JP2009086441A - Charging device, process cartridge and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charging device, capable of stably removing foreign matter such as a toner stuck to a charging member over a long period. <P>SOLUTION: The charging device includes a cylindrical charging member, and a charging member cleaning member for cleaning a surface of the charging member while following the rotation of the charging member in contact therewith, which includes a core material and a cylindrical elastic layer formed on the outer circumference of the core material, wherein the concentricity of the core material and the cylindrical elastic layer is within the range of 1/5 and 1/2 of the average nip quantity of the charging member and the charging member cleaning member. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

  In recent years, image forming apparatuses such as printers and copiers have been widely used, and technologies relating to various elements constituting such image forming apparatuses have also been widely used. Among image forming apparatuses that employ an electrophotographic system, a photosensitive member such as a photosensitive drum is charged by using a charging device, and an electrostatic latent image having a different potential from the surroundings is formed on the charged photosensitive member. A pattern to be printed is often formed by forming an image. The electrostatic latent image formed in this way is developed with toner, and finally transferred onto a transfer medium.

  The charging device is a device that plays an important role of charging the photoconductor. It is a contact charging type charging device that directly contacts the photoconductor to charge the photoconductor, and the vicinity of the photoconductor without contacting the photoconductor. The charging device is roughly classified into two types, that is, a non-contact charging device that charges the photosensitive member by corona discharge or the like. In recent years, there has been an increase in charging devices that employ a contact charging method that generates less chemical substances such as ozone and nitrogen oxides than non-contact charging devices.

  The charging device of the contact charging system is provided with a charging member such as a cylindrical charging roll for charging the photosensitive member by directly contacting the photosensitive member. When the photosensitive member is charged, toner on the photosensitive member or an external additive of the toner may adhere to the charging member. For this reason, a contact charging type charging device is usually provided with a mechanism for cleaning the surface of the charging member.

  As a method for cleaning the surface of the charging member, there is a method in which a rubber blade, a pad, or the like is pressed against the surface of the charging member to scrape off deposits. Since the charging member may be worn if a rubber blade or pad is always pressed against the surface of the charging member, the charging member surface is cleaned while suppressing the influence on the charging member by intermittently pressing. Is also known. In addition, there has been proposed a method of cleaning the surface of the charging member with a cleaning roll that is rotated in contact with the rotating charging roll (see, for example, Patent Document 1 or 2).

JP-A-2-272594 JP-A-8-62948

  The present invention is a charging device that can stably remove foreign matters such as toner adhering to a charging member over a long period of time, a process cartridge including the charging device, and an image forming apparatus.

  The present invention includes a cylindrical charging member, and a core material and a cylindrical elastic layer formed on the outer periphery of the core material for cleaning the surface of the charging member while rotating in contact with the charging member. A charging member cleaning member, and a coaxial degree of the core material and the cylindrical elastic layer is in a range of 1/5 to 1/2 of an average nip amount between the charging member and the charging member cleaning member. Is a charging device.

  In the charging device, the straightness with the longitudinal end of the cylindrical elastic layer of the charging member cleaning member as a datum is 1/5 or more of the average nip amount between the charging member and the charging member cleaning member. A range of less than 2 is preferred.

  Further, in the charging device, a thickness difference in a circumferential direction of the cylindrical elastic layer of the charging member cleaning member is in a range of 2/5 to 1 of an average nip amount between the charging member and the charging member cleaning member. Preferably there is.

  The charging device preferably includes a bearing mechanism that holds the charging member and the core member of the charging member cleaning member at a constant displacement.

  In the charging device, it is preferable that the cylindrical elastic layer is formed of a porous foam having an open cell structure.

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

  The present invention also provides an image carrier, the charging device that charges the surface of the image carrier, a latent image forming unit that forms a latent image on the surface of the image carrier, and a surface of the image carrier. Developing means for developing the formed latent image with toner to form a toner image, transfer means for transferring the toner image formed on the surface of the image holding member to the transfer target, and the image holding member after transfer And an image carrier cleaning means for cleaning the surface of the image forming apparatus.

  According to the first aspect of the present invention, compared to the case where the coaxiality of the core member of the charging member cleaning member and the cylindrical elastic layer is out of this range, foreign matters such as toner adhering to the charging member can be stabilized for a long time. Can be removed.

  According to the second aspect of the present invention, foreign matters such as toner adhering to the charging member can be stably removed over a long period of time as compared with the case where the straightness of the charging member cleaning member is outside this range.

  According to claim 3 of the present invention, compared to the case where the thickness difference in the circumferential direction of the cylindrical elastic layer of the charging member cleaning member is out of this range, foreign matters such as toner adhering to the charging member are stable over a long period of time. Can be removed.

  According to the fourth aspect of the present invention, compared to a case where there is no bearing mechanism for holding the charging member and the core member of the charging member cleaning member at a constant displacement, foreign matters such as toner adhering to the charging member are kept for a long time. Can be removed more stably.

  According to claim 5 of the present invention, compared to a case where the cylindrical elastic layer is not composed of a porous foam having an open cell structure, foreign matters such as toner adhering to the charging member are more stable over a long period of time. Can be removed.

  According to claim 6 of the present invention, it is possible to provide a process cartridge capable of stably removing foreign matters such as toner adhering to the charging member over a long period of time as compared with the case where the present configuration is not provided. Is possible.

  According to the seventh aspect of the present invention, compared to the case where the present configuration is not provided, foreign matters such as toner adhering to the charging member can be stably removed over a long period of time, and a stable image over a long period of time. An image forming apparatus capable of being formed can be provided.

  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. 1 is a schematic view of an end portion of a charging device according to an embodiment of the present invention. The charging device 1 includes a rotating cylindrical charging member 10 and a charging member cleaning member 12 for cleaning the surface of the charging member 10 while rotating in contact with the charging member 10. The charging member 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 member cleaning member 12 includes a core member 18 and a cylindrical elastic layer 20 formed on the outer periphery of the core member 18. The conductive core material 14 of the charging member 10 and the core material 18 of the charging member cleaning member 12 are held by a conductive bearing 22. In addition, a voltage is applied to the charging member 10 by the high voltage power supply 24.

  In the charging device 1 according to the present embodiment, the coaxiality between the core member 18 of the charging member cleaning member 12 and the cylindrical elastic layer 20 is 1 / of the average nip amount between the charging member 12 and the charging member cleaning member 18. It is in the range of 5 or more and 1/2 or less, and preferably in the range of 1/5 or more and 1/4 or less. When the coaxiality between the core material 18 and the cylindrical elastic layer 20 is less than 1/5 or more than 1/2, foreign matters such as toner adhering to the charging member 10 can be stably removed over a long period of time. Can not.

  In the present embodiment, the coaxiality between the core member 18 and the cylindrical elastic layer 20 is a value obtained by measuring the coaxiality with a shaft end portion as a datum, using a shape measuring device (model 52B manufactured by Acceltech).

  In order to set the coaxiality of the core material and the cylindrical elastic layer within the above range, for example, the straightness with the longitudinal end portion of the cylindrical elastic layer of the charging member cleaning member as the datum is set as the charging member and the charging member cleaning member. Or the difference in thickness in the circumferential direction of the cylindrical elastic layer of the charging member cleaning member is the difference between the charging member and the charging member cleaning member. And a method of setting the average nip amount in the range of 2/5 to 1 inclusive. Moreover, you may combine these methods.

  Any method may be used as long as the coaxiality between the core material and the cylindrical elastic layer is in the above range, but from the viewpoint of ease of manufacture, the difference in thickness in the circumferential direction of the cylindrical elastic layer is calculated as the average thickness. A method in which the nip amount is in the range of 2/5 to 1 is preferable.

  An example of the former method is shown in FIG. FIG. 2 is a sectional view along the axial direction of the charging member cleaning member 12. The cylindrical elastic layer 20 and the core member 18 are bent as shown in FIG. At this time, the maximum straightness with the longitudinal end portion of the cylindrical elastic layer 20 of the charging member cleaning member 12 as a datum is 1 / the average nip amount between the charging member 10 and the charging member cleaning member 12 in FIG. The range is preferably 5 or more and 1/2 or less, and more preferably 1/5 or more and 1/4 or less. When the maximum value of the straightness is less than 1/5 of the average nip amount between the charging member 10 and the charging member cleaning member 12, or when it exceeds 1/2, foreign matters such as toner adhering to the charging member 10 are removed for a long time. In some cases, it cannot be stably removed.

  Further, in the charging member cleaning member 12, the position where the straightness is maximized is not particularly limited. However, since the vicinity of the center of the charging member 10 is usually easily contaminated, the center in the longitudinal direction of the cylindrical elastic layer 20 is a datum. It is preferable that the maximum is in the vicinity of the portion (for example, within the range of 40 to 60% of the length in the longitudinal direction of the cylindrical elastic layer 20 from the central portion in the longitudinal direction of the cylindrical elastic layer 20).

  This straightness is formed, for example, by polishing the cylindrical elastic layer 20 with a cylindrical polishing machine or the like and then pressing it with a constant load using a straightness forming mold 26 as shown in FIG. A U-shaped groove 28 is dug in the bending forming mold 26, the charging member cleaning members 12 are mounted one by one, and the operating-side mold 30 is pushed into the charging member cleaning member 12 by pressing. It becomes possible to give straightness. In addition to this method, the straightness forming means for forming the straightness is not particularly limited, such as means for bending the charging member cleaning member by applying a load from the slaft direction, and means for obtaining the required straightness is appropriately employed. If the straightness is ½ or less of the average nip amount between the charging member 10 and the charging member cleaning member 12, a sufficient nip difference when driven by the charging member 10 is obtained, and stable foreign matter removal is not affected by the environment. Performance is obtained.

  Here, the straightness with the end portion in the longitudinal direction of the cylindrical elastic layer of the charging member cleaning member 12 as a datum means a value measured by the following method.

  For measurement, a laser measuring instrument manufactured by Keyence is used. Both ends of the core material 18 of the charging member cleaning member 12 are set on the roller of the measuring instrument, the distance between each of the both ends of the cylindrical elastic layer 20 and the knife edge of the measuring instrument is measured, and the reference points A and B are calculated. The reference points A and B were connected for calculation and used as a reference line, and the difference between the cylindrical elastic layer outer diameter portion and the reference line was defined as straightness.

  An example of the latter method is shown in FIG. FIG. 3 is a cross-sectional view perpendicular to the axis of the charging member cleaning member 12. The shaft core of the cylindrical elastic layer 20 and the shaft core of the core material 18 are formed in an eccentric state as shown in FIG. At this time, the circumferential thickness difference of the cylindrical elastic layer 20 of the charging member cleaning member 12 is in the range of 2/5 to 1 of the average nip amount between the charging member 10 and the charging member cleaning member 12 of FIG. It is preferable that it is in the range of 2/5 or more and 1/2 or less. When the eccentricity is less than 2/5 of the average nip amount between the charging member 10 and the charging member cleaning member 12 or exceeds 1, the foreign matter such as toner adhering to the charging member 10 is stably removed over a long period of time. Sometimes it cannot be removed.

  This thickness difference is formed, for example, by shifting the rotating shaft core of the polishing machine and the chuck shaft core of the polishing machine that holds the core 18 when polishing the cylindrical elastic layer 20 with a cylindrical polishing machine or the like. If the thickness difference is equal to or less than the average nip amount between the charging member 10 and the charging member cleaning member 12, a sufficient nip difference is obtained when the charging member 10 is driven, and stable foreign matter removal is not affected by the environment. Performance is obtained.

  Here, the thickness difference between the core member 18 of the charging member cleaning member 12 and the cylindrical elastic layer 20 is a value measured by the following method.

  The measurement is not particularly limited as long as it is a measuring instrument capable of measuring the thickness on the core material, and methods such as a caliper, a micrometer, a laser measuring instrument, and a projector are used.

  In the present embodiment, the average nip amount between the charging member 10 and the charging member cleaning member 12 is the distance between the center of the conductive core 14 of the charging member 10 and the center of the core 18 of the charging member cleaning member 12. It is a value obtained from the distance and the radius of both members. For example, if the inter-axis distance A is 11 mm, the radius r1 of the charging member 10 is 7 mm, and the radius r2 of the charging member cleaning member 12 is 5 mm, the average nip amount is (r1 + r2) −A = 1 mm. The average nip amount is usually in the range of 0.2 mm to 1.0 mm. If the average nip amount is less than 0.2 mm, sufficient dirt removal may not be possible, and if it exceeds 1.0 mm, rotation failure may occur.

  In the contact charging type charging device, the cylindrical charging member is in contact with the image holding member with a substantially constant load, and the surface of the image holding member is charged while the charging member rotates with the rotating image holding member. At this time, the surface of the charging member is contaminated by foreign matters such as toner remaining on the image holding member moving to the charging member. The charging member cleaning member for removing contaminants on the surface of the charging member is normally brought into contact with the charging member with a substantially constant nip amount. However, if the nip amount is small, the desired removal performance cannot be obtained. If it is large, contaminants are rubbed and fixed on the surface of the charging member, and an optimum nip amount design is required. Contaminants adhering to the surface of the charging member have a large variation in adhesion depending on the environment such as humidity, and the charging member and the charging member cleaning member may not be able to sufficiently remove dirt with a constant nip amount. In such a charging device, since the axial center of the core material and the cylindrical elastic layer is deviated, the nip amount of the charging member and the driven charging member cleaning member has a width, and stable foreign matter even if the environment changes Removal performance can be obtained.

  For example, in the charging device according to this embodiment, since the cylindrical elastic layer of the charging member cleaning member has a bend, the nip amount of the charging member cleaning member driven by the charging member has a difference in the circumferential direction by the amount of the bend. Thus, it is possible to obtain stable foreign matter removal performance even when the environment changes. Further, in the charging device according to the present embodiment, since the core member of the charging member cleaning member and the cylindrical elastic layer are decentered by the thickness difference, the nip amount of the charging member cleaning member driven by the charging member is different from the thickness difference. As a result of the rotation and rotation, the nip amount has a width, and stable foreign matter removal performance can be obtained even if the environment changes. Accordingly, it is possible to prevent the adhesion of foreign matters such as toner adhering to the charging member regardless of the environment.

  The maximum value of straightness with the longitudinal end of the cylindrical elastic layer of the charging member cleaning member as a datum, the range of 1/5 to 1/2 of the average nip amount between the charging member and the charging member cleaning member, and When the thickness difference of the cylindrical elastic layer of the charging member cleaning member is set to a range of 2/5 or more and 1 or less, it is preferable in terms of productivity to form the thickness difference.

  The charging device according to the present embodiment preferably includes a bearing mechanism that holds the charging member and the core member of the charging member cleaning member at a constant displacement. In particular, when the thickness difference of the cylindrical elastic layer of the charging member cleaning member is in the range of 2/5 or more and 1 or less, the core member of the charging member and the charging member cleaning member is held at a constant displacement by an integral bearing. By fixing the shaft core with a low displacement, the nip amount between the charging member and the charging member cleaning member that is driven is shifted by the difference in thickness, and the nip amount has a width by being rotated. In addition, it is possible to obtain stable foreign matter removal performance.

  As the material of the core member 18 of the charging member cleaning member 12, free-cutting steel, stainless steel or the like is used, and the material and surface treatment method are appropriately selected according to the use such as slidability, and the material does not have conductivity. Is processed by a general process such as a plating process, and a conductive process is performed.

  Further, since the charging member cleaning member 12 is in contact with the charging member 10 via the cylindrical elastic layer 20, a material that does not bend at the time of nip or a shaft diameter that is sufficiently rigid with respect to the shaft length is selected. The

  The cylindrical elastic layer 20 of the charging member cleaning member 12 is formed on the outer periphery of the core material 18 provided with an adhesive layer that hardly damages the cylindrical elastic layer 20 for adhesion to the core material 18 and is made of polyurethane, polyethylene, The foam is preferably selected from resins such as polyamide or polypropylene, and has a porous open-cell structure (three-dimensional structure). Thereby, the foreign substance removal effect of the charging member 10 becomes higher.

  The charging member 10 in the present embodiment is a charging roll in which a conductive foamed elastic layer, a resistance layer, a surface layer, and the like are sequentially formed as a charging layer 16 on a conductive core material 14, and has a predetermined charging performance. Needless to say, the present invention is not limited to the following configuration.

  The conductive core 14 is selected and manufactured in the same manner as the conductive core 18 of the charging member cleaning member 12.

  The charging layer 16 of the charging member 10 may be formed of a resistance layer, a surface layer, or the like, and a primer layer for enhancing adhesion between the conductive core material 14 and the resistance layer may be directly formed on the conductive core material 14.

  Examples of the elastic body constituting the resistance layer of the charging layer 16 include urethane rubber, nitrile rubber, isoprene rubber, butadiene rubber, epichlorohydrin-ethylene oxide copolymer rubber, ethylene-propylene-diene rubber, acrylonitrile-butadiene rubber, styrene-butadiene rubber, silicone. Elastic bodies, such as rubber | gum, are used, and these elastic bodies can be used individually or in mixture of 2 or more types.

  The resistance of an elastic body such as rubber may be adjusted by a conductive material such as carbon black. If necessary, 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.

  Specifically, carbon black as a conductive material includes “Special Black 350”, “Special Black 100”, “Special Black 250”, “Special Black 5”, and “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 conductive metal oxide particles, which are conductive particles contained in the resistance layer, had conductivity such as tin oxide, tin oxide doped with antimony, zinc oxide, anatase titanium oxide, indium tin oxide (ITO), etc. Any conductive material can be used as long as it is a conductive material using electrons as charge carriers, 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. From the viewpoint of resistance adjustment and rubber strength, tin oxide, antimony-doped tin oxide, anatase type is preferable. Titanium oxide is preferred, and tin oxide and tin oxide doped with antimony are preferred.

  As a material for the surface layer of the charging layer 16, the surface layer is formed for preventing contamination by toner or the like, and any of resin, rubber and the like may be used and is not particularly limited. .

  Examples of the resin that can be used for the surface layer include urethane resin, polyester, phenol, acrylic, polyurethane, epoxy resin, cellulose, copolymer nylon, and the like. Among these, copolymer nylon includes one or more of 610 nylon, 11 nylon, 12 nylon and the like as a polymer unit, and other polymer units included in this copolymer include , 6 nylon, 66 nylon and the like. Here, the proportion of polymer units such as 610 nylon, 11 nylon, and 12 nylon contained in the copolymer is preferably 10% by weight or more in total by weight ratio. When the polymerized unit is 10% by weight or more, the composition is excellent in liquid preparation and film formability at the time of coating the surface layer, and particularly, there is little abrasion of the resin layer and adhesion of foreign matter to the resin layer during repeated use. Has excellent durability and at the same time has low hygroscopicity, and changes in properties due to the environment are reduced.

The surface layer can contain a conductive material. As the conductive material, those having a volume average particle diameter of 3 μm or less and a volume resistivity of 10 ⁹ Ωcm or less are preferable. For example, particles containing metal oxides such as tin oxide, titanium oxide, zinc oxide, CeO ₂ , ZrO ₂ , In ₂ O ₃ or alloys thereof, or these metals on the surface of particles such as BaSO ₄ or TiO _2. An oxide-coated one or carbon black can be used.

  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 particles may be added to the surface layer, and in this case, the surface becomes hydrophobic and acts to prevent adhesion of foreign matters to the surface of the charging member. . In addition, insulating particles such as alumina and silica are added to give unevenness to the surface of the charging member, reducing the burden during rubbing against the photosensitive member, and the wear resistance between the charging member and the photosensitive member. It is also possible to improve the performance. It is also possible to add a coupling agent in order to improve the adhesion with the lower layer.

  Further, the surface layer can be made to have a physical property different from that of the resistance layer by UV irradiation of the resistance layer, heat treatment, chemical treatment with a coupling agent, or the like.

  Next, the conductive bearing 22 will be described. The conductive bearing 22 holds the charging member cleaning member 12 and the charging member 10 as a pair, thereby forming an inter-axis distance between the two members. The material of the conductive bearing 22 is appropriately selected from materials having conductivity and materials having slidability and strength as a bearing.

  Next, the high voltage power supply 24 will be described. The high-voltage power supply 24 is a device that charges the charging member 10 and the charging member cleaning member 12 to the same polarity by marking a voltage on the conductive bearing 22, and is a known high-voltage power supply device.

<Process cartridge>
A process cartridge according to this embodiment includes an image carrier and the charging device that charges the surface of the image carrier. 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.

  FIG. 5 shows a schematic configuration of an example of a process cartridge according to an embodiment of the present invention, and the configuration will be described. The process cartridge 3 includes an electrophotographic photosensitive member (photosensitive drum) 50 as an image carrier on which an electrostatic latent image is formed, a cylindrical charging member 10 that contacts and charges the surface of the electrophotographic photosensitive member 50, and a charging A toner image is formed by adhering toner to the charging member cleaning member 12 and the electrostatic latent image formed on the surface of the electrophotographic photosensitive member 50 to clean the surface of the charging member 10 while contacting and rotating the member 10. 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 electrophotographic photosensitive member 50 and cleans the toner remaining on the electrophotographic photosensitive member 50 after the transfer are integrated. It is supported and is detachable from the image forming apparatus. As a latent image forming means for forming an electrostatic latent image on the surface of the electrophotographic photosensitive member 50 around the electrophotographic photosensitive member 50 when mounted on the image forming apparatus by the charging member 10, laser light, or reflected light of the document. The transfer device 54, the developing roller 52, the transfer roller 54 as a transfer means for transferring the toner image on the surface of the electrophotographic photosensitive member 50 to the recording paper 62 as the transfer target, and the cleaning blade 56 are arranged in this order. It has become. In FIG. 5, 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 electrophotographic photoreceptor 50 is uniformly charged to a high potential by supplying a voltage from a high voltage power source (not shown) to the charging member 10 in contact with the surface of the electrophotographic photoreceptor 50. At this time, the electrophotographic photosensitive member 50 and the charging member 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 electrophotographic photosensitive member 50 by the exposure device 58, the potential of the irradiated portion decreases. Since the image light 60 has a light amount distribution according 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 electrophotographic photosensitive member 50 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 the toner image on the surface of the electrophotographic photoreceptor 50. After the toner image is transferred to the recording paper 62 by the transfer roll 54, the recording paper 62 is separated from the electrophotographic photosensitive member 50. 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 member cleaning member 12 is installed on the charging member 10 provided in the process cartridge 3, and a voltage is applied to the conductive bearing 22 from a high voltage power source, so that the charging member cleaning member 12 has the same polarity as the charging member 10. By having this, contaminants can be transferred without accumulating on the surface of the charging member cleaning member 12 and the charging member 10, and can be collected by the cleaning blade 56, so that foreign matters such as toner adhering to the charging member can be stably maintained for a long time. Can be removed. For this reason, the charging member 10 does not accumulate dirt over a long period of time and is excellent in uniform charging performance, and stable charging performance can be maintained.

  The electrophotographic photoreceptor 50 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, the surface of the electrophotographic photoreceptor 50 can be exposed to a light source such as semiconductor laser light, LED light, and liquid crystal shutter light in a desired image-like manner, an LED array, and the like. And optical system equipment.

  The developing means has a function of developing the electrostatic latent image formed on the electrophotographic photosensitive member 50 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 electrophotographic photoreceptor 50 can be used. It may be the one that does not. For example, as shown in FIG. 5, the toner is attached to the electrophotographic photoreceptor 50 using a developing device having a function of attaching the electrostatic image developing toner to the electrophotographic photoreceptor 50 using the developing roll 52 or a brush. A known developing device such as a developing device having a function may be used. 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, as shown in FIG. 5, a transfer roll 54 and a transfer roll pressing device (not shown) using a conductive or semiconductive roll or the like that directly contacts and transfers to the surface of the recording paper 62 via the recording paper 62. ) Can be used. Further, a recording paper 62 may be used in which a charge opposite in polarity to the toner is applied to the recording paper 62 from the back side 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 electrophotographic photoreceptor 50, or an alternating current may be applied in a superimposed manner. The transfer roll 54 can be arbitrarily set according to the image area width 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 in which the surface of plain paper is coated with a 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, the charging device that charges the surface of the image carrier, a latent image forming unit that forms a latent image on the surface of the image carrier, and the surface of the image carrier. A developing means for developing a latent image formed on the surface of the toner image with a toner, a transfer means for transferring the toner image formed on the surface of the image holding member to a transfer target, and an image holding member after transfer. An image carrier cleaning means for cleaning the surface. The image forming apparatus according to the present embodiment may use the process cartridge.

  A schematic configuration of an example of the image forming apparatus according to the present embodiment is shown in FIG. 6 and the configuration will be described. The image forming apparatus 5 includes an electrophotographic photosensitive member 50 as an image carrier on which an electrostatic latent image is formed, a cylindrical charging member 10 that contacts and charges the surface of the electrophotographic photosensitive member 50, and contacts the charging member 10. As a latent image forming means for forming an electrostatic latent image on the surface of the electrophotographic photosensitive member 50 by using the charging member cleaning member 12 for cleaning the surface of the charging member 10 while moving around, and the reflected light of the laser beam or the document. An exposure device 58, a developing roll 52 as a developing means for forming a toner image by attaching toner to the electrostatic latent image formed on the surface of the electrophotographic photoreceptor 50, and a toner image on the surface of the electrophotographic photoreceptor 50 An image holding unit that contacts a transfer roll 54 serving as a transfer unit that performs transfer processing on a recording sheet 62 that is a transfer target, and the surface of the electrophotographic photosensitive member 50 to clean toner remaining on the electrophotographic photosensitive member 50 after transfer. Body cleaning And a cleaning blade 56 as a stage. In the image forming apparatus 5, the charging member 10, the exposure device 58, the developing roll 52, the transfer roll 54, and the cleaning blade 56 are arranged in this order around the electrophotographic photoreceptor 50. In FIG. 6, the description of functional units normally required in other electrophotographic processes is omitted. 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.

  A charging member cleaning member 12 is installed on the charging member 10 provided in the image forming apparatus 5, and a voltage is applied to the conductive bearing 22 from the high voltage power supply 24, so that the charging member cleaning member 12 is electrically the same as the charging member 10. By having the polarity, contaminants can be transferred without accumulating on the surfaces of the charging member cleaning member 12 and the charging member 10 and can be collected by the cleaning blade 56, so that foreign matters such as toner adhering to the charging member can be collected for a long time. , Can be removed stably. For this reason, the charging member 10 does not accumulate dirt over a long period of time and is excellent in uniform charging performance, 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 above-described charging device, for example, a latent image forming unit, a developing unit, a transfer unit, an image carrier cleaning unit, a charge eliminating unit, a sheet feeding unit, a conveying unit, an image control unit, and the like are conventionally known as necessary. Are appropriately employed. These configurations are not particularly limited in the present embodiment.

  Further, as the image forming apparatus according to the present embodiment, the image forming apparatus having only one photoconductor has been described. However, the configuration other than the charging device is not limited thereto, for example, the toner held on the image holding body. Conventionally known color image forming apparatus that repeats primary transfer to an intermediate transfer body sequentially, a tandem type color image forming apparatus in which a plurality of image holding bodies each having a developing device for each color are arranged on the intermediate transfer body Is appropriately adopted. 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
<Production of charging member cleaning member>
A 15 mm square material of urethane foam (product name: ERG-H, manufactured by INOAC), in which hot melt (manufactured by Nisshin Chemical Co., Ltd., BR4301) is applied onto a SUS303 Φ6 mm cylindrical core material and a core hole is formed as an elastic layer After molding on the outer periphery of the material, bonding was performed in an oven at 90 ° C.

  Next, it is processed with a cylindrical polishing machine for elastic layer processing until the outer diameter becomes 12 mm. After forming a cylindrical elastic body, it is mounted in a bending mold and pressed to form a bend near the center. Thus, a charging member cleaning member having a straightness of 0.28 mm was obtained. The coaxiality between the core material and the cylindrical elastic layer was 0.29 mm.

<Production of charging member>
A mixture having the following composition is kneaded with an open roll, and a 15 mm diameter roll is formed on the surface of the conductive core material of SUS303 with a diameter of 8 mm using a press molding machine through an adhesive layer. Got a roll.
Rubber material (epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber, Gechron 3106, manufactured by Nippon Zeon) 100 parts by weight Conductive agent (carbon black, Asahi Thermal, manufactured by Asahi Carbon Co.) 15 parts by weight Conductive agent (Ketjen Black EC, Lion 5 parts by weight Ionic conductive agent (lithium perchlorate) 1 part by weight Vulcanizing agent (sulfur, 200 mesh, manufactured by Tsurumi Chemical Co., Ltd.) 1 part by weight Vulcanization accelerator (Noxeller DM, Ouchi Shinsei Chemical Co., Ltd.) Manufactured) 2.0 parts by mass Vulcanization accelerator (Noxeller TT, manufactured by Ouchi Shinsei Chemical Co., Ltd.) 0.5 parts by mass Vulcanization accelerator (Zinc oxide, zinc oxide 1 type, manufactured by Shodo Chemical Industry Co., Ltd.) 3 Parts by weight stearic acid 1.5 parts by weight

[Formation of surface layer]
A dispersion obtained by dispersing a mixture having the following composition in a bead mill is diluted with 15 parts by mass of MEK (methyl ethyl ketone), dip-coated on the surface of the conductive elastic roll, and then heated and dried at 180 ° C. for 30 minutes. A surface layer having a thickness of 7 μm was formed to obtain a charging roll as a charging member.
Polymer material (saturated copolymer polyester resin solution, Byron 30SS, manufactured by Toyobo Co., Ltd.) 100 parts by mass Curing agent (amino resin solution, Super Becamine G-821-60, manufactured by Dainippon Ink & Chemicals, Inc.) 26.3 masses Part Conductive agent a1 (carbon black, MONARCH1000, manufactured by Cabot) 10 parts by mass

  The charging member cleaning member and the charging roll obtained above were integrally held with a conductive bearing having an average nip amount of 0.7 mm to obtain a charging unit.

The charging unit thus obtained is mounted on a modified DocuCenterColor f450 cartridge and a modified DocuCenterColor f450 machine (manufactured by Fuji Xerox Co., Ltd.) at a nip load of 800 g with a high temperature and high humidity (28 ° C., 85%) environment. After printing 10,000 sheets, a printing test was conducted after standing for 12 hours in a low-temperature and low-humidity environment (10 ° C., 15%), and visually evaluated based on the following criteria. The results are shown in Table 1.
Printing condition: A3 paper (J paper manufactured by Fuji Xerox Co., Ltd.) front side is output with 50% halftone. Criteria:
◎: No streaking or density unevenness due to charging member ○ ○: No streaking or density unevenness due to charging member is generated, but the surface of the charging member is dirty ×: Streaking or density due to charging member There is unevenness

  Also, 10,000 sheets were printed in a low-temperature, low-humidity environment (10 ° C, 15%) using a charging unit with the same configuration as above, and a printing test was conducted after leaving in the same environment for 12 hours. Went. The results are shown in Table 1.

(Example 2)
In the preparation of the charging member cleaning member, the charging member cleaning member having a straightness of 0.14 mm was prepared by mounting in a bending forming mold and changing the press pressure, and the same method as in Example 1 was used. A charging unit was produced and evaluated in the same manner as in Example 1. The coaxiality between the core material and the cylindrical elastic layer was 0.14 mm. The results are shown in Table 1.

(Example 3)
In the preparation of the charging member cleaning member, the charging member cleaning member having a straightness of 0.35 mm was prepared by using the same method as in Example 1 except that the charging member cleaning member was mounted in a bending forming mold and the press pressure was changed. A charging unit was produced and evaluated in the same manner as in Example 1. The coaxiality between the core material and the cylindrical elastic layer was 0.35 mm. The results are shown in Table 1.

Example 4
The charging member cleaning member and the charging roll obtained in Example 1 were integrated with a conductive bearing having an average nip amount of 0.56 mm to produce a charging unit, and the same evaluation as in Example 1 was performed. The results are shown in Table 1.

(Example 5)
The charging member cleaning member and the charging roll obtained in Example 1 were integrally held with a conductive bearing having an average nip amount of 1.0 mm to produce a charging unit, and the same evaluation as in Example 1 was performed. The results are shown in Table 1.

(Comparative Example 1)
In the preparation of the charging member cleaning member, the charging member cleaning member having a straightness of 0.1 mm was prepared by using the same method as in Example 1 except that the charging member cleaning member was mounted in the bending forming mold and the press pressure was changed. A charging unit was produced and evaluated in the same manner as in Example 1. The coaxiality between the core material and the cylindrical elastic layer was 0.12 mm. The results are shown in Table 1.

(Comparative Example 2)
In the preparation of the charging member cleaning member, the charging member cleaning member having a straightness of 0.4 mm was prepared by using the same method as in Example 1 except that the charging member cleaning member was mounted in a bending forming mold and the press pressure was changed to make a straightness 0.4 mm. A charging unit was produced and evaluated in the same manner as in Example 1. The coaxiality between the core material and the cylindrical elastic layer was 0.4 mm. The results are shown in Table 1.

  As can be seen from Table 1, the charging units of Examples 1 to 5 were able to stably remove foreign matters such as toner adhering to the charging member over a long period of time.

(Example 6)
<Production of charging member cleaning member>
A 15 mm square material of urethane foam (product name: ERG-H, manufactured by INOAC), in which hot melt (manufactured by Nisshin Chemical Co., Ltd., BR4301) is applied onto a SUS303 Φ6 mm cylindrical core material and a core hole is formed as an elastic layer After molding on the outer periphery of the material, bonding was performed in an oven at 90 ° C.

  Next, in the cylindrical polishing machine for processing the elastic layer, the core material is set in the state where the chuck axis is eccentric with respect to the rotational axis of the cylindrical grinding machine and the chuck is set on the cylindrical grinding machine. The charged square member was chucked to obtain a charging member cleaning member having an outer diameter of 12 mm and a circumferential thickness difference of 0.56 mm. The coaxiality between the core material and the cylindrical elastic layer was 0.28 mm. A charging unit was produced and evaluated in the same manner as in Example 1. The results are shown in Table 2.

(Example 7)
In the production of the charging member cleaning member, the eccentric state of the chuck was changed with respect to the rotational axis of the cylindrical grinding machine, and a charging member cleaning member having a circumferential thickness difference of 0.28 mm was produced and used in the experiment. Except for this, a charging unit was produced in the same manner as in Example 6, and the same evaluation as in Example 1 was performed. The coaxiality between the core material and the cylindrical elastic layer was 0.14 mm. The results are shown in Table 2.

(Example 8)
In the production of the charging member cleaning member, the eccentric state of the chuck was changed with respect to the rotational axis of the cylindrical grinding machine, and a charging member cleaning member having a circumferential thickness difference of 0.7 mm was produced and used in the experiment. Except for this, a charging unit was produced in the same manner as in Example 6, and the same evaluation as in Example 1 was performed. The coaxiality between the core material and the cylindrical elastic layer was 0.35 mm. The results are shown in Table 2.

Example 9
A charging unit was prepared by integrating the charging member cleaning member obtained in Example 6 and the charging roll obtained in Example 1 with a conductive bearing having an average nip amount of 0.56 mm, and the same evaluation as in Example 1 was made. Went. The results are shown in Table 2.

(Example 10)
A charging unit was prepared by integrating the charging member cleaning member obtained in Example 6 and the charging roll obtained in Example 1 with a conductive bearing having an average nip amount of 1.0 mm, and the same evaluation as in Example 1 was made. Went. The results are shown in Table 2.

(Comparative Example 3)
In the production of the charging member cleaning member, the eccentric state of the chuck was changed with respect to the rotational axis of the cylindrical grinding machine, and a charging member cleaning member having a circumferential thickness difference of 0.2 mm was produced and used in the experiment. Except for this, a charging unit was produced in the same manner as in Example 6, and the same evaluation as in Example 1 was performed. The coaxiality between the core material and the cylindrical elastic layer was 0.1 mm. The results are shown in Table 2.

(Comparative Example 4)
In the production of the charging member cleaning member, the eccentric state of the chuck was changed with respect to the rotational axis of the cylindrical grinding machine, and a charging member cleaning member having a circumferential thickness difference of 0.8 mm was produced and used in the experiment. Except for this, a charging unit was produced in the same manner as in Example 6, and the same evaluation as in Example 1 was performed. The coaxiality between the core material and the cylindrical elastic layer was 0.4 mm. The results are shown in Table 2.

  As can be seen from Table 2, the charging units of Examples 6 to 10 were able to stably remove foreign matters such as toner adhering to the charging member over a long period of time.

It is a schematic block diagram which shows an example of the charging device which concerns on embodiment of this invention. It is a schematic sectional drawing along the axial direction which shows an example of the charging member cleaning member which concerns on embodiment of this invention. It is a schematic sectional drawing of the orthogonal | vertical direction with respect to the axis | shaft which shows the other example of the charging member cleaning member which concerns on embodiment of this invention. In the charging member cleaning member according to the embodiment of the present invention, it is a schematic view showing an example of a bending formation method. 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 member, 12 Charging member cleaning member, 14 Conductive core material, 16 Charging layer, 18 Core material, 20 Cylindrical elastic layer, 22 Conductive bearing, 24 High pressure Power supply, 26 Bending mold, 28 groove, 30 mold, 50 electrophotographic photosensitive member, 52 developing roll, 54 transfer roll, 56 cleaning blade, 58 exposure device, 60 image light, 62 recording paper.

Claims (7)

A cylindrical charging member;
A charging member cleaning member having a core and a cylindrical elastic layer formed on the outer periphery of the core for cleaning the surface of the charging member while rotating in contact with the charging member;
Have
The charging device according to claim 1, wherein a coaxial degree of the core member and the cylindrical elastic layer is in a range of 1/5 to 1/2 of an average nip amount between the charging member and the charging member cleaning member. The charging device according to claim 1,
The straightness with the longitudinal end of the cylindrical elastic layer of the charging member cleaning member as a datum is in the range of 1/5 to 1/2 of the average nip amount between the charging member and the charging member cleaning member. A charging device. The charging device according to claim 1 or 2,
The thickness difference in the circumferential direction of the cylindrical elastic layer of the charging member cleaning member is in the range of 2/5 to 1 of the average nip amount between the charging member and the charging member cleaning member. apparatus. The charging device according to any one of claims 1 to 3,
A charging device comprising a bearing mechanism that holds the charging member and a core material of the charging member cleaning member at a constant displacement. The charging device according to any one of claims 1 to 4,
The charging device according to claim 1, wherein the cylindrical elastic layer is made of a porous foam having an open cell structure.   A process cartridge comprising: an image carrier; and the charging device according to claim 1 for charging a surface of the image carrier.   An image carrier, a charging device according to any one of claims 1 to 5 that charges a surface of the image carrier, a latent image forming unit that forms a latent image on the surface of the image carrier, and A developing unit that develops a latent image formed on the surface of the image carrier with toner to form a toner image, a transfer unit that transfers the toner image formed on the surface of the image carrier to a transfer target, and a transfer An image forming apparatus comprising: an image holding member cleaning unit that cleans a surface of the subsequent image holding member.

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