JP6256046B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus.

  In general, an image forming apparatus (printer, copier, facsimile, etc.) using an electrophotographic process technology generates an electrostatic latent image by irradiating (exposing) a charged photoconductor with a laser beam based on image data. Form. Then, by supplying toner from the developing device to the photosensitive member (image carrier) on which the electrostatic latent image is formed, the electrostatic latent image is visualized to form a toner image. Further, after the toner image is directly or indirectly transferred to the paper, it is fixed by heating and pressurizing to form an image on the paper.

  By the way, in an image forming apparatus, it is known that when an image forming process is performed for a long time, a filming phenomenon occurs in which the surface of an image carrier such as a photosensitive member or an intermediate transfer belt is contaminated. The filming phenomenon is a phenomenon in which toner, toner additives, paper dust, discharge products, etc. (hereinafter referred to as “adhesives”) adhere to the surface of the image carrier. For example, when a filming phenomenon occurs on the surface of the intermediate transfer belt, the smoothness of the intermediate transfer belt is lowered and the resistance is increased, and thereafter, an image defect such as a difference in density in the formed image is caused.

  As a technique related to the above problem, there has been proposed a technique that can effectively remove the transfer residual toner and adhering substances on the photosensitive member and can maintain the cleaning function for a long period of time ( For example, see Patent Document 1). In the technique described in Patent Document 1, two blades of a first cleaning blade and a second cleaning blade are provided in order from the upstream side in the rotation direction of the image carrier, and the second cleaning blade includes a blade base layer, abrasive particles, A polishing blade having a two-layer structure of a lubricant particle-containing layer. The first cleaning blade contacts the image carrier by a counter method, and the second cleaning blade contacts the image carrier by a counter method or a trailing method.

  In addition, both the abrasive and the protective agent do not interfere with each other, and both the polishing effect by the abrasive on the surface of the image bearing member and the protective effect by the protective agent are compatible, and a good image can be stably obtained over a long period of time. A technique that can be obtained has been proposed (see, for example, Patent Document 2). The technique described in Patent Document 2 has an abrasive supply means for supplying an abrasive to the image carrier and a protective agent supply means for supplying a protective agent to the image carrier, and the control means is based on the abrasive supply means. Control is performed so that the supply of the abrasive to the image carrier and the supply of the protective agent to the image carrier by the protective agent supply means are not performed simultaneously.

JP 2008-20515 A JP 2010-32602 A

  However, in the technique described in Patent Document 1, it is difficult to uniformly disperse the abrasive particles and the lubricant particles in the abrasive particle and lubricant particle-containing layer of the second cleaning blade. In order to obtain the substance removal performance, it is necessary to select the particle diameter of the abrasive particles and the lubricant particles, which increases the cost. Furthermore, there is also a problem that the replacement of the second cleaning blade due to use wear occurs in a short time, and the maintenance cost increases.

  Further, the technique described in Patent Document 2 has a problem that the configuration becomes complicated and the cost increases. As described above, the techniques described in Patent Documents 1 and 2 cannot be used as they are as means for efficiently removing the deposits adhering to the surface of the image carrier.

  An object of the present invention is to provide an image forming apparatus capable of removing deposits attached to the surface of an image carrier.

An image forming apparatus according to the present invention includes:
An image forming unit for supplying toner containing abrasive particles to a rotating image carrier;
A cleaning unit for removing toner remaining on the surface of the image carrier from the toner supplied by the image forming unit;
A collecting member provided on the downstream side of the cleaning unit in the rotation direction of the image carrier, and electrostatically collects the abrasive particles not removed by the cleaning unit and slidably rubs the image carrier The charging of the abrasive particles so that the charging amount of the charging member provided on the downstream side of the cleaning unit and the upstream side of the collecting member in the rotation direction of the image carrier and the abrasive particles is increased. A polishing unit having a second voltage application unit that applies a voltage of the same polarity as the polarity to the charging member ;
It is characterized by providing.

  According to the present invention, since the collected abrasive particles rub against the surface of the image carrier, the surface of the image carrier is polished, so that the deposits attached to the surface of the image carrier can be removed. it can.

1 is a diagram schematically showing an overall configuration of an image forming apparatus in the present embodiment. FIG. 2 is a diagram illustrating a main part of a control system of the image forming apparatus according to the present embodiment. FIG. 3 is a diagram illustrating a configuration on a downstream side of a belt cleaning device in a rotation direction of an intermediate transfer belt. FIG. 3 is a diagram illustrating a configuration on a downstream side of a belt cleaning device in a rotation direction of an intermediate transfer belt. FIG. 3 is a diagram illustrating a configuration on a downstream side of a belt cleaning device in a rotation direction of an intermediate transfer belt. It is a table | surface showing the generation | occurrence | production situation of the filming phenomenon according to image formation conditions.

  Hereinafter, the present embodiment will be described in detail with reference to the drawings. FIG. 1 is a diagram schematically showing an overall configuration of an image forming apparatus 1 according to an embodiment of the present invention. FIG. 2 shows a main part of the control system of the image forming apparatus 1 according to the present embodiment. An image forming apparatus 1 shown in FIGS. 1 and 2 is an intermediate transfer type color image forming apparatus using electrophotographic process technology. That is, the image forming apparatus 1 transfers the toner images of Y (yellow), M (magenta), C (cyan), and K (black) formed on the photosensitive drum 413 to the intermediate transfer belt 421 (primary transfer). Then, after superposing four color toner images on the intermediate transfer belt 421, the toner images are transferred to the paper S (secondary transfer) to form an image.

  Further, in the image forming apparatus 1, the photosensitive drums 413 corresponding to the four colors of YMCK are arranged in series in the running direction of the intermediate transfer belt 421, and the respective color toner images are sequentially transferred to the intermediate transfer belt 421 in one step. Tandem system is adopted.

  As shown in FIG. 2, the image forming apparatus 1 includes an image reading unit 10, an operation display unit 20, an image processing unit 30, an image forming unit 40, a paper transport unit 50, a fixing unit 60, high-voltage power supplies 80 and 90, and a control unit. 100.

  The control unit 100 includes a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, and the like. The CPU 101 reads a program corresponding to the processing content from the ROM 102 and develops it in the RAM 103, and centrally controls the operation of each block of the image forming apparatus 1 in cooperation with the developed program. At this time, various data stored in the storage unit 72 is referred to. The storage unit 72 includes, for example, a nonvolatile semiconductor memory (so-called flash memory) or a hard disk drive.

  The control unit 100 transmits and receives various data to and from an external device (for example, a personal computer) connected to a communication network such as a LAN (Local Area Network) or a WAN (Wide Area Network) via the communication unit 71. Do. For example, the control unit 100 receives image data transmitted from an external device, and forms an image on the paper S based on the image data (input image data). The communication unit 71 is composed of a communication control card such as a LAN card, for example.

  The image reading unit 10 includes an automatic document feeder 11 called an ADF (Auto Document Feeder), a document image scanning device 12 (scanner), and the like.

  The automatic document feeder 11 transports the document D placed on the document tray by a transport mechanism and sends it out to the document image scanning device 12. The automatic document feeder 11 can continuously read images (including both sides) of a large number of documents D placed on the document tray all at once.

  The document image scanning device 12 optically scans a document conveyed on the contact glass from the automatic document feeder 11 or a document placed on the contact glass, and reflects light from the document to a CCD (Charge Coupled Device). ) An image is formed on the light receiving surface of the sensor 12a, and an original image is read. The image reading unit 10 generates input image data based on the reading result by the document image scanning device 12. The input image data is subjected to predetermined image processing in the image processing unit 30.

  The operation display unit 20 is configured by, for example, a liquid crystal display (LCD) with a touch panel, and functions as a display unit 21 and an operation unit 22. The display unit 21 displays various operation screens, image states, operation states of functions, and the like according to a display control signal input from the control unit 100. The operation unit 22 includes various operation keys such as a numeric keypad and a start key, receives various input operations by the user, and outputs an operation signal to the control unit 100.

  The image processing unit 30 includes a circuit that performs digital image processing on input image data according to initial settings or user settings. For example, the image processing unit 30 performs gradation correction based on the gradation correction data (gradation correction table) under the control of the control unit 100. Further, the image processing unit 30 performs various correction processes such as color correction and shading correction, a compression process, and the like on the input image data in addition to the gradation correction. The image forming unit 40 is controlled based on the image data subjected to these processes.

  The image forming unit 40 is based on the input image data, and image forming units 41Y, 41M, 41C, 41K, and an intermediate transfer unit 42 for forming an image using colored toners of Y component, M component, C component, and K component. Etc.

  The Y component, M component, C component, and K component image forming units 41Y, 41M, 41C, and 41K have the same configuration. For convenience of illustration and explanation, common constituent elements are denoted by the same reference numerals, and Y, M, C, or K are added to the reference numerals when distinguished from each other. In FIG. 1, only the components of the Y-component image forming unit 41Y are denoted by reference numerals, and the constituent elements of the other image forming units 41M, 41C, and 41K are omitted.

  The image forming unit 41 includes an exposure device 411, a developing device 412, a photosensitive drum 413, a charging device 414, a drum cleaning device 415, and the like.

  The photosensitive drum 413 has an undercoat layer (UCL) and a charge generation layer (CGL) on the peripheral surface of an aluminum conductive cylinder (aluminum tube) having a drum diameter of 80 mm, for example. It is a negatively charged organic photoconductor (OPC) in which a generation layer (CTL) and a charge transport layer (CTL) are sequentially stacked. The charge generation layer is made of an organic semiconductor in which a charge generation material (for example, phthalocyanine pigment) is dispersed in a resin binder (for example, polycarbonate), and generates a pair of positive charges and negative charges by exposure by the exposure device 411. The charge transport layer consists of a material in which a hole transport material (electron donating nitrogen-containing compound) is dispersed in a resin binder (for example, polycarbonate resin), and transports positive charges generated in the charge generation layer to the surface of the charge transport layer. To do.

  The control unit 100 controls a drive current supplied to a drive motor (not shown) that rotates the photosensitive drum 413, so that the photosensitive drum 413 rotates at a constant peripheral speed.

  The charging device 414 uniformly charges the surface of the photoconductive drum 413 to negative polarity by generating corona discharge.

  The exposure device 411 is composed of, for example, a semiconductor laser, and irradiates the photosensitive drum 413 with laser light corresponding to the image of each color component. A positive charge is generated in the charge generation layer of the photosensitive drum 413 and is transported to the surface of the charge transport layer, whereby the surface charge (negative charge) of the photosensitive drum 413 is neutralized. An electrostatic latent image of each color component is formed on the surface of the photosensitive drum 413 due to a potential difference from the surroundings.

  The developing device 412 is a two-component developing type developing device, and attaches toner of each color component to the surface of the photosensitive drum 413 to visualize the electrostatic latent image to form a toner image.

  The drum cleaning device 415 includes a drum cleaning blade that is slidably contacted with the surface of the photosensitive drum 413, and removes transfer residual toner remaining on the surface of the photosensitive drum 413 after primary transfer.

  The intermediate transfer unit 42 includes an intermediate transfer belt 421, a primary transfer roller 422, a plurality of support rollers 423, a secondary transfer roller 424, a belt cleaning device 426, and the like.

  The intermediate transfer belt 421 is an endless belt, and is stretched in a loop shape on a plurality of support rollers 423 (including 423A to 423D). At least one of the plurality of support rollers 423 is configured by a driving roller, and the other is configured by a driven roller. For example, it is preferable that the roller 423A disposed downstream of the K component primary transfer roller 422 in the belt traveling direction is a drive roller. This makes it easy to keep the belt running speed constant in the primary transfer portion.

  The intermediate transfer belt 421 is a belt having conductivity and elasticity, and has a high resistance layer having a volume resistivity of 8 to 11 [log Ω · cm] on the surface. The intermediate transfer belt 421 travels at a constant speed in the direction of arrow A when the driving roller 423A is rotated by a control signal from the control unit 100. Note that the material, thickness, and hardness of the intermediate transfer belt 421 are not limited as long as they have conductivity and elasticity.

  In the present embodiment, abrasive particles contained in the transfer residual toner remaining on the surface of the intermediate transfer belt 421 are collected on the downstream side of the belt cleaning device 426 in the rotation direction of the intermediate transfer belt 421 to form the intermediate transfer belt 421. A collecting member 85 to be rubbed is provided (not shown in FIG. 1).

  The primary transfer roller 422 is disposed on the inner peripheral surface side of the intermediate transfer belt 421 so as to face the photosensitive drum 413 of each color component. The primary transfer roller 422 is pressed against the photosensitive drum 413 with the intermediate transfer belt 421 interposed therebetween, thereby forming a primary transfer nip for transferring a toner image from the photosensitive drum 413 to the intermediate transfer belt 421.

  The secondary transfer roller 424 is disposed on the outer peripheral surface side of the intermediate transfer belt 421 so as to face a roller 423B (hereinafter referred to as “backup roller 423B”) disposed on the downstream side of the driving roller 423A in the belt traveling direction. The secondary transfer roller 424 is pressed against the backup roller 423B with the intermediate transfer belt 421 interposed therebetween, thereby forming a secondary transfer nip for transferring the toner image from the intermediate transfer belt 421 to the paper S.

  When the intermediate transfer belt 421 passes through the primary transfer nip, the toner images on the photoconductive drum 413 are primarily transferred onto the intermediate transfer belt 421 in sequence. Specifically, a primary transfer bias is applied to the primary transfer roller 422, and an electric charge having a polarity opposite to that of the toner is applied to the back side of the intermediate transfer belt 421 (the side in contact with the primary transfer roller 422). It is electrostatically transferred to the intermediate transfer belt 421.

  Thereafter, when the sheet S passes through the secondary transfer nip, the toner image on the intermediate transfer belt 421 is secondarily transferred to the sheet S. Specifically, a toner image is applied by applying a secondary transfer bias to the secondary transfer roller 424 and applying a charge having a polarity opposite to that of the toner to the back side of the paper S (the side in contact with the secondary transfer roller 424). Is electrostatically transferred to the paper S. The sheet S to which the toner image is transferred is conveyed toward the fixing unit 60.

  The belt cleaning device 426 removes transfer residual toner remaining on the surface of the intermediate transfer belt 421 after the secondary transfer. A specific configuration of the belt cleaning device 426 will be described later. Instead of the secondary transfer roller 424, a configuration (so-called belt-type secondary transfer unit) in which a secondary transfer belt is looped around a plurality of support rollers including the secondary transfer roller is adopted. Also good.

  The fixing unit 60 includes an upper fixing unit 60A having a fixing surface side member disposed on the fixing surface (surface on which the toner image is formed) of the paper S, and the back surface (surface opposite to the fixing surface) of the paper S. A lower fixing unit 60B having a rear side support member to be disposed, a heating source 60C, and the like are provided. When the back surface side support member is pressed against the fixing surface side member, a fixing nip for nipping and transporting the paper S is formed.

  The fixing unit 60 fixes the toner image on the paper S by heating and pressurizing the paper S on which the toner image is secondarily transferred and conveyed at the fixing nip. The fixing unit 60 is disposed in the fixing device F as a unit. The fixing device F may be provided with an air separation unit that separates the sheet S from the fixing surface side member or the back surface side support member by blowing air.

  The paper transport unit 50 includes a paper feed unit 51, a paper discharge unit 52, a transport path unit 53, and the like. In the three paper feed tray units 51a to 51c constituting the paper feed unit 51, paper S (standard paper, special paper) identified based on basis weight, size, or the like is stored for each preset type. . The conveyance path unit 53 includes a plurality of conveyance roller pairs such as registration roller pairs 53a.

  The sheets S stored in the sheet feed tray units 51 a to 51 c are sent one by one from the top and are conveyed to the image forming unit 40 by the conveyance path unit 53. At this time, the registration roller portion provided with the registration roller pair 53a corrects the inclination of the fed paper S and adjusts the conveyance timing. In the image forming unit 40, the toner image on the intermediate transfer belt 421 is secondarily transferred onto one side of the sheet S at a time, and a fixing process is performed in the fixing unit 60. The sheet S on which the image has been formed is discharged out of the apparatus by a discharge unit 52 having a discharge roller 52a.

  Next, referring to FIG. 3, the configuration of the downstream side of the belt cleaning device 426 (corresponding to the “cleaning part” of the present invention) in the rotation direction of the intermediate transfer belt 421 (corresponding to the “image carrier” of the present invention). explain. The belt cleaning device 426 includes a cleaning blade 500, a foaming roller 510, a toner discharge regulating member 520, a toner scattering preventing member 530, a toner collecting roller 540, and a casing 550. The cleaning blade 500, the foaming roller 510, the toner discharge regulating member 520, the toner scattering preventing member 530, and the toner collecting roller 540 are provided in the casing 550. Below the belt cleaning device 426, a temperature / humidity detection sensor 75 for detecting the temperature and humidity in the image forming apparatus 1 is provided.

  The intermediate transfer belt 421 has an arrow in the figure at a predetermined rotation speed (for example, 460 [mm / s]) under the control of the control unit 100 during the image forming process of the image forming apparatus 1 (when the print job is executed). Rotate in the direction.

  The cleaning blade 500 is attached to a support metal plate (not shown) that supports the cleaning blade 500. The cleaning blade 500 contacts the surface of the intermediate transfer belt 421 and scrapes off toner remaining on the surface of the intermediate transfer belt 421.

  The cleaning blade 500 is a rubber blade, and intermediately transfers the front end portion (blade edge portion) of the cleaning blade 500 in a counter direction (a direction opposite to the rotation direction of the intermediate transfer belt 421) with respect to the rotation direction of the intermediate transfer belt 421. It is in contact with the surface of the belt 421. The material of the cleaning blade 500 is, for example, urethane rubber (hardness: 74 [degrees], rebound resilience: 23 [%]), but any other elastic material may be used.

  On the upstream side of the cleaning blade 500 in the rotation direction of the intermediate transfer belt 421, a toner storage unit 560 that temporarily stores toner (also referred to as waste toner) scraped by the cleaning blade 500 is formed. The toner reservoir 560 is a space formed by the foam roller 510, the toner discharge regulating member 520, and the intermediate transfer belt 421.

  As the intermediate transfer belt 421 rotates, the toner stored in the toner storage unit 560 is carried to the cleaning blade 500 side, and the external additive (abrasive particles) contained in the toner is supplied to the cleaning blade 500. . As a result, the blade edge portion of the cleaning blade 500 is appropriately polished, so that the sliding contact between the cleaning blade 500 and the intermediate transfer belt 421 can be made smooth, and damage to the cleaning blade 500 due to excessive frictional force can be prevented. .

  Immediately after shipment from the factory or after replacing the belt cleaning device 426 for maintenance work, a solid image of a predetermined length with the maximum print width is formed on the intermediate transfer belt 421, and is untransferred to reach the cleaning blade 500 for removal. By doing so, an appropriate amount of toner is stored in the toner storage unit 560. Thereafter, an appropriate amount of untransferred toner is generated in image formation, and a constant amount of toner is always stored in the toner storage unit 560.

  The toner discharge regulating member 520 is fixed to the fixing member 570 with a double-sided tape or the like. The toner discharge regulating member 520 is a flexible member made of, for example, polyethylene terephthalate (PET). One end side of the toner discharge regulating member 520 hangs down and contacts the surface of the foaming roller 510. The foaming roller 510 is in contact with the intermediate transfer belt 421 and the toner discharge regulating member 520.

  The foaming roller 510 is an elastic roller having a cored bar and an elastic layer covering the outer periphery of the cored bar. The material of the metal core is a metal such as aluminum. The material of the elastic layer is a polyurethane foam having conductivity. The outer diameter dimension of the foaming roller 510 is, for example, 20 [mm]. The hardness of the foaming roller 510 is, for example, 40 ° (Asker C hardness).

  The foaming roller 510 is disposed on the upstream side of the cleaning blade 500 so as to be rotatable in the forward rotation direction with respect to the intermediate transfer belt 421 while being pressed against the intermediate transfer belt 421. The foaming roller 510 may be configured to be connected to a drive motor (not shown) so as to be able to rotate independently of the intermediate transfer belt 421, or to be rotated along with the travel of the intermediate transfer belt 421. Also good.

  The foaming roller 510 has a function as a so-called toner storage roller. For example, the toner reservoir 560 may be configured to leak toner from an opening (not shown) formed in the vicinity of the other end side (fixing member 570 side) of the toner discharge regulating member 520 when the toner volume increases. . Further, the toner stored in the toner storage section 560 passes through the gap with the toner discharge regulating member 520 little by little as the foaming roller 510 rotates, and falls below the casing 550. The toner that has dropped below the casing 550 is collected by the toner collection roller 540. The toner collected by the toner collecting roller 540 is collected at one place of the belt cleaning device 426 and discarded.

  The toner storage unit 560 is configured to forcibly discharge when the amount of stored toner increases. Further, for example, in the toner storage unit 560, when the amount of stored toner exceeds a certain amount, the contact state between the toner discharge regulating member 520 and the foaming roller 510 is released by pressure, so that the toner flows down. Can be applied.

  The toner scattering prevention member 530 is disposed in contact with the intermediate transfer belt 421 on the upstream side of the foaming roller 510 in the rotation direction of the intermediate transfer belt 421. The toner scattering prevention member 530 prevents scattering of the toner (toner scraped off by the cleaning blade 500) sent from the foaming roller 510 to the toner recovery roller 540, so that the toner leaks to the outside of the belt cleaning device 426. To prevent.

  On the downstream side of the belt cleaning device 426 in the rotation direction of the intermediate transfer belt 421, a collecting member 85 (corresponding to the “polishing unit” of the present invention) is provided so as to contact the intermediate transfer belt 421. Specifically, the collecting member 85 has the leading end portion of the collecting member 85 in contact with the surface of the intermediate transfer belt 421 in a counter direction with respect to the rotation direction of the intermediate transfer belt 421. The collecting member 85 is fixed by the fixing member 120. The collecting member 85 may be brought into contact with the surface of the intermediate transfer belt 421 in the width direction with respect to the rotation direction of the intermediate transfer belt 421.

  The collecting member 85 collects the abrasive particles 130 that have not been removed by the belt cleaning device 426, that is, has passed through the cleaning blade 500, and slides them on the intermediate transfer belt 421. In the present embodiment, the toner storage unit 560 is provided in the belt cleaning device 426, or a solid image is formed between images (between sheets) and supplied to the cleaning blade 500, thereby moving the intermediate transfer belt 421 in the moving direction. The abrasive particles 130 are uniformly distributed in the main scanning direction orthogonal to the above.

  The abrasive particles 130 are silica and glass components, and are on the positive polarity side in the triboelectric charging series. That is, the abrasive particles 130 have a property of being easily charged to a positive polarity when rubbed with other substances. The collecting member 85 is a sheet-like flexible member and is on the opposite polarity (minus polarity) side to the abrasive particles 130 in the triboelectric charging series. That is, the abrasive particles 130 have a property of being easily charged to a positive polarity when rubbed with other substances. Examples of the collecting member 85 include polyphenylene sulfide (PPS), acrylic, polypropylene, polyvinyl chloride, and silicon. The collecting member 85 may not be a sheet.

  As the abrasive particles 130 passing through the cleaning blade 500 of the belt cleaning device 426 and the collecting member 85 are rubbed, the abrasive particles 130 and the collecting member 85 are charged with positive polarity and negative polarity, respectively. That is, an attractive force (electrostatic force) attracting electrostatically is generated between the abrasive particles 130 and the collecting member 85, and the abrasive particles 130 are held by the collecting member 85. As a result, the abrasive particles 130 polish the surface of the intermediate transfer belt 421 by rubbing the intermediate transfer belt 421. As a result, deposits (toner, toner additives, paper dust, discharge products, etc.) adhering to the surface of the intermediate transfer belt 421 due to the filming phenomenon can be removed.

  As described above, it is easy to stably supply the abrasive particles 130 by polishing the surface of the intermediate transfer belt 421 using the abrasive particles 130 contained in the transfer residual toner remaining on the surface of the intermediate transfer belt 421. There is no need to provide a dedicated supply mechanism for supplying the abrasive particles 130, and an effect that the cost can be reduced can be obtained. Further, since the collecting member 85 is provided on the downstream side of the belt cleaning device 426 in the rotation direction of the intermediate transfer belt 421, the abrasive particles 130 having a particle diameter of several hundred [nm] or less that have passed through the cleaning blade 500. Thus, it is possible to prevent the surface of the intermediate transfer belt 421 from being damaged by the abrasive particles 130 having a large particle diameter. Further, the collecting member 85 only needs to satisfy the condition that it is easily charged to the opposite polarity to the abrasive particles 130 in the triboelectric charging series, and can be realized with a simple configuration.

  As shown in FIG. 4, a high-voltage power supply 80 (in the present invention) that applies a voltage having a polarity opposite to the charged polarity (for example, positive polarity) and the opposite polarity (for example, negative polarity) to the fixed member 120 and the collecting member 85, (Corresponding to “first voltage application unit”) may be connected to the fixing member 120. In this case, the collecting member 85 has a high resistance layer having semiconductivity and having a volume resistivity of, for example, 6 to 11 [log Ω · cm] on the surface. The controller 100 controls the high-voltage power supply 80 to apply a voltage having a polarity opposite to the charged polarity of the abrasive particles 130 to the collecting member 85. As a result, a stronger electrostatic force is generated between the abrasive particles 130 charged to the positive polarity and the negative polarity by friction and the collecting member 85, and the abrasive particles 130 held by the collecting member 85 are retained. The amount increases. As a result, the polishing force of the abrasive particles 130 on the surface of the intermediate transfer belt 421 can be increased. Further, even if the collecting member 85 is physically worn due to friction between the collecting member 85 and the abrasive particles 130, the influence of the electrostatic force on the collecting ability of the abrasive particles is small, so that deterioration of the polishing performance is prevented. In addition, the life of the collecting member 85 can be prolonged. By finely controlling the voltage value applied to the collecting member 85, the amount of the abrasive particles 130 collected by the collecting member 85, and hence the polishing force of the abrasive particles 130, can be finely adjusted.

  When reducing the polishing power of the abrasive particles 130, the control unit 100 controls the high voltage power supply 80 so that a voltage having a polarity opposite to the charged polarity of the abrasive particles 130 is not applied to the collecting member 85, or A voltage having the same polarity is applied to the collecting member 85 to reduce the amount of abrasive particles 130 collected by the collecting member 85. In the configuration shown in FIG. 4, since the abrasive particles 130 are collected by the collecting member 85 by applying a voltage having a polarity opposite to the charged polarity of the abrasive particles to the collecting member 85, the collecting member 85 is frictionally charged. It is not always necessary to be on the opposite polarity (minus polarity) side to the abrasive particles 130 in the series. In the configuration of FIG. 4, the collecting member 85 and the high-voltage power supply 80 correspond to the “polishing unit” of the present invention.

  Further, as shown in FIG. 5, for example, a scorotron charging member 95 and an abrasive particle 130 are charged on the downstream side of the belt cleaning device 426 and the upstream side of the collecting member 85 in the rotation direction of the intermediate transfer belt 421. A high-voltage power supply 90 (corresponding to the “second voltage application unit” of the present invention) is provided that increases the charge amount of the abrasive particles 130 by applying a voltage having the same polarity as the polarity (for example, plus polarity) to the charging member 95. May be.

  The control unit 100 controls the high-voltage power supply 90 to charge the abrasive particles 130 with a charge amount (plus polarity) by applying a voltage having the same polarity as the charged polarity (for example, plus polarity) of the abrasive particles 130 to the charging member 95. Increase the amount. As a result, compared to the configuration shown in FIG. 4 in which no voltage is applied to the charging member 95, a stronger electrostatic force is generated between the abrasive particles 130 and the collecting member 85 and collected by the collecting member 85. The amount of abrasive particles 130 increases. As a result, the polishing force of the abrasive particles 130 on the surface of the intermediate transfer belt 421 can be increased. By finely controlling the voltage value to be applied to the charging member 95 and the collecting member 85, the amount of the abrasive particles 130 collected by the collecting member 85 and the polishing force of the abrasive particles 130 can be finely adjusted.

  When reducing the polishing power of the abrasive particles 130, the control unit 100 controls the high-voltage power supplies 80 and 90 so that no voltage is applied to the collecting member 85 and the charging member 95, or the collecting member 85 and the charging member 95. By making the voltage applied to the same polarity, the amount of abrasive particles 130 collected by the collecting member 85 is reduced. Further, the control unit 100 may control the high-voltage power supplies 80 and 90 so that the voltage is not applied to the collecting member 85 while the voltage is applied to the charging member 95. In this case, in order to collect the abrasive particles 130 on the collecting member 85, the collecting member 85 is preferably on the opposite polarity (minus polarity) side to the abrasive particles 130 in the triboelectric charging series. In the configuration of FIG. 5, the collecting member 85, the charging member 95, and the high-voltage power supplies 80 and 90 correspond to the “polishing unit” of the present invention.

  4 and 5, the control unit 100 starts the image forming process (this embodiment) based on the detection result of the temperature / humidity detection sensor 75 and the print job at the start of execution of the image forming process corresponding to the print job. In this embodiment, when the temperature / humidity environment, the image coverage, the paper type) are acquired, and the acquired image forming conditions are conditions in which a filming phenomenon is likely to occur, A control operation for applying a voltage to the charging member 95 may be performed.

  By the control operation by the control unit 100, the deposits attached to the surface of the intermediate transfer belt 421 can be efficiently removed. Further, since the control operation is performed during the execution of the image forming process, it is possible to remove the deposits attached to the surface of the intermediate transfer belt 421 without reducing the productivity. In addition, when the image forming conditions are such that filming is unlikely to occur, the control operation is not performed unnecessarily, thereby reducing the risk of scratches on the intermediate transfer belt 421 and the wear risk of the intermediate transfer belt 421. be able to.

  FIG. 6 is a table showing the occurrence of filming phenomenon according to the image forming conditions (temperature / humidity environment, image coverage, paper type) according to the following criteria.

(Occurrence of filming phenomenon)
○: Filming phenomenon did not occur.
Δ: Filming phenomenon occurred, but no image defect occurred in the formed image.
X: Filming phenomenon occurred, and further, an image defect occurred in the formed image.

  Here, when the temperature and humidity environment is a high temperature and high humidity environment, the filming phenomenon tends to occur more easily than when the temperature and humidity environment is a normal temperature and humidity environment. This is because the fluidity of the agent is lowered and the external additive easily adheres to the surface of the intermediate transfer belt 421. In addition, when the temperature and humidity environment is a low temperature and low humidity environment, the filming phenomenon tends to occur more easily than the normal temperature and humidity environment. The reason why the hardness of the cleaning blade 500 increases and the surface of the intermediate transfer belt 421 is increased. This is because the follow-up property is deteriorated, so that the adhered matter adhering to the surface of the intermediate transfer belt 421 cannot be sufficiently scraped off. Also, the filming phenomenon tends to occur more easily when the coverage exceeds 70 [%] than when the coverage is 1 to 70 [%] because the amount of toner supplied to the cleaning blade 500 is large and the middle This is because there is a case where the adhered matter adhered to the surface of the transfer belt 421 cannot be scraped off. Further, when the coverage is less than 1%, the filming phenomenon tends to occur more easily than when the coverage is 1 to 70%. The amount of toner supplied to the cleaning blade 500 (external additive) As a result, the blade edge portion of the cleaning blade 500 is not properly polished, and as a result, the sliding contact between the cleaning blade 500 and the intermediate transfer belt 421 is not smooth. It is because it becomes impossible to scrape off. In addition, the filming phenomenon tends to occur more easily when the paper type is recycled paper than when it is coated paper because paper dust is more likely to occur with recycled paper.

  Note that the above control operation by the control unit 100 is preferably performed until the rotation distance of the intermediate transfer belt 421 reaches a predetermined distance (for example, 10 [m]) even after the execution of the image forming process is completed. This is because the deposit attached to the surface of the intermediate transfer belt 421 is surely removed by extending the polishing time of the abrasive particles 130 on the surface of the intermediate transfer belt 421 as much as possible. In particular, in the table shown in FIG. 6, in the case of an image forming condition in which the filming phenomenon is “×”, the attachment attached to the surface of the intermediate transfer belt 421 is compared to the case of other image forming conditions. The amount of kimono tends to increase. Therefore, it is preferable to perform the control operation even after the execution of the image forming process is completed. The control operation by the control unit 100 may be performed until a predetermined time (for example, 15 [s]) elapses after the execution of the image forming process is completed.

  As described above in detail, in the present embodiment, the image forming apparatus 1 includes the image forming unit 40 that supplies toner including abrasive particles 130 to the rotating intermediate transfer belt 421, and the toner supplied by the image forming unit 40. Among them, a belt cleaning device 426 that removes toner remaining on the surface of the intermediate transfer belt 421 and a belt cleaning device 426 that is provided downstream of the belt cleaning device 426 in the rotation direction of the intermediate transfer belt 421 and are not removed by the belt cleaning device 426. And a polishing unit that collects the abrasive particles 130 and rubs them against the intermediate transfer belt 421.

  According to this embodiment configured as described above, the collected abrasive particles 130 rub against the surface of the intermediate transfer belt 421 so that the surface of the intermediate transfer belt 421 is polished. Deposits adhered to the surface can be removed.

  In the above embodiment, the example in which the photosensitive drum 413 corresponds to the “image carrier” of the present invention has been described, but the present invention is not limited to this. For example, the intermediate transfer belt 421 may correspond to the “image carrier” of the invention. When the image forming apparatus 1 includes a secondary transfer belt for transferring the toner on the intermediate transfer belt 421 to the paper S, the secondary transfer belt corresponds to the “image carrier” of the invention. You may do it.

  In the above-described embodiment, the example in which the collecting member 85 electrostatically collects the abrasive particles 130 has been described. However, a magnetic force (attractive force) is generated between the collecting member 85 and the abrasive particles 130. By configuring as above, the collecting member 85 may collect the abrasive particles 130.

  In addition, each of the above-described embodiments is merely an example of a specific example for carrying out the present invention, and the technical scope of the present invention should not be construed as being limited thereto. That is, the present invention can be implemented in various forms without departing from the gist or the main features thereof.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Image reading part 20 Operation display part 21 Display part 22 Operation part 30 Image processing part 40 Image forming part 50 Paper conveyance part 60 Fixing part 71 Communication part 72 Storage part 75 Temperature / humidity detection sensor 80,90 High voltage power supply 85 Collecting member 95 Charging member 100 Control unit 130 Abrasive particle 413 Photosensitive drum 421 Intermediate transfer belt 426 Belt cleaning device

Claims (3)

An image forming unit for supplying toner containing abrasive particles to a rotating image carrier;
A cleaning unit for removing toner remaining on the surface of the image carrier from the toner supplied by the image forming unit;
A collecting member provided on the downstream side of the cleaning unit in the rotation direction of the image carrier, and electrostatically collects the abrasive particles not removed by the cleaning unit and slidably rubs the image carrier The charging of the abrasive particles so that the charging amount of the charging member provided on the downstream side of the cleaning unit and the upstream side of the collecting member in the rotation direction of the image carrier and the abrasive particles is increased. A polishing unit having a second voltage application unit that applies a voltage of the same polarity as the polarity to the charging member ;
An image forming apparatus comprising: The scavenged member is easy to charge the abrasive particles opposite polarity in triboelectric series, according to claim 1, characterized that you are collecting the abrasive particles in a state of contact with the image bearing member Image forming apparatus. The collecting member has conductivity,
The image forming apparatus according to claim 2 , wherein the polishing unit includes a first voltage application unit that applies a voltage having a polarity opposite to a charging polarity of the abrasive particles to the collecting member.

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