JP2008070836A - Cleaning device and cleaning method for electrifying roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cleaning device and a cleaning method for cleaning the surface of an electrifying roller 8 while preventing toner left after transfer or the like adhering to the surface of the electrifying roller 8 from firmly adhering to the surface of the electrifying roller 8 in a developing device 30. <P>SOLUTION: In the electrophotographic developing device 30, the cleaning device is equipped with a cleaning roller 7 for cleaning the electrifying roller 8 and a cleaning roller holding member 9 for arranging the cleaning roller 7 to contact with/separate from the electrifying roller 8. In the cleaning method for cleaning the electrifying roller 8, the cleaning roller 7 is separated from the electrifying roller 8 at the beginning of operation of the developing device 30, and the cleaning roller 7 is made to abut on the electrifying roller 8 so as to clean the electrifying roller 8 when predetermined time elapses as cumulative operation time of the developing device 30 by measuring the cumulative operation time of the developing device 30. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a charging roller cleaning device, a developing device, a process cartridge, an image forming apparatus, a charging roller cleaning method, and an image recording body manufacturing method.

  In an electrophotographic image forming apparatus, in a developing device, a charge having a predetermined polarity is applied to a surface of a photoconductor as an image carrier by a charging means, the charged photoconductor surface is exposed and discharged, and there is a difference in charge. An electrostatic latent image is formed, and a toner charged with the same polarity as the charged polarity is supplied to the electrostatic latent image to form and develop a toner image. Further, the toner image formed on the photoconductor is then transferred to a recording substrate such as recording paper and fixed on the recording substrate by heat and pressure. Recently, a contact roller charging method for charging a photosensitive member by bringing the charging roller into contact with the surface of the photosensitive member, which is an image carrier, in the charging step has been widely employed.

  In such a developing device, the transfer residual toner remaining on the surface of the photoconductor after the transfer of the toner image is not completely removed by the cleaning process of the photoconductor surface, and when the toner reaches the vicinity of the charging roller, the transfer residual toner is charged. Stick to the roller. If the transfer residual toner adheres to the surface of the charging roller, there is a problem in that the charge imparting performance to the photosensitive member is deteriorated, causing development failure of the developing device. In particular, some untransferred toners are charged with a polarity opposite to the design when stirring with a developer or the like. If the toner is charged to a normal polarity, it will repel electrostatically with the charging roller and will not adhere to its surface, but reversely charged toner will attract electrostatically to the charging roller and easily adhere to the surface of the charging roller. . In addition to the reversely charged toner, for example, dust such as paper powder that is charged and electrostatically attracts the charging roller adheres to the surface of the charging roller. If toner, paper powder, or the like adheres to the surface of the charging roller, the charge imparting performance to the photoreceptor is lowered, causing development failure of the developing device.

  Furthermore, in recent years, as the demand for higher image quality and higher definition of images has increased, toner having a reduced particle size and a spherical shape has come to be used. By using such a toner, it is intended to achieve high image quality and high definition by closely attaching the toner to the electrostatic latent image. However, the above-described toner having a reduced particle size and a spherical shape has a problem in that the surface of the photoreceptor cannot be sufficiently cleaned because it easily slips through the cleaning blade in the photoreceptor cleaning process.

In order to prevent the transfer residual toner remaining on the surface of the photoconductor without being cleaned in this way from adhering to the charging roller, the performance of the charging roller is deteriorated, and uniform charging of the surface of the photoconductor cannot be prevented. Cleaning is necessary. Therefore, as a cleaning means for the charging roller, a method is proposed in which the tip of the blade is in contact with the outer peripheral surface of the charging roller at a certain angle, and the toner adhering to the outer peripheral surface is scraped off by rotating the charging roller. (Patent Document 1). Also proposed are a method (Patent Document 2) in which a sponge material is always brought into sliding contact with the outer peripheral surface of the charging roller to remove toner adhering to the surface (Patent Document 2), a method using a brush roller (Patent Document 3), and the like. . These cleaning units remove a deposit such as toner by rubbing the cleaning member relatively against the surface of the charging roller. The adhering substance adheres to the internal pores if it is a sponge material, and adheres between the fibers of the brush if it is a brush roller, and peels off the charging roller. Further, a cleaning member that is in sliding contact with the charging roller is disposed so as to be able to come into contact with and separate from the charging roller, and the charging roller is cleaned at a time other than the time of image formation (Patent Document 4). There has been proposed a method (Patent Document 5) for cleaning while rotating the toner around the charging roller.
JP 58-194061 A Japanese Patent Laid-Open No. 3-101768 JP 2002-211883 A Japanese Patent No. 2702847 JP 2004-361916 A

  As described above, many methods and apparatuses have been proposed for cleaning the charging roller in the developing device. By these cleaning methods, most of transfer residual toner and the like adhering to the surface of the charging roller can be removed. However, transfer residual toner that adheres relatively firmly to the surface of the charging roller or dirt that easily deforms or melts due to pressure is rubbed or pressed against the surface of the charging roller by the cleaning member. It may adhere more strongly. This tendency is particularly strong in the cleaning method in which the cleaning member is rubbed against the surface of the charging roller. The transfer residual toner or the like adhering to the surface of the charging roller without being rubbed off is naturally peeled off and does not cause much development trouble in the developing process using the photosensitive member of the developing device. However, the transfer residual toner or the like strongly adhered to the surface of the charging roller is liable to cause a charging failure of the photosensitive member and is difficult to peel off from the charging roller, which tends to cause a serious development trouble. Until now, a charging roller cleaning method and a cleaning apparatus that can cope with the adverse effects of such a cleaning member have not been considered, including the proposal of the above-described charging roller cleaning method.

  In view of such problems, the object of the present invention is to clean the surface of the charging roller while firmly preventing dirt such as transfer residual toner adhering to the surface of the charging roller from adhering to the surface of the charging roller in the developing device. A cleaning device and a cleaning method are provided. Another object of the present invention is to provide a developing device, a process cartridge, and an image forming apparatus provided with the cleaning device. It is another object of the present invention to provide a method for manufacturing an image recording body by an image forming apparatus using the cleaning method.

  As a result of intensive studies to solve the above problems, the present inventors have separated the cleaning device from the charging roller while cleaning the charging roller surface while the charging roller maintains the charging performance. It should be noted that the above problem can be solved by a method of cleaning the charging roller that contacts the charging roller only when cleaning of the charging roller is necessary, and is separated from the charging roller when it seems to have a great adverse effect. Based on this finding, the present invention has been completed.

  The present invention according to claim 1 includes at least a photosensitive member, a charging roller for charging the surface of the photosensitive member, a developing roller for developing a latent image formed on the surface of the photosensitive member, and a photosensitive member for cleaning the surface of the photosensitive member. An electrophotographic developing device including a cleaning device, comprising: a cleaning roller that cleans the charging roller; and a cleaning roller holding member that is disposed so that the cleaning roller can be brought into contact with and separated from the charging roller. is there.

  According to a second aspect of the present invention, there is provided the cleaning device according to the first aspect, further comprising pressure contact means for pressing the cleaning roller against the charging roller.

  According to a third aspect of the present invention, there is provided an operation time detecting means for detecting an operation time of the developing device, and a cleaning for bringing the cleaning roller into contact with the charging roller according to a predetermined operation time detected by the operation time detecting means. The cleaning apparatus according to claim 1, further comprising a roller control unit.

  The present invention described in claim 4 is the cleaning device according to any one of claims 1 to 3, wherein the cleaning roller is provided with a melamine resin foam layer on an outer periphery of a cored bar.

  According to a fifth aspect of the present invention, in the cleaning according to the fourth aspect, the melamine resin foam layer is composed of a melamine resin foam obtained by compressing a once-foamed melamine resin foam and reducing the volume by 20 to 40% by volume. Device.

  The present invention according to claim 6 includes at least a photosensitive member, a charging roller for charging the surface of the photosensitive member, a developing roller for developing a latent image formed on the surface of the photosensitive member, and a photosensitive member for cleaning the surface of the photosensitive member. A developing device comprising: a cleaning device; a lubricity imparting unit that imparts lubricity to the surface of the photoreceptor; and a cleaning device according to any one of claims 3 to 5, wherein the lubricity imparting unit includes: The developing device includes a lubricity imparting material consumption detecting unit that includes a solid lubricity imparting material and detects consumption of the lubricity imparting material.

  A seventh aspect of the present invention is the developing device according to the sixth aspect, wherein the lubricity imparting material consumption amount detecting means is a sensor for detecting a size of the lubricity imparting material.

  An eighth aspect of the present invention is the developing device according to the sixth aspect, wherein the lubricity imparting material consumption amount detecting means is a cleaning roller control rod in contact with the lubricity imparting material.

  According to a ninth aspect of the present invention, there is provided a process cartridge for an image forming apparatus including at least the developing device according to any one of the sixth to eighth aspects.

  According to a tenth aspect of the present invention, there is provided an image forming apparatus including the developing device according to any one of the sixth to eighth aspects or the process cartridge according to the ninth aspect.

  The present invention according to claim 11 includes at least a photosensitive member, a charging roller for charging the surface of the photosensitive member, a developing roller for developing a latent image formed on the surface of the photosensitive member, and a photosensitive member for cleaning the surface of the photosensitive member. A cleaning method for a charging roller in an electrophotographic developing device having a cleaning device and a cleaning device for cleaning the charging roller, wherein the cleaning roller is separated from the charging roller at the beginning of operation of the developing device, and development is performed. This is a charging roller cleaning method in which the cumulative operation time of the apparatus is measured, and the cleaning roller is brought into contact with the charging roller to clean the charging roller when the predetermined operation time has elapsed.

  According to a twelfth aspect of the present invention, there is provided the charging roller cleaning method according to the eleventh aspect, wherein the cumulative operation time of the developing device is replaced by the cumulative number of development times of the developing device.

  According to a thirteenth aspect of the present invention, the cumulative operation time of the developing device is replaced with a consumption amount of a lubricity imparting material provided in the developing device to impart lubricity to the surface of the photoreceptor. This is a method for cleaning the charging roller.

  According to a fourteenth aspect of the present invention, in cleaning the charging roller by bringing the cleaning roller into contact with the charging roller, the cleaning roller is caused to rotate around the charging roller or stop rotating. The charging roller cleaning method according to claim 1.

  According to a fifteenth aspect of the present invention, in cleaning the charging roller by bringing the cleaning roller into contact with the charging roller, the cleaning roller is swung. Is the method.

  The present invention according to claim 16 includes at least a photosensitive member, a charging roller for charging the surface of the photosensitive member, a developing roller for developing a latent image formed on the surface of the photosensitive member, and a photosensitive member for cleaning the surface of the photosensitive member. The charging roller of an image forming apparatus having an electrophotographic developing device including a cleaning device and a cleaning device for cleaning the charging roller is obtained by the charging roller cleaning method according to claim 11. This is a method of manufacturing an image recording body that forms an image on an image recording substrate by cleaning.

  According to the cleaning device and the charging roller cleaning method of the present invention, in the developing device, while preventing the transfer residual toner or the like adhering to the surface of the charging roller during operation from being firmly adhered to the surface of the charging roller, the surface of the charging roller is Cleaning can remove residual toner and the like that are harmful to the development process, thereby extending the life of the charging roller. The developing device, the process cartridge, and the image forming apparatus of the present invention have a long life of the charging roller of the charging roller, and there are few development troubles due to poor charging of the photoreceptor. Furthermore, according to the method for producing an image recording body of the present invention, it is possible to provide an image recording body free from dirt and image unevenness.

  The first embodiment of the present invention is a charging roller cleaning device provided in an electrophotographic developing device. The cleaning device includes at least a photoconductor, a charging roller for charging the surface of the photoconductor, a developing roller for developing a latent image formed on the surface of the photoconductor, and a photoconductor cleaning device for cleaning the surface of the photoconductor. It is attached to the electrophotographic developing device provided. The cleaning device includes at least a cleaning roller that cleans the charging roller, and a cleaning roller holding member that is disposed so that the cleaning roller can be brought into contact with and separated from the charging roller. Preferably, the cleaning device includes a pressing unit that presses the cleaning roller against the charging roller. More preferably, the cleaning device includes an operation time detection unit that detects an operation time of the developing device, and a cleaning roller control that causes the cleaning roller to contact the charging roller according to a predetermined operation time detected by the operation time detection unit. Means.

  The cleaning device of this embodiment is provided in an electrophotographic developing device, and this developing device is usually provided in an electrophotographic image forming apparatus. In particular, the developing device can be detachably attached to the image forming apparatus as a process cartridge.

  First, the image forming apparatus will be briefly described. FIG. 7 shows an image forming apparatus 100 including the cleaning device of the present invention. Similar to a normal image forming apparatus, the image forming apparatus 100 includes an image reading unit (scanner) 50 at an upper portion thereof, an exposure unit 33 for image recording paper, a transfer belt 31, a fixing device 32, a conveying belt, and the like. An image forming unit including the developing device 30 is provided, and a recording substrate storage unit 40 such as a recording sheet is provided at the bottom. The cleaning device of the present invention is included in the developing device 30 and is adjacent to the charging roller 8, but is not illustrated because it is very small when viewed from the entire image forming apparatus. The cleaning device of the present invention is shown as a cleaning roller 7 as a main part in FIG.

  In this image forming apparatus, image information read as electronic information by the image reading unit 50 is converted into optical information by the exposure means 33 of the image forming unit, and is first recorded as a latent image on the developing device 30. Image information recorded as a latent image is further developed into a toner image by toner supplied from a developing roller. The image information developed into the toner image is transferred from the recording substrate storage unit to the recording substrate (usually recording paper) conveyed by the conveying belt 31, and fixed by the fixing device 32 to be formed on the recording substrate. The image information is discharged to the left tray of the image forming apparatus 100 (see FIGS. 7 and 8). In such a schematic image forming process of the image forming apparatus 100 including the cleaning device of the present invention, there is no difference from the image forming process of the conventional image forming apparatus.

  An outline of the developing device 30 will be described with reference to FIG. The developing device 30 includes a photosensitive member 1, a charging roller 8 that charges the surface of the photosensitive member 1, a developing roller 34 that develops a latent image formed on the surface of the photosensitive member 1, and a photosensitive member that cleans the surface of the photosensitive member 1. A cleaning device (cleaning blade) 6 is provided. Further, the developing device 30 includes the cleaning device of the present invention, and is illustrated as a cleaning roller 7. The operation of the developing device 30 is similar to that of the conventional developing device. The surface of the photoconductor 1 uniformly charged by the charging roller 8 is rotated from the exposure device 33 while the photoconductor 1 rotates counterclockwise. A latent image due to the difference in charge is formed by the light signal. The formed latent image is supplied with toner by the developing roller 34 and is developed on the surface of the photoreceptor 1 as a toner image. The toner image formed on the surface of the photoreceptor 1 is transferred onto the transfer belt 31 or a recording substrate that has been conveyed to the transfer belt 31. The photosensitive member 1 to which the toner image has been transferred further rotates, and dirt such as transfer residual toner on the surface of the photosensitive member 1 is removed by a photosensitive member cleaning device including a cleaning blade 6. The surface of the photoreceptor 1 from which the dirt has been removed is charged again by the charging roller 8, and the development process is repeated.

  There is no problem as long as the dirt to be removed by the photoconductor cleaning device is completely removed and the surface of the photoconductor before charging is completely clean, but usually a part of the transfer residual toner etc. is removed. Instead, the charging operation is performed while remaining on the surface of the photoreceptor 1. Then, this dirt will also adhere to the surface of the charging roller 8. Then, uniform charging of the surface of the photoreceptor 1 by the charging roller 8 is hindered.

  The cleaning device of the present invention removes dirt such as transfer residual toner on the surface of the charging roller 8 described above, and maintains uniform charging performance of the surface of the photoreceptor 1 by the charging roller 8. Further, the cleaning device of the present invention will be described based on the embodiment of FIG. 1. The cleaning device comprises a cleaning roller 7 that contacts the charging roller 8 and removes dirt on the charging roller 8 and a holding member 9. Yes. The holding member 9 also serves as a bearing for the cleaning roller 7. In FIG. 1, the cleaning roller 7 is in contact with the charging roller 8, but the holding member 9 can move in the upper left direction in the figure, and the cleaning roller 7 can be separated from the charging roller 8. The holding member 9 presses the cleaning roller 7 against the charging roller 8 by a spring that is a pressure contact member. As a result, the cleaning roller 7 can be easily rotated along with the rotation of the charging roller 8. Further, residual toner on the charging roller 8 is easily removed.

  The cleaning device uses an operation time detection unit that detects an operation time of the developing device 30, that is, an accumulated use time of the charging roller 8, and a cleaning roller as a charging roller according to a predetermined operation time detected by the operation time detection unit. Cleaning roller control means for contacting. The specific operation time detecting means of the developing device 30 in this example may be a cumulative image processing number counting device (commonly known as a cumulative processing number counter) that measures the cumulative number of development times of the developing device in the image forming apparatus. In the form shown in FIG. 1, this developing device includes a cleaning blade 6 and a fur brush 2 as a photoconductor cleaning device, and the fur brush 2 is a solid lubricant that imparts lubricity to the surface of the photoconductor 1. The property imparting material 4 is in contact. The lubricity imparting material 4 is always pressed against the fur brush 2 by a lubricity imparting material pressing spring 5 with a predetermined pressing force. The lubricity imparting material 4 is a consumable item and wears out in proportion to the cumulative usage time of the developing device. The portion of the lubricity imparting material 4 that is in contact with the lubricity imparting material pressing spring 5 approaches the fur brush 2 in accordance with the wear of the lubricity imparting material 4. In FIG. 1, the contact portion of the lubricity imparting material 4 with the lubricity imparting material pressing spring 5 is lowered. The position of the contact portion between the lubricity imparting material 4 and the lubricity imparting material pressing spring 5 is measured by the sensor 20, and the position of the contact portion between the lubricity imparting material 4 and the lubricity imparting material pressing spring 5 is measured. Thus, the cumulative operation time of the developing device can be detected. This is an example of solid lubricant consumption detecting means.

  The usage time of the charging roller 8 can be calculated by converting the solid lubricant consumption detected by the solid lubricant consumption detection means into the cumulative operation time of the developing device. At the beginning of use of the charging roller 8, dirt adhering to the charging roller 8 does not significantly affect the charging performance, but the charging roller 8 is used for a long period of time, and the dirt adhering to the charging roller 8 is solidified over time. If the density of the charging roller 8 is increased or the temperature is chemically changed, the charging performance of the charging roller 8 to the photosensitive member 1 is likely to be abnormal. Further, if the cleaning roller 7 is brought into contact with the charging roller 8 from the beginning of use of the charging roller 8, a small amount of dirt that adheres to the charging roller 8 and is not removed by the cleaning roller 7 is instead applied to the cleaning roller 7. It is hardened by being pressed or densified and adheres firmly to the charging roller 8, so that the charging performance of the charging roller 8 to the photosensitive member 1 is likely to be abnormal.

  In order to prevent the trouble as described above, at the beginning of use of the charging roller 8, that is, at the beginning of use of the developing device, the cleaning roller 7 is separated from the charging roller 8, and dirt on the charging roller 8 causes the charging roller 8 to become dirty. The charging roller 8 may be cleaned by bringing the cleaning roller 7 into contact with the charging roller 8 just before the charging performance is affected. At this time, in order to improve the cleaning effect of the cleaning roller 7, in this developing device, the accumulated operation time until the charging performance of the charging roller 8 is lowered is checked in advance, and the cleaning roller 7 is applied to the charging roller 8. What is necessary is just to determine the optimal time which touches and starts cleaning of the charging roller 8. As a calculation method of the cumulative operation time for that purpose, the above-mentioned cumulative number of developments and consumption of the lubricity imparting material can be used as indexes.

  Any method and structure may be used for separating the cleaning roller 7 from the charging roller 8 or bringing it into contact with the charging roller 8, but at the beginning of the operation of the developing device, the cleaning roller 7 is separated from the charging roller 8 for a predetermined time. A method and a structure in which contact is made after the passage is preferable. For example, when the cumulative operation time of the developing device or the calculated cumulative operation time calculated using an index that can be substituted for the cumulative operation time as described above reaches a predetermined time, the holding member 9 is moved by a spring pressing force or an electric device. The cleaning roller 7 may be brought into contact with the charging roller 8.

  Specific examples of the contact and separation structure of the cleaning roller are shown in FIGS. In this contact / separation structure example, the consumption of the lubricity imparting material 4 is mechanically detected, and the cleaning roller 7 is brought into contact with the charging roller 8 by the spring 13 with the hook 15 as an information transmission means. Referring to the drawing, FIG. 2 shows a state where the lubricity imparting material 4 is sufficiently large and the hook 15 is fixed to the side surface of the lubricity imparting material 4 at the beginning of operation of the developing device. At this time, the shaft 11 of the cleaning roller 7 is supported by the end of the hook 15 opposite to the end in contact with the lubricity imparting material 4 and is in a separated state from the charging roller 8. FIG. 3 shows that the developing device is operated for a predetermined period, and the lubricity imparting material 4 is consumed and moved relative to the hook 15 in the direction of the arrow a in the figure. Then, the hook 15 rotates in the direction of the arrow b in the figure by the action of the spring 10. Then, the shaft 11 of the cleaning roller supported by the other end of the hook 15 is detached from the hook 15, and the cleaning roller 7 is pressed against a charging roller 8 by being pressed by a spring (not shown). This situation is shown as a side view in FIGS. In FIG. 4, since the cleaning roller 7 is supported by the hook 15, it does not contact the charging roller 8. In FIG. 5, since the cleaning roller 7 is detached from the support of the hook 15, it is pressed by the spring 13 and is in contact with the charging roller 8. In this state, the cleaning roller 7 cleans the charging roller 8. In this structural example, the amount of consumption of the lubricity imparting material 4 is a measure of the operating time of the developing device. Then, when a predetermined amount of the lubricity imparting material 4 is consumed, the hook 15 is detached from the lubricity imparting material 4 and the cleaning roller 7 is brought into contact with the charging roller 8, so that the charging roller after the predetermined operation time is reached. 8 can be cleaned and the life of the charging roller 8 can be extended.

  An example of the contact / separation structure of another cleaning roller is shown in FIG. The structure shown in FIG. 6 also uses the consumption of the lubricity imparting material 4 as an indicator of operation time, and the cleaning roller 7 that has been separated from the charging roller 8 at the beginning of the operation comes into contact with the charging roller 8 after a predetermined time to perform cleaning. Is the structure that starts. FIG. 6 a shows that at the beginning of operation, the lubricity imparting material 4 is sufficiently large and the cleaning roller control rod 16 is supported by the fulcrum 19 and the lubricity imparting material 4, and is opposite to the fulcrum of the cleaning roller control rod 16. These ends support the holding member 17 together with the fulcrum 21 of the holding member 17 so that the cleaning roller 7 does not contact the charging roller 8. In FIG. 6 b, the lubricity imparting material 4 is consumed and shortened after the developing device has been operated for a predetermined time, and the cleaning roller control rod 16 is pressed down by the spring 5 correspondingly. Accordingly, the holding member 17 of the cleaning roller 7 is also pressed downward by the spring 18, and the cleaning roller 7 comes into contact with the charging roller 8. At this time, the cleaning action of the cleaning roller 7 starts to work. Further, when the developing device is operated and the lubricity imparting material 4 is consumed, as shown in FIG. 6c, the end of the cleaning roller control rod 16 on the cleaning roller 7 side is further lowered, but the cleaning roller 7 remains as it is. You can continue cleaning.

  It is preferable that the cleaning roller 7 is rotatably supported and rotates with the charging roller 8. In this way, by driving the cleaning roller 7 according to the rotation of the charging roller 8, the cleaning roller 7 does not require a driving device, and the configuration can be simplified. Further, the outer periphery of the cleaning roller 7 is preferably a resin foam, so that a sufficient cleaning performance can be obtained without requiring a particularly strong pressing force for contact with the surface of the charging roller 8. For this reason, wear on the surface of the charging roller 8 can be suppressed.

  Furthermore, the cleaning roller 7 preferably includes a swing mechanism that swings in the longitudinal direction as the charging roller 8 rotates. This mechanism includes, for example, a bearing provided at the tip of the core shaft of the cleaning roller 7 so as to abut against the cam surface of the gear with the swing cam. When the gear with the swing cam rotates as the charging roller 8 rotates, the cam surface A mechanism or the like in which the cleaning roller 7 swings in the longitudinal direction according to the unevenness can be used. In this way, the cleaning of the surface of the charging roller 8 can be made uniform by swinging the cleaning roller 7. In particular, since paper dust is often generated from both ends of the recording paper, the adhesion position on the photosensitive member 1 is biased, and accordingly, the dust is also biased on the surface of the charging roller 8. Therefore, by swinging the cleaning roller 7, it is possible to deal with the unevenness of the deposits and make the cleaning of the charging roller 8 uniform.

  As another example, a rotation stop device such as a one-way clutch may be provided at the end of the core shaft of the cleaning roller 7. The rotation stopping device can control the rotation of the cleaning roller 7 and the charging roller 8. Normally, the cleaning roller 7 rotates with the charging roller 8. However, for example, during the image forming operation, the one-way clutch is locked, whereby the rotation of the cleaning roller 7 is stopped, and cleaning is performed by sliding the surface of the charging roller 8 by rotation. On the other hand, at the end of image formation, the photosensitive member 1 stops with a slight reverse rotation. At this time, due to the one-way clutch, the cleaning roller 7 slightly rotates along with the charging roller 8 and stops. With such a configuration, the resin foam portion of the cleaning roller 7 does not excessively hit the surface of the charging roller 8, so that the surface of the charging roller 8 can be prevented from being worn and the charging roller 8 can be cleaned. The contact position of the roller 7 can be sequentially shifted, and good cleaning can be performed.

The material of the cleaning roller 7 in the cleaning device of the present invention will be described. As the cleaning roller 7, for example, a resin foam layer can be formed by winding a resin foam around a core metal in a cylindrical shape. As the resin foam, a resin foam having an open-cell structure showing a physical property value of a density of 5 to 15 kg / m ³ and a tensile strength of 1.7 ± 0.5 kg / cm ² can be used. . The cleaning property and scratching property of the surface of the charging roller 8 can be evaluated by the state of the image to be formed. That is, if the cleaning performance of the cleaning roller 7 is insufficient and the surface of the charging roller 8 is contaminated, the photosensitive member 1 is not charged well, and the recording medium is soiled. The condition gets worse. Further, when the surface of the charging roller 8 is scratched by the rubbing of the cleaning roller 7, a streak-like defect occurs on the image. When the density of the resin foam is 5 kg / m ³ or more, sufficient cleaning performance of the cleaning roller 2b can be obtained. If the density is less than 5 kg / m ³ , sufficient cleaning performance cannot be obtained, charging failure occurs at an early stage, and problems such as background smearing occur in the image. On the other hand, if the density is higher than 15 kg / m ³ , the surface of the charging roller 8 is greatly scraped even if the cleaning performance is good, and the surface of the charging roller 8 is scratched early, causing streak-like defects in the image. It becomes easy to let.

If the tensile strength of the resin foam is 1.2 kg / cm ² or more, the cleaning roller 7 can obtain a sufficient cleaning performance. When the tensile strength is less than 1.2 kg / cm ² , the strength is not sufficient, and the resin foam becomes tattered at an early stage, and the cleaning performance is not exhibited. On the other hand, if the tensile strength is larger than 2.2 kg / cm ² , even if the cleaning performance is good, the surface of the charging roller 8 is scratched at an early stage to cause streak-like defects in the image. Accordingly, the physical properties of the resin foam constituting the cleaning roller 7 may be a density of 5 to 15 kg / m ³ and a tensile strength of 1.7 ± 0.5 kg / cm ² . The resin foam having an open-cell structure having a density in the above range exhibits a network-like form having fine pores, and can remove scraps such as toner on the surface of the charging roller 8 at the skeleton portion of the foam. In addition, the resin foam having a tensile strength in the above range exhibits a brittle property and peels off due to the frictional force received on the contact surface with the charging roller 8. Since the deposits such as toner held in the pores of the resin foam are also peeled off at this time, the deposits are not collected in the pores of the foam unlike the resin foams used conventionally. , Cleaning on a fresh surface is always possible. In addition, good cleaning performance can be obtained over a long period of time without scratching the surface of the charging roller.

  Among the resin foams showing the above physical property values, melamine resin foam is particularly preferable. Since the foam formed of the melamine resin has a hard mesh-like fiber, the deposit on the charging roller 8 can be easily scraped off or caught off. As described above, since the cleaning performance is excellent and the above-described fragile property is exhibited, the fresh surface of the cleaning roller 7 is always in contact with the surface of the charging roller 8 and the good cleaning performance can be maintained. In particular, the use of a melamine resin foam increases the efficiency of removing deposits such as toner adhering to the charging roller, and can prevent the occurrence of abnormal images. Since the charging roller 8 and the cleaning roller 7 are separated from each other at the start of use of the developing device and come into contact after a certain period of time, the toner recovery capability of the melamine resin foam does not saturate and abnormal Increases the margin for images.

In particular, as the resin foam for the cleaning roller, it is preferable to use a melamine resin foam obtained by compressing a foamed melamine resin foam by 20 to 40% by volume. A melamine resin foam obtained by compressing a foamed melamine resin foam by 20 to 40% by volume can reduce the diameter of bubbles generated at the time of the first foaming by compression, thereby preventing the occurrence of uneven cleaning on the surface of the charging roller. The cleaning device of the present invention described above includes at least a photosensitive member and a charging unit, and further includes an arbitrary unit selected from a developing roller and a photosensitive member cleaning device, and integrally supports the image. It can be used for a developing device and a process cartridge as shown in FIG. In the developing device or the process cartridge of the present invention, the cleaning device of the present invention is provided to appropriately clean the surface of the charging roller and maintain the charging uniformity. Further, the charging performance of the charging roller is not impaired until the life of the developing device or the process cartridge comes.

  The image forming apparatus equipped with the cleaning device of the present invention is not limited to the configuration shown in FIG. 7, but includes a configuration including an intermediate transfer body that once transfers and carries the toner image on the photoreceptor 1, and forms a multicolor image. In order to achieve this, a configuration including a plurality of photoconductors may be employed.

  The image recording body formed by the image forming apparatus using the cleaning method of the present invention should be a clear image recording body free of scratches such as background stains and streaks on the image recorded on the surface of a recording substrate such as paper. Can do.

  Although the embodiments of the present invention have been specifically described above, the present invention is not limited to these embodiments, and the embodiments of the present invention are within the spirit and scope of the present invention. Changes or modifications can be made without departing.

Sectional view around the charging roller of the image forming apparatus The perspective view showing the separation state of a cleaning roller The perspective view showing the contact state of a cleaning roller Side view showing the separated state of the cleaning roller Side view showing the contact state of the cleaning roller Schematic diagram showing the operating status of other cleaning rollers Cross section of image forming apparatus Cross section of process cartridge (developing device)

Explanation of symbols

1: Photoconductor 2: Fur brush 3: Waste toner conveying coil 4: Lubricating material 5: Lubricating material pressing spring 6: Cleaning blade 7: Cleaning roller 8: Charging roller 9: Holding member 10: Spring 11: Cleaning Roller shaft 12: Charging roller shaft 13: Spring 14: Charging roller bearing 15: Hook 16: Cleaning roller control rod 17: Holding member 18: Spring 19: Support point 20: Sensor 21: Support point 30: Developing device (process cartridge) )
31: transfer belt 32: fixing device 33: exposure means 34: developing roller 40: recording substrate storage unit 50: image reading unit 100: image forming apparatus

Claims (16)

  An electrophotographic system comprising at least a photoconductor, a charging roller for charging the surface of the photoconductor, a developing roller for developing a latent image formed on the surface of the photoconductor, and a photoconductor cleaning device for cleaning the surface of the photoconductor A developing device comprising: a cleaning roller that cleans the charging roller; and a cleaning roller holding member that is disposed so as to be in contact with and away from the charging roller.   The cleaning device according to claim 1, further comprising a pressing unit that presses the cleaning roller against the charging roller.   An operation time detecting means for detecting an operation time of the developing device, and a cleaning roller control means for bringing the cleaning roller into contact with the charging roller according to a predetermined operation time detected by the operation time detecting means. Item 3. The cleaning device according to Item 1 or 2.   The cleaning device according to any one of claims 1 to 3, wherein the cleaning roller is provided with a melamine resin foam layer on an outer periphery of a cored bar.   The cleaning device according to claim 4, wherein the melamine resin foam layer is made of a melamine resin foam obtained by compressing a once-foamed melamine resin foam and reducing the volume by 20 to 40% by volume.   At least a photoconductor, a charging roller for charging the surface of the photoconductor, a developing roller for developing a latent image formed on the surface of the photoconductor, a photoconductor cleaning device for cleaning the photoconductor surface, and lubricating the photoconductor surface A developing device comprising a lubricity imparting means for imparting a property and the cleaning device according to any one of claims 3 to 5, wherein the lubricity imparting means includes a solid lubricity imparting material, A developing device having a lubricity imparting material consumption amount detecting means for detecting a consumption amount of the lubricity imparting material.   The developing device according to claim 6, wherein the lubricity imparting material consumption amount detecting means is a sensor that detects a size of the lubricity imparting material.   The developing device according to claim 6, wherein the lubricity imparting material consumption amount detecting means is a cleaning roller control rod that contacts the lubricity imparting material.   A process cartridge of an image forming apparatus comprising at least the developing device according to any one of claims 6 to 8.   An image forming apparatus comprising the developing device according to any one of claims 6 to 8 or the process cartridge according to claim 9.   At least the photosensitive member, a charging roller that charges the surface of the photosensitive member, a developing roller that develops a latent image formed on the surface of the photosensitive member, a photosensitive member cleaning device that cleans the photosensitive member surface, and a cleaning roller. A charging roller cleaning method in an electrophotographic developing device including a cleaning device, wherein the cleaning roller is separated from the charging roller at the beginning of operation of the developing device, and the cumulative operation time of the developing device is measured, A charging roller cleaning method for cleaning a charging roller by bringing the cleaning roller into contact with the charging roller when a cumulative operation time has elapsed.   The charging roller cleaning method according to claim 11, wherein the cumulative operation time of the developing device is replaced by the cumulative number of development times of the developing device.   The charging roller cleaning method according to claim 11, wherein the cumulative operation time of the developing device is replaced with a consumption amount of a lubricity imparting material provided in the developing device for imparting lubricity to the surface of the photoreceptor.   The cleaning of the charging roller according to any one of claims 11 to 13, wherein when the cleaning roller is brought into contact with the charging roller to clean the charging roller, the cleaning roller is rotated around the charging roller or stopped. Method.   15. The charging roller cleaning method according to claim 11, wherein the cleaning roller is swung when the cleaning roller is brought into contact with the charging roller to clean the charging roller.   At least the photosensitive member, a charging roller that charges the surface of the photosensitive member, a developing roller that develops a latent image formed on the surface of the photosensitive member, a photosensitive member cleaning device that cleans the photosensitive member surface, and a cleaning roller. An image forming apparatus having an electrophotographic developing device including a cleaning device is cleaned by the charging roller cleaning method according to claim 11 to form an image on an image recording substrate. A method for manufacturing an image recording body.

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