JP2015075725A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of surely preventing the occurrence of cleaning failure.SOLUTION: An image forming apparatus 1 includes an intermediate transfer belt 421, a cleaning blade 80, a driving part 75, a scraper 82, a toner scattering prevention member 86, and a control part 100. The scraper 82 is provided on the upstream side of the cleaning blade 80 in the normal rotation direction of the intermediate transfer belt 421 and comes into contact with the intermediate transfer belt 421 in a trail direction with respect to the normal rotation direction of the intermediate transfer belt 421. The control part 100 controls the driving part 75, so as to stop rotation drive in the normal rotation direction of the intermediate transfer belt 421 and then, reversely rotate the intermediate transfer belt 421 by not less than a distance L1 from a contact position P1 between the intermediate transfer belt 421 and the cleaning blade 80 to a contact position P2 between the intermediate transfer belt 421 and the scraper 82.

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.

  For example, in an intermediate transfer belt type image forming apparatus, a toner image formed on a photoreceptor is transferred to an intermediate transfer belt, and the toner image transferred to the intermediate transfer belt is transferred to a sheet. In this process, the toner remains on the surface of the intermediate transfer belt without being completely transferred onto the sheet. The remaining toner hinders the formation of a new image and causes a failure to obtain a good transfer image. Therefore, the image forming apparatus is provided with a cleaning device for removing the toner remaining on the intermediate transfer belt.

  In the cleaning device, a cleaning blade is brought into pressure contact with the surface of the intermediate transfer belt in order to remove toner remaining on the intermediate transfer belt. Then, as the image forming process continues, as shown in FIG. 1, a foreign matter 230 (mainly paper) is applied to a portion where the cleaning blade 210 is pressed against the intermediate transfer belt 220 (hereinafter referred to as “blade edge portion 212”). Agglomerates such as paper dust) accumulate and gradually accumulate. As a result, the foreign matter 230 is sandwiched between the cleaning blade 210 and the intermediate transfer belt 220, in other words, the blade edge portion 212 of the cleaning blade 210 is lifted from the surface of the intermediate transfer belt 220. When the blade edge portion 212 continues to float from the surface of the intermediate transfer belt 220, a part of the toner 240 remaining on the intermediate transfer belt 220 (hereinafter referred to as toner 250) in the rotational axis direction of the intermediate transfer belt 220. The cleaning blade 210 and the intermediate transfer belt 220 slip through from a place where the foreign matter 230 does not exist.

  As described above, when the toner 250 slips between the cleaning blade 210 and the intermediate transfer belt 220, that is, when cleaning failure occurs, the residual toner 250 is transferred onto an image formed by the next image forming process, and the black toner is transferred. Striped image noise occurs.

  In order to prevent such a cleaning failure, a technique has been proposed in which foreign matter sandwiched between the cleaning blade and the intermediate transfer belt is removed by reversing the intermediate transfer belt (for example, patents). Reference 1).

JP 2007-328088 A

  However, in the conventional technique for reversing the intermediate transfer belt, when the foreign matter once removed from between the cleaning blade and the intermediate transfer belt enters the blade edge portion again by the forward rotation of the intermediate transfer belt, In some cases, the portion collected again at the blade edge portion and was sandwiched between the cleaning blade and the intermediate transfer belt. As described above, the prior art cannot completely eliminate the possibility of causing a cleaning failure in which toner slips between the cleaning blade and the intermediate transfer belt.

  An object of the present invention is to provide an image forming apparatus that can reliably prevent the occurrence of defective cleaning.

An image forming apparatus according to the present invention includes:
An image carrier capable of rotating forward and backward, and
A cleaning blade that contacts the image carrier and removes toner remaining on the image carrier;
A drive unit that rotationally drives the image carrier in a forward rotation direction or a reverse rotation direction;
A toner scattering prevention member that is provided on the upstream side of the cleaning blade in the positive rotation direction of the image carrier so as to contact the image carrier and prevents the toner removed by the cleaning blade from scattering;
A scraper provided on the upstream side of the cleaning blade and the downstream side of the toner scattering prevention member in the forward rotation direction of the image carrier, and abuts on the image carrier in the trail direction with respect to the forward rotation direction of the image carrier. When,
After stopping the rotation of the image carrier in the forward rotation direction, the image is equal to or longer than the distance from the contact position between the image carrier and the cleaning blade to the contact position between the image carrier and the scraper. A control unit for controlling the drive unit to reversely rotate the carrier;
It is characterized by providing.

  According to the present invention, the foreign matter sandwiched between the cleaning blade and the image carrier moves to the scraper by the reverse rotation of the image carrier and is removed by the scraper. Therefore, when the image carrier again rotates forward, foreign matter does not enter the blade edge portion of the cleaning blade again, and the foreign matter is prevented from being caught again between the cleaning blade and the image carrier. Can do. Therefore, it is possible to reliably prevent the occurrence of defective cleaning.

It is a figure explaining the problem of a prior art. 1 is a diagram schematically showing an overall configuration of an image forming apparatus according to a first embodiment. FIG. 3 is a diagram illustrating a main part of a control system of the image forming apparatus according to the first embodiment. It is a figure which shows the principal part structure of the belt cleaning apparatus which concerns on 1st Embodiment. 3 is a flowchart illustrating a foreign matter removal control operation of the image forming apparatus according to the first embodiment. It is a figure which shows the principal part structure of the belt cleaning apparatus which concerns on 2nd Embodiment. 10 is a flowchart illustrating a foreign matter removal control operation of the image forming apparatus according to the second embodiment. 6 is a table showing the relationship between the temperature in the image forming apparatus and the timing at which the toner stored in the toner storage unit is discharged. 6 is a table showing a relationship between humidity in the image forming apparatus and timing for discharging toner stored in a toner storage unit. FIG. 6 is a diagram illustrating an operation for discharging toner stored in a toner storage unit. FIG. 6 is a diagram illustrating an operation for discharging toner stored in a toner storage unit. FIG. 6 is a diagram illustrating an operation for discharging toner stored in a toner storage unit. FIG. 6 is a diagram illustrating an operation for discharging toner stored in a toner storage unit.

Hereinafter, the present embodiment will be described in detail with reference to the drawings.
[Configuration of Image Forming Apparatus 1]
FIG. 2 is a diagram schematically showing the overall configuration of the image forming apparatus 1 according to the embodiment of the present invention. FIG. 3 shows the main part of the control system of the image forming apparatus 1 according to the first embodiment. An image forming apparatus 1 shown in FIGS. 2 and 3 is an intermediate transfer type color image forming apparatus using an 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. 3, 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 (corresponding to a “toner supply unit” of the present invention), a paper transport unit 50, A fixing unit 60 and a control unit 100 are provided.

  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. 2, 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 a negative polarity. 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 drum unit including the photoconductor drum 413 (photoconductor) is provided with a lubricant application device that applies the lubricant, which has been scraped off by the lubricant application brush, to the photoconductor drum 413.

  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 around a plurality of support rollers 423 in a loop shape. 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 traveling speed of the intermediate transfer belt 421 in the primary transfer portion constant. As the driving roller 423A rotates, the intermediate transfer belt 421 travels in the direction of arrow A at a constant speed.

  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 is rotationally driven 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.

  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 (corresponding to the “image carrier” of the present invention) 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.

[Main Configuration of Belt Cleaning Device 426]
Next, with reference to FIG. 4, the structure of the main part of the belt cleaning device 426 will be described. The belt cleaning device 426 includes a cleaning blade 80, a scraper 82, a scraper support sheet metal 84, a toner scattering prevention member 86, a waste toner screw 88, and a casing 90. The cleaning blade 80, the scraper 82, the scraper support metal plate 84, the toner scattering prevention member 86, and the waste toner screw 88 are provided in the casing 90.

  The intermediate transfer belt 421 is configured to be rotated forward and backward by a drive unit 75 (for example, a motor) that is controlled by the control unit 100. The intermediate transfer belt 421 rotates in the arrow direction (forward rotation direction) in the figure at a predetermined rotation speed (for example, 460 [mm / s]) during the image forming process (when the print job is executed) of the image forming apparatus 100. To do.

  The cleaning blade 80 is attached to a support metal plate (not shown) that supports the cleaning blade 80. The cleaning blade 80 is in contact with the surface of the intermediate transfer belt 421, and foreign matter including toner remaining on the surface of the intermediate transfer belt 421 (paper powder of the paper S, aggregates such as external additives and lubricants contained in the toner) ) Is removed by scraping. The foreign matter removed by the cleaning blade 80 falls below the casing 90 and is collected by the waste toner screw 88. The foreign matter collected by the waste toner screw 88 is collected at one place of the belt cleaning device 426 and discarded.

  The cleaning blade 80 abuts the front end portion (blade edge portion) of the cleaning blade 80 against the surface of the intermediate transfer belt 421 in a counter direction with respect to the positive rotation direction of the intermediate transfer belt 421 (rotation direction during image formation processing). I am letting. The material of the cleaning blade 80 is, for example, urethane rubber (hardness: 74 [degrees], rebound resilience: 23 [%]), but any other elastic material may be used.

  The scraper 82 is provided on the upstream side of the cleaning blade 80 in the forward rotation direction of the intermediate transfer belt 421. The scraper 82 has a thickness of 0.2 [mm] and a free length of 6 [mm]. As a material of the scraper 82, for example, PET is used.

  The scraper 82 is attached to a scraper support sheet metal 84 that supports the scraper 82. The scraper support metal plate 84 is configured to be rotatable in a clockwise direction in the drawing and a counterclockwise direction in the drawing by a driving unit 77 (for example, a motor) that is controlled by the control unit 100. When the scraper support metal plate 84 rotates in the clockwise direction in the drawing, the tip of the scraper 82 contacts the surface of the intermediate transfer belt 421 in the trail direction with respect to the normal rotation direction of the intermediate transfer belt 421. FIG. 4 shows a state where the tip of the scraper 82 is in contact with the surface of the intermediate transfer belt 421. The contact angle of the scraper 82 with the intermediate transfer belt 421 is, for example, 30 [°]. The amount of biting of the scraper 82 into the intermediate transfer belt 421 is, for example, 0.3 [mm]. On the other hand, when the scraper support metal plate 84 rotates counterclockwise in the figure, the tip of the scraper 82 is separated from the surface of the intermediate transfer belt 421. The drive unit 77 and the scraper support sheet metal 84 correspond to the contact / separation unit of the present invention.

  The toner scattering prevention member 86 (scattering prevention sheet) is provided on the upstream side of the scraper 82 in the forward rotation direction of the intermediate transfer belt 421 so as to contact the surface of the intermediate transfer belt 421. The toner scattering prevention member 86 prevents the toner removed by the cleaning blade 80 from scattering, thereby preventing the toner from leaking outside the belt cleaning device 426.

  In the rotation direction of the intermediate transfer belt 421, a distance L1 from the contact position P1 between the intermediate transfer belt 421 and the cleaning blade 80 to the contact position P2 between the intermediate transfer belt 421 and the scraper 82 is, for example, 3 [mm]. . In the rotational direction of the intermediate transfer belt 421, a distance L2 from the contact position P2 between the intermediate transfer belt 421 and the scraper 82 to the contact position P3 between the intermediate transfer belt 421 and the toner scattering prevention member 86 is, for example, 7 [ mm].

  Next, the foreign matter removal control operation of the image forming apparatus 1 in the first embodiment will be described with reference to the flowchart of FIG. The foreign matter removal control operation removes the foreign matter 110 (see FIG. 4) sandwiched between the blade edge portion (tip portion) of the cleaning blade 80 and the surface of the intermediate transfer belt 421 by continuing the image forming process. Therefore, the control operation is to reverse the intermediate transfer belt 421. The process of step S100 is started when the execution of the print job is completed, for example.

  First, the control unit 100 controls the drive unit 75 to stop the rotation of the intermediate transfer belt 421 in the normal rotation direction (step S100). Next, the control unit 100 controls the drive unit 77 to bring the tip of the scraper 82 into contact with the surface of the intermediate transfer belt 421 (step S120).

  Next, the control unit 100 controls the drive unit 75 so that the distance from the contact position P1 between the intermediate transfer belt 421 and the cleaning blade 80 to the contact position P2 between the intermediate transfer belt 421 and the scraper 82 is equal to or longer than the distance L1. The transfer belt 421 is reversely rotated (step S140). As a result, the foreign matter 110 sandwiched between the cleaning blade 80 and the intermediate transfer belt 421 moves to the scraper 82 by the reverse rotation of the intermediate transfer belt 421 (refreshing of the blade edge portion), and the reverse rotation direction of the intermediate transfer belt 421. On the other hand, it is scraped off and removed by a scraper 82 that contacts the intermediate transfer belt 421 in the counter direction. The foreign matter 110 removed by the scraper 82 falls below the casing 90 and is collected by the waste toner screw 88.

  Finally, the control unit 100 controls the drive unit 77 to separate the front end portion of the scraper 82 from the surface of the intermediate transfer belt 421 (step S160). Thereafter, the image forming apparatus 1 ends the processing in FIG. After the foreign matter removal control operation of the image forming apparatus 1 is completed, the execution of a new print job is started, whereby the control unit 100 controls the drive unit 75 to drive the intermediate transfer belt 421 to rotate in the forward rotation direction. To resume.

  As described above in detail, in the first embodiment, the image forming apparatus 1 is in contact with the intermediate transfer belt 421 that can rotate forward and backward and the intermediate transfer belt 421, and remains on the intermediate transfer belt 421. A cleaning blade 80 that removes toner to be transferred, a drive unit 75 that rotationally drives the intermediate transfer belt 421 in the forward rotation direction or the reverse rotation direction, and an intermediate transfer belt upstream of the cleaning blade 80 in the forward rotation direction of the intermediate transfer belt 421. A toner scattering prevention member 86 that is provided so as to contact the belt 421 and prevents the toner removed by the cleaning blade 80 from scattering; and an upstream side of the cleaning blade 80 in the forward rotation direction of the intermediate transfer belt 421 and a toner scattering prevention member 86 is provided downstream of the intermediate transfer belt 421 in the forward rotation direction. After the scraper 82 that contacts the intermediate transfer belt 421 in the direction of the roller and the rotational drive of the intermediate transfer belt 421 in the forward rotation direction are stopped, the intermediate transfer belt 421 starts from the contact position P1 between the intermediate transfer belt 421 and the cleaning blade 80. And a control unit 100 that controls the drive unit 75 so as to reversely rotate the intermediate transfer belt 421 by a distance L1 or more between the contact point P2 and the scraper 82.

  According to the first embodiment configured as described above, the foreign matter 110 sandwiched between the cleaning blade 80 and the intermediate transfer belt 421 moves to the scraper 82 by the reverse rotation of the intermediate transfer belt 421, and the scraper 82. Is scraped off and removed. Therefore, when the intermediate transfer belt 421 rotates forward again, the foreign matter 110 does not enter the blade edge portion of the cleaning blade 80 again, and the foreign matter 110 is sandwiched between the cleaning blade 80 and the intermediate transfer belt 421 again. This can be prevented. Accordingly, it is possible to reliably prevent the occurrence of a cleaning failure in which the toner slips between the cleaning blade 80 and the intermediate transfer belt 421.

  In the first embodiment, the control unit 100 causes the scraper 82 to contact the intermediate transfer belt 421 when the intermediate transfer belt 421 is rotated in the reverse direction, and scraper 82 when the intermediate transfer belt 421 is not rotated in the reverse direction. Is separated from the intermediate transfer belt 421. Accordingly, for example, when the intermediate transfer belt 421 is not rotated reversely during the image forming process of the image forming apparatus 1, the amount of toner remaining on the intermediate transfer belt 421 is supplied to the blade edge portion of the cleaning blade 80. As a result, the toner can be prevented from being suitably removed.

  In the first embodiment, in the rotational direction of the intermediate transfer belt 421, from the contact position P2 between the intermediate transfer belt 421 and the scraper 82 to the contact position P3 between the intermediate transfer belt 421 and the toner scattering prevention member 86. The distance L2 is longer than the distance L1 from the contact position P1 between the intermediate transfer belt 421 and the cleaning blade 80 to the contact position P2 between the intermediate transfer belt 421 and the scraper 82. As a result, when the intermediate transfer belt 421 rotates in the reverse direction until the foreign matter 110 sandwiched between the cleaning blade 80 and the intermediate transfer belt 421 hits the scraper 82, the scraper 82 accumulates in a portion in contact with the intermediate transfer belt 421. It is possible to prevent the toner that has passed through the contact position P3 between the intermediate transfer belt 421 and the toner scattering preventing member 86 from leaking to the outside of the belt cleaning device 426.

  Hereinafter, a second embodiment will be described in detail with reference to the drawings. FIG. 6 is a diagram showing a main configuration of a belt cleaning device according to the second embodiment. As shown in FIG. 6, the belt cleaning device 426 further includes a toner storage roller 92, a storage pet 94, and a storage pet support sheet metal 96 as compared with the belt cleaning device 426 of FIG. 4. In addition, the same code | symbol is attached | subjected about the thing similar to each part structure in 1st Embodiment, and the description is abbreviate | omitted.

  On the upstream side of the cleaning blade 80 in the forward rotation direction of the intermediate transfer belt 421, a toner storage unit 98 that temporarily stores the toner 120 (also referred to as waste toner) scraped by the cleaning blade 80 is formed. The toner storage unit 98 is a space formed by the toner storage roller 92, the storage pet 94, and the intermediate transfer belt 421. As the intermediate transfer belt 421 rotates in the forward rotation direction, the toner 120 stored in the toner storage unit 98 is carried to the cleaning blade 80 side, and the external additive contained in the toner 120 is supplied to the cleaning blade 80. The Thereby, the sliding contact between the cleaning blade 80 and the intermediate transfer belt 421 can be made smooth, and damage to the cleaning blade 80 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 reaches the cleaning blade 80 without being transferred. By doing so, an appropriate amount of toner 120 is stored in the toner storage unit 98. Thereafter, an appropriate amount of untransferred toner is generated in image formation, and a constant amount of toner 120 is always stored in the toner storage unit 98.

  The storage pet 94 is fixed to a storage pet support sheet metal 96 that supports the storage pet 94 with double-sided tape or the like. The storage pet 94 is a flexible member made of, for example, polyethylene terephthalate (PET). One end side of the storage pet 94 hangs downward and contacts the surface of the toner storage roller 92. The toner storage roller 92 is pinched by the intermediate transfer belt 421 and the storage pet 94.

  The toner storage roller 92 is rotatable while being in contact with the intermediate transfer belt 421 on the upstream side of the contact position P1 between the intermediate transfer belt 421 and the cleaning blade 80 in the forward rotation direction of the intermediate transfer belt 421. Be placed. As the toner storage roller 92, for example, a sponge roller, a rubber roller, or a resin roller can be applied. The toner storage roller 92 may be configured to be connected to a drive motor 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. good.

  As the toner storage roller 92 rotates, the toner 120 stored in the toner storage unit 98 gradually passes through the gap between the storage pet 94 and falls below the casing 90. The toner 120 dropped below the casing 90 is collected by the waste toner screw 88. The toner 120 collected by the waste toner screw 88 is collected at one place of the belt cleaning device 426 and discarded.

  The toner storage unit 98 is configured to forcibly discharge when the amount of stored toner 120 increases. For example, the toner storage section 98 has a configuration in which the toner 120 leaks from an opening (not shown) formed in the vicinity of the other end side (storage pet support sheet metal 96 side) of the storage pet 94 when the bulk of the toner 120 increases. Applicable. Further, for example, in the toner storage unit 98, when the stored toner 120 exceeds a certain amount, the contact state between the storage pet 94 and the toner storage roller 92 is released due to the pressure, and the pressure adjusting valve of the toner 120 falls off. Such a configuration can be applied.

  The toner scattering prevention member 86 is disposed on the upstream side of the toner storage roller 92 in the forward rotation direction of the intermediate transfer belt 421, and the toner 120 sent from the toner storage roller 92 to the waste toner screw 88 is outside the belt cleaning device 426. Prevents leakage.

  In the rotation direction of the intermediate transfer belt 421, a distance L1 from the contact position P1 between the intermediate transfer belt 421 and the cleaning blade 80 to the contact position P2 between the intermediate transfer belt 421 and the scraper 82 is, for example, 5 [mm]. . In the rotational direction of the intermediate transfer belt 421, a distance L3 from the contact position P3 between the intermediate transfer belt 421 and the toner storage roller 92 to the contact position P4 between the intermediate transfer belt 421 and the toner scattering prevention member 86 is, for example, 10 [mm].

  Next, the foreign matter removal control operation of the image forming apparatus 1 in the second embodiment will be described with reference to the flowchart of FIG. The process of step S200 is started when the execution of the print job is completed, for example.

  First, the control unit 100 controls the drive unit 75 to stop the rotational drive of the intermediate transfer belt 421 in the forward rotation direction (step S200). Next, the control unit 100 controls the driving unit 77 to bring the tip of the scraper 82 into contact with the surface of the intermediate transfer belt 421 (step S220).

  Next, the control unit 100 controls the drive unit 75 so that the distance from the contact position P1 between the intermediate transfer belt 421 and the cleaning blade 80 to the contact position P2 between the intermediate transfer belt 421 and the scraper 82 is equal to or longer than the distance L1. The transfer belt 421 is reversely rotated (step S240). As a result, the foreign matter 110 sandwiched between the cleaning blade 80 and the intermediate transfer belt 421 moves to the scraper 82 due to the reverse rotation of the intermediate transfer belt 421 and is intermediate in the counter direction with respect to the reverse rotation direction of the intermediate transfer belt 421. The scraper 82 abutting on the transfer belt 421 is scraped off and removed. The foreign material 110 removed by the scraper 82 is taken into the toner 120 stored in the toner storage unit 98. Therefore, after that, when the intermediate transfer belt 421 rotates forward, the foreign material 110 can be prevented from being caught between the cleaning blade 80 and the intermediate transfer belt 421 again.

  Next, the control unit 100 determines whether it is a discharge timing for discharging the toner 120 stored in the toner storage unit 98 according to the use history (for example, travel distance) of the intermediate transfer belt 421 ( Step S260). Here, the discharge timing means that the amount of the foreign matter 110 that enters the blade edge portion of the cleaning blade 80 during the image forming process increases, and as a result, the foreign matter 110 taken into the toner 120 stored in the toner storage portion 98. This is the timing when the amount of the foreign matter 110 removed by the scraper 82 is expected to increase.

  In the present embodiment, the control unit 100 determines that it is the discharge timing when the travel distance of the intermediate transfer belt 421 exceeds 300 [m] from the previous discharge timing, but exceeds 300 [m]. If not, it is determined that it is not the discharge timing.

  Note that the control unit 100 preferably changes the discharge timing in accordance with the image forming conditions. For example, the discharge timing may be changed according to the paper type of the paper S to be passed. Specifically, when the paper type of the paper S is coated paper, the basic condition (hereinafter the same) is defined as a case where the traveling distance of the intermediate transfer belt 421 exceeds 300 [m], and is five times the basic condition. The discharge timing is changed to an interval (interval of use history of the intermediate transfer belt 421) of (when the travel distance of the intermediate transfer belt 421 exceeds 1500 [m]). This is because in the case of coated paper, the amount of paper dust generated is small, and foreign matter is unlikely to collect at the portion where the cleaning blade 80 contacts the intermediate transfer belt 421.

  Further, the discharge timing may be changed according to the print mode. Specifically, when the print mode is the monochrome mode, the discharge timing is changed to an interval four times the basic condition (when the travel distance of the intermediate transfer belt 421 exceeds 1200 [m]). In the monochrome mode, the amount of lubricant transferred from the photosensitive drum 413 to the intermediate transfer belt 421 is as small as ¼ that in the color mode, and foreign matter is unlikely to collect at the portion where the cleaning blade 80 contacts the intermediate transfer belt 421. Because.

  Further, as shown in FIG. 8, the discharge timing may be changed according to the temperature in the image forming apparatus 1. Specifically, when the temperature is less than 15 [° C.], the discharge timing is set to the basic condition (1 time of the basic condition). On the other hand, when the temperature is 15 [° C.] or higher and lower than 35 [° C.], the discharge timing is set at an interval twice as long as the basic condition (when the travel distance of the intermediate transfer belt 421 exceeds 600 [m]). change. When the temperature is 35 [° C.] or higher, the discharge timing is changed to an interval that is three times the basic condition (when the traveling distance of the intermediate transfer belt 421 exceeds 900 [m]). In a low temperature environment, the lubricant application brush that scrapes off the lubricant becomes hard, so that the amount of lubricant applied to the photosensitive drum 413 increases, and the amount of transfer from the photosensitive drum 413 to the intermediate transfer belt 421 increases, while the high temperature This is because, in the environment, the lubricant application brush becomes soft, so that the amount of lubricant applied to the photosensitive drum 413 decreases, and the amount of transfer from the photosensitive drum 413 to the intermediate transfer belt 421 decreases.

  Further, as shown in FIG. 9, the discharge timing may be changed according to the humidity in the image forming apparatus 1. Specifically, when the humidity is less than 10 [%], the discharge timing is set to the basic condition (1 time of the basic condition). On the other hand, when the humidity is 10 [%] or more and less than 50 [%], the sheet is discharged at an interval of 1.5 times the basic condition (when the travel distance of the intermediate transfer belt 421 exceeds 450 [m]). Change the timing. When the humidity is 50% or more and less than 80%, the discharge timing is set at an interval twice the basic condition (when the travel distance of the intermediate transfer belt 421 exceeds 600 m). change. When the humidity is 80% or more, the discharge timing is changed to an interval that is three times the basic condition (when the travel distance of the intermediate transfer belt 421 exceeds 900 [m]). In a low humidity environment, the lubricant application brush becomes hard, so the amount of lubricant applied to the photosensitive drum 413 increases, and the amount of transfer from the photosensitive drum 413 to the intermediate transfer belt 421 increases. On the other hand, in a high humidity environment, lubrication occurs. This is because the agent application brush becomes soft, the amount of lubricant applied to the photosensitive drum 413 decreases, and the amount of transfer from the photosensitive drum 413 to the intermediate transfer belt 421 decreases. 8 and 9, in the LL environment (temperature: less than 15 [° C.], humidity: less than 10 [%]), the discharge timing is set to 1 time (= 1 × 1) of the basic condition, while HH In an environment (temperature: 35 [° C.] or higher, humidity: 80 [%] or higher), the discharge timing may be changed to an interval 9 times (= 3 × 3) the basic condition.

  As a result of the determination in step S260, when it is not the discharge timing (step S260, NO), the process transitions to step S320. On the other hand, when it is the discharge timing (step S260, YES), the control unit 100 performs a control operation to discharge the toner 120 stored in the toner storage unit 98 when the image forming process is interrupted (step S280). .

  For example, as shown in FIG. 10, the toner 120 stored in the toner storage unit 98 may be discharged by rotating the stored pet support sheet metal 96. In this case, the stored pet support sheet metal 96 is configured to be rotatable by a drive motor that receives a control command from the control unit 100. FIG. 10A shows a state before the stored pet support sheet metal 96 is rotated. FIG. 10B shows a state after the stored pet support sheet metal 96 is rotated in the direction of the arrow in the figure. As shown in FIG. 10B, the toner 120 and the foreign matter 110 stored in the toner storage unit 98 pass through the gap with the storage pet 94 little by little as the toner storage roller 92 rotates, and fall below the casing 90. .

  In addition, as shown in FIG. 11, the toner 120 stored in the toner storage unit 98 may be dropped and discharged by separating the toner storage roller 92 from the surface of the intermediate transfer belt 421. FIG. 11A shows a state immediately after the rotation of the toner storage roller 92 is stopped and the toner storage roller 92 is separated from the surface of the intermediate transfer belt 421 in the direction of the arrow using a known means such as a cam. ing. FIG. 11B shows a state where the toner 120 and the foreign material 110 stored in the toner storage unit 98 are falling below the casing 90.

  Also, as shown in FIG. 12, the toner storage roller 92 is separated from the surface of the intermediate transfer belt 421, and the toner storage roller 92 is rotated in the reverse direction, whereby the toner 120 stored in the toner storage unit 98 is efficiently dropped. May be discharged. FIG. 12A shows a state immediately after the rotation of the toner storage roller 92 is stopped and the toner storage roller 92 is separated from the surface of the intermediate transfer belt 421 in the direction of the arrow using a known means such as a cam. ing. FIG. 12B shows a state in which the toner 120 and the foreign matter 110 stored in the toner storage unit 98 are dropped below the casing 90 by rotating the toner storage roller 92 in the reverse direction of the arrow in the drawing.

  Further, as shown in FIG. 13, the toner 120 stored in the toner storage unit 98 may be discharged by increasing the rotation speed of the toner storage roller 92 from the normal time. FIG. 13A shows a state immediately after the rotation speed of the toner storage roller 92 is increased from the normal time. FIG. 13B shows a state where the rotation speed of the toner storage roller 92 is continuously increased. As shown in FIGS. 13A and 13B, the toner 120 and the foreign matter 110 stored in the toner storage section 98 gradually pass through the gap with the storage pet 94 as the toner storage roller 92 rotates, and below the casing 90. Fall.

  Next, the control unit 100 controls the image forming unit 40 to supply new toner 120 to the intermediate transfer belt 421, thereby storing a certain amount of toner 120 in the toner storage unit 98 (step S300). Even after the toner 120 is discharged, the new toner 120 stored in the toner storage unit 98 is carried to the cleaning blade 80 side so that the external additive contained in the toner 120 is supplied to the cleaning blade 80. is there. Thereafter, the process proceeds to step S320.

  In step S <b> 320, the control unit 100 controls the driving unit 77 to separate the tip end portion of the scraper 82 from the surface of the intermediate transfer belt 421. Thereafter, the image forming apparatus 1 ends the processing in FIG. After the foreign matter removal control operation of the image forming apparatus 1 is completed, the execution of a new print job is started, whereby the control unit 100 controls the drive unit 75 to drive the intermediate transfer belt 421 to rotate in the forward rotation direction. To resume.

  As described above in detail, in the second embodiment, the image forming apparatus 1 further includes the toner storage unit 98 that stores the toner 120 scraped off by the cleaning blade 80. The control unit 100 rotates the intermediate transfer belt 421 in the reverse direction, and then discharges the toner 120 stored in the toner storage unit 98.

  According to the second embodiment configured as described above, the foreign material 110 sandwiched between the cleaning blade 80 and the intermediate transfer belt 421 moves to the scraper 82 by the reverse rotation of the intermediate transfer belt 421, and the scraper 82. Is scraped off and removed. The foreign material 110 removed by the scraper 82 is taken into the toner 120 stored in the toner storage unit 98 and discharged together with the toner 120. Therefore, when the intermediate transfer belt 421 rotates forward again, the foreign matter 110 does not enter the blade edge portion of the cleaning blade 80 again, and the foreign matter 110 is sandwiched between the cleaning blade 80 and the intermediate transfer belt 421 again. This can be prevented. Accordingly, it is possible to reliably prevent the occurrence of a cleaning failure in which the toner slips between the cleaning blade 80 and the intermediate transfer belt 421.

  In the second embodiment, the contact position between the intermediate transfer belt 421 and the toner storage roller 92 from the contact position P3 between the intermediate transfer belt 421 and the toner storage roller 92 in the rotational direction of the intermediate transfer belt 421. The distance L3 to P4 is longer than the distance L1 from the contact position P1 between the intermediate transfer belt 421 and the cleaning blade 80 to the contact position P2 between the intermediate transfer belt 421 and the scraper 82. As a result, when the intermediate transfer belt 421 rotates in the reverse direction until the foreign matter sandwiched between the cleaning blade 80 and the intermediate transfer belt 421 hits the scraper 82, the toner storage roller 92 accumulates in the portion that contacts the intermediate transfer belt 421. Therefore, the toner 120 can be prevented from passing through the contact position P4 between the intermediate transfer belt 421 and the toner scattering preventing member 86 and leaking outside the belt cleaning device 426.

  In the first and second embodiments, the example in which the intermediate transfer belt 421 corresponds to the “image carrier” of the present invention has been described, but the present invention is not limited to this. For example, the photosensitive drum 413 may correspond to the “image carrier” of the invention. When the image forming apparatus 1 includes a secondary transfer roller or a secondary transfer belt for transferring the toner on the intermediate transfer belt 421 to the paper S, the secondary transfer roller or the secondary transfer belt is It may correspond to the “image carrier” of the present invention.

  In addition, each of the above-described embodiments is merely an example of actualization in 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 75,77 Drive part 80 Cleaning blade 82 Scraper 84 Scraper support metal plate 86 Toner scattering prevention member 88 Waste toner screw 90 Casing 92 Toner storage roller 94 Storage pet 96 Storage pet support metal plate 98 Toner storage unit 100 Control unit 101 CPU
102 ROM
103 RAM
110 foreign matter 120 toner 421 intermediate transfer belt 426 belt cleaning device

Claims (9)

An image carrier capable of rotating forward and backward, and
A cleaning blade that contacts the image carrier and removes toner remaining on the image carrier;
A drive unit that rotationally drives the image carrier in a forward rotation direction or a reverse rotation direction;
A toner scattering prevention member that is provided on the upstream side of the cleaning blade in the positive rotation direction of the image carrier so as to contact the image carrier and prevents the toner removed by the cleaning blade from scattering;
A scraper provided on the upstream side of the cleaning blade and the downstream side of the toner scattering prevention member in the forward rotation direction of the image carrier, and abuts on the image carrier in the trail direction with respect to the forward rotation direction of the image carrier. When,
After stopping the rotation of the image carrier in the forward rotation direction, the image is equal to or longer than the distance from the contact position between the image carrier and the cleaning blade to the contact position between the image carrier and the scraper. A control unit for controlling the drive unit to reversely rotate the carrier;
An image forming apparatus comprising: A contact / separation part for contacting the scraper with the image carrier or separating the scraper from the image carrier;
The control unit causes the scraper to abut on the image carrier when the image carrier is rotated in a reverse direction, and separates the scraper from the image carrier when the image carrier is not rotated in a reverse direction. The image forming apparatus according to claim 1, wherein the contact / separation unit is controlled.   In the rotational direction of the image carrier, the distance from the contact position between the image carrier and the scraper to the contact position between the image carrier and the toner scattering prevention member is the image carrier and the cleaning blade. The image forming apparatus according to claim 1, wherein the distance is longer than a distance from a contact position between the image carrier and the scraper. A toner storage unit that is formed on the upstream side of the cleaning blade and the downstream side of the toner scattering prevention member in the forward rotation direction of the image carrier, and stores toner scraped off by the cleaning blade;
The image forming apparatus according to any one of claims 1 to 3, wherein the scraper is provided on the upstream side of the cleaning blade and the downstream side of the toner storage portion in the forward rotation direction of the image carrier. apparatus.   The image forming apparatus according to claim 4, wherein the control unit causes the toner stored in the toner storage unit to be discharged after the image carrier is reversely rotated. A toner supply unit for supplying toner to the image carrier;
The control unit causes the toner storage unit to store toner by controlling the toner supply unit to supply toner to the image carrier after discharging the toner stored in the toner storage unit. The image forming apparatus according to claim 5.   The image forming apparatus according to claim 5, wherein the control unit determines a discharge timing for discharging the toner stored in the toner storage unit according to a use history of the image carrier. .   The image forming apparatus according to claim 7, wherein the control unit changes the determined discharge timing according to an image forming condition. A toner storage roller that contacts the image carrier and forms the toner storage part between the image carrier and the image carrier;
In the rotation direction of the image carrier, the distance from the contact position of the image carrier and the toner storage roller to the contact position of the image carrier and the toner scattering prevention member is the distance between the image carrier and the toner scattering prevention member. The image forming apparatus according to claim 4, wherein the image forming apparatus is longer than a distance from a contact position with a cleaning blade to a contact position between the image carrier and the scraper.

Images