JP2010139658A - Lubricant applicator and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lubricant applicator which is provided in an image forming apparatus such as a copying machine, a facsimile machine and a printer and capable of stabilizing application of lubricant, regardless of the amount of residues after transfer, even when a cleaning position is on the downstream side from a lubricant applying position in the moving direction of an image carrier and further, capable of adjusting a lubricant application amount per unit time, and to provide the image forming apparatus provided with such the lubricant applicator. <P>SOLUTION: A lubricant applying member 47Y comes into contact with the image carrier 20Y to apply the lubricant to the image carrier 20Y, at the lubricant applying position TP on the downstream side from a transfer position NP where an image is transferred and on the upstream side from the cleaning position CP where the residues after transfer on the image carrier 20Y is removed, in the moving direction B1 of the image carrier 20Y. The lubricant applying member 47Y is brought into contact with and separated from the image carrier 20Y, to be separated from the image carrier 20Y, when the residues after transfer on the image carrier 20Y passes through the lubricant applying position TP. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a lubricant application device that applies a lubricant to an image carrier provided in an image forming apparatus such as a copying machine, a facsimile machine, or a printer, and to such an image forming apparatus having the same.

  In recent years, in an image forming apparatus such as a copying machine, a facsimile machine, a printer, etc., by applying a lubricant to the surface of the image carrier, the coefficient of friction with respect to the toner on the surface of the image carrier is reduced. A lubricant is applied to the surface of the image carrier to suppress the occurrence of transfer failure when transferring the formed toner image to a transfer material such as paper and to improve the image quality of the transferred toner image. An image forming apparatus including a lubricant application unit has been proposed (see, for example, [Patent Document 1] to [Patent Document 3]). Such an image forming apparatus is particularly advantageous in that it is possible to improve the image quality by suppressing the occurrence of a character part dropout phenomenon in which a part of the character image lacks a worm-eating shape. The application of the lubricant to the image carrier also has the advantage of preventing the toner filming on the surface of the image carrier due to a charging hazard and contributing to the extension of the life of the image carrier by suppressing the abrasion of the surface layer. .

  On the other hand, such an image forming apparatus generally includes a cleaning unit that removes and cleans transfer residue remaining on the surface of the image carrier after the image on the surface of the image carrier is transferred to a transfer material. (For example, see [Patent Document 1] to [Patent Document 3]).

  The positional relationship between the cleaning position of the image carrier by the cleaning unit and the lubricant application position on the image carrier by the lubricant application unit in the moving direction of the image carrier is as follows. There are two types (for example, refer to [Patent Document 1] and [Patent Document 2]) and other types (for example, refer to [Patent Document 3]) in which the cleaning position occupies the upstream side in the moving direction.

  In the former type, it is known that the cleaning means functions as a lubricant leveling means for leveling the lubricant applied to the image carrier by the lubricant application means on the image carrier. (For example, refer to [Patent Document 1]). Further, in the conventional lubricant application means, a lubricant application member that applies lubricant to the image carrier is always in contact with the image carrier (see, for example, [Patent Document 1] to [Patent Document 3]). Further, in the conventional lubricant application means, the amount of lubricant applied per unit time during driving is constant under the same conditions.

JP 2007-127737 A JP 2006-259091 A JP 2007-219506 A

  However, if the lubricant application member is always in contact with the image carrier, the former type has a problem that the amount of lubricant applied depends on the amount of transfer residue, and this advantage cannot be obtained. That is, the transfer residue prevents the lubricant from being applied to the image carrier. For example, if the image area ratio is high and the amount of transfer residue is large, the transfer residue adheres to the lubricant application member. There is a problem in that it becomes difficult for the lubricant to be applied to the image carrier, and the coefficient of friction of the image carrier increases to make it difficult to obtain this advantage. For example, when the image forming apparatus is an image forming apparatus capable of forming not only a monochrome image but also a color image as a composite image of toner images of respective colors carried on a plurality of image carriers, a monochrome image is formed. Since the amount of toner carried on the image carrier is greatly different between the case of forming an image and the case of forming a color image, the amount of transfer residue is also greatly different, and this problem is likely to occur.

  In the latter type, since the cleaning means is located upstream of the lubricant application means in the moving direction of the image carrier, such a problem is unlikely to occur. However, the cleaning means in this position is used as a lubricant leveling means. It is difficult to provide functions. In view of this, a configuration has been proposed in which lubricant leveling means is separately provided on the downstream side of the lubricant application position in the moving direction of the image carrier (see, for example, [Patent Document 3]). However, from the standpoint of the recent increasing demand for downsizing the image forming apparatus, the area of the surface of the image carrier is limited, and therefore it is necessary to avoid providing the lubricant leveling means as a separate configuration as much as possible.

  On the other hand, in order to stabilize the amount of lubricant on the surface of the image carrier, in addition to adjusting the drive time of the lubricant application means in accordance with the number of images formed, the image forming apparatus is installed in a place close to the user. In response to a request for shortening the waiting time of a user accompanying a recent situation, a technique for applying a lubricant after image formation has been proposed so that the time required for the lubricant application does not affect the first print time (for example, [See Patent Document 2]. However, in this technique, in order to increase the lubricant application amount, it is necessary to lengthen the drive time of the lubricant application means when the lubricant application amount per unit time is constant. Even if it should be started immediately after the previous image forming operation, the next image forming operation cannot be started until the lubricant application is completed, so that the first print time can be extended. In view of such circumstances, it is preferable that the amount of lubricant applied to the image carrier by the lubricant applying unit per unit time can be adjusted as necessary, and the lubricant application can be completed in a short time.

  The present invention is provided in an image forming apparatus such as a copying machine, a facsimile machine, a printer, etc., and does not depend on the amount of transfer residue even when the cleaning position is downstream of the lubricant application position in the moving direction of the image carrier. Provided are a lubricant application device capable of stabilizing lubricant application, a lubricant application device capable of adjusting a lubricant application amount per unit time, and such an image forming apparatus having such a lubricant application device. For the purpose.

  In order to achieve the above object, the invention according to claim 1 is a cleaning in which the transfer residue on the image carrier is cleaned downstream of the transfer position where the image is transferred in the moving direction of the image carrier. A lubricant application member that contacts the image carrier and applies the lubricant to the image carrier at a lubricant application position upstream of the position, and a transfer residue on the image carrier passes through the lubricant application position. And a contact / separation means for contacting / separating the lubricant application member to / from the image carrier so that the lubricant application member is separated from the image carrier.

  According to a second aspect of the present invention, in the lubricant application device according to the first aspect, the lubricant application device includes a pressing unit that presses the lubricant against the lubricant application member, and the contact / separation unit is configured to apply the lubricant from the image carrier. The separation distance of the application member can be adjusted, and the pressing force of the lubricant to the lubricant application member by the pressing means changes according to the separation distance.

  According to a third aspect of the present invention, in the lubricant application device according to the second aspect, the pressing means includes a spring member that urges the lubricant from the opposite side of the image carrier toward the lubricant application member. Further, the larger the separation distance, the larger the urging force of the lubricant applied to the lubricant application member by the spring member, and the pressing force increases.

  According to a fourth aspect of the present invention, in the lubricant application device according to the second or third aspect, the pressing force passes through the lubricant application position in a state where the lubricant application member is separated from the image carrier. It is characterized by being adjusted according to the amount of residue.

  According to a fifth aspect of the present invention, in the lubricant application device according to the fourth aspect, the number of image forming images and / or the number of pixels of the image conveyed by the image conveying body in order to adjust the pressing force according to the amount. It is characterized by using information.

  According to a sixth aspect of the present invention, there is provided an image forming apparatus comprising: the lubricant application device according to any one of the first to fifth aspects; and an image carrier to which the lubricant is applied by the lubricant application device. .

  According to a seventh aspect of the present invention, in the image forming apparatus according to the sixth aspect, the image carrier is a photosensitive member and / or an intermediate transfer member and / or a recording medium carrier.

  The present invention provides a lubricant application position downstream of the transfer position where the image is transferred and upstream of the cleaning position where the transfer residue on the image carrier is cleaned in the moving direction of the image carrier. A lubricant application member that contacts the image carrier and applies a lubricant to the image carrier, and the lubricant application member conveys the lubricant when a transfer residue on the image carrier passes through the lubricant application position. Since the lubricant application device has contact / separation means for contacting / separating the lubricant application member to / from the image carrier so as to be separated from the body, the lubricant is applied to the image carrier regardless of the amount of transfer residue. The application amount can be stabilized, and it can contribute to the formation of high-quality images and the long life of the image carrier, and the use by the user due to the waiting time for applying the lubricant to the image carrier. Lubricant applicator that can prevent or suppress deterioration in feeling It is possible to provide.

  A pressing unit that presses the lubricant against the lubricant application member, and the contact / separation unit is capable of adjusting a separation distance of the lubricant application member from the image carrier, and the pressing according to the separation distance. If the pressing force of the lubricant to the lubricant application member by the means changes, the amount of lubricant applied to the image carrier per unit time can be adjusted by adjusting the separation distance, and transfer residual Regardless of the amount of material, the amount of lubricant applied to the image carrier can be further stabilized, making it possible to contribute to high-quality image formation and extending the life of the image carrier, It is possible to provide a lubricant application device capable of preventing or suppressing a decrease in user's feeling of use due to a waiting time for applying the lubricant to the image carrier.

  The pressing means includes a spring member that urges the lubricant from the opposite side of the image carrier toward the lubricant application member, and lubrication of the lubricant application member by the spring member increases as the separation distance increases. If the urging force of the agent increases and the pressing force increases, the amount of lubricant applied to the image carrier per unit time can be adjusted by adjusting the separation distance with a relatively simple configuration using such a spring member. The amount of lubricant applied to the image carrier can be further stabilized regardless of the amount of transfer residue, making a high contribution to high-quality image formation and extending the life of the image carrier. In addition, it is possible to provide a lubricant application device that can prevent or suppress a decrease in user's feeling of use due to a waiting time for applying the lubricant to the image carrier.

  When the pressing force is adjusted according to the amount of the transfer residue passing through the lubricant application position in a state where the lubricant application member is separated from the image carrier, lubrication on the image carrier is performed. By adjusting the separation distance according to the amount of transfer residue that can affect the agent adhesion amount, the amount of lubricant applied to the image carrier per unit time can be adjusted better, and the image carrier The amount of lubricant applied to the toner can be further stabilized, and it is possible to make a high contribution to high-quality image formation and long life of the image carrier, and the lubricant is applied to the image carrier. Therefore, it is possible to provide a lubricant application device capable of preventing or suppressing a decrease in user's feeling of use due to the waiting time.

  If the image forming number information and / or the pixel number information of the image conveyed by the image carrier is used to adjust the pressing force according to the amount, the amount of lubricant adhering on the image carrier is affected. The amount of lubricant applied to the image carrier per unit time can be adjusted better by adjusting the separation distance according to the amount of transfer residue that depends on the number of image formation and the number of pixels. The amount of lubricant applied to the image carrier can be further stabilized, can contribute to high-quality image formation and long life of the image carrier, and the lubricant. It is possible to provide a lubricant application device capable of preventing or suppressing a decrease in user's feeling of use due to a waiting time for applying the toner to the image carrier.

  The present invention resides in an image forming apparatus having such a lubricant application device and an image carrier to which a lubricant is applied by the lubricant application device, and therefore lubricates the image carrier regardless of the amount of transfer residue. The application amount of the agent can be stabilized, can contribute to the formation of high-quality images and the long life of the image carrier, and the user who waits for applying the lubricant to the image carrier. It is possible to provide an image forming apparatus capable of preventing or suppressing a decrease in feeling of use.

  If the image carrier is a photoconductor and / or an intermediate transfer member and / or a recording medium carrier, the amount of lubricant applied to the various image carriers can be set regardless of the amount of transfer residue. It can stabilize and contribute to the formation of high-quality images and the long life of the image carrier, and the user's feeling of use due to the waiting time for applying the lubricant to the image carrier. An image forming apparatus capable of preventing or suppressing the decrease can be provided.

  FIG. 1 shows an outline of an image forming apparatus to which the present invention is applied. The image forming apparatus 100 is a complex machine of a color laser copying machine and a printer, but may be other image forming apparatuses such as other types of copying machines, facsimile machines, printers, and complex machines of these. The image forming apparatus 100 performs image forming processing based on image data of a document read by the image forming apparatus 100 or an image signal corresponding to image information received from the outside. The image forming apparatus 100 forms an image as a sheet-like recording medium, which is a transfer material, in addition to plain paper such as paper generally used for copying, OHP sheets, cardboard, cardboard, cardboard, and envelopes. Can be performed.

  The image forming apparatus 100 is a first toner carrier that is a latent image carrier as an image carrier capable of carrying an image as an image corresponding to each color separated into yellow, magenta, cyan, and black. A tandem structure in which photoconductor drums 20Y, 20M, 20C, and 20BK as drum-shaped photoconductors that are image transport bodies of the above are arranged in parallel, in other words, a tandem system, specifically, a quadruple tandem system is adopted.

  The photoconductor drums 20Y, 20M, 20C, and 20BK are OPC photoconductors that are rotatably supported by a frame (not shown) of the main body 99 of the image forming apparatus 100, and are intermediate transfer media as transfer media that are image carriers. They are arranged in this order from the upstream side in the A1 direction, which is the moving direction of the transfer belt 11 as the second image carrier. Y, M, C, and BK added after the numerals of the respective symbols indicate members for yellow, magenta, cyan, and black.

  Each of the photosensitive drums 20Y, 20M, 20C, and 20BK has image forming units 60Y, 60M, 60C, and 60BK for forming yellow (Y), magenta (M), cyan (C), and black (BK) images, respectively. Is provided.

  The photosensitive drums 20Y, 20M, 20C, and 20BK are on the outer peripheral surface side of the transfer belt 11 as a belt-like intermediate transfer member that is an endless belt disposed slightly above the central portion inside the main body 99, that is, the work. Located on the image plane side.

  The transfer belt 11 is movable in the direction of the arrow A1 while facing the photosensitive drums 20Y, 20M, 20C, and 20BK. Visible images, that is, toner images formed on the respective photoconductive drums 20Y, 20M, 20C, and 20BK are respectively superimposed and transferred onto the transfer belt 11 that moves in the direction of the arrow A1, and then transferred as a recording medium and a transfer medium. It is designed to be batch transferred onto paper. Therefore, the image forming apparatus 100 employs an intermediate transfer method, specifically, a four-tandem intermediate transfer method. Illustration of the transfer paper is omitted.

  The upper portion of the transfer belt 11 faces the photosensitive drums 20Y, 20M, 20C, and 20BK, and the opposed portions transfer the toner images on the photosensitive drums 20Y, 20M, 20C, and 20BK. A primary transfer portion 98 for transferring to the belt 11 is formed.

  In the superimposing transfer to the transfer belt 11, the toner images formed on the photosensitive drums 20Y, 20M, 20C, and 20BK are transferred to the same position on the transfer belt 11 while the transfer belt 11 moves in the A1 direction. As described above, voltage application by primary transfer rollers 12Y, 12M, 12C, and 12BK disposed at positions facing the photosensitive drums 20Y, 20M, 20C, and 20BK across the transfer belt 11 causes the A1 direction upstream. The timing is shifted toward the downstream side.

  The transfer belt 11 exhibits conductivity with a volume resistance of 10 ^ 5 to 10 ^ 11 Ω · cm 2. When the surface resistance is less than 10 ^ 5Ω / □, when the toner image is transferred from the photosensitive drums 20Y, 20M, 20C, and 20BK onto the transfer belt 11, the toner image is disturbed due to discharge, so-called transfer dust. If it exceeds 10 ^ 11Ω / □, the toner image is transferred from the transfer belt 11 to the sheet, and then the counter charge of the toner image remains on the transfer belt 11 and the afterimage on the next image. May appear as

  The transfer belt 11 is, for example, a belt-like shape obtained by extruding a metal oxide such as tin oxide or indium oxide, conductive particles such as carbon black, or a conductive polymer alone or in combination with a thermoplastic resin, and then extruding. Cylindrical plastics can be used. In addition, the above-mentioned conductive particles and conductive polymer are added to a resin solution containing a thermal crosslinking reactive monomer or oligomer, if necessary, and centrifugal molding is performed while heating to obtain an endless belt-shaped transfer belt 11. You can also

  Each of the transfer belts 11 has a detent guide (not shown) as a detent member at each edge thereof. The offset guide is provided to prevent the transfer belt 11 from being biased in any direction perpendicular to the paper surface in FIG. 1 when the transfer belt 11 rotates in the A1 direction. The stopper guide is made of urethane rubber, but can be made of various rubber materials such as silicon rubber.

  The image forming apparatus 100 is disposed in the main body 99 so as to face four image forming units 60Y, 60M, 60C, and 60BK as image forming means and above the photosensitive drums 20Y, 20M, 20C, and 20BK. A transfer belt unit 10 as an intermediate transfer means as an intermediate transfer unit including the transfer belt 11, and a secondary transfer bias as a transfer member which is disposed opposite to the transfer belt 11 and is driven by the transfer belt 11 and rotated. Light as a writing device as an optical writing unit as a latent image forming device as a latent image forming means disposed opposite to the secondary transfer roller 5 as a roller and the image forming units 60Y, 60M, 60C and 60BK. And a scanning device 8.

  The image forming apparatus 100 also feeds a sheet as a sheet feeding cassette capable of stacking a large number of transfer sheets transported between the photosensitive drums 20Y, 20M, 20C, and 20BK and the transfer belt 11 in the main body 99. The sheet feeding device 61 that functions as a recording medium conveying unit and the transfer paper conveyed from the sheet feeding device 61 are matched with the timing of toner image formation by the image forming units 60Y, 60M, 60C, and 60BK. At a predetermined timing, a registration roller 4 that feeds toward the secondary transfer portion 97 between the transfer belt 11 and the secondary transfer roller 5 and a sensor (not shown) that detects that the leading edge of the transfer paper has reached the registration roller 4. And have.

  The image forming apparatus 100 also includes a fixing device 6 as a belt-fixing type fixing unit for fixing the toner image onto the transfer paper onto which the toner image has been transferred, and a fixed transfer paper in the main body 99. And a paper discharge roller 7 as a pair of paper discharge rollers for discharging to the outside.

  The image forming apparatus 100 also has a paper discharge tray 17 on the side of the main body 99 on which the transfer paper discharged from the main body 99 by the discharge rollers 7 is stacked. As an image reading means for reading a document, a reading device 14 having a contact glass (not shown) on which a document is placed, and an automatic document conveying means arranged above the reading device 14 and feeding the document to the reading device 14 And an automatic document feeder (so-called ADF) 15 having a document table (not shown) on which the document is placed.

  The image forming apparatus 100 also includes a driving device (not shown) that rotationally drives the photosensitive drums 20Y, 20M, 20C, and 20BK, and a power source as a bias applying unit (not shown) that applies a secondary transfer bias to the secondary transfer roller 5. Bias control means, an instruction including an image formation start instruction for the image forming apparatus 100, and other settings such as a start switch capable of issuing an image formation start instruction and a numeric keypad capable of inputting the number of image formations And a control unit (not shown) including a CPU, a memory, and the like that control the overall operation of the image forming apparatus 100 based on detection results by various detection units. .

  In addition to the transfer belt 11, the transfer belt unit 10 includes primary transfer rollers 12Y, 12M, 12C, and 12BK as primary transfer bias rollers, and a drive roller 77 that is a drive member around which the transfer belt 11 is wound. A cleaning counter roller 75 that is a driven roller, tension rollers 68, 72, and 74 that are driven rollers that stretch the transfer belt 11 together with the driving roller 77 and the cleaning counter roller 75, and a cleaning counter roller via the transfer belt 11. 75, and a cleaning device 13 as a belt cleaning device disposed on the transfer belt 11 to clean the surface of the transfer belt 11.

  The transfer belt unit 10 also includes a drive system (not shown) that rotationally drives the drive roller 77, and a power source and bias control as a bias application unit (not shown) that applies a primary transfer bias to the primary transfer rollers 12Y, 12M, 12C, and 12BK. And a biasing member (not shown) for biasing the primary transfer rollers 12Y, 12M, 12C, and 12BK toward the photosensitive drums 20Y, 20M, 20C, and 20BK, respectively.

  The primary transfer rollers 12Y, 12M, 12C, and 12BK press the transfer belt 11 from the back surface thereof toward the photosensitive drums 20Y, 20M, 20C, and 20BK to form primary transfer nips.

  In each primary transfer nip, a primary transfer electric field is formed between the photosensitive drums 20Y, 20M, 20C, and 20BK and the primary transfer rollers 12Y, 12M, 12C, and 12BK due to the influence of the primary transfer bias. . The toner images of the respective colors formed on the photosensitive drums 20Y, 20M, 20C, and 20BK are primarily transferred onto the transfer belt 11 in an electrostatic transfer manner by the influence of the primary transfer electric field and nip pressure.

The tension roller 72 is in contact with the secondary transfer roller 5 via the transfer belt 11 and functions as a secondary transfer counter roller that forms a secondary transfer nip.
The cleaning counter roller 75 has a function as a tension roller as a pressure member that gives the transfer belt 11 a predetermined tension suitable for transfer.

  Since the cleaning device 13 has the same configuration and function as a cleaning device 70Y described later, the description thereof is omitted here, but it functions as a secondary transfer cleaning device for cleaning the transfer belt 11.

The sheet feeding device 61 accommodates a plurality of transfer papers as a stack of transfer papers, and is arranged in multiple stages below the main body 99. The sheet feeding device 61 feeds the transfer paper toward the registration roller 4 at a predetermined timing.
The transfer paper fed from the sheet feeding device 61 reaches the registration roller 4 through the paper feed path and is sandwiched between the rollers of the registration roller 4.

  The fixing device 6 includes a belt unit 62 and a pressure roller 63 pressed against the belt unit 62. The belt unit 62 includes an endless fixing belt 64, a fixing roller 65 that moves the fixing belt 64 in an endless manner, and a heating roller 66 that has the fixing belt 64 wound around the fixing roller 65 and has a heat source (not shown) inside. have

  The fixing device 6 passes the transfer paper carrying the toner image through a fixing unit, which is a pressure contact part between the belt unit 62 and the pressure roller 63, so that the carried toner image is caused by the action of heat and pressure. It is fixed on the surface of the transfer paper.

  Regarding the image forming units 60Y, 60M, 60C, and 60BK that constitute the image forming means, the configuration will be described on behalf of the configuration of the image forming unit 60Y as an image forming station including the photosensitive drum 20Y. Since the configurations of the other image forming units are substantially the same, in the following description, for the sake of convenience, reference numerals corresponding to the reference numerals assigned to the configuration of the image forming unit 60Y are used for the configurations of the other image forming units. Or omitted, and detailed description will be omitted as appropriate.

  As shown in FIG. 2, the image forming unit 60Y including the photosensitive drum 20Y includes a primary transfer roller 12Y around the photosensitive drum 20Y along a rotation direction B1 that is counterclockwise in the drawing. A cleaning device 70Y as a primary transfer cleaning device as a drum cleaning device as a cleaning means, a charge eliminating device 90Y as a charge removing means, a charging device 30Y as a charging means, and a developing device as a developing unit as a developing means. Device 80Y.

  The photosensitive drum 20Y, the cleaning device 70Y, the charge eliminating device 90Y, the charging device 30Y, and the developing device 80Y are integrated to form an image forming unit 60Y as a process cartridge. The image forming unit 60Y, which is a process cartridge, is detachable from the main body 99. Such a process cartridge having a plurality of structures can be handled as a replacement part, so that maintainability is remarkably improved, which is very preferable. In addition, since the life of each part, which is an element of the process cartridge, is equal, unnecessary replacement is prevented and suppressed, and the structure is further preferable.

  A primary transfer nip formed by the primary transfer roller 12Y pressing the transfer belt 11 toward the photosensitive drum 20Y is a contact position between the transfer belt 11 and the photosensitive drum 20Y. Constitutes a transfer position NP at which the toner image is transferred to the transfer belt 11.

  The static eliminator 90Y includes a static elimination lamp (not shown) disposed in the vicinity of the surface of the photoconductor drum 20Y, and the surface of the photoconductor drum 20Y is neutralized by making it electrically clean. Is initialized.

  The charging device 30Y includes a charging roller 31Y that rotates in contact with the surface of the photosensitive drum 20Y, and a cleaning roller 32Y as a charging cleaning member that rotates in contact with the charging roller 31Y.

  The charging roller 31Y is connected to a voltage applying means (not shown) for applying a bias of an alternating current component to a direct current, and in the charging region facing the photosensitive drum 20Y, the charging drum 31Y is charged by the discharging device 90Y. The surface is uniformly charged to a predetermined polarity.

The cleaning roller 32Y is driven to rotate by the charging roller 31Y to clean the charging roller 31Y.
As described above, in this embodiment, the charging system using the contact roller is adopted. However, the charging system may be one using a proximity roller or one using a corotron system. .

  The optical scanning device 8 irradiates the region between the charging area where the charging device 30Y is opposed to the photosensitive drum 20Y and the developing region where the developing device 80Y is facing, while scanning the laser light L which has been modulated and deflected. Then, the surface to be scanned on the surface of the photosensitive drum 20Y charged by the charging device 30Y is exposed by spot irradiation, and is visualized as a yellow toner image by the developing device 80Y. The latent image is written. Therefore, as shown in FIG. 1, the optical scanning device 8 includes a laser optical system such as a light source 31 that is a semiconductor laser, a polygon mirror 32 that is a polygonal polygon mirror that rotates at high speed, an fθ lens 33, and a reflection mirror 34. Have.

  As shown in FIG. 2, the developing device 80Y includes a developing roller 81Y carrying a two-component developer (hereinafter referred to as developer) including a toner and a carrier disposed in close proximity to the photosensitive drum 20Y, and a developing roller 81Y. A doctor blade 82Y that regulates the developer on the roller 81Y to a certain height and a first conveying screw 83Y that is arranged to face each other and stirs the developer and supplies the developer to the developing roller 81Y. The second conveying screw 84Y, the partition wall 87Y provided between the first conveying screw 83Y and the second conveying screw 84Y, the toner bottle 88Y containing yellow toner, and the developing bias of the DC component with the developing roller 81Y. FIG. 5 is a diagram for driving a bias applying means (not shown) to be applied to the developing roller 81Y, the first conveying screw 83Y, the second conveying screw 84Y, and the like. And a developing drive means such as a driving means not.

  The developing roller 81Y has a developing sleeve (not shown) that is a developer carrying member that carries the developer on the surface thereof. The bias applying means applies a developing bias having an appropriate size between the exposed portion and the non-exposed portion of the photosensitive drum 20Y to the developing sleeve.

  In the developing device 80Y, a partition wall 87Y forms a first supply unit that accommodates the developing roller 81Y and the first conveyance screw 83Y and a second supply unit that accommodates the second conveyance screw 84Y. Has been.

  The first transport screw 83Y is rotationally driven by a driving unit, and supplies the developer in the first supply unit to the developing roller 81Y while transporting the developer from the back side to the front side in FIG. The developer conveyed to the vicinity of the end in the first supply unit by the first conveyance screw 83Y enters the second supply unit through an opening (not shown) formed in the partition wall 87Y.

  In the second supply unit, the second transport screw 84Y transports the developer sent from the first supply unit in the direction opposite to that of the first transport screw 83Y by being rotationally driven by the driving unit. The developer transported to the vicinity of the end of the second supply unit by the second transport screw 84Y returns to the first supply unit through another opening (not shown) provided in the partition wall 87Y.

  The developer in the developing case 85Y is a two-component developer including a magnetic carrier and a yellow toner that is a negatively charged color toner. The developer is supplied with yellow toner from a toner bottle 88Y. The supplied yellow toner and developer are agitated and mixed by the first conveying screw 83Y and the second conveying screw 84Y while being agitated and conveyed, frictionally charged, and supplied to and supported by the developing roller 81Y.

  The developing roller 81Y whose developer thickness is regulated by the doctor blade 82Y and whose layer thickness is regulated is developed in the developing region between the developing roller 81Y and the photosensitive drum 20Y by the rotation and the developing bias by the bias applying means. An appropriate amount of developer is carried by the doctor blade 82Y, and the yellow toner in the developer is electrostatically transferred to the electrostatic latent image formed on the surface of the photosensitive drum 20Y, and the electrostatic latent image is formed. It is made visible as a yellow toner image and visualized as an image.

The developer that has consumed the yellow toner by the development is returned to the developing device 80Y as the developing roller 81Y rotates.
In this embodiment, the DC component developing bias is applied by the bias applying means. However, the developing bias may be an AC component, or an AC component superimposed on the DC component.

  The cleaning device 70Y includes a cleaning case 71Y having a housing, a transfer residual toner and a carrier that are housed in the cleaning case 71Y, the tip of which contacts the photosensitive drum 20Y, and is a transfer residue on the photosensitive drum 20Y. The cleaning blade 78Y as a cleaning member that scrapes off and collects foreign matters such as paper dust, the blade support 73Y that supports the cleaning blade 78Y with respect to the cleaning case 71Y, and the blade support 73Y as the cleaning case 71Y. A support shaft 69Y that is rotatably supported and a spring 79Y that presses the cleaning blade 78Y against the photosensitive drum 20Y with a predetermined elastic force so that the edge thereof is pressed against the photosensitive drum 20Y.

  The cleaning device 70Y is also rotatably supported by the cleaning case 71Y, and the cleaning blade 78Y scrapes off the transfer residual toner and the like from the photosensitive drum 20Y, and also removes unnecessary items such as waste toner generated by the removal. A discharge screw 67Y as a waste toner conveyance screw constituting a part of a waste toner path (not shown) for conveying the toner toward a waste toner tank as a waste toner storage case (not shown), and a lubricant for protecting the photosensitive drum 20Y And a protective film forming device 40Y as a lubricant coating device, which is a protective film forming means for applying the protective agent 42Y to the photosensitive drum 20Y.

  The cleaning blade 78Y is in contact with the photosensitive drum 20Y at an angle similar to a so-called counter type, that is, a reading type. The cleaning position CP is a position where the cleaning blade 78Y contacts the photosensitive drum 20Y and unnecessary materials such as transfer residual toner on the photosensitive drum 20Y are cleaned.

  The protective film forming apparatus 40Y includes an image carrier protective agent that is a solid lubricant formed in a bar shape, a protective agent 42Y as an image carrier protective agent, and a forward direction with respect to the rotation direction B1 of the photosensitive drum 20Y. As a lubricant application brush as a lubricant application member as a scraping member that is a protective agent supply member that rotates in the direction D1 and scrapes off the protective agent 42Y to protect the photosensitive drum 20Y and supplies it to the photosensitive drum 20Y. And a brush roller 47Y which is an application brush as a fur brush.

  The protective film forming apparatus 40Y also holds the protective agent 42Y and supports it with respect to the cleaning case 71Y, and supports 49Y as a lubricant holding member that supports the protective agent 42Y in the direction of contacting and separating from the brush roller 47Y. A spring 48Y as a spring member as a lubricant pressing spring, which is a pressure spring as an elastic member as a pressing means for pressing the protective agent 42Y against the brush roller 47Y via the support 49Y, and a cleaning blade 78Y. Yes.

  The protective film forming apparatus 40Y is also composed of a bearing 91Y shown in FIGS. 3 and 4 in which both ends of the brush roller 47Y are integrally supported by the cleaning case 71Y, and a developing driving means, and is used for rotationally driving the brush roller 47Y. It has a lubricant application drive means as a drive means, and a brush clutch as a clutch (not shown) for switching whether or not to transmit the driving force of the lubricant application drive means to the brush roller 47Y.

  The protective agent 42Y is made of, for example, a dry solid hydrophobic lubricant. Representative examples of this lubricant include zinc stearate, barium stearate, lead stearate, iron stearate, nickel stearate, cobalt stearate, copper stearate, strontium stearate, calcium stearate, cadmium stearate, stearic acid. Magnesium, zinc oleate, manganese oleate, iron oleate, cobalt oleate, lead oleate, magnesium oleate, copper oleate, palmitic acid, zinc cobalt palmitate, copper palmitate, magnesium palmitate, aluminum palmitate, Examples include relatively higher fatty acids such as calcium palmitate, lead caprylate, lead caproate, zinc linolenate, cobalt linolenate, calcium linolenate, and cadmium ricolinolenate. That. Natural wax such as carnauba wax may also be used.

Although not shown in detail, the brush roller 47Y includes a shaft member extending in the width direction of the photosensitive drum 20Y, which is a direction perpendicular to the paper surface of FIG. 1, and a plurality of standing upright on the outer peripheral surface of the shaft member. And have raised hair. The brush roller 47Y is formed by winding and fixing a base cloth (not shown) in which a plurality of raised brushes are planted around a shaft member.
The length of the brush roller 47Y in the width direction is adjusted so that the raised portions are in contact with at least the entire width direction of the photosensitive drum 20Y.

In order to uniformly apply the protective agent 42Y to the surface of the photosensitive drum 20Y, the density of the brush bristles that are the raised portions of the brush roller 47Y is 20,000 / 645.16 [mm ² ] or higher. Is preferred. If the coating amount of the protective agent 42Y on the photosensitive drum 20Y is non-uniform, the amount of toner that forms the toner image formed on the surface of the photosensitive drum 20Y becomes non-uniform due to the non-uniform coating. This is because density unevenness occurs and the formed image quality may deteriorate. Specifically, the toner adhesion amount is small in the portion where the coating amount of the protective agent 42Y is large, and conversely, a large amount of toner adheres to the portion where the coating amount of the protection agent 42Y is small, thereby causing uneven density in the toner image. Will occur. In particular, uneven density tends to occur in a low-density toner image.

  The brush roller 47Y abuts on the photosensitive drum 20Y at a position TP downstream of the transfer position NP and upstream of the cleaning position CP in the B1 direction, and applies the protective agent 42Y to the photosensitive drum 20Y at this position TP. It is possible. This position TP is a lubricant application position.

  When the brush clutch is turned on, the brush roller 47Y rotates in the D1 direction by transmission of the rotational driving force from the lubricant application driving means to the shaft member. As a result of this rotation, the protective agent 42Y is scraped off and attached to the raised portions of the brush roller 47Y, and then the brush roller 47Y is in contact with the photosensitive drum 20Y, and then on the surface of the photosensitive drum 20Y at the lubricant application position TP. Applied.

  At the cleaning position CP, the cleaning blade 78Y applies a protective agent 42Y applied or supplied to the photosensitive drum 20Y at the lubricant application position TP by the brush roller 47Y on the photosensitive drum 20Y, and forms a film on the surface of the photosensitive drum 20Y. It functions as a coating blade for forming a protective film as a protective layer. The cleaning blade 78Y leveles the protective agent 42Y on the photosensitive drum 20Y so as to eliminate even a slight distribution unevenness in the protective agent 42Y on the photosensitive drum 20Y.

  Thus, when the brush roller 47Y is rotationally driven, the cleaning device 70Y is driven as the protective film forming device 40Y. Note that the rotation direction of the brush roller 47Y may be not the forward direction but the opposite direction to the B1 direction.

  The film formed on the surface of the photoconductive drum 20Y by the protective agent 42Y has a function of preventing the surface of the photoconductive drum 20Y from being deteriorated due to proximity discharge, and the protective film forming apparatus 40Y functions as a discharge deterioration preventing means. It is. The deterioration here refers to both wear of the photosensitive drum 20Y due to discharge, acceleration of the wear, and activation of the surface of the photosensitive drum 20Y.

In addition, the coating prevents deterioration such as wear caused by friction between the photosensitive drum 20Y and the cleaning blade 78Y, and the protective film forming apparatus 40Y functions as a friction deterioration preventing unit.
As described above, the protective film forming apparatus 40Y suppresses the deterioration by applying the protective agent 42Y to the surface of the photosensitive drum 20Y.
In addition, the configuration of the cleaning device 70Y will be described later.

In such an image forming unit 60Y, an image is formed by a negative-positive process.
An image forming sequence when a full color image is copied by the image forming apparatus 100 will be described.

  After setting the document on the document table of the automatic document feeder 15 or opening the reading device 14 and placing the document on the contact glass, the reading device 14 is closed and the document is brought into close contact with the contact glass. When the start switch on the operation panel is pressed, when the document is set on the document table, the automatic document feeder 15 drives the reading device 14 while conveying the document to read the document, and the document is placed on the contact glass. Is placed, the reading device 14 is driven as it is to read the document. When a plurality of copies are made, a desired number of numbers are entered using the numeric keypad before the start switch is pressed.

  Based on the read original image, original image information corresponding to the color used for copying is generated. This document image information includes pixel number information that is information relating to the number of pixels of an image carried on the photosensitive drum corresponding to the color. This pixel number information is generated by the control means. In this respect, the control unit functions as a pixel number information generation unit.

  The operation for forming the yellow toner image will be described. Following the original reading operation, the photosensitive drum 20Y is uniformly negatively charged by the charging device 30Y in accordance with the rotation in the B1 direction. The electrostatic latent image corresponding to the yellow color is formed by the exposure scanning of the laser beam L emitted from the optical scanning device 8 based on the document image information corresponding to. In this way, the electrostatic latent image forming step is performed by at least the latter of charging by the charging device 30Y and writing by the optical scanning device 8.

  The electrostatic latent image is developed with the yellow toner in the developer by the developing device 80Y, and the yellow toner image obtained by the developing process is transferred to the transfer belt 11 that is moved in the A1 direction by the primary transfer roller 12Y. After the primary transfer, the transfer process is performed, the transfer residual toner remaining after the transfer is removed by the cleaning device 70Y, the cleaning process is performed, and the protective agent 42Y is supplied by the protective film forming device 40Y at a timing described later. Then, a static elimination process is performed in which the residual charge is removed by the static eliminator 90Y, and it is used for the next charging by the charging device 30Y.

At this time, the cleaning device 70Y also removes the protective agent on the photosensitive drum 20Y partially or wholly deteriorated due to charging or the like as a surface residue together with other components such as transfer residual toner. The protective film forming apparatus 40Y performs a protective film forming process as a protective layer forming method process for forming a protective film with a protective agent on the surface of the photoreceptor drum 20Y after cleaning.
The cleaning device 70Y stores the collected toner in a waste toner tank. However, the cleaning device 70Y may be configured to perform a predetermined recycling process so that the collected toner can be used again for development.

  Similarly, toner images of the respective colors are formed on the other photosensitive drums 20M, 20C, and 20BK, and the formed toner images of the respective colors are transferred to the A1 direction by the primary transfer rollers 12M, 12C, and 12BK. 11 is sequentially transferred to the same position on the head. The toner image, which is a composite color image superimposed on the transfer belt 11, moves to the secondary transfer nip, which is the position facing the secondary transfer roller 5, as the transfer belt 11 rotates in the A1 direction. They are in close contact with each other and are secondarily transferred onto the transfer paper by the action of the secondary transfer bias and nip pressure, and a full-color image is formed on the transfer paper.

The transfer paper transported between the transfer belt 11 and the secondary transfer roller 5 is fed from the sheet feeding device 61 and fed, and is transferred onto the transfer belt 11 by the registration roller 4 based on a detection signal from the sensor. The leading edge of the toner image is sent out at a timing when it faces the secondary transfer roller 5.
The secondary transfer roller 5 is applied with a potential having a polarity opposite to the polarity of toner charging by bias applying means.

  When the toner image of all colors is transferred and carried on the transfer paper, it enters the fixing device 6 and passes through the fixing portion between the pressure roller 63 and the belt unit 62 due to the action of heat and pressure. The carried toner image is fixed, and a full-color image is fixed on the transfer paper. The fixed transfer paper that has passed through the fixing device 6 and has undergone the fixing process passes through the paper discharge roller 7 and is stacked on the paper discharge tray 17. On the other hand, the surface of the transfer belt 11 that has passed the secondary transfer nip after the secondary transfer is cleaned by a cleaning device 13, and a protective film forming step similar to that described above is performed at the timing described later. Prepare for the transfer process.

  As described above, the image forming apparatus 100 performs an image forming method and an image forming operation including an electrostatic latent image forming process, a developing process, a transfer process, a protective layer forming process, a fixing process, a charge eliminating process, and a recycling process. It has become.

  Here, as already described, in the image forming apparatus 100, the lubricant application position TP is downstream of the transfer position NP and upstream of the cleaning position CP in the B1 direction. When the coating member is always in contact with the image bearing member, the photosensitive drums 20Y, 20M, 20C, and 20BK that are the image carrier, and the transfer belt 11, the transfer residual toner on the image carrier and the image carrier is a lubricant. By adhering to the application member, the amount of lubricant applied to the image carrier and the image carrier changes depending on the amount of residual toner, and the intended purpose of lubricant application cannot be satisfactorily achieved. In order to cope with this, a configuration in which the lubricant application position TP is disposed on the downstream side of the transfer position NP and the cleaning position CP in the B1 direction is also conceivable, but in this configuration, the image carrier at the lubricant application position TP. It is difficult to level the lubricant applied to the image carrier at the cleaning position CP. However, if a configuration for leveling such a lubricant is disposed downstream of the lubricant application position TP in the B1 direction, This may go against the recent increasing demand for smaller image forming apparatuses.

  Therefore, the image forming apparatus 100 has contact / separation means for contacting / separating the lubricant application member to / from the image carrier and the image carrier. By this contact / separation means, transfer residual toner on the image carrier and the image carrier is transferred. The lubricant application member is separated from the image carrier and the image carrier when passing through the lubricant application position TP as the image carrier and the image carrier are rotated, that is, moved.

  This contact / separation means will be described as a representative of the contact / separation means 50Y shown in FIGS. 3 and 4 provided in the protective film forming apparatus 40Y of the image forming unit 60Y. The contact / separation means having the same configuration as the contact / separation means 50Y is provided in the image forming units 60M, 60C, and 60BK in the same manner, but the description thereof is omitted.

  The contact / separation means 50Y is a lubricant application member support member in which the bearings 91Y positioned at both ends of the brush roller 47Y are disposed at the center thereof, thereby supporting the both ends of the brush roller 47Y integrally with the cleaning case 71Y. The lever 51Y is a swing lever, a shaft 52Y having one end of the lever 51Y rotatably supported on the cleaning case 71Y, and one end fixed to the other end of the lever 51Y and the other end fixed to the cleaning case 71Y. A spring 53Y, which is a tension spring as an urging member, a cam 54Y disposed so as to be always in contact with the lever 51Y by the urging force of the spring 53Y, and a drive for rotationally driving the cam 54Y, which is constituted by a developing drive means. Cam drive means as a means and whether or not to transmit the driving force of the cam drive means to the cam 54Y. And a cam clutch as a clutch (not shown) obtain.

The spring constant of the spring 53Y and the spring 48Y are set such that the biasing force of the tension by the spring 53Y acting on the lever 51Y around the shaft 52Y is larger than the pressing force of the spring 48Y acting on the lever 51Y around the shaft 52Y. A spring constant is defined.
Therefore, the cam 54Y contacts the lever 51Y when the large diameter portion of the cam 54Y faces the lever 51Y as shown in FIG. 3 and when the small diameter portion of the cam 54Y faces the lever 51Y as shown in FIG. .
With this configuration, the lever 51Y swings according to the phase of the cam 54Y.

  As shown in FIG. 3, in a state where the large diameter portion of the cam 54Y is in contact with the lever 51Y, the brush roller 47Y is in contact with the photosensitive drum 20Y and is at a position suitable for applying the protective agent 42Y to the photosensitive drum 20Y. It comes to occupy. As shown in FIG. 4, in a state where the small diameter portion of the cam 54Y is in contact with the lever 51Y, the brush roller 47Y is separated from the photosensitive drum 20Y, and the protective agent 42Y is not applied to the photosensitive drum 20Y. The transfer residual toner on 20Y is prevented from adhering to the brush roller 47Y.

  The separation distance x (> 0), which is the distance between the brush roller 47Y and the photosensitive drum 20Y, varies in a range larger than 0 shown in FIG. 3 and smaller than X shown in FIG. 4 according to the phase of the cam 54Y. Thus, the contact / separation means 50Y can adjust the separation distance x of the brush roller 47Y from the photosensitive drum 20Y, and functions as a separation distance adjustment means.

The drive of the cam clutch is controlled by the control means. Therefore, the control unit functions as a contact / separation control unit that performs control to bring the brush roller 47Y into contact with and away from the photosensitive drum 20Y.
When the cam clutch is turned on under the control of the control means, the cam 54Y rotates by transmission of the rotational driving force from the cam drive means. This rotational speed is relatively fast. The control means monitors the time during which the cam clutch is ON, and grasps the phase of the cam 54Y and / or the separation distance x. In this respect, the control unit functions as a separation distance adjustment control unit.

  The spring 48Y biases the protective agent 42Y from the opposite side of the photosensitive drum 20Y toward the brush roller 47Y, and expands and contracts according to the separation distance x. Therefore, the protective agent 42Y applied to the brush roller 47Y by the spring 48Y. For example, the pressing force increases as the separation distance x increases. In this respect, the contacting / separating means 50Y as the separation distance adjusting means functions as a pressing force adjusting means for adjusting the pressing force, and the control means as the separating distance adjusting control means is a pressing force adjustment control for controlling the pressing force. Functions as a means. The pressing force adjustment control means grasps the pressing force. As described above, the spring 47Y that urges the protective agent 42Y toward the brush roller 47Y is used to adjust the pressing force according to the separation distance x. 50Y has an advantage that the number of components is suppressed and the configuration is small and inexpensive.

  When the pressing force increases, the amount of the protective agent 42Y attached to the brush roller 47Y increases. Therefore, when the brush roller 47Y is rotated in a state where the brush roller 47Y is separated from the photosensitive drum 20Y, the separation distance x increases. The amount of the protective agent 42Y that adheres to the brush roller 47Y increases. Therefore, the larger the separation distance x is, the more the protective agent is applied to the photosensitive drum 20Y when the brush roller 47Y is rotationally driven at the separation distance x and then the brush roller 47Y is rotationally driven in contact with the photosensitive drum 20Y. The coating amount per unit time of 42Y and the coating amount over time increase. In this regard, the contact / separation means 50Y as the separation distance adjustment means and the pressing force adjustment means functions as a lubricant application amount adjustment means for adjusting the application amount, and controls as the separation distance adjustment control means and the pressing force adjustment control means. The means functions as a lubricant application amount adjustment control means for controlling the application amount.

  Since the rotational speed of the cam 42Y is relatively fast, the operation from when the brush roller 47Y starts to move away from the photosensitive drum 20Y until the desired separation distance x is reached, or the brush roller 47Y that is separated from the photosensitive drum 20Y is exposed to the photosensitive member. The operation up to the contact with the drum 20Y is completed quickly. The protective agent 42Y is always in contact with the brush roller 47Y, and as will be described later, during the image forming operation, the time during which the brush roller 47Y is separated from the photosensitive drum 20Y is the time during which the brush roller 47Y is in contact with the photosensitive drum 20Y. More generally, the rotation speed of the brush roller 47Y is set to a relatively high speed. Therefore, the amount of the protective agent 42Y attached to the brush roller 47Y at the separation distance x is determined by the brush roller 47Y. As soon as it is separated from the photosensitive drum 20Y, the amount of the protective agent 42Y applied to the photosensitive drum 20Y when the brush roller 47Y moves to the photosensitive drum 20Y is almost constant depending on the separation distance x. It becomes. Therefore, the lubricant application amount adjustment control means grasps the application amount.

  As described above, the contacting / separating means 50Y moves the brush roller 47Y from the photosensitive drum 20Y when the transfer residual toner on the photosensitive drum 20Y passes through the lubricant application position TP as the photosensitive drum 20Y rotates. It is designed to be separated. Specifically, the brush roller 47Y is separated from the photosensitive drum 20Y at least when the transfer residual toner on the photosensitive drum 20Y passes through the lubricant application position TP as the photosensitive drum 20Y rotates. Thus, even when the transfer residual toner on the photosensitive drum 20Y does not pass through the lubricant application position TP as the photosensitive drum 20Y rotates, the brush roller 47Y is kept away from the photosensitive drum 20Y. Also good. However, in order to increase the coating amount of the protective agent 42Y to the photosensitive drum 20Y, it is preferable to shorten the time for separating the brush roller 47Y from the photosensitive drum 20Y.

  Accordingly, the contact / separation means 50Y is configured such that the circumferential surface position of the photosensitive drum 20Y corresponding to the leading position of the toner image in the B1 direction passes through the transfer position NP from the above-described electrostatic latent image forming process start timing. When the time to reach TP has elapsed, the brush roller 47Y is separated from the photosensitive drum 20Y, and the peripheral surface position of the photosensitive drum 20Y corresponding to the rear end position of the toner image in the B1 direction is When the time from the end of the latent image forming process to the lubricant application position TP after passing through the transfer position NP has passed, the brush roller 47Y is brought into contact with the photosensitive drum 20Y to protect the photosensitive drum 20Y. 42Y is applied.

  The contact / separation means 50Y is applied every time the photosensitive drum 20Y makes one rotation even when the same image is continuously formed on a plurality of transfer papers, for example, when the number of images formed per 1 job is a plurality of sheets. Perform the action. During the image forming operation, the time during which the brush roller 47Y is separated from the photoconductive drum 20Y is generally longer than the time during which the brush roller 47Y is brought into contact with the photoconductive drum 20Y. Therefore, the brush roller 47Y is separated from the photoconductive drum 20Y. Meanwhile, the amount of the protective agent 42Y adhering to the brush roller 47Y reaches the saturation amount at the separation distance x, and when the brush roller 47Y comes into contact with the photosensitive drum 20Y thereafter, the photosensitive drum 20Y per unit time. The amount of the protective agent 42Y to be applied is almost fixed at the separation distance x as described above, in combination with the fact that the transfer residual toner is prevented from adhering to the brush roller 47Y. Then, the protective agent 42Y applied or supplied to the photosensitive drum 20Y at the lubricant application position TP by the brush roller 47Y is leveled on the photosensitive drum 20Y by the cleaning blade 78Y, and is made uniform on the photosensitive drum 20Y. .

  The circumferential length of the photosensitive drum 20Y in the B1 direction is such that image forming is performed so that the protective agent 42Y is more evenly distributed on the surface of the photosensitive drum 20Y until the end of 1 job even when the brush roller 47Y contacts and separates from the photosensitive drum 20Y. A non-integer multiple of the length of the transfer paper used in the apparatus 100 is preferable. The brush roller 47Y may be brought into contact with the photosensitive drum 20Y until another job is started after the end of one job.

  Even if such an operation is performed, for example, when the separation distance x is constant, the amount of the protective agent 42Y applied to the photosensitive drum 20Y when the brush roller 47Y subsequently contacts the photosensitive drum 20Y is equal to Since the separation distance x is almost constant, for example, the higher the image area ratio of the formed image, the more the protective agent 42Y transferred and consumed together with the toner from the surface of the photosensitive drum 20Y during transfer, and the residual transfer toner Since the protective agent 42Y scraped off from the surface of the photosensitive drum 20Y together with the transfer residual toner during cleaning increases, unevenness may occur in the distribution of the adhesion amount of the protective agent 42Y on the surface of the photosensitive drum 20Y, or This can easily occur, and the amount of the protective agent 42Y attached on the surface of the photoreceptor drum 20Y can be reduced.

  Therefore, the pressing force adjusting means, the contacting / separating means 50Y as the lubricant application amount adjusting means, the pressing force adjustment control means, and the control means as the lubricant application amount adjusting control means are the pressing forces of the protective agent 42Y to the brush roller 47Y. Is adjusted according to the amount of residual toner that passes through the lubricant application position TP after the brush roller 47Y is separated from the photosensitive drum 20Y.

  The amount of the transfer residual toner is substantially determined by the amount of toner carried on the photoreceptor drum 20Y, and this toner amount is determined by the number of pixels of the image carried on the photoreceptor drum 20Y. It is grasped by the pixel number information. As described above, this pixel number information is included in the document image information, and is generated by the control means as the pixel number information generating means. Then, the control means as the contact / separation control means, the separation distance adjustment control means, the pressing force adjustment control means, and the lubricant application amount adjustment control means uses the pixel number information generated by the control means as the pixel number information generation means. Thus, it functions as a separation distance determining means for determining the separation distance x so that the amount of the protective agent 42Y adhering to the photosensitive drum 20Y becomes an appropriate amount and becomes uniform.

  In addition, the amount of the transfer residual toner substantially increases as the number of image formations up to the end of 1 job increases. This is because, when image formation is performed with 1 job, continuous sheet passing with a short distance between sheets is performed, and therefore, the time during which the brush roller 47Y is separated from the photosensitive drum 20Y is substantially increased. Therefore, as the number of images formed until the end of 1 job increases, the consumption of the protective agent 42Y increases, and the adhesion amount of the protective agent 42Y on the surface of the photosensitive drum 20Y can decrease. Therefore, the control means as the separation distance determination means uses the number-of-images information related to the number of image formations up to the end of 1 job together with the number-of-pixels information when determining the separation distance x. This image forming number information is the number when the number is set by the numeric keypad, and is 1 when the number is not set, and is grasped by the control means.

  Since both the pixel number information and the image forming number information can be grasped before the start of the electrostatic latent image forming process in the above-mentioned image forming operation, the control means as the separation distance determining means is that the brush roller 47Y is the photosensitive drum. The separation distance x is determined before the separation from 20Y. Therefore, if the contact and separation of the brush roller 47Y with respect to the photosensitive drum 20Y is performed at a constant separation distance x, even if unevenness or deficiency in the adhesion state of the protective agent 42Y on the photosensitive drum 20Y may occur at the end of image formation, the separation is performed. By adjusting the distance x and adjusting the supply amount of the protective agent 42Y to the photosensitive drum 20Y, such unevenness is suppressed or prevented, and excess or deficiency of the protective agent 42Y is suppressed or prevented.

  In order to suppress or prevent such unevenness more satisfactorily, the control unit as the separation distance determination unit grasps the position on the surface of the photosensitive drum 20Y where the brush roller 47Y contacts after being separated from the photosensitive drum 20Y. The separation distance x is determined so that the coating amount of the protective agent 42Y becomes an appropriate amount at that position. For this reason, the control means as the separation distance determining means is a history regarding the position on the photosensitive drum 20Y where the brush roller 47Y is brought into and out of contact with the photosensitive drum 20Y, and the coating amount of the protective agent 42Y corresponding thereto. Know and remember. In this respect, the control unit functions as a lubricant application history information generation unit and a lubricant application history information storage unit.

  According to such an operation, the adhesion state and the application state of the protective agent 42Y on the photosensitive drum 20Y are properly maintained without affecting the first print time at the start of the next job.

  The above operation can be performed not only during normal image forming operation but also when creating a test pattern for image adjustment, color misregistration adjustment, etc., which is called process control. In addition, it can be similarly performed in a non-image forming sequence such as a charging bias adjustment mode.

  As described above, the case where the present invention is applied to an image forming apparatus that employs an intermediate transfer method, specifically, a four-tandem tandem intermediate transfer method has been described. However, the present invention includes a four-tandem tandem direct transfer method shown in FIG. The present invention is also applicable to an image forming apparatus that employs the intermediate transfer method. This figure shows a part of such an image forming apparatus, and the remaining part has the same configuration as the image forming apparatus 100 described above. In the following, with respect to the configuration shown in FIG. 5, portions different from the image forming apparatus 100 described above will be mainly described.

The transfer belt unit 10 in this image forming apparatus is a recording medium conveyance body that conveys transfer paper between the photosensitive drums 20Y, 20M, 20C, and 20BK and the primary transfer rollers 12Y, 12M, 12C, and 12BK. A conveyance belt 55 as a third image conveyance body for conveying the first image. The transfer paper is conveyed in the A1 direction by the conveyance belt 55, and in this process, the toner images of the respective colors on the photosensitive drums 20Y, 20M, 20C, and 20BK are sequentially transferred and superimposed on the same position. And the carried toner image is fixed.
For example, the cleaning device 13 is configured so that the transfer residual toner input to the lubricant application member is suppressed and the amount of lubricant adhering on the conveyance belt 55 is maintained at an appropriate amount. The lubricant application member is brought into and out of contact with the conveyor belt 55 in a mode in which the lubricant is applied in a region excluding the area. As a result, the input of the transfer residual toner to the lubricant application member is suppressed, the lubricant is satisfactorily applied to the conveyor belt 55, and the transfer residue on the conveyor belt 55 caused by toner scattering or the like is removed from the cleaning device 13. The advantages such as good removal can be obtained.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the specific embodiments, and the present invention described in the claims is not specifically limited by the above description. Various modifications and changes are possible within the scope of the above.

  For example, the pressing means is not limited to a spring as long as it presses the lubricant against the lubricant application member, but a motor and a cam that is rotationally driven by the motor may be used, but a spring member is used as the pressing means. As described above, there is an advantage that a desired pressing force for pressing the lubricant against the lubricant application member can be obtained by the spring member if the lubricant application member is separated from the image carrier and the separation distance is appropriately set.

  The lubricant may be liquid instead of solid if the configuration is appropriately changed, such as a configuration in which the pressing means is omitted. In this case, the lubricant application member is applied by infiltrating the liquid lubricant. It can be configured to be applied to the image carrier by other methods as appropriate, such as being carried and supplied to the image carrier.

The contact / separation means may use another mechanism such as a pinion rack.
The photosensitive member and the intermediate transfer member, which are image carriers as the image carrier, may be either a drum or a belt, and the recording medium carrier as the image carrier may be a drum or a belt.
The developer is not limited to the two-component developer as described above, and may be a one-component developer whose component is composed only of toner or mainly composed of toner.

  The image forming apparatus is not a so-called tandem type image forming apparatus, but a so-called one-drum type image forming apparatus in which each color toner image is sequentially formed on one photosensitive drum and the respective color toner images are sequentially superimposed to obtain a color image. The same applies to the device. Further, the present invention can be applied not only to a color image forming apparatus but also to a monochrome image forming apparatus.

  The effects described in the embodiments of the present invention are only the most preferable effects resulting from the present invention, and the effects of the present invention are limited to those described in the embodiments of the present invention. is not.

1 is a schematic front view of an image forming apparatus to which the present invention is applied. FIG. 2 is a schematic front view showing a configuration around one image carrier among a plurality of image carriers provided in the image forming apparatus shown in FIG. 1 and including a lubricant application device to which the present invention is applied. FIG. 3 is a schematic front view showing a configuration of contact / separation means provided in the lubricant application device shown in FIG. 2 and a state in which a lubricant application member provided in the lubricant application device is in contact with the image carrier. is there. FIG. 3 is a schematic front view showing a configuration of contact / separation means provided in the lubricant application device shown in FIG. 2 and a state in which the lubricant application member provided in the lubricant application device is separated from the image carrier. is there. FIG. 10 is a schematic front view illustrating a part of another configuration example of the image forming apparatus to which the present invention is applicable.

Explanation of symbols

20Y, 20M, 20C, 20BK Image carrier, photoconductor 11 Image carrier, intermediate transfer member 47Y Lubricant coating member 48Y Pressing means, spring member 50Y Contacting / separating means 55 Image carrier, recording medium carrier 100 Image forming apparatus B1 Movement direction of image carrier CP Cleaning position NP Transfer position TP Lubricant application position X Separation distance

Claims (7)

In the moving direction of the image carrier, the image carrier at a lubricant application position downstream of the transfer position where the image is transferred and upstream of the cleaning position where the transfer residue on the image carrier is cleaned. A lubricant application member that abuts on and applies a lubricant to the image carrier;
Contact / separation means for contacting / separating the lubricant application member to / from the image carrier so that the transfer residue on the image carrier passes through the lubricant application position so that the lubricant application member is separated from the image carrier. And a lubricant application device. The lubricant application device according to claim 1, wherein
A pressing means for pressing a lubricant against the lubricant application member;
The contact / separation means is capable of adjusting a separation distance of the lubricant application member from the image carrier,
The lubricant application device according to claim 1, wherein a pressing force of the lubricant to the lubricant application member by the pressing means is changed according to the separation distance. The lubricant application device according to claim 2,
The pressing means includes a spring member that urges the lubricant from the opposite side of the image carrier toward the lubricant application member,
The lubricant application device according to claim 1, wherein the greater the separation distance, the greater the biasing force of the lubricant on the lubricant application member by the spring member, and the greater the pressing force. In the lubricant application device according to claim 2 or 3,
The lubricant application apparatus, wherein the pressing force is adjusted according to an amount of the transfer residue passing through the lubricant application position in a state where the lubricant application member is separated from the image carrier. The lubricant application device according to claim 4,
In order to adjust the said pressing force according to the said quantity, the image forming number information and / or the pixel number information of the image conveyed by the image conveyance body are used.   6. An image forming apparatus comprising: the lubricant application device according to claim 1; and an image carrier on which the lubricant is applied by the lubricant application device. The image forming apparatus according to claim 6.
An image forming apparatus, wherein the image carrier is a photosensitive member and / or an intermediate transfer member and / or a recording medium carrier.

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