JP2015141224A - Rubbing member, protective layer forming apparatus, process cartridge, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubbing member configured to prevent deterioration for a long time.SOLUTION: An image forming apparatus 100 forms a toner image on an outer peripheral surface 3a (image formation surface) of a photoreceptor drum 3, and transfers the toner image to a sheet for fixation. The image forming apparatus 100 includes a protective agent leveling member 72 (rubbing member) which rubs the outer peripheral surface 3a (image formation surface) of the photoreceptor drum 3 with a protective agent applied thereto, to level the protective agent, and forms a protective agent layer on the outer peripheral surface 3a (image formation surface) of the photoreceptor drum 3. The protective agent leveling member 72 includes a curved surface 72a-2 projecting toward the outer peripheral surface 3a (image formation surface), formed in substantially parallel with a width direction of the outer peripheral surface 3a (image formation surface) of the photoreceptor drum 3, along a circulation direction of the outer peripheral surface 3a (image formation surface). The curved surface 72a-2 is in contact with the outer peripheral surface 3a (image formation surface) of the photoreceptor drum 3, in the width direction, across the full width thereof.

Description

  The present invention relates to a rubbing member for rubbing an image forming surface of a photosensitive drum or an intermediate transfer belt of an image forming apparatus for cleaning or forming a protective layer, and a protective layer forming apparatus provided with such a rubbing member, The present invention relates to a process cartridge and an image forming apparatus.

  In an image forming apparatus using a so-called electrophotographic process, an electric charge is applied to the outer peripheral surface of a photosensitive drum by discharge to charge the outer peripheral surface, and the charged outer peripheral surface is exposed to form an electrostatic latent image. The electrostatic latent image is developed with toner, and the formed toner image is directly transferred onto a sheet or transferred via an intermediate transfer belt, and then fixed and discharged. Since deposits such as untransferred toner remain on the image forming surface such as the outer peripheral surface of the photosensitive drum or the intermediate transfer belt after the transfer, the image forming surface is not adversely affected by the next image formation. The image forming surface is cleaned by a cleaning member that rubs and is prepared for the next image formation.

  Here, when the outer peripheral surface of the photosensitive drum is charged, electrical stress is applied to the photosensitive drum, and the state of the outer peripheral surface of the photosensitive drum may be changed greatly. This electrical stress is particularly prominent in the contact charging method and the proximity charging method with a discharge phenomenon in the vicinity of the outer peripheral surface of the photosensitive drum. In these charging methods, many active species and reaction products are generated on the outer peripheral surface of the photosensitive drum, and active species and reaction products generated in the atmosphere in the discharge area are adsorbed on the outer peripheral surface of the photosensitive drum. There are things to do. When such adsorption occurs, the adhesion force of the outer peripheral surface of the photosensitive drum is increased, the cleaning performance by the cleaning member is lowered, and foreign matter adhesion (filming) is likely to occur. In particular, in the charging method in which the AC component is superimposed on the DC component, the influence on the material in the surface layer of the photosensitive drum is large, and the molecular weight is decreased by the resin molecular chain breakage, the degree of entanglement of the polymer chain is decreased, the resin is evaporated, etc. Chemical degradation may occur. Under such circumstances, when the outer peripheral surface of the photosensitive drum is mechanically rubbed by the cleaning member, the wear of the photosensitive drum is further promoted.

  As a cleaning member, a cleaning blade made of an elastic material such as rubber or a cleaning brush formed of a fiber made of synthetic resin in a brush shape is rubbed against the outer peripheral surface of the photosensitive drum to remove deposits from the outer peripheral surface of the photosensitive drum. What is removed is generally known. However, such a cleaning member also wears over time. The wear of the cleaning member causes a decrease in cleaning performance, and as a result, adhesion of foreign matter (filming) to the outer peripheral surface of the photosensitive drum is likely to occur.

  Therefore, in order to prevent chemical deterioration of the photosensitive drum, and to reduce frictional resistance acting between the photosensitive drum and the cleaning member to prevent abrasion due to rubbing of the photosensitive drum and the cleaning member. A technique such as applying a protective agent to the outer peripheral surface of the body drum is employed. If the amount of the protective agent applied to the outer peripheral surface of the photosensitive drum is too small, uneven coating may occur, resulting in poor cleaning in a portion where the protective agent is not sufficiently applied, and wear of the cleaning member progressing. There is a fear. On the other hand, if the amount of the protective agent is too large, a space for arranging the protective agent becomes large due to, for example, an increase in the size of the solid protective agent, which may increase the size of the machine. In addition, the protective agent may contaminate the surface of the charging roller that is close to or in contact with the outer peripheral surface of the photosensitive drum, so that uniform charging may not be performed and a streak-like image defect may be caused. Therefore, it is important to apply an appropriate amount of protective agent to the outer peripheral surface of the photosensitive drum.

  Therefore, in order to apply an appropriate amount of the protective agent to the outer peripheral surface of the photosensitive drum, for example, it has been proposed to define the density of the fibers of the brush roller to which the protective agent is applied (for example, Patent Document 1, 2). In these Patent Documents 1 and 2, in addition to the regulation of the fiber density of the brush roller, a pressurizing member that pressurizes the solid protective agent on the brush roller side is provided to regulate the pressure, or the photosensitive drum of the brush roller Proposals have also been made to regulate the amount of biting into the outer peripheral surface. Further, in order to optimize the coating amount of the protective agent on the outer peripheral surface of the photosensitive drum, a method for controlling the coating amount of the protective agent based on image data information has been proposed (for example, see Patent Document 3). ).

  Incidentally, in recent years, there has been an increasing demand for higher image quality, and in order to realize particularly high-definition color image formation, the toner has been reduced in particle size and spheroidized. The reproducibility of dots is improved by reducing the particle size, and the developability and transferability can be improved by making the particles spherical. Since it is very difficult to produce such a small particle size and spherical toner by the conventional kneading and pulverization method, the polymerization produced by suspension polymerization method, emulsion polymerization method, dispersion polymerization method, etc. Toner is being adopted.

  However, when a toner having a spherical shape or a small particle size is used, some problems may occur in cleaning the adhered matter such as residual toner attached to the outer peripheral surface of the photosensitive drum after transfer. One of them is that it is difficult to clean a toner having a spherical shape and a small particle size with a cleaning blade generally used as a cleaning member. The cleaning blade removes toner while rubbing the outer peripheral surface of the photosensitive drum, but the edge portion of the cleaning blade may be deformed due to frictional resistance with the outer peripheral surface of the photosensitive drum. When such deformation occurs, a minute space is generated between the outer peripheral surface of the photosensitive drum and the cleaning blade. The smaller the toner particle size, the easier it is to enter this space. The closer the toner that has entered the shape is, the easier it is to roll and the lower the frictional force. Such toner enters the space between the outer peripheral surface of the photosensitive drum and the cleaning blade and rolls, and eventually the toner may slip through the cleaning blade. For this reason, the toner having a spherical shape and a reduced particle size tends to easily cause a cleaning failure.

  As a countermeasure for preventing such a cleaning failure, a method of increasing the contact pressure of the cleaning blade to the outer peripheral surface of the photosensitive drum is taken. For example, a method has been proposed in which the surface pressure on the outer peripheral surface of the photosensitive drum of the cleaning blade is increased by making the ridge line portion of the tip edge portion in contact with the outer peripheral surface of the photosensitive drum in the cleaning blade an obtuse shape (for example, , See Patent Document 4). However, the frictional force between the outer peripheral surface of the photosensitive drum and the cleaning blade increases due to the increase in surface pressure. As a result, the wear of the photosensitive drum and the cleaning blade may easily progress. Further, when the above-described surface pressure is high, stick-slip in which the cleaning blade vibrates irregularly is likely to occur, and blade squeal due to stick-slip and blade turn-up are likely to occur. Also from the viewpoint of suppressing the occurrence of such stick-slip, it is important to apply an appropriate amount of a protective agent to the outer peripheral surface of the photosensitive drum.

  Here, even when an appropriate amount of protective agent is applied to the outer peripheral surface of the photosensitive drum, the following situation may occur when the layer is not uniformly thinned. That is, in such a case, the static friction coefficient μ is not uniform on the outer peripheral surface of the photosensitive drum. Therefore, the transfer of the toner image is not performed well, and various image abnormalities such as a void in the image portion called “worm bite” and a spot-like white dropout in the image portion called “Bosseki” occur. There is.

  The following two patterns are conceivable for the order of the two treatments of applying the protective agent and cleaning the deposits after the transfer. That is, there are two patterns: a post-application cleaning relationship where the protective agent is applied first and cleaning is later, and a post-cleaning application relationship where the cleaning is applied first and the protective agent is applied later. In these two patterns, the above-mentioned image abnormality occurrence mechanism is different as follows.

  In the post-application cleaning, a protective agent is applied to the outer peripheral surface of the photosensitive drum in which toner remains before being removed by the cleaning member. Here, on the outer peripheral surface of the photoconductive drum, a portion on which the toner forming the toner image is placed has a larger amount of deposits typified by residual toner after transfer to the transfer material than other portions. ing. When cleaning is performed after application of the protective agent, for such a portion where the amount of adhered matter is large, an application member such as an application brush for applying the protective agent applies the protective agent once applied to the toner. May be scraped off together. Furthermore, a cleaning member that performs cleaning after application may scrape the protective agent together with the toner. As a result, the applied amount of the protective agent on the outer peripheral surface of the photosensitive drum after cleaning becomes uneven. If a uniform protective agent layer cannot be formed on the outer peripheral surface of the photosensitive drum, the static friction coefficient μ of the outer peripheral surface is biased. In some cases, the static friction coefficient μ of the outer peripheral surface may not be low enough to transfer the toner image formed again after application of the protective agent. As a result, uneven transfer may occur, and various image abnormalities such as insect erosion and blurring may occur.

  In the post-cleaning application, the applied protective agent is not scraped off with the toner by the application member or the cleaning member, so that the situation that may occur in the post-application cleaning described above is avoided. However, if the protective agent is simply applied to the outer peripheral surface of the photosensitive drum and a uniform protective agent layer cannot be formed, the protective agent may be a granular lump on the outer peripheral surface of the photosensitive drum. is there. When such a lump of protective agent passes directly under the charging member as the photosensitive drum rotates, the protective agent may adhere to the charging member and contaminate the charging member. The contamination of the charging member causes non-uniform charging on the outer peripheral surface of the photosensitive drum, and as a result, various image abnormalities such as worm biting and vomit occur on the toner image itself formed on the outer peripheral surface of the photosensitive drum. Sometimes. In addition, if a uniform protective agent layer cannot be formed on the outer peripheral surface of the photosensitive drum, the static friction coefficient μ of the outer peripheral surface may not be uniform, or may not be low enough to transfer the toner image. There is. As a result, uneven transfer may occur, and various image abnormalities such as insect erosion and blurring may occur.

  Therefore, in order to form a uniform protective agent layer on the outer peripheral surface of the photoconductor drum, a protective agent leveling member that uniformly levels the protective agent after application is provided separately from the protective agent application member that applies the protective agent. Has been proposed (see Patent Documents 5 to 7).

  FIG. 4 is a view showing an example of a conventional protective agent leveling member. In FIG. 4, a protective layer forming apparatus 500 having a conventional protective agent leveling member 520 is shown together with a photosensitive drum 550 and a cleaning member 560 that rotate in the rotational direction indicated by the arrow AD1 in FIG. ing. The protective layer forming apparatus 500 includes a protective agent application member 510 and a protective agent leveling member 520.

  The cleaning member 560 includes a cleaning blade 561 and a blade holding member 562. The blade holding member 562 is fixed to the case 501 of the protective layer forming apparatus 500. The cleaning blade 561 is cantilevered by the blade holding member 562, and its free end abuts against the surface of the photosensitive drum 550 from the counter direction with respect to the movement direction of the outer peripheral surface 551 of the photosensitive drum 550 after transfer. Then, the cleaning blade 561 rubs the outer peripheral surface 551 of the photosensitive drum 550 after the transfer, and removes the deposits represented by the residual toner remaining on the outer peripheral surface 551.

  The protective agent application member 510 includes a brush roller 511, a solid protective agent 512, and a pressure member 513. The brush roller 511 is housed in the case 501 so that the hair tip is pressed against the photosensitive drum 550 at a position downstream of the cleaning member 560 in the rotation direction of the photosensitive drum 550. The brush roller 511 is rotationally driven in a rotational direction opposite to the rotational direction of the photosensitive drum 550, as indicated by an arrow AD2 in FIG. The solid protective agent 512 has a rectangular parallelepiped shape extending substantially parallel to the rotation axis of the brush roller 511, and is pressed against the brush roller 511 by a pressure member 513 from the side opposite to the photosensitive drum 550 side. . The pressure member 513 is a compression spring. The brush roller 511 rotates in the direction of the arrow AD2 to scrape off the protective agent from the solid protective agent 512 and apply the scraped protective agent to the outer peripheral surface 551 of the photosensitive drum 550 after cleaning by the cleaning member 560. .

The protective agent leveling member 520 includes a blade 521 and a holding member 522. The blade 521 is disposed at a position downstream of the protective agent applying member 510 in the rotation direction of the photosensitive drum 550. The blade 521 is provided on the outer peripheral surface 551 of the photosensitive drum 550.
In addition, it is fixed to the case 501 via the holding member 522 so that the leading edge portion 521a abuts from the trailing direction with respect to the rotational direction. When the photosensitive drum 550 after application of the protective agent rotates in the direction of the arrow AD1 and the outer peripheral surface 551 on which the protective agent is applied passes directly below the front edge portion 521a, the blade 521 has a front edge portion 521a. Evenly protect the agent. As a result, a uniform protective agent layer is formed on the outer peripheral surface 551 of the photosensitive drum 550.

  FIG. 5 is a view showing another example of a conventional protective agent leveling member. The protective layer forming apparatus 600 having the protective agent leveling member 610 of this other example is different from the protective layer forming apparatus 500 shown in FIG. 4 only in the protective agent leveling member 610. Therefore, in FIG. 5, components equivalent to the components of the protective layer forming apparatus 500 shown in FIG. 4 are denoted by the same reference numerals as those in FIG. 4. The duplicate description of is omitted.

  This other protective agent leveling member 610 also has a blade 611 and a holding member 612. In this alternative example, the blade 611 has a tip edge portion 611 a that is in contact with the outer peripheral surface 551 of the photosensitive drum 550 from the counter direction with respect to the rotation direction. Further, the leading edge portion 611 a of the blade 611 has an obtuse angled ridge portion, and the obtuse angled leading edge portion 611 a is in contact with the outer peripheral surface 551 of the photosensitive drum 550.

  Also in this other example, when the outer peripheral surface 511 of the photosensitive drum 550 to which the protective agent is applied passes immediately below the front edge portion 611a of the blade 611, the front edge portion 611a uniformly equalizes the protective agent. As a result, a uniform protective agent layer is formed on the outer peripheral surface 511 of the photosensitive drum 550.

  Each of the conventional protective agent leveling members as described with reference to FIGS. 4 and 5 has a blade, and its leading edge is in contact with the outer peripheral surface of the photosensitive drum. Therefore, in such a conventional protective agent leveling member, the leading edge portion of the blade is easily drawn in the rotation direction of the photosensitive drum. Further, in such a conventional protective agent leveling member, only the tip edge portion of the blade is in contact with the outer peripheral surface of the photosensitive drum, and therefore, a stick slip in which the tip edge portion vibrates irregularly occurs. It has become easier. When the leading edge or the stick slip occurs, the protective agent leveling member may deteriorate over time, such as blade wear or sag. When the protective agent leveling member deteriorates, the protective agent layer becomes non-uniform, and there is a possibility that image abnormalities such as the above-mentioned worm-eaten and vomits may occur.

  Heretofore, the deterioration due to pull-in or stick-slip has been described by taking the protective agent leveling member of the protective layer forming apparatus that forms the protective agent layer on the outer peripheral surface of the photosensitive drum as an example. However, such deterioration is not limited to the protective agent leveling member. For example, a protective agent layer may be formed on the outer peripheral surface of an intermediate transfer belt on which a toner image is formed by primary transfer of the toner image from a photosensitive drum. In such a case, the same deterioration may occur in the protective agent leveling member of the protective layer forming apparatus that forms the protective agent layer on the outer peripheral surface of the intermediate transfer belt. Further, not only such a protective agent leveling member, but also a cleaning member that rubs an image forming surface such as the outer peripheral surface of a photosensitive drum or an intermediate transfer belt for cleaning is deteriorated due to pull-in or stick-slip. obtain. That is, such deterioration may occur in a rubbing member that rubs the image forming surface.

  Then, this invention makes it a subject to provide the rubbing member which can suppress deterioration over a long term.

  In order to solve the above-described problem, the invention according to claim 1 is an image forming method in which a toner image is formed on an image forming surface having a predetermined width and circulated, and the toner image is transferred to a sheet and fixed on the sheet. Mounted in the apparatus to rub the image forming surface after transfer of the toner image to remove deposits from the image forming surface or to protect the image forming surface and lubricate the image forming surface In the rubbing member for rubbing the image forming surface on which the protective agent for imparting the property is applied to level the protective agent and forming the protective agent layer on the image forming surface, the image formation A curved surface that extends substantially parallel to the width direction of the surface and is curved toward the image forming surface along the circulation movement direction of the image forming surface, and the curved surface forms the image in the width direction. The rubbing member is characterized by being in contact with the surface over the entire width.

  According to the first aspect of the present invention, the curved surface of the rubbing member, which is curved convexly toward the image forming surface along the circulation movement direction of the image forming surface, is provided on the image forming surface in the width direction. Abuts across the entire width of the image forming surface. For this reason, for example, as described with reference to FIGS. 4 and 5, the leading edge portion of the blade is retracted as compared with a conventional rubbing member such as a protective agent leveling member in contact with the outer peripheral surface of the photosensitive drum. And stick-slip are suppressed. As a result, deterioration such as wear and sag of the rubbing member is suppressed over a long period of time. That is, according to the first aspect of the present invention, deterioration of the rubbing member can be suppressed over a long period of time.

1 is a schematic configuration diagram illustrating a configuration of an image forming apparatus according to an exemplary embodiment of the present invention. FIG. 3 is an enlarged configuration diagram showing a configuration of a process cartridge. It is a figure which shows a protective layer forming apparatus with a photoreceptor drum and a cleaning member. It is a figure which shows an example of the conventional protective agent leveling member. It is a figure which shows another example of the conventional protective agent leveling member.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  Hereinafter, an image forming apparatus according to an embodiment of the present invention will be described. First, a basic configuration of the image forming apparatus will be described. FIG. 1 is a schematic configuration diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus 100 includes a printer unit 1, a paper feed unit 10, and a document conveyance reading unit 20. The document conveying / reading unit 20 includes a scanner 21 serving as a document reading device fixed on the printer unit 1 and an ADF 22 serving as a document conveying device supported by the scanner 21.

  The printer unit 1 includes four process cartridges 2Y, 2M, 2C, and 2K for forming yellow (Y), magenta (M), cyan (C), and black (K) toner images. The process cartridges 2Y, 2M, 2C, and 2K for the respective colors are detachably attached to the casing 100a of the image forming apparatus 100. Each of these four process cartridges 2Y, 2M, 2C, and 2K corresponds to an example of a process cartridge according to the present invention.

  The process cartridges 2Y, 2M, 2C, and 2K for the respective colors have photosensitive drums 3Y, 3M, 3C, and 3K arranged at a predetermined pitch above the intermediate transfer belt 41 that is rotationally driven in the direction of the arrow in the drawing. ing. A toner image based on Y, M, C, and K image information is formed on the photosensitive drums 3Y, 3M, 3C, and 3K for each color as described later.

  Above the process cartridges 2Y, 2M, 2C, and 2K, an optical writing unit 30 serving as a latent image forming unit is provided. The optical writing unit 30 includes a laser diode, a polygon mirror, various lenses, and the like. The optical writing unit 30 drives the laser diode based on image information read by the scanner 21 or image information sent from an external personal computer. The optical writing unit 30 optically scans the photosensitive drums 3Y, 3M, 3C, and 3K of the process cartridges 2Y, 2M, 2C, and 2K. Specifically, the optical writing unit 30 deflects the laser light L in the direction of the rotation axis of the photosensitive member, respectively, with respect to the photosensitive drums 3Y, 3M, 3C, and 3K that are driven to rotate counterclockwise in the drawing. The light scanning process is performed by irradiating. Thereby, electrostatic latent images based on image information of each color of Y, M, C, and K are formed on the photosensitive drums 3Y, 3M, 3C, and 3K.

  Below the process cartridges 2Y, 2M, 2C, and 2K, an intermediate transfer unit 40 serving as a transfer unit is disposed. The intermediate transfer unit 40 includes an intermediate transfer belt 41 that is stretched and rotated by a plurality of rollers. The intermediate transfer belt 41 is an endless belt made of a heat-resistant material such as polyimide or polyamide and made of a base adjusted to a medium resistance. Then, the intermediate transfer unit 40 forms a primary transfer nip by sandwiching the intermediate transfer belt between the photosensitive drums 3Y, 3M, 3C, and 3K and primary transfer rollers 42Y, 42M, 42C, and 42K to which a predetermined voltage is applied. To do. Further, the intermediate transfer unit 40 forms a secondary transfer nip by sandwiching the intermediate transfer belt 41 between the secondary transfer backup roller 43 and the secondary transfer roller 44 to which a predetermined voltage is applied. Further, the intermediate transfer unit 40 includes a cleaning device 45 that removes transfer residual toner remaining on the intermediate transfer belt 41. The toner images on the photosensitive drums 3Y, 3M, 3C, and 3K formed by the process cartridges 2Y, 2M, 2C, and 2K are transferred to the intermediate transfer belt 41 at the primary transfer nip. The toner image transferred onto the intermediate transfer belt 41 is transferred to a sheet as a transfer medium at the secondary transfer nip. The residual transfer toner remaining on the intermediate transfer belt 41 after passing through the secondary transfer nip is removed by the cleaning device 45.

  Below the intermediate transfer unit 40, there are a first receiving branch path 52, a receiving and conveying roller pair 53, a second receiving and branching path 54, a manual separation roller pair 55, a pre-transfer conveying path 56, a registration roller pair 57, and a conveying belt unit 58. A switchback device 59 is arranged. These components form a conveyance path for paper fed from the paper feed unit 10 or the manual feed tray 51.

  A fixing device 60 is disposed below the intermediate transfer unit 40. In the fixing device 60, a fixing nip is formed between the fixing belt 61 and the pressure roller 62. The sheet on which the full-color toner image is transferred at the secondary transfer nip is conveyed into the fixing device 60 by the conveying belt unit 58, and the toner image is fixed by pressure and heat received at the fixing nip. The sheet on which the toner image is fixed is sent out toward the paper discharge roller pair 63.

  In the single-sided print mode in which an image is formed only on the first surface of the paper P, the paper P sandwiched between the paper discharge nips between the rollers of the paper discharge roller pair 63 is directly discharged out of the apparatus and discharged into the paper discharge tray 64. Stacked on top. In the double-sided print mode in which images are formed on both sides of the paper P, the paper P sandwiched in the paper discharge nip is returned in the reverse direction and enters the switchback device 59. Then, after being turned upside down in the switchback device 59, it is sent again to the secondary transfer nip, and the other side of the image is subjected to image secondary transfer processing and fixing processing.

  The paper feed unit 10 includes four paper feed cassettes 12, paper feed rollers 13, a separation roller pair 14, a paper feed path 15, and a transport roller pair 16 arranged in four stages in a paper bank 11. The paper feeding unit 10 rotates the paper feeding roller 13 based on a control signal from the printer unit 1 to separate the uppermost paper P in the paper bundle in the paper feeding cassette 12 into the separation roller pair 14. To send. The paper P that has been separated into one sheet by the separation roller pair 14 and then sent to the paper feed path 15 passes through the transport nips of the plurality of transport roller pairs 16 provided in the paper feed path 15, and the printer unit 1. To the first receiving branch 52.

  A pre-transfer conveyance path 56 for conveying the sheet P immediately before the secondary transfer nip branches into a first reception branch path 52 and a second reception branch path 54 on the upstream side in the sheet conveyance direction. The sheet P sent out from the sheet feeding path 15 of the sheet feeding unit 10 is received by the first receiving branch path 52 of the printer unit 1, and then the receiving transport roller pair 53 disposed in the first receiving branch path 52. Is sent to the pre-transfer conveyance path 56 via the conveyance nip. The paper P manually fed from the manual feed tray 51 is separated into one sheet by the manual separation roller pair 55, then sent out toward the second receiving branch path 54, and sent to the pre-transfer conveyance path 56.

  The scanner 21 fixed on the printer unit 1 has a fixed reading unit and a moving reading unit as reading means for reading an image of a document (not shown). A fixed reading unit having a light source, a reflection mirror, an image reading sensor such as a CCD, and the like is disposed immediately below a first contact glass (not shown) fixed to the upper wall of the casing of the scanner 21 so as to contact the document. Then, when the document conveyed by the ADF 22 passes over the first contact glass, the light emitted from the light source is sequentially reflected by the document surface, and is received by the image reading sensor via a plurality of reflection mirrors. Thus, the original is scanned without moving the optical system including the light source and the reflecting mirror.

  The moving reading unit of the scanner 21 is disposed immediately below a second contact glass (not shown) fixed to the upper wall of the casing of the scanner 21 so as to come into contact with the document, and an optical system including a light source, a reflection mirror, and the like. It can be moved in the left-right direction in the figure. Then, in the process of moving the optical system from the left side to the right side in the figure, the light emitted from the light source is reflected by a document (not shown) placed on the second contact glass and then passed through a plurality of reflecting mirrors. The image is received by an image reading sensor fixed to the scanner body. Accordingly, the original is scanned while moving the optical system.

  Next, the configuration of the process cartridges 2Y, 2M, 2C, and 2K will be described in detail. FIG. 2 is an enlarged configuration diagram showing the configuration of the process cartridge. The process cartridges 2Y, 2M, 2C, and 2K have the same configuration except that the colors of the toners used are different from each other. Therefore, the following description omits the reference numerals indicating the distinction of colors.

  The process cartridge 2 includes a charging device 4 and a developing device 5 around the photosensitive drum 3. The charging device 4 uniformly charges the outer peripheral surface 3 a of the photosensitive drum 3. The developing device 5 develops the electrostatic latent image formed on the outer peripheral surface 3 a of the photosensitive drum 3 with toner by scanning exposure of the laser light L from the optical writing unit 30.

  In the present embodiment, the outer peripheral surface 3a of the rotating photosensitive drum 3 corresponds to an example of “an image forming surface having a predetermined width and circulatingly moving” according to the present invention. The photosensitive drum 3 corresponds to an example of the image carrier referred to in the present invention. A combination of the charging device 4, the optical writing unit 30, and the developing device 5 corresponds to an example of the image forming unit referred to in the present invention. Further, the intermediate transfer unit 40 shown in FIG. 1 corresponds to an example of a transfer unit according to the present invention, and the fixing device 60 corresponds to an example of a fixing unit according to the present invention.

  Further, the process cartridge 2 has a cleaning member 6 for removing transfer residual toner attached to the outer peripheral surface 3 a of the photosensitive drum 3 around the photosensitive drum 3, and a protective agent on the outer peripheral surface 3 a of the photosensitive drum 3. And a protective layer forming apparatus 7 for forming the above layer. The cleaning member 6 corresponds to an example of the cleaning member according to the present invention, and the protective layer forming apparatus 7 corresponds to an example of the protective layer forming apparatus according to the present invention.

  The cleaning member 6 is fixed to the protective layer forming apparatus 7 as described later. The protective layer forming apparatus 7 includes a protective agent application member 71 that applies a protective agent to the outer peripheral surface 3 a of the photosensitive drum 3, and a protective agent leveling member that equalizes the protective agent applied to the outer peripheral surface 3 a of the photosensitive drum 3. 72. The protective agent application member 71 corresponds to an example of the protective agent application member according to the present invention, and the protective agent leveling member 72 corresponds to an example of the protective agent leveling member according to the present invention. In the present embodiment, the protective agent leveling member 72 also corresponds to an example of a rubbing member according to the present invention.

  The photosensitive drum 3 rotates in the rotation direction indicated by the arrow D1 in FIG. By this rotation, the outer peripheral surface 3a sequentially passes through the charging device 4, the developing device 5, the primary transfer roller 42, the cleaning member 6, and the protective layer forming device 7 in this order.

  The photoconductor drum 3 is an organic photoconductor that has a cylindrical shape and rotates in a rotation direction indicated by an arrow D1 with the central axis of the cylindrical shape as a rotation axis, and a surface protective layer is formed on the outer peripheral surface 3a with a polycarbonate-based resin. Is formed. The charging device 4 includes a charging roller 4 a configured by covering a conductive metal core with an intermediate resistance elastic layer. The charging roller 4a is connected to a power source (not shown) and is applied with a predetermined voltage. The charging roller 4 a is disposed with a small gap with respect to the photosensitive drum 3. This minute gap is caused by, for example, winding a spacer member having a certain thickness around the non-image forming regions at both ends of the charging roller 4 a to bring the surface of the spacer member into contact with the outer peripheral surface 3 a of the photosensitive drum 3. Can be set. Further, the charging device 4 is provided with a charging cleaning member 4b that cleans by contacting the surface of the charging roller 4a.

  In the developing device 5, a developing sleeve 5 a including a magnetic field generating unit is disposed at a position facing the outer peripheral surface 3 a of the photosensitive drum 3. The developing sleeve 5a rotates in the rotation direction indicated by the arrow D2. Below the developing sleeve 5a, there are provided two screws 5b for mixing toner introduced from a toner bottle (not shown) with a magnetic carrier and pumping it up to the developing sleeve 5a while stirring. The developer composed of toner and magnetic carrier pumped up by the developing sleeve 5a is regulated to a predetermined developer layer thickness by the doctor blade 5c, and is carried on the developing sleeve 5a. The surface of the developing sleeve 5a moves in the same direction at the position facing the photosensitive drum 3, while carrying and carrying the developer, and supplies toner to the latent image surface of the photosensitive drum 3 to form a toner image. In the present embodiment, the configuration of the two-component developing type developing device 5 is shown in FIG. 2, but the present invention is not limited to this, and a one-component developing type developing device can also be applied.

  The cleaning member 6 has a cleaning blade 6a and a blade holding member 6b. The blade holding member 6 b is fixed to the case 7 a of the protective layer forming device 7. The cleaning blade 6a is cantilevered by a blade holding member 6b, and the free end of the cleaning blade 6a from the counter direction with respect to the moving direction of the outer peripheral surface 3a of the photosensitive drum 3 from the outer peripheral surface 3a of the photosensitive drum 3 after transfer. Abut. Then, the cleaning blade 6a rubs the outer peripheral surface 3a of the photosensitive drum 3 after the transfer, and removes deposits represented by residual toner remaining on the outer peripheral surface 3a. The material used for the cleaning blade 6a is not particularly limited, and elastic bodies such as urethane rubber, hydrin rubber, silicone rubber, and fluorine rubber can be used singly or in a blend. Further, the contact portion of the rubber blade with the photosensitive drum 3 may be coated with a low friction material or impregnated. Further, in order to adjust the hardness of the elastic body, fillers represented by other organic fine particles and inorganic fine particles may be dispersed therein. The cleaning blade 6a is fixed to a blade holding member 6b made of metal, plastic, ceramic or the like by any method such as adhesion and fusion. In this embodiment, the cleaning blade 6a is made of an insulating rubber, but the cleaning blade 6a may be conductive. Further, instead of the cleaning blade 6a, a cleaning brush in which a bias is applied to a conductive brush having a medium resistance to a low resistance may be used.

  Next, the protective layer forming apparatus 7 will be described. FIG. 3 is a view showing the protective layer forming apparatus together with the photosensitive drum and the cleaning member. In FIG. 3, the rotation direction of the photosensitive drum 3 and the relative position of the protective layer forming apparatus 7 with respect to the cleaning member 6 are easily compared with the conventional protective layer forming apparatus shown in FIGS. 4 and 5. The position is matched with FIG. 4 and FIG. As a result, in FIG. 3 and FIG. 2, the rotation direction of the photosensitive drum 3 and the relative position with respect to the cleaning member 6 are different from each other, but these two views of the protective layer forming device 7 are substantially the same. Show. Therefore, the same reference numerals as those in FIG. 2 are given to the components in FIG. 3, and the following description will be given with reference to FIGS. 2 and 3 without particularly distinguishing them.

  As described above, the protective layer forming apparatus 7 rubs the protective agent application member 71 that applies a protective agent to the outer peripheral surface 3 a of the photosensitive drum 3 and the outer peripheral surface 3 a of the photosensitive drum 3 to which the protective agent is applied. And a protective agent leveling member 72 for leveling the protective agent. The protective agent application member 71 corresponds to an example of the protective agent application member according to the present invention, and the protective agent leveling member 72 corresponds to an example of the protective agent leveling member according to the present invention. First, the protective agent application member 71 will be described.

  The protective agent application member 71 includes a brush roller 71a, a solid protective agent 71b, and a pressure member 71c. The brush roller 71 a is accommodated in the case 7 a of the protective layer forming apparatus 7 so as to be rotatable about a rotation axis substantially parallel to the rotation axis of the photosensitive drum 3. The brush roller 71a is disposed on the downstream side of the cleaning member 6 with respect to the rotation direction of the photosensitive drum 3 (the direction of the arrow D1). The brush roller 71a is rotationally driven in a rotation direction indicated by an arrow D3 by a driving source (not shown), and rubs the outer peripheral surface 3a of the photosensitive drum 3 after the deposits are removed by the cleaning member 6. The solid protective agent 71b has a rectangular parallelepiped shape extending substantially parallel to the rotation axis of the brush roller 71a, and is pressed against the brush roller 71a from the side opposite to the photosensitive drum 3 side by a pressure member 71c. . The pressurizing member 71c is preferably a member that presses the solid protective agent 71b with a spring such as a plate spring or a compression spring, and a member using a compression spring as shown in FIGS. 2 and 3 is particularly suitable. The solid protective agent 71b is scraped off and consumed by the rotating brush roller 71a, and the thickness of the solid protective agent 71b decreases with time. However, the solid protective agent 71b is always in contact with the brush roller 71a because it is pressurized by the pressure member 3c. The brush roller 71 a applies the protective agent scraped off while rotating to the outer peripheral surface 3 a of the photosensitive drum 3. The protective agent scraped off from the solid protective agent 71b corresponds to an example of the protective agent referred to in the present invention. Further, the protective agent application member 71 may have a driving means (not shown) that swings the brush roller 71a or the solid protective agent 71b in a longitudinal direction substantially parallel to the rotation axis of the brush roller 71a. By swinging the brush roller 71a or the solid protective agent 71b, the coating unevenness is reduced and the protective agent can be applied more uniformly. The rotation direction of the brush roller 71a is preferably forward with respect to the rotation direction of the photosensitive drum 3, as indicated by an arrow D3 in FIGS. 2 and 3, but may be rotated in the reverse direction.

  The protective agent forming the solid protective agent 7b protects the outer peripheral surface 3a of the photosensitive drum 3 and imparts lubricity to the outer peripheral surface 3a. As this protective agent, it is possible to use a dry solid hydrophobic protective agent, for example, zinc stearate. In addition to zinc stearate, those having the following stearic acid groups can be used as the protective agent for forming the solid protective agent 7b. That is, barium stearate, lead stearate, iron stearate, nickel stearate, cobalt stearate, copper stearate, strontium stearate, calcium stearate, cadmium stearate, magnesium stearate and the like can be mentioned. Further, zinc oleate, manganese oleate, iron oleate, cobalt oleate, lead oleate, magnesium oleate, and copper oleate having the same fatty acid group may be used as the protective agent forming the solid protective agent 7b. Examples of those having a fatty acid group also include zinc palmitate, cobalt palmitate, copper palmitate, magnesium palmitate, aluminum palmitate, and calcium palmitate. In addition to these, as a protective agent constituting the solid protective agent 7b, metal salts of fatty acids such as lead caprylate, lead caproate, zinc linolenate, cobalt linolenate, calcium linolenate, and cadmium ricolinolenate can be used. . Furthermore, waxes such as candelilla wax, carnauba wax, rice wax, wax, ooba oil, beeswax, and lanolin can be used as the protective agent forming the solid protective agent 7b. More preferably, the protective agent contains inorganic fine particles. Examples of the fine particles include, but are not limited to, mica, boron nitride, molybdenum disulfide, tungsten disulfide, talc, kaolin, montmorillonite, calcium fluoride, and graphite. For example, boron nitride has a crystal structure in which hexagonal mesh planes in which atoms are tightly combined are stacked at wide intervals, and the layers are bonded only by weak van der Waals forces, so the layers spread easily and the direction of the hexagonal mesh planes Slippery and exhibits excellent lubricity. By mixing such fine particles with a fatty acid metal salt, it becomes easy to extend the protective agent into a thin layer. Here, the protective agent exemplified above may be cooled after melting and used as a bar-shaped solid protective agent, but in addition to that, a powdered fatty acid metal salt and inorganic fine particles are mixed and compressed into a bar shape. And may be used as a solid protective agent. Alternatively, the protective agent in powder form may be accommodated in a mesh bag, the bag may be pressed against the brush roller 71a, and the protective agent in the bag may be scraped off by the brush roller 71a.

  Next, the protective agent leveling member 72 included in the protective layer forming apparatus 7 will be described. The protective agent leveling member 72 includes a contact member 72a and a holding member 72b. As shown in FIGS. 2 and 3, the abutting member 72 a is moved by the holding member 72 b fixed to the case 7 a of the protective layer forming apparatus 7 with respect to the rotation direction of the photosensitive drum 3 (arrow D 1). It is supported at a downstream position. The abutting member 72 a is a belt-like elastic member that extends substantially in parallel with the direction in which the rotation axis of the photosensitive drum 3 extends, that is, the width direction of the outer peripheral surface 3 a of the photosensitive drum 3. A curved surface 72a-2 in which the outer surface of the contact member 72a facing the outer peripheral surface 3a side of the photosensitive drum 3 is convexly curved toward the outer peripheral surface 3a along the circulation movement direction of the outer peripheral surface 3a. It has become. In the present embodiment, the curved surface 72a-2 is along the short direction around the curved central axis 72a-1 extending substantially parallel to the rotation axis of the photosensitive drum 3, and the outer peripheral surface 3a of the photosensitive drum. Is curved convexly toward the outer circumferential surface 3a. The curved surface 72a-2 corresponds to an example of the curved surface referred to in the present invention. The curved surface 72a-2 is in contact with the outer peripheral surface 3a of the photosensitive drum 3 at the approximate center in the short side direction over the entire width in the direction in which the rotation axis of the photosensitive drum 3 extends. The protective agent applied by the protective agent applying member 71 is rubbed and smoothed by the contact member 72a that contacts the outer peripheral surface 3a of the photosensitive drum in this way, and the protective agent is applied to the outer peripheral surface 3a of the photosensitive drum. A layer is formed.

  The protective agent leveling member referred to in the present invention is not limited to the one having the belt-like contact member 72a as described above. For example, the protective agent leveling member has a roller shape, and its outer peripheral surface is the outer peripheral surface 3a of the photosensitive drum. It may be one that contacts the image forming surface.

  Here, the ratio R2 / R1 of the curvature radius R2 of the curved surface 72a-2 to the curvature radius R1 of the photosensitive drum 3 is set to be in a range of 0.08 to 1020. The curvature radius R1 of the photosensitive drum 3 corresponds to an example of “the curvature radius of the image forming surface” in the present invention. In the present embodiment, the contact line pressure in the longitudinal direction of the curved surface 72a-2 along the curved central axis 72a-1 with respect to the outer peripheral surface 3a of the photosensitive drum 3 is 0.008 N / cm or more and 72 N / cm. cm or less.

  Any method may be used to form the curved surface 72a-2 of the abutting member 72a. However, by forming the curved surface 72a-2 on the holding member 72b formed to have a curved surface with a radius of curvature R2, a uniform curve can be obtained. Surface 72a-2 can be formed. The material used for the contact member 72a is not particularly limited, and an elastic body such as urethane rubber, hydrin rubber, silicone rubber, or fluororubber can be used alone or blended in the same manner as the cleaning blade 6a. . In addition, these rubber blades may be those in which a contact portion with the photosensitive drum 3 is coated with a low friction material or impregnated. Further, in order to adjust the hardness of the elastic body, fillers represented by other organic fine particles and inorganic fine particles may be dispersed therein. The contact member 72a is fixed to the holding member 72b made of metal, plastic, ceramic, or the like by any method such as adhesion or fusion.

  According to the protective agent leveling member 72 in the protective layer forming apparatus 7 of the present embodiment described above, the curved surface of the contact surface 72a of the protective agent leveling member 72 is provided on the outer peripheral surface 3a of the photosensitive drum 3. 72a-2 abuts at the approximate center in the lateral direction. For this reason, as described with reference to FIGS. 4 and 5, for example, the leading edge portion of the blade is less brought into contact with the outer peripheral surface of the photosensitive drum, and the pulling-in and stick slip are suppressed. Is done. As a result, deterioration such as wear and sag of the protective agent leveling member 72 is suppressed over a long period of time. That is, according to the protective layer forming apparatus 7 of the present embodiment, deterioration in the protective agent leveling member 72 can be suppressed over a long period of time.

  In the present embodiment, as described above, the ratio R2 / R1 of the curvature radius R2 of the curved surface 72a-2 of the contact member 72a to the curvature radius R1 of the photosensitive drum 3 is 0.08 or more and 1020 or less. It has become. By setting the ratio R2 / R1 to 0.08 or more, the gradient in the short direction of the region of the curved surface 72a that contacts the outer peripheral surface 3a of the photosensitive drum 3 can be suppressed. As a result, the gradient in the lateral direction of the contact linear pressure on the outer peripheral surface 3a of the photosensitive drum in that region is also suppressed. Thereby, the uniform application | coating property of the protective agent in the area | region will improve. Further, by setting the above ratio R2 / R1 to 1020 or less, the width in the short direction of the region in contact with the outer peripheral surface 3a of the photosensitive drum on the curved surface 72a can be suppressed. When this region leveles the protective agent on the outer peripheral surface 3a of the photosensitive drum, the protective agent plays a role in establishing lubrication between this region and the outer peripheral surface 3a of the photosensitive drum. In this embodiment, since the width of this region is suppressed, the amount of the protective agent required to establish the above-described lubrication can be reduced. Accordingly, since the amount of the protective agent applied to the outer peripheral surface 3a of the photosensitive drum can be suppressed, filming by the protective agent itself on the outer peripheral surface 3a, adhesion of the protective agent to the charging roller 4a, and the like can be suppressed. The ratio R2 / R1 of the curvature radius R2 of the curved surface 72a-2 of the contact member 72a to the curvature radius R1 of the photosensitive drum 3 is 0.08 or more and 1020 or less as in the present embodiment. It is more preferable that it is 0.1 or more and 1000 or less. The ratio R2 / R1 is more preferably 1 or more and 100 or less.

  In the present embodiment, as described above, the contact line pressure in the longitudinal direction of the curved surface 72a-2 with respect to the outer peripheral surface 3a of the photosensitive drum 3 is 0.008 N / cm or more and 72 N / cm or less. . Thereby, the amount of the protective agent passing between the outer peripheral surface 3a and the curved surface 72a-2 of the photosensitive drum 3 is uniform, and the protective layer having an appropriate thickness is uniform while suppressing the adhesion of the protective agent to the charging roller 4a. The amount is suitable for being formed. Incidentally, the contact line pressure in the longitudinal direction of the curved surface 72a-2 with respect to the outer peripheral surface 3a of the photosensitive drum 3 is preferably 0.008 N / cm or more and 72 N / cm or less as in the present embodiment. It is more preferable that it is 0.01 N / cm or more and 70 N / cm or less. The contact linear pressure is more preferably 1 N / cm or more and 50 N / cm or less.

  In the present embodiment, the protective agent is mainly composed of zinc stearate, which is a fatty acid metal salt, and contains inorganic fine particles. By using a fatty acid metal salt as a main component, particularly zinc stearate, a good hydrophobic protective agent can be obtained. Furthermore, it becomes easy to extend the protective agent into a thin layer by containing inorganic fine particles.

  In addition, this embodiment only showed the typical form of this invention, and this invention is not limited to this embodiment. That is, those skilled in the art can implement various modifications in accordance with conventionally known knowledge without departing from the scope of the present invention. Of course, such modifications are also included in the scope of the present invention as long as they include the structures of the rubbing member, protective layer forming apparatus, process cartridge, and image forming apparatus of the present invention.

  For example, in the present embodiment, as an example of the protective layer forming apparatus according to the present invention, a protective layer forming apparatus 7 that forms a protective agent layer on the outer peripheral surface 3a of the photosensitive drum 3 is illustrated. The protective layer forming apparatus is not limited to this. The protective layer forming apparatus according to the present invention may form a protective agent layer on the outer peripheral surface of the intermediate transfer belt 41, for example. In this case, the protective layer forming device may be provided adjacent to the cleaning device 45 of the intermediate transfer belt 41 or may be provided by being incorporated in the cleaning device 45. In this case, the outer peripheral surface of the intermediate transfer belt 41 that circulates corresponds to an example of “an image forming surface that circulates with a predetermined width” according to the present invention. The intermediate transfer belt 41 corresponds to an example of an image carrier according to the present invention. The protective layer leveling member included in the protective layer forming apparatus for the intermediate transfer belt 41 corresponds to an example of the rubbing member according to the present invention. Further, as shown in FIG. 1, the radius of curvature at the contact position of the protective layer leveling member on the outer peripheral surface of the intermediate transfer belt 41 stretched around a plurality of rollers is referred to as "the above-mentioned" This corresponds to an example of “the radius of curvature of the image forming surface”. Furthermore, the protective layer forming apparatus referred to in the present invention is not limited to being provided only on either the photosensitive drum or the intermediate transfer belt, but may be provided on both the photosensitive drum and the intermediate transfer belt.

  In the present embodiment, the protective agent leveling member 72 for leveling the protective agent is exemplified as an example of the rubbing member according to the present invention, but the rubbing member according to the present invention is not limited to this. . The rubbing member referred to in the present invention may be, for example, a cleaning member that cleans the outer peripheral surface 3 a of the photosensitive drum 3 or a cleaning member that cleans the outer peripheral surface of the intermediate transfer belt 41. As described above, even when the rubbing member according to the present invention is applied to the cleaning member, the pulling-in and stick-slip of the cleaning member can be suppressed, and as a result, the deterioration of the cleaning member can be suppressed over a long period of time. .

  Next, an example in which image formation is actually performed using the image forming apparatus corresponding to the above-described embodiment will be described. In the following embodiments, the radius of curvature of the curved surface 72a-2 of the protective agent leveling member 72, the contact pressure on the outer peripheral surface 3a of the photosensitive drum, and the material of the protective agent will be specifically described. It is an example to the last and this invention is not limited to these.

(First embodiment)
In the first example, the image forming apparatus imagio MP C4500 manufactured by Ricoh Co., Ltd. was modified like the image forming apparatus 100 of the embodiment described with reference to FIGS. First, the protective agent leveling member in the protective layer forming device mounted on the image forming apparatus imagio MP C4500 manufactured by Ricoh Co., Ltd. was replaced with the protective agent leveling member 72 shown in FIGS. However, in the first embodiment, the ratio R2 / R1 of the curvature radius R2 of the curved surface 72a-2 of the protective agent leveling member 72 to the curvature radius R1 of the photosensitive drum 3 is set to “0.05”. Further, the contact line pressure in the longitudinal direction of the curved surface 72a-2 of the protective agent leveling member 72 with respect to the outer peripheral surface 3a of the photosensitive drum 3 was set to “10 N / cm”.

  Furthermore, in the first example, a protective agent in which zinc stearate was incorporated with boron nitride as inorganic fine particles was used. The compounding ratio (mass ratio) of zinc stearate and boron nitride is “9” for zinc stearate and “1” for boron nitride.

  Except for the protective agent leveling member 72 and the protective agent, the image forming apparatus of the first example was obtained using the components of the image forming apparatus imagio MP C4500 manufactured by Ricoh Co., Ltd. as they were.

(Second embodiment)
In the second embodiment, the ratio R2 / R1 of the curvature radius R2 of the curved surface 72a-2 of the protective agent leveling member 72 to the curvature radius R1 of the photosensitive drum 3 is set to “0.1”. Except for this, the image forming apparatus of the second example was obtained under the same conditions as the first example.

(Third embodiment)
In the third embodiment, the ratio R2 / R1 of the curvature radius R2 of the curved surface 72a-2 of the protective agent leveling member 72 to the curvature radius R1 of the photosensitive drum 3 is set to “1”. Except for this, the image forming apparatus of the third example was obtained under the same conditions as in the first example.

(Fourth embodiment)
In the fourth embodiment, the ratio R2 / R1 of the curvature radius R2 of the curved surface 72a-2 of the protective agent leveling member 72 to the curvature radius R1 of the photosensitive drum 3 is set to “10”. Except for this, the image forming apparatus of the fourth example was obtained under the same conditions as in the first example.

(5th Example)
In the fifth embodiment, the ratio R2 / R1 of the curvature radius R2 of the curved surface 72a-2 of the protective agent leveling member 72 to the curvature radius R1 of the photosensitive drum 3 is set to “100”. Except for this, the image forming apparatus of the fifth example was obtained under the same conditions as in the first example.

(Sixth embodiment)
In the sixth example, the ratio R2 / R1 of the radius of curvature R2 of the curved surface 72a-2 of the protective agent leveling member 72 to the radius of curvature R1 of the photosensitive drum 3 was set to “1000”. Except for this, the image forming apparatus of the sixth example was obtained under the same conditions as in the first example.

(Seventh embodiment)
In the seventh embodiment, the ratio R2 / R1 of the curvature radius R2 of the curved surface 72a-2 of the protective agent leveling member 72 to the curvature radius R1 of the photosensitive drum 3 is set to “1100”. Except for this, the image forming apparatus of the seventh example was obtained under the same conditions as in the first example.

(Eighth embodiment)
In the eighth embodiment, the ratio R2 / R1 of the curvature radius R2 of the curved surface 72a-2 of the protective agent leveling member 72 to the curvature radius R1 of the photosensitive drum 3 is set to “10”. Further, the contact line pressure in the longitudinal direction of the curved surface 72a-2 of the protective agent leveling member 72 with respect to the outer peripheral surface 3a of the photosensitive drum 3 was set to “0.005 N / cm”. Except for this, the image forming apparatus of the eighth example was obtained under the same conditions as in the first example.

(Ninth embodiment)
In the ninth embodiment, the ratio R2 / R1 of the curvature radius R2 of the curved surface 72a-2 of the protective agent leveling member 72 to the curvature radius R1 of the photosensitive drum 3 is set to “10”. Further, the contact linear pressure in the longitudinal direction of the curved surface 72a-2 of the protective agent leveling member 72 with respect to the outer peripheral surface 3a of the photosensitive drum 3 was set to "0.01 N / cm". Except for this, the image forming apparatus of the ninth example was obtained under the same conditions as in the first example.

(Tenth embodiment)
In the tenth embodiment, the ratio R2 / R1 of the curvature radius R2 of the curved surface 72a-2 of the protective agent leveling member 72 to the curvature radius R1 of the photosensitive drum 3 is set to “10”. Further, the contact line pressure in the longitudinal direction of the curved surface 72a-2 of the protective agent leveling member 72 with respect to the outer peripheral surface 3a of the photosensitive drum 3 was set to “0.1 N / cm”. Except for this, the image forming apparatus of the tenth example was obtained under the same conditions as the first example.

(Eleventh embodiment)
In the eleventh embodiment, the ratio R2 / R1 of the curvature radius R2 of the curved surface 72a-2 of the protective agent leveling member 72 to the curvature radius R1 of the photosensitive drum 3 is set to “10”. Further, the contact linear pressure in the longitudinal direction of the curved surface 72a-2 of the protective agent leveling member 72 with respect to the outer peripheral surface 3a of the photosensitive drum 3 was set to “1 N / cm”. Except for this, the image forming apparatus of the eleventh example was obtained under the same conditions as in the first example.

(Twelfth embodiment)
In the twelfth embodiment, the ratio R2 / R1 of the curvature radius R2 of the curved surface 72a-2 of the protective agent leveling member 72 to the curvature radius R1 of the photosensitive drum 3 is set to “10”. Further, the contact line pressure in the longitudinal direction of the curved surface 72a-2 of the protective agent leveling member 72 with respect to the outer peripheral surface 3a of the photosensitive drum 3 was set to “30 N / cm”. Except for this, the image forming apparatus of the twelfth example was obtained under the same conditions as the first example.

(Thirteenth embodiment)
In the thirteenth embodiment, the ratio R2 / R1 of the curvature radius R2 of the curved surface 72a-2 of the protective agent leveling member 72 to the curvature radius R1 of the photosensitive drum 3 is set to “10”. Further, the contact linear pressure in the longitudinal direction of the curved surface 72a-2 of the protective agent leveling member 72 with respect to the outer peripheral surface 3a of the photosensitive drum 3 was set to “50 N / cm”. Except for this, the image forming apparatus of the thirteenth example was obtained under the same conditions as the first example.

(14th embodiment)
In the fourteenth embodiment, the ratio R2 / R1 of the curvature radius R2 of the curved surface 72a-2 of the protective agent leveling member 72 to the curvature radius R1 of the photosensitive drum 3 is set to “10”. Further, the contact line pressure in the longitudinal direction of the curved surface 72 a-2 of the protective agent leveling member 72 with respect to the outer peripheral surface 3 a of the photosensitive drum 3 was set to “70 N / cm”. Except for this, the image forming apparatus of the fourteenth example was obtained under the same conditions as in the first example.

(15th embodiment)
In the fifteenth embodiment, the ratio R2 / R1 of the curvature radius R2 of the curved surface 72a-2 of the protective agent leveling member 72 to the curvature radius R1 of the photosensitive drum 3 is set to “10”. Further, the contact linear pressure in the longitudinal direction of the curved surface 72a-2 of the protective agent leveling member 72 with respect to the outer peripheral surface 3a of the photosensitive drum 3 was set to “80 N / cm”. Except for this, the image forming apparatus of the fifteenth example was obtained under the same conditions as in the first example.

(First comparative example)
In the first comparative example, an image forming apparatus imagio MP C4500 manufactured by Ricoh Co., Ltd. was used as it was. In this image forming apparatus imagio MP C4500, the protective agent leveling member in the protective layer forming apparatus uses a blade like the protective agent leveling member 520 in the conventional protective layer forming apparatus 500 described with reference to FIG. It has become a thing. The leading edge portion is in contact with the outer peripheral surface of the photosensitive drum. That is, in the first comparative example, like the protective agent leveling member 520 in the conventional protective layer forming apparatus 500 described with reference to FIG. 4, the leading edge portion is in the trailing direction on the outer peripheral surface of the photosensitive drum. Abut. However, in the first comparative example, the contact line pressure is adjusted to “10 N / cm”.

(Second comparative example)
In the second comparative example, an image forming apparatus imagio MP C5002 manufactured by Ricoh Co., Ltd. was used as it was. In this image forming apparatus imagio MP C5002, the protective agent leveling member in the protective layer forming apparatus uses a blade like the protective agent leveling member 610 in the conventional protective layer forming apparatus 600 described with reference to FIG. It has become a thing. That is, the blade has an obtuse angle at the ridgeline at the tip edge. Further, the leading edge portion is in contact with the outer peripheral surface of the photosensitive drum from the counter direction like a protective agent leveling member 610 shown in FIG. Also in this second comparative example, the contact linear pressure is adjusted to “10 N / cm”.

(Evaluation)
In each of the image forming apparatuses of the first to fifteenth embodiments and the first and second comparative examples obtained in this way, the image area ratio is 5% and the A4 size test chart covers 100,000 sheets. The images were continuously formed. The 100,000 sheets of images were formed in two environments: a normal temperature environment where the temperature was 23 ° C. and a relative humidity of 50% RH, and a low temperature environment where the temperature was 10 ° C. and the relative humidity was 15% RH. . However, after image formation under one environment, the photosensitive drum, the charging roller, and the protective agent coating device of each example and each comparative example are replaced with new ones, and the same conditions except for the environment are used. Then, image formation was performed in the following environment.

First, it was confirmed whether or not an image abnormality called black streak appeared in an image formed under each environment. Further, the charging roller in each image forming apparatus after formation under each environment was visually checked for contamination. Then, image abnormalities (black streaks) and dirt on the charging roller were comprehensively evaluated based on the following five evaluation criteria.
Rank 1: Image abnormality (black streak) is not confirmed in both the normal temperature environment and the low temperature environment, and the charging roller after formation is hardly contaminated.
Rank 2: An image abnormality (black streak) is not confirmed in both the normal temperature environment and the low temperature environment, but some contamination is confirmed on the charging roller after formation.
Rank 3: Image abnormality (black streaks) is confirmed in a low-temperature environment, and a slight contamination is confirmed on the formed charging roller.
Rank 4: Image abnormalities (black streaks) appear in the image from about 5,000 sheets in both the normal temperature environment and the low temperature environment, and the charging roller after the formation is also confirmed to be dirty. Lighter than rank 5.
Rank 5: Image abnormalities (black streaks) exceeding the allowable limit appear on the image from about 5,000 sheets in both the normal temperature environment and the low temperature environment, and the charging roller after the formation is also confirmed to have excessive contamination. .

Next, it was confirmed whether or not an image abnormality such as a white streak-like defect appeared in an image formed under each environment. Further, visual wear and filming were confirmed on the photosensitive drum in each image forming apparatus after formation in each environment. Then, image abnormality, photoconductor drum wear and filming were comprehensively evaluated based on the following five-level evaluation criteria.
Rank 1: Image abnormality (white streaks) is not confirmed in both the normal temperature environment and the low temperature environment, and almost no wear or filming is confirmed on the formed photosensitive drum.
Rank 2: Image abnormality (white streaks) is not confirmed in both the normal temperature environment and the low temperature environment, and no abrasion is confirmed on the formed photosensitive drum, but a slight filming is confirmed on the photosensitive drum.
Rank 3: Image abnormality (white streaks) appears in the image from about 20,000 sheets in both the normal temperature environment and the low temperature environment. No abrasion is confirmed on the formed photosensitive drum, but filming is confirmed on the photosensitive drum.
Rank 4: About 5,000 images in both normal temperature environment and low temperature environment.
White stripes) appear. Wear or filming is confirmed on the formed photosensitive drum. However, the degree of image abnormality, wear, and filming is lighter than rank 5.
Rank 5: Image abnormalities (white streaks) exceeding the allowable range appear from about 5,000 sheets in both the normal temperature environment and the low temperature environment. Excessive wear or filming is confirmed on the formed photosensitive drum.

(Evaluation results)
The evaluation results for the first to fifteenth examples and the first and second comparative examples described above are shown in Table 1 below.

  As shown in Table 1, in the first and second comparative examples, an evaluation of rank 5 is seen, whereas in the first to fifteenth examples, all are ranked 4 or more. . The above-described image abnormality, charging roller contamination, photoconductor drum wear and filming all occur due to deterioration of the protective agent leveling member. Therefore, from the above evaluation results, in the first to fifteenth embodiments in which the protective agent leveling member is in contact with the outer peripheral surface of the photosensitive drum at approximately the center in the short side direction of the curved surface, the number is 100,000. It can be seen that deterioration of the protective agent leveling member can be suppressed even after image formation.

  Further, as shown in Table 1, the ratio R2 / R1 of the radius of curvature is in the range of 0.08 or more and 1020 or less, specifically in the range of 0.1 or more and 1000 or less. In the sixth embodiment, the evaluation results are as follows. That is, in the second to sixth examples, the evaluation results are higher than those in the first and seventh examples in which the ratio R2 / R1 of the radius of curvature is outside the above range. Furthermore, in the third to fifth embodiments in which the radius-of-curvature ratio R2 / R1 is within the range of 1 to 100, the first and second ratios of the radius-of-curvature R2 / R1 are outside this range. The evaluation results are higher than those of the second, sixth, and seventh examples. From this, the curvature radius ratio R2 / R1 is preferably 0.08 or more and 1020 or less, more preferably 0.1 or more and 1000 or less, and further preferably 1 or more and 100 or less. I understand.

  Further, as shown in Table 1, the contact linear pressure is in the range of 0.008 N / cm to 72 N / cm, specifically in the range of 0.01 N / cm to 70 N / cm. In the ninth to fourteenth examples, the evaluation results are as follows. That is, in the ninth to fourteenth embodiments, the evaluation results are higher than those in the eighth and fifteenth embodiments in which the contact line pressure is outside the above range. Furthermore, in the 11th to 13th embodiments in which the contact line pressure is in the range of 1 N / cm or more and 50 N / cm or less, the contact line pressures are out of this range. Compared with the fifteenth embodiment, the evaluation results are all high. For this reason, the contact linear pressure is preferably 0.008 N / cm or more and 72 N / cm or less, more preferably 0.01 N / cm or more and 70 N / cm or less, and 1 N / cm or more and 50 N / cm or less. It turns out that it is still more preferable.

2, 2Y, 2M, 2C, 2K Process cartridge 3 Photosensitive drum (an example of an image carrier)
3a Photosensitive drum outer peripheral surface (an example of an image forming surface)
4 Charging device (part of an example of image forming unit)
5 Development device (part of an example of image forming unit)
6 Cleaning member 7 Protective layer forming device 30 Optical writing unit (part of an example of image forming unit)
40 Intermediate transfer unit (example of transfer section)
60 fixing device (an example of a fixing unit)
71 protective agent application member 71b solid protective agent 72 protective agent leveling member (an example of a rubbing member, protective agent leveling member)
72a-2 Curved surface 100 Image forming apparatus

Japanese Patent Laid-Open No. 10-260614 JP 2003-57996 A JP 2002-244485 A JP 2006-154747 A JP 2001-305907 A JP 2006-251751 A JP 2007-264347 A

Claims (9)

It is mounted on an image forming apparatus that forms a toner image on an image forming surface that has a predetermined width and circulates, transfers the toner image to a sheet, and fixes it on the sheet.
For protecting the image forming surface and providing lubricity to the image forming surface by rubbing the image forming surface after transfer of the toner image to remove the deposits from the image forming surface. In the rubbing member for rubbing the image forming surface coated with an agent to level the protective agent and forming a layer of the protective agent on the image forming surface,
A curved surface that extends substantially parallel to the width direction of the image forming surface and is convexly curved toward the image forming surface along the circulation movement direction of the image forming surface; A rubbing member which is in contact with the image forming surface over its entire width.   The ratio of the radius of curvature of the curved surface to the radius of curvature of the image-formed surface at a position where the image-forming surface and the curved surface are in contact is 0.08 or more and 1020 or less. The rubbing member as described.   The rubbing member according to claim 1 or 2, wherein a contact line pressure in a longitudinal direction of the curved surface with respect to the image forming surface is 0.008 N / cm or more and 72 N / cm or less. The rubbing member is a protective agent leveling member that leveles the protective agent and forms a layer of the protective agent on the image forming surface;
The rubbing member according to any one of claims 1 to 3, wherein the protective agent is a protective agent containing a fatty acid metal salt as a main component.   The rubbing member according to claim 4, wherein the fatty acid metal salt contains zinc stearate.   The rubbing member according to claim 4 or 5, wherein the protective agent contains a fatty acid metal salt and inorganic fine particles. An image forming apparatus that forms a toner image on an image forming surface having a predetermined width and circulates, transfers the toner image onto a sheet, and fixes the image on the sheet is slid onto the image forming surface after the transfer of the toner image. It is mounted with a cleaning member that rubs to remove deposits from the image forming surface, and a layer of a protective agent that protects the image forming surface and imparts lubricity to the image forming surface is formed on the image forming surface. In the protective layer forming apparatus,
A protective agent applying member for applying the protective agent to the image forming surface;
A protective agent leveling member that rubs the image forming surface on which the protective agent has been applied by the protective agent application member, leveles the protective agent, and forms a layer of the protective agent on the image forming surface; Prepared,
The protective layer forming apparatus, wherein the protective agent leveling member is a rubbing member according to any one of claims 1 to 6. A toner image is formed on an image forming surface that has a predetermined width and circulates, and the toner image is transferred to a sheet and fixed on the sheet. The image forming surface is detachably mounted on the image forming surface. An image forming portion for forming the toner image, an image carrier having the image forming surface, a cleaning member for rubbing the image forming surface after transfer to remove deposits from the image forming surface, and the image Protecting the image forming surface and rubbing the image forming surface coated with a protective agent that imparts lubricity to the image forming surface, leveling the protective agent and forming the protective agent layer on the image forming surface In a process cartridge provided with a protective agent leveling member
7. The process cartridge according to claim 1, wherein at least one of the cleaning member and the protective agent leveling member is a rubbing member according to claim 1. An image carrier having an image forming surface that circulates and has a predetermined width, an image forming unit that forms a toner image on the image forming surface, a transfer unit that transfers the toner image onto a sheet, and the toner image that is transferred to a sheet A fixing portion that fixes the image forming surface, a cleaning member that rubs the image forming surface after transfer to remove deposits from the image forming surface, and protects the image forming surface and provides lubricity to the image forming surface. An image forming apparatus comprising: a protective agent leveling member that rubs the image forming surface coated with the protective agent and smoothes the protective agent to form a layer of the protective agent on the image forming surface. ,
7. The image forming apparatus according to claim 1, wherein at least one of the cleaning member and the protective agent leveling member is a rubbing member according to claim 1.

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