JP2006189651A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus equipped with a lubricant applying device capable of prolonging the service life period of a photoreceptor by stably keeping the frictional coefficient of a photoreceptor surface low and enhancing a cleaning effect. <P>SOLUTION: The lubricant applying device 20 for applying the lubricant on the photoreceptor surface is constituted of a driving roller 21, an application sleeve 22, and the solid lubricant M. The sleeve 22 is a cylindrical member made of a metal or a synthetic resin, and loosely loaded to the driving roller 21 arranged close to the photoreceptor 11, and the sleeve 22 is caught between the driving roller and the photoreceptor, and rotated following the rotation of the photoreceptor with frictional force, alternatively, rotated while having a linear velocity difference from the circumferential velocity of the photoreceptor. When the sleeve 22 comes in contact with the solid lubricant M, the outer surface is elastically deformed, and the surface of the solid lubricant is pressurized with nearly fixed pressure, irrespective of wear of the solid lubricant. The solid lubricant M on the sleeve scraped with the pressurization of the application sleeve is applied on the surface of the photoreceptor 11, then, the frictional coefficient of the photoreceptor surface is stably kept low. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus, and more particularly, to an image forming apparatus that extends the life of an image carrier and a cleaning blade by supplying a lubricant to the image carrier and improves image quality.

  2. Description of the Related Art Conventional image forming apparatuses such as electrophotographic copying machines and printers use a charging device to uniformly charge the surface of an image carrier (for example, a photosensitive drum) and expose an image on the surface to expose an image latent image. Form an image. The formed image latent image is developed with toner to form a toner image, which is transferred to a recording medium, or transferred onto an intermediate transfer member, and further transferred to a recording medium. The transferred toner image Is heated and fixed by a fixing device to form an image.

  In such an image forming apparatus, after a toner image formed on an image carrier or an intermediate transfer member (hereinafter referred to as an image carrier) is transferred to a recording medium, toner remaining on the photosensitive member is removed and cleaned. A cleaning device is provided.

  A cleaning device is widely used to scrape residual toner by bringing the cleaning blade into contact with the surface of the image carrier, but in this configuration, if the frictional force between the cleaning blade and the image carrier is large, This causes wear of the cleaning blade and abrasion of the photosensitive film on the surface of the image bearing member, and shortens the life of each member. As a countermeasure, a technique is known in which a lubricant is applied to the surface of the image carrier to reduce the coefficient of friction on the surface of the image carrier to solve the above disadvantages.

  FIG. 4 is a cross-sectional view illustrating the configuration of such a conventional image forming apparatus. The image forming apparatus 100 includes a main charger around a photoconductor 101 that is rotated at a constant speed in the direction of arrow a by a driving device (not shown). 102, an exposure device 103, a developing device 104, a transfer device 105, a lubricant application device 106, and a cleaning blade 107 are arranged. A fixing device 108 is disposed on the downstream side in the transport direction of the recording medium P after passing through the transfer device 105. The cleaning blade 107 is in contact with the surface of the photoconductor 101 at the tip thereof, and scrapes off residual toner remaining on the surface of the photoconductor.

  The image forming operation performed by the image forming apparatus 100 will be briefly described. First, the surface of the photoconductor 101 is uniformly charged by the main charger 102. Laser light emitted from the laser device of the exposure device 103 is modulated by an image signal output by reading an original image on a document table (not shown) by a scanning optical system, or an image signal output from a personal computer (not shown). The modulated laser light is projected onto the surface of the photoconductor 101 to form an image latent image.

  The latent image formed on the surface of the photoreceptor 101 is developed with the developer of the developing device 104 to form a toner image. The toner image is transferred to the recording medium P by the action of the transfer device 105 onto the recording medium P conveyed to the transfer position from a paper feeding device (not shown) at the timing when the toner image reaches the transfer position. Thereafter, the recording medium P to which the toner image is transferred is further fixed by the fixing device 108, and the image forming process is completed. Waste toner remaining on the surface of the photoreceptor 101 is cleaned and removed by the cleaning blade 107, and the next image forming operation is started.

  The lubricant application device 106 presses and scrapes the solid lubricant 110 against the application brush 112 by the pressing force of the spring 111, brings the application brush 112 to which the solid lubricant 110 has adhered into contact with the surface of the photoreceptor 101, and applies the lubricant. Although it is configured to be applied to the surface of the photosensitive member, this is a configuration for obtaining a degree of freedom in the arrangement of the cleaning device inside the image forming apparatus.

  In such a lubricant application device configured using a spring pressing force, the amount of spring displacement decreases and the pressing force decreases as the solid lubricant is gradually consumed and reduced over time. The amount of lubricant applied to the image carrier is reduced, the amount of lubricant on the surface of the image carrier is reduced, and there is a problem that the coefficient of friction on the surface of the image carrier cannot be reduced to a desired value.

  As a countermeasure, a rotating roller is arranged between the photosensitive member and the application brush, the surface roughness of the rotating roller and the pressing force for pressing the solid lubricant against the rotating roller are defined, and an appropriate amount of lubricant is always applied to the surface of the photosensitive member. Has been proposed (see Patent Document 1).

Also, in a configuration in which an application roller formed of an elastic material such as a sponge is pressed against the solid lubricant, and the solid lubricant that has been shaved off is applied to the surface of the photoreceptor, the displacement of the holder that holds the solid lubricant is detected to detect the solid lubricant. There has been proposed one that indicates that the agent has been consumed (see Patent Document 2).
Japanese Patent Laid-Open No. 9-90847. JP-A-8-146842.

  As described above, in the conventional lubricant application device using the pressing force of the spring, when the solid lubricant is consumed and reduced, the amount of spring displacement decreases and the pressing force decreases, resulting in image bearing. There is an inconvenience that the friction coefficient of the body surface cannot be reduced to a desired value, and the configuration as described above has been proposed as a countermeasure. However, the former configuration described above, that is, a rotating roller disposed between the photosensitive member and the application brush and defining the surface roughness of the rotating roller and the pressing force of the rotating roller complicates the configuration and increases the manufacturing cost. I was letting.

  Further, in the latter configuration, that is, in the case where an elastic body such as a sponge is used for the application roller, the pressing force generated with respect to the displacement is not proportional, and an excessive pressing force is generated on the image carrier. There is a disadvantage that the amount of the lubricant cannot be maintained properly.

  The present invention provides an image forming apparatus capable of maintaining an appropriate amount of the lubricant on the image carrier without requiring any special means unlike the means for solving the disadvantages of the conventional lubricant application apparatus described above. It is intended to do.

  The present invention solves the above-mentioned problems, and the invention according to claim 1 is directed to an image carrier, a cylindrical member made of an elastic material, and a solid lubricant disposed so as to contact the cylindrical member. In the image forming apparatus configured to apply the solid lubricant that comes into contact with and adheres to the cylindrical member to the surface of the image carrier through the cylindrical member, the cylindrical member is The image forming apparatus is characterized in that the surface of the solid lubricant is brought into contact with the surface of the solid lubricant with a substantially constant pressing force by a reaction force in a restoring direction based on elastic deformation caused by being pressed by the solid lubricant.

  The cylindrical member is inserted and held loosely on a driving roller arranged in parallel to the image carrier, and is sandwiched between the image carrier and the driving roller to be driven by the rotation of the image carrier. And configured to rotate.

  The cylindrical member may be a cylindrical belt made of nickel. The cylindrical member may be a cylindrical belt made of a polymer synthetic resin.

  A fatty acid metal salt is used for the solid lubricant.

  As described above, in the first aspect of the invention, the cylindrical member made of the elastic material is solid lubricated with a substantially constant pressing force by the reaction force in the restoring direction based on the elastic deformation generated by being pressed by the solid lubricant. Since the image forming apparatus is used for a long period of time and the solid lubricant gradually decreases, a substantially constant amount of solid lubricant is always attached to the cylindrical member. Since it is applied to the image carrier, it has a lubricant coating device that can stably maintain a low coefficient of friction on the surface of the image carrier for a long period of time and can enhance the cleaning effect and extend the lifetime of the photoreceptor. An image forming apparatus can be provided.

  Embodiments of the present invention will be described below. FIG. 1 is a diagram for explaining the schematic configuration of an image forming apparatus according to an embodiment of the present invention.

  In FIG. 1, an image forming apparatus 10 includes a main charger 12, an exposure device 13, a developing device 14, a transfer device 15, and a lubricant coating around a photoreceptor 11 that is rotated at a constant speed in the direction of arrow a by a driving device (not shown). An apparatus 20 and a cleaning blade 17 are arranged. A fixing device 18 is disposed on the downstream side in the transport direction of the recording medium P after passing through the transfer device 15. The tip of the cleaning blade 17 is in contact with the surface of the photoconductor 11 and scrapes off residual toner remaining on the surface of the photoconductor.

  The image forming operation by the image forming apparatus 10 will be briefly described. First, the surface of the photoconductor 11 is uniformly charged by the main charger 12. Laser light emitted from the laser device of the exposure device 13 is modulated by an image signal output by reading an original image on a document table (not shown) by a scanning optical system, or an image signal output from a personal computer (not shown). The modulated laser light is projected onto the surface of the photoconductor 11 to form an image latent image.

  The latent image formed on the surface of the photoconductor 11 is developed with the developer of the developing device 14 to form a toner image. The toner image is transferred to the recording medium P by the action of the transfer device 15 onto the recording medium P transported from the paper feeding device (not shown) to the transfer position in accordance with the timing at which the toner image reaches the transfer position. Thereafter, the recording medium P on which the toner image is transferred is further fixed by the fixing device 18 and the image forming process is completed. Waste toner remaining on the surface of the photoconductor 11 is cleaned and removed by the cleaning blade 17, and the process proceeds to the next image forming operation.

  The lubricant application device will be described. First, the characteristics of the application sleeve will be described. The application sleeve is constituted by a cylindrical film made of a metal material or a synthetic resin material. In this configuration, the application sleeve maintains a cylindrical shape in a state where no external force is applied, but when pressed by another member (for example, a solid lubricant), a reaction force that elastically deforms and tries to restore the original shape, That is, a pressing force toward the solid lubricant is generated.

  As shown in FIG. 3, the reaction force of the coating sleeve, that is, the pressing force toward the solid lubricant, is not proportional to the displacement, and in the region where the displacement is large (the region indicated by S in FIG. 3). The pressing force becomes saturated with respect to the displacement, and the pressing force hardly changes even if the displacement increases.

  The lubricant application device of the image forming apparatus according to the present invention utilizes the above-described characteristics of the application sleeve. Even if the solid lubricant is scraped off by the application sleeve and becomes gradually smaller, the displacement amount of the application sleeve increases. Used in the above-described region S where the pressing force hardly changes. As a result, the amount of solid lubricant that adheres to the coating sleeve does not decrease and the amount of solid lubricant applied to the surface of the photoconductor even if the solid lubricant is scraped off by the coating sleeve and gradually decreases with time. Can always be maintained within a certain range.

  FIG. 2 is a cross-sectional view illustrating the configuration of the lubricant application device 20. The lubricant application device 20 includes a drive roller 21, an application sleeve 22, and a solid lubricant M, and is disposed on the downstream side in the rotation direction of the photoconductor 11 when viewed from the transfer device 15. The solid lubricant M is attached to the housing 29 of the apparatus by an appropriate means.

  The coating sleeve 22 is a cylindrical film and is loosely attached to the driving roller 21, and is sandwiched between the driving roller 21 and the photosensitive member 11 disposed close to the photosensitive member 11, so that the photosensitive member 11. And the rotation of the photosensitive member 11 due to the frictional force between the photosensitive member 11 and the driving roller 21, or a linear velocity difference from the peripheral speed of the photosensitive member 11 (sliding) It is configured to rotate).

  A solid lubricant M is disposed on the opposite side of the drive roller 21 from the side facing the photoconductor 11, and the space between the photoconductor 11 and the surface of the solid lubricant M is a coating sleeve in a state where no external force is applied. It is set narrower than the diameter of 22. Since the application sleeve 22 is sandwiched between the photoconductor 11 and the driving roller 21, the application sleeve 22 is elastically deformed near the surface of the solid lubricant M, and is a reaction force to restore the original shape, that is, A pressing force toward the solid lubricant is generated.

  When the application sleeve 22 is rotated by the rotation of the photoconductor 11 and the driving roller 21, the outer surface of the application sleeve 22 is deformed by contacting the surface of the solid lubricant M, and the solid lubricant is applied by the pressing force toward the solid lubricant M. Rub the surface of M. The solid lubricant M rubbed and scraped adheres to the outer surface of the coating sleeve 22, but when the coating sleeve 22 rotates and contacts the photoreceptor 11, the solid lubricant M adhered to the outer surface of the coating sleeve 22. M is applied to the surface of the photoreceptor 11.

  In the above-described embodiment, the driving roller 21 rotates in the direction opposite to the rotation direction (arrow a direction) of the photoconductor 11 at the same peripheral speed or at a peripheral speed different from the peripheral speed of the photoconductor 11. Although configured, the drive roller 21 may not be rotated. In this case, the coating sleeve 22 is driven by the rotation of the photoconductor 11 by the frictional force with the surface of the photoconductor 11 while being affected by the frictional force with the non-rotating drive roller 21 or the linear velocity difference. Rotate while holding (sliding).

  In the above embodiment, the driving roller 21 is disposed on the photosensitive member 11 side. However, the driving roller 21 may be disposed on the solid lubricant M side.

  The material of the application sleeve 22 may be any material as long as it has a low permanent set, is easily processed, and has a high elasticity that generates a restoring force against deformation caused by an external force. Specifically, nickel can be used for metal materials, and synthetic resin materials include crystalline resins such as polyimide, polyamide, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), modified polyphenylene ether (modified PPE), polycarbonate. Non-crystalline resins, etc. are added to these resins, and if necessary, for example, in the case of imparting conductivity or controlling the surface roughness, various additives, fillers, etc. are added. And

  When nickel, which is a metal material, is used, the application sleeve is a nickel sleeve. When a synthetic resin material is used, the application sleeve is a synthetic resin sleeve. Scraping performance and imparting performance to the photoreceptor 11 are required, and a surface roughness in the range of Ra 0.01 to 1.0 in terms of the centerline surface roughness is suitable for satisfying the above performance. In consideration of durability and workability, the film thickness is suitably 30 μm to 200 μm.

  The solid lubricant M is required to be chemically inert and thermally stable in addition to the property of low surface energy. Specifically, higher fatty acid metal salts (so-called metal soaps) such as zinc stearate (ST-Zn), magnesium stearate (ST-Mg), calcium stearate (ST-Ca), PTFE, ETFE, polyvinylidene fluoride, etc. Those obtained by solidifying a fluorine-based polymer can be used.

  The lubricant coating device and the image forming apparatus including the lubricant coating device according to the present invention have been described above. The lubricant coating device according to the present invention includes a monochrome image forming device, a color image forming device, a printer, and a FAX. Needless to say, the present invention can be applied to any of a multifunction machine having a printer function and a FAX function. .

  An image forming apparatus capable of extending the lifetime of the image carrier by maintaining the amount of lubricant applied to the surface of the image carrier within a certain range while removing waste toner remaining on the image carrier by a cleaning blade It is.

1 is a diagram illustrating an outline of a configuration of an image forming apparatus according to an embodiment of the invention. Sectional drawing explaining the structure of a lubricant coating device. The figure explaining the relationship between the displacement of an application sleeve, and pressing force. Sectional drawing explaining the structure of the conventional image forming apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 11 Image carrier (photosensitive body)
DESCRIPTION OF SYMBOLS 12 Main charger 13 Exposure apparatus 14 Developing apparatus 15 Transfer apparatus 17 Cleaning blade 18 Fixing apparatus 20 Lubricant coating apparatus 21 Driving roller 22 Coating sleeve 29 Housing M Solid lubricant

Claims (5)

An image carrier, a cylindrical member made of an elastic material, and a solid lubricant disposed so as to contact the cylindrical member, and the solid lubricant adhered to and attached to the cylindrical member is In the image forming apparatus configured to be applied to the surface of the image carrier through a cylindrical member,
2. The image forming apparatus according to claim 1, wherein the cylindrical member contacts the surface of the solid lubricant with a substantially constant pressing force by a reaction force in a restoring direction based on elastic deformation caused by being pressed by the solid lubricant. The cylindrical member is inserted and held loosely on a driving roller arranged in parallel to the image carrier, and is sandwiched between the image carrier and the driving roller to be driven by the rotation of the image carrier. The image forming apparatus according to claim 1, wherein the image forming apparatus rotates. The image forming apparatus according to claim 1, wherein the cylindrical member is a cylindrical belt made of nickel. The image forming apparatus according to claim 1, wherein the cylindrical member is a cylindrical belt made of a synthetic polymer resin. The image forming apparatus according to claim 1, wherein the solid lubricant is a fatty acid metal salt.

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