66K. A toner image of a predetermined color is obtained.

  For example, when a full-color image is formed, charging, exposure, and development processes are performed on the surface of the photoreceptor 22 of each color in 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 photoreceptor 22 of each color.

  The yellow (Y), magenta (M), cyan (C), and black (K) toner images sequentially formed on the photoconductor 22 are sequentially applied to the recording paper 62 held on the paper transport belt 68. After the transfer, the recording paper 62 onto which the toner image has been transferred is conveyed to the fixing device 70, and heated and pressed by the fixing device 70 to fix the toner image 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 part of the image forming apparatus 7 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.

  Note that the surface of the photoconductor 22 after the toner image transfer process is completed is made up of residual toner, paper dust, and the like by a cleaning blade 56 disposed obliquely above the photoconductor 22 every time the photoconductor 22 rotates once. Is removed, and is prepared for the next image forming step.

  A cleaning roll 12 is installed on the charging roll 10 provided in the image forming apparatus 7. The cleaning roll 12 is supported on its outer peripheral portion so as to be rotatable by a support member or a housing (not shown). A voltage is applied to the bearing from the high-voltage power source, and the cleaning roll 12 has the same polarity as the charging roll 10, so that foreign matter can be transferred without accumulating on the surfaces of the cleaning roll 12 and the charging roll 10. Since it can be collected, foreign matters such as toner adhering to the charging member can be stably removed over a long period of time. For this reason, dirt is not accumulated on the charging roll 10 over a long period of time, and the uniform charging performance is excellent, and stable charging performance can be maintained.

  The configuration other than the charging device of the image forming apparatus using the charging device 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 member, for example, a charging unit, a latent image forming unit, a developing unit, a transfer unit, an image carrier cleaning unit, a neutralizing unit, a paper feeding unit, a conveying unit, an image control unit, etc. According to the above, conventionally known ones are appropriately employed. These configurations are not particularly limited in the present embodiment.

  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.

Example 1
<Preparation of cleaning roll>
A core material having a cross-sectional shape of an ellipse (the outer periphery of the cross section and the outer periphery of the circumscribed circle are in contact at two points) as shown in FIG. The ratio of the shortest distance from the center of the cross section to the outer periphery with respect to the radius of the circumscribed circle was 80%. A cylindrical elastic foam layer having an outer diameter of 8 mm was formed thereon using a urethane resin, and a cleaning roll was produced.

<Charging roll>
The charging roll used in DocuPrint C1100 (Fuji Xerox Co., Ltd.) was used.

<Evaluation>
The cleaning roll and the charging roll obtained above were set to 0.8 mm bite (nip amount) to obtain an integral holding structure, thereby obtaining a charging unit.

  The cartridge having the contact charging unit thus obtained is mounted on the image forming apparatus DocuPrint C1100 (manufactured by Fuji Xerox Co., Ltd.) at a nip load of 800 gf (7.85 N) with low temperature and low humidity (10 ° C., A printing test was performed to print 100,000 sheets of A4 paper at 20% RH), and image quality and charging roll contamination were evaluated as follows. The results are shown in Table 1.

[Image quality evaluation]
The following criteria were used for visual evaluation.
○: Good △: Slightly uneven density, no problem in practical use ×: Uneven density

[Evaluation of dirt on charging roll]
The contamination of the charging roll was visually evaluated.
◎: No dirt ○: Some dirt ×: Overall dirt

(Example 2)
A core material having a cross-sectional shape of a regular triangle (the outer periphery of the cross section and the outer periphery of the circumscribed circle are in contact with each other at three points) as shown in FIG. The ratio of the shortest distance from the center of the cross section to the outer periphery with respect to the radius of the circumscribed circle was 50%. A cylindrical elastic foam layer having an outer diameter of φ12 mm was formed thereon using urethane resin to produce a cleaning roll. Evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 3)
A core material with a circumscribed circle of φ4 mm having a star shape (the outer periphery of the cross section and the outer periphery of the circumscribed circle are in contact at four points) as shown in FIG. 5 was made of aluminum. The ratio of the shortest distance from the center of the cross section to the outer periphery with respect to the radius of the circumscribed circle was 60%. A cylindrical elastic foam layer having an outer diameter of φ12 mm was formed thereon using urethane resin to produce a cleaning roll. Evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

Example 4
A core material having an oval cross-sectional shape as shown in FIG. 3 (where the outer periphery of the cross section and the outer periphery of the circumscribed circle are in contact at two points) with a circumscribed circle of φ4 mm was made of aluminum. The ratio of the shortest distance from the center of the cross section to the outer periphery with respect to the radius of the circumscribed circle was 98%. A cylindrical elastic foam layer having an outer diameter of φ12 mm was formed thereon using urethane resin to produce a cleaning roll. Evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 5)
A core material having an oval cross-sectional shape as shown in FIG. 3 (where the outer periphery of the cross section and the outer periphery of the circumscribed circle are in contact at two points) with a circumscribed circle of φ4 mm was made of aluminum. The ratio of the shortest distance from the center of the cross section to the outer periphery with respect to the radius of the circumscribed circle was 37%. A cylindrical elastic foam layer having an outer diameter of φ12 mm was formed thereon using urethane resin to produce a cleaning roll. Evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 1)
A core material having a circular cross section and a diameter of 4 mm was made of aluminum. A cylindrical elastic foam layer having an outer diameter of φ12 mm was formed thereon using urethane resin to produce a cleaning roll. Evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

  In Examples 1 to 5, the charging roll was free of contamination that would cause charging failure, and good image quality without image quality failure was obtained. As described above, the deposit on the surface of the charging roll can be efficiently removed, and the life of the charging roll can be extended. However, in Comparative Example 1, unevenness in density was caused in the image quality due to unevenness in dirt that caused charging failure.

It is a side view showing a schematic structure of an example of a charging device using a charging member cleaning member according to an embodiment of the present invention. It is a front view which shows schematic structure of an example of the charging device using the charging member cleaning member which concerns on embodiment of this invention. It is the schematic which shows an example of the core material for charging member cleaning members which concerns on embodiment of this invention. It is the schematic which shows the other example of the core material for charging member cleaning members which concerns on embodiment of this invention. It is the schematic which shows the other example of the core material for charging member cleaning members 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. It is a schematic block diagram which shows the other example of the image forming apparatus which concerns on embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Charging device, 3 Process cartridge, 5, 7 Image forming apparatus, 10 Charging roll, 12 Cleaning roll, 14 Conductive core material, 16 Charging layer, 18 Core material, 20 Elastic layer, 22 Photoconductor, 24 Coil spring, 26 Bearing 28 cross section, 30 center, 32 circumscribed circle, 52 developing roll, 54 transfer roll, 56 cleaning blade, 58 exposure device, 60 image light, 62 recording paper, 63 high voltage power supply, 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 (7)

For use in a charging member cleaning member for cleaning in contact with the surface of the charging member provided in the image forming apparatus,
A charging member cleaning member core material, wherein an area of a cross section perpendicular to an axial center in a longitudinal direction is smaller than an area of a circumscribed circle centering on the center of the cross section at least in a cleaning region. The charging member cleaning member core material according to claim 1,
At least in the cleaning region, the outer periphery of the cross section and the outer periphery of the circumscribed circle are in contact with each other at 1 point or more and 6 points or less. The charging member cleaning member core according to claim 1 or 2,
A core member for a charging member cleaning member, wherein a ratio of a shortest distance from a center of the cross section to an outer periphery with respect to a radius of the circumscribed circle is in a range of 40% to 95%.   A charging member cleaning member comprising the core member for a charging member cleaning member according to claim 1 and a cleaning portion formed on an outer periphery of the core member. The charging member cleaning member according to claim 4,
The charging member cleaning member, wherein the cleaning part is a cylindrical elastic foam layer.   A process cartridge comprising: an image holding member; a charging member that charges a surface of the image holding member; and a charging member cleaning member according to claim 4.   An image carrier, a charging member that charges the surface of the image carrier, the charging member cleaning member according to claim 4 or 5, and 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 the surface of the image carrier with toner to form a toner image.

Images