JP2005292296A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus in which maintenance improvement and a cost reduction are achieved. <P>SOLUTION: An area of the surface of a transfer material conveying member 11, onto which area a transfer material P is conveyed while held on the member 11 and a toner image is transferred thereto by a transfer device, is subjected to the cleaning of the transfer material conveying member 11 at least one time such that toner sticking to the surface of the transfer material conveying member is removed before the subsequent transfer material P is conveyed again while held on the member 11. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a printer, and a facsimile.

  Conventionally, various methods such as an electrophotographic method, a thermal transfer method, and an ink jet method have been adopted as an image forming apparatus. Among these, an image forming apparatus using an electrophotographic method is superior to others in terms of high speed, high image quality, and quietness.

  In recent years, color image forming apparatuses using an electrophotographic method have been widely used, but these color image forming apparatuses are also divided into various methods. For example, in addition to the multiple transfer system and the intermediate transfer body system, a multiple development system in which a color image is superimposed on the surface of the photosensitive member and then transferred at once to form an image, or a plurality of different color image forming means (process stations). And an in-line method for transferring toner onto a transfer material (for example, paper or transparent film) conveyed by a transfer material conveying member. In the color image forming apparatus as described above, a belt is often used as a transfer material conveying member.

  FIG. 9 shows an example of a schematic configuration of an electrophotographic image forming apparatus using a conveyance belt as a transfer material conveyance member. The image forming apparatus shown in FIG. 1 has a rotatable drum-shaped electrophotographic photosensitive member as an image carrier, that is, photosensitive drums 1a, 1b, 1c, and 1d. The surfaces of the photosensitive drums 1a, 1b, 1c, and 1d are uniformly charged by charging rollers (charging devices) 2a, 2b, 2c, and 2d, and then exposed to exposure devices 3a, 3b, 3c, and the like such as LEDs and laser scanners. The exposure according to the image information is performed by 3d, whereby an electrostatic latent image is formed. Thereafter, the electrostatic latent image is developed as a toner image by electrostatically attaching toner to the developing devices 4a, 4b, 4c, and 4d. The toner images on the photosensitive drums are transferred onto a transfer material P that has been transported by a transport belt (transfer material transport member) 11 to a transfer position facing the photosensitive drums 1a, 1b, 1c, and 1d. Electrostatic transfer is performed by 12a, 12b, 12c, and 12d.

  The unfixed toner image thus transferred onto the transfer material P is fixed onto the transfer material P by being heated and pressed by the fixing device 20. Thereby, a permanent image is formed.

  On the other hand, the toner remaining on the surfaces of the photosensitive drums 1a, 1b, 1c, and 1d after the toner image transfer is removed by cleaning blades (photoconductor cleaning devices) 6a, 6b, 6c, and 6d and collected in a waste toner container. The The photosensitive drums 1a, 1b, 1c and 1d whose surfaces have been cleaned in this way are repeatedly used for image formation.

  In the case of the above-described electrophotographic image forming apparatus, if toner adheres on the conveyor belt 11, the transfer material P is soiled and causes image defects. For this reason, it is necessary to provide toner removing means for removing the toner adhering to the transport belt 11. As a toner removing unit, there is a method of attaching a conveyor belt cleaning member 14c that contacts the conveyor belt 11. Generally, a member such as a blade or a brush is used as the transport belt cleaning member 14c. If there is a blade or the like on the conveyor belt 11 as the conveyor belt cleaning member 14c, the conveyor belt 11 is always cleaned during its rotation, and the removed toner is a waste toner container for the conveyor belt 11. To be recovered. Therefore, image defects due to poor cleaning of the conveyor belt 11 are unlikely to occur. However, a member such as a blade and a brush as described above is required as a transport belt cleaning member, and a waste toner container dedicated to the transport belt is also required. Therefore, there is a problem that the apparatus is easily complicated and large. Further, it is necessary to periodically replace the waste toner container dedicated to the conveyor belt, which causes a problem of increasing the number of consumables. As a result, the maintainability of the image forming apparatus is reduced and the cost is increased.

  As a cleaning method for the conveyance belt 11 that can solve these problems, a positive bias or a negative bias is applied to the transfer rollers 12a, 12b, 12c, and 12d so that the toner on the conveyance belt 11 is statically applied to the photosensitive drum. Electrostatic cleaning that is electrically reversely transferred, removed by the photosensitive drum cleaning devices 6a, 6b, 6c, and 6d that are in contact with the photosensitive drums 1a, 1b, 1c, and 1d, and collected in a waste toner container. There is a method. According to this method, a member such as a blade or a brush as described above is not necessary as a conveying belt cleaning member, and a waste toner container dedicated to the conveying belt is not necessary, thereby simplifying the configuration of the image forming apparatus. It is possible to improve maintainability and reduce costs (for example, see Patent Document 1).

In addition, the code | symbol which is not demonstrated in FIG. 9 is demonstrated in the below-mentioned embodiment.
JP 2000-338821 A

  2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus, an image is generally formed with a margin of at least several millimeters secured from an end of a transfer material P. However, with the recent diversification of printer demand and the spread of digital image recording devices such as digital still cameras, there is an increasing demand for marginless printing such as silver halide photography. Marginless printing has already been put to practical use in recent ink jet type image forming apparatuses.

  In a conventional electrophotographic image forming apparatus, for example, in order to output image data to a transfer material without a margin, conventionally, a margin portion is printed after printing on a paper that is slightly larger than the size of the target transfer material P. However, for the purpose of simplifying this work, the need for printing without margins is increasing.

  In order to realize an image with no margins in the image forming apparatus, there is a method in which the size of the image formed in the image forming apparatus, that is, the printing area is slightly larger than the size of the transfer material P, and this is transferred to a sheet. However, simultaneously with the transfer of the toner image to the transfer material P, the toner image located outside the end of the transfer material P is directly transferred to the transport belt 11, and the transfer material P is soiled during continuous image formation. There is a problem. For example, since the toner image located outside the leading edge or the trailing edge of the transfer material P is attached in the sheet passing area on the conveying belt 11, the conveying belt 11 is again attached with the toner image adhered as it is. When the transfer material P is carried, the transfer material P is soiled. Further, the toner image positioned outside the left end or the right end of the transfer material P is also used when the position of the transferred transfer material P is shifted in a direction perpendicular to the sheet passing direction, or when the width of the transferred transfer material P is again loaded. Is wider than the previous transfer material P, the transfer material P is soiled.

  The problem of soiling the transfer material P as described above is that when a conveyor belt cleaning member such as a cleaning blade is provided on the conveyor belt 11, cleaning is always possible while the conveyor belt 11 is rotating. It does not occur.

  However, as described above, the toner adhering to the conveyance belt 11 is reversely transferred to the photosensitive drums 1a, 1b, 1c, and 1d, and the inside of the waste toner containers of the cleaning devices 6a, 6b, 6c, and 6d for the photosensitive drum 1 is used. In the recovery method, since it is necessary to provide a cleaning sequence for the conveying belt 11 separately from the image forming sequence, the cleaning of the conveying belt 11 cannot be performed at all times. For this reason, there is a problem that the toner adhering to the conveyor belt 11 stains the next transfer material P when images without margins are continuously printed.

  The present invention has been made in view of the above-mentioned circumstances, and removes unnecessary toner transferred onto a conveyor belt that is generated when a marginless image is formed, thereby preventing the transfer material from being stained due to unnecessary toner. An object of the present invention is to provide an image forming apparatus configured as described above.

  The present invention can solve the above problems by providing the following configuration.

  (1) A photosensitive member whose surface is movable, a charging device for charging the surface of the photosensitive member, an exposure device for exposing the charged surface of the photosensitive member to form an electrostatic latent image, and the electrostatic latent image A developing device that develops a toner image by attaching toner to the toner, a transfer material conveying member that carries and conveys a transfer material onto which the toner image is transferred, and a transfer material carried on the transfer material conveying member on the photosensitive member. A transfer device for transferring the toner image, and can form an image with no margin at at least one of the front end, rear end, left end, and right end of the transfer material. In an image forming apparatus, the region on the transfer material conveying member carrying and transferring the transfer material and transferring the toner image by the transfer device is transferred before the transfer material is carried and conveyed again. The toner adhering to the surface of the transfer material conveying member Image forming apparatus which comprises carrying out at least once a transfer material transport member cleaning for removing over.

  (2) The image forming apparatus includes a photoconductor cleaning device that cleans the surface of the photoconductor after the toner image is transferred, and the transfer material transport member cleaning electrostatically removes unnecessary toner attached to the transfer material transport member. The image forming apparatus according to (1), wherein the image forming apparatus is reversely transferred to the photoreceptor and removed by the photoreceptor cleaning device.

  (3) A photosensitive member whose surface is movable, a charging device for charging the surface of the photosensitive member, an exposure device for exposing the charged surface of the photosensitive member to form an electrostatic latent image, and the electrostatic latent image A developing device that attaches toner to the toner and develops it as a toner image, an intermediate transfer member to which the toner image is transferred, a first transfer device that transfers the toner image on the photosensitive member to the intermediate transfer member, and A transfer material conveying member for carrying and transferring a transfer material onto which the toner image is transferred from an intermediate transfer member; and a second transfer device for transferring the toner image on the intermediate transfer member to the transfer material. In the image forming apparatus capable of forming an image without a blank portion at at least one of the front end portion, the rear end portion, the left end portion, and the right end portion, among the regions on the transfer material conveying member The transfer material is carried and conveyed by the transfer device. The transfer material conveying member cleaning for removing the toner adhering to the surface of the transfer material conveying member is performed at least once before the transfer of the transfer material to the area where the toner image has been transferred again. An image forming apparatus.

  (4) The image forming apparatus includes an intermediate transfer body cleaning device that cleans the surface of the intermediate transfer body after the transfer of the toner image, and the transfer material transport member cleaning statically removes unnecessary toner adhering to the transfer material transport member. The image forming apparatus according to (3), wherein the intermediate transfer member is electrically reversely transferred to the intermediate transfer member and removed by the intermediate transfer member cleaning device.

  (5) In the image forming apparatus, the print area of the toner image is outside the transfer material at at least one of the front end, rear end, left end, and right end of the transfer material. The image forming apparatus according to any one of (1) and (3), wherein an image without a margin is formed on a transfer material by performing image formation.

  (6) The image forming apparatus includes a first image forming mode for forming an image having a margin at all of the leading edge, the trailing edge, the left edge, and the right edge of the transfer material, and the leading edge and the trailing edge of the transfer material. A second image forming mode for forming an image having no margin at at least one of the end, the left end, and the right end, and the transfer material conveying member in the first image forming mode. The image forming apparatus according to any one of (1) and (3), wherein cleaning is not performed, and transfer material conveying member cleaning is performed in the second image forming mode.

  (7) The transfer material conveying member has a circumferential length equal to or longer than a length in a sheet passing direction of a print area for forming a marginless image. Image forming apparatus.

  According to the present invention, the transfer material conveying member is cleaned before the region on the transfer material conveying member where the transfer material is carried and conveyed and the toner image is transferred by the transfer device is carried and conveyed again. By carrying out at least once, it is possible to satisfactorily remove the unnecessary toner transferred to the transfer material conveying member, which is generated at the time of forming a marginless image, and to prevent the transfer material from being stained. Further, since the cleaning member for the transfer material conveying member is not required, the configuration of the image forming apparatus can be simplified, and the maintenance of the image forming apparatus can be improved and the cost can be reduced.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to examples.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, what attached | subjected the same code | symbol in each drawing has the same structure or effect | action, The duplication description about these was abbreviate | omitted suitably.

<First Embodiment>
[Schematic configuration of image forming apparatus]
FIG. 1 shows an example of an image forming apparatus according to the present invention. The image forming apparatus shown in the figure is an electrophotographic four-color full-color laser printer having four image forming stations (image forming units), and the figure is a longitudinal sectional view showing a schematic configuration thereof. FIG. 2 is a longitudinal sectional view of the process cartridge. The image forming apparatus according to the present invention may be an electrophotographic laser printer, an electrophotographic copying machine, a facsimile, or an electrostatic recording printer, copying machine, facsimile, or the like. There may be.

  A laser printer (hereinafter referred to as “image forming apparatus”) shown in FIG. 1 includes four image forming stations (image forming units) in order from the bottom along the conveyance direction of the transfer material P inside the image forming apparatus main body 100. ) Sa, Sb, Sc, Sd. In this order, cyan, yellow, magenta, and black toner images are formed. These image forming stations Sa, Sb, Sc, Sd are provided with process cartridges 7a, 7b, 7c, 7d, respectively. Each process cartridge 7a, 7b, 7c, 7d has a drum as an image carrier. 1a, 1b, 1c, and 1d are disposed in the shape of an electrophotographic photosensitive member (hereinafter referred to as “photosensitive drum”). Hereinafter, when it is not necessary to distinguish colors, a, b, c, and d are omitted, and generic names such as “image forming station S”, “process cartridge P”, and “photosensitive drum 1” are used. I write. This also applies to other members.

  FIG. 2 is an enlarged vertical sectional view of the cyan process cartridge 7a. The configuration and operation of the other three color process cartridges 7b, 7c, and 7d are the same as those of the cyan process cartridge 7a, and therefore the description thereof will be omitted as appropriate.

  The photosensitive drums 1a, 1b, 1c, and 1d are rotationally driven counterclockwise in FIG. 1 by driving means (not shown). Around the photosensitive drums 1a, 1b, 1c, and 1d, the charging devices 2a, 2b, 2c, and 2d, the exposure devices 3a, 3b, 3c, and 3d, and the developing devices 4a, 4b, and 4c are sequentially arranged along the rotation direction. , 4d, transfer rollers (transfer members, transfer devices) 12a, 12b, 12c, 12d, cleaning devices 6a, 6b, 6c, 6d, and the like.

  The charging devices 2a, 2b, 2c and 2d uniformly charge the surfaces of the photosensitive drums 1a, 1b, 1c and 1d. The exposure devices (scanner units) 3a, 3b, 3c, 3d form electrostatic latent images by irradiating the charged photosensitive drums 1a, 1b, 1c, 1d with laser beams based on image information. . The developing devices 4a, 4b, 4c, and 4d develop toner images by attaching toner to the electrostatic latent images formed by the exposure devices 3a, 3b, 3c, and 3d. The transfer rollers 12a, 12b, 12c, and 12d transfer the toner images formed on the photosensitive drums 1a, 1b, 1c, and 1d to the transfer material P. The cleaning devices 6a, 6b, 6c, and 6d remove toner (residual toner) remaining on the surfaces of the photosensitive drums 1a, 1b, 1c, and 1d after the transfer.

  Here, as shown in FIGS. 1 and 2, the photosensitive drums 1a, 1b, 1c, 1d, the charging devices 2a, 2b, 2c, 2d, the developing devices 4a, 4b, 4c, 4d, and the cleaning devices 6a, 6b, 6c and 6d are integrated into a cartridge to form process cartridges 7a, 7b, 7c and 7d. These process cartridges 7a, 7b, 7c and 7d are further divided into a photosensitive drum unit 50a and a developing unit 4a (developing device) as shown in the cyan process cartridge 7a in FIG. The photosensitive drum unit 50a is a unit having a photosensitive drum 1a, a charging device 2a, and a cleaning device 6a.

  Hereinafter, the photosensitive drum 1 will be described in detail.

  The photosensitive drum 1 is configured by coating an organic photosensitive semiconductor layer (OPC photosensitive layer) on the outer peripheral surface of an aluminum cylinder having a diameter of 30 mm, for example. Both ends of the photosensitive drum 1 are rotatably supported by a support member (not shown), and a driving force from a drive motor (not shown) is transmitted to one end so that the photosensitive drum 1 in FIG. It is driven to rotate counterclockwise.

  The charging device 2 includes a charging roller (conductive roller) formed in a roller shape, and a charging bias application power source (not shown). The charging device 2 brings the charging roller into contact with the surface of the photosensitive drum 1 and applies a charging bias to the charging roller by the above-described charging bias application power source so that the surface of the photosensitive drum 1 has a uniform polarity and potential. (Uniformly) charged. In the present embodiment, the surfaces of the photosensitive drums 1a, 1b, 1c, and 1d are uniformly charged negatively by the charging devices 2a, 2b, 2c, and 2d.

  The exposure devices 3a, 3b, 3c, 3d are arranged on the left side of the respective photosensitive drums 1a, 1b, 1c, 1d in FIG. 1, and image light corresponding to image signals is scanned by a laser diode (not shown). The polygon mirrors 9a, 9b, 9c, and 9d that are rotated at high speed by a motor (not shown) are irradiated. The image light reflected by the polygon mirrors 9a, 9b, 9c, 9d selectively exposes the charged photosensitive drums 1a, 1b, 1c, 1d through the imaging lenses 10a, 10b, 10c, 10d. An electrostatic latent image is formed. In the present embodiment, the electrostatic latent image is formed by removing the charge of the portion irradiated with the image light.

  The developing devices 4a, 4b, 4c, and 4d have toner containers that store toners of cyan, yellow, magenta, and black, respectively. As shown in the cyan toner container 41a in FIG. 2, the developing device 4a feeds the toner in the toner container 41a to the toner supply roller 43a by the feeding mechanism 42a, and rotates clockwise (in the direction of arrow Z) in FIG. The toner supply roller 43a and the developing blade 44a pressed against the outer peripheral surface of the developing roller 40a are applied to the outer peripheral surface of the developing roller 40a rotating in the arrow Y direction, and charge is applied to the applied toner. Then, a developing bias is applied by a developing bias applying power source (not shown) to the developing roller 40a that is opposed to and in contact with the photosensitive drum 1a on which the electrostatic latent image is formed, thereby forming the electrostatic latent image on the photosensitive drum 1a. A negative toner is attached to the toner image and developed as a toner image. The other color developing devices 4b, 4c, and 4d have the same configuration and operation as the cyan developing device 4a.

A transfer device 5 is disposed on the right side of the process cartridges 7a, 7b, 7c, and 7d in FIG. The transfer device 5 includes a transport belt (electrostatic transfer belt as a transfer material transport member) 11 that circulates (rotates) so as to be in contact with and contact the photosensitive drums 1a, 1b, 1c, and 1d. The conveyor belt 11 is formed of a film-like member having a volume resistivity of 10 ⁸ to 10 ¹³ Ω · cm and a thickness of 50 to 300 μm. In the present embodiment, the conveyor belt 11 is made of PVdF (polyvinylidene fluoride). The conveyor belt 11 is stretched around four rollers 13, 14, 15, 16 arranged in parallel to each other, and is arranged in the vertical direction as a whole. The conveyance belt 11 rotates in a state where the transfer material P is electrostatically adsorbed on the outer peripheral surface at a portion located between the roller 13 and the roller 14 in FIG. As a result, the transfer material P is sequentially transported to the above-described photosensitive drums 1a, 1b, 1c, and 1d at the transfer positions, and the toner images on the photosensitive drums 1a, 1b, 1c, and 1d are transferred as described below. The images are sequentially transferred by the rollers 12a, 12b, 12c, and 12d.

  Inside the transport belt 11, four transfer rollers 12a, 12b, 12c, and 12d are disposed at positions corresponding to the photosensitive drums 1a, 1b, 1c, and 1d, respectively. These transfer rollers 12a, 12b, 12c, and 12d are in contact with the back side of the conveyance belt 11, and the conveyance belt 11 is sandwiched between the photosensitive drums 1a, 1b, 1c, and 1d. As a result, first, second, third, and fourth transfer portions (transfer nip portions) are formed between the photosensitive drums 1a, 1b, 1c, and 1d and the conveyor belt 11. In the present embodiment, a positive transfer bias is applied to the transfer rollers 12a, 12b, 12c, and 12d by a transfer bias application power source (not shown), thereby negative polarity on the photosensitive drums 1a, 1b, 1c, and 1d. The color toner images are sequentially transferred onto the transfer material P in the first to fourth transfer portions.

  Residual toner remaining on the photosensitive drums 1a, 1b, 1c, and 1d without being transferred to the transfer material P when the toner image is transferred is removed by the cleaning devices 6a, 6b, 6c, and 6d. As shown in FIG. 2, the cyan cleaning device 6a has a cleaning blade 60a that contacts the surface of the photosensitive drum 1a to remove residual toner on the surface of the photosensitive drum 1a. Residual toner removed from the surface of the photosensitive drum 1a by the cleaning blade 60a is sequentially sent to a waste toner chamber 53a provided behind the cleaning frame 51a by the toner feeding mechanism 52a.

  A detachable paper feed cassette 17 is disposed at the bottom of the image forming apparatus main body 100. A plurality of transfer materials P (for example, plain paper, envelopes, transparent films) are stored in the paper feed cassette 17 in a stacked state. The transfer material P in the paper feed cassette 17 is separated and fed one by one by the drive rotation of the paper feed roller 18 (half moon roller) during image formation, and is temporarily stopped by abutting the leading end against the registration roller pair 19. To form a loop. Thereafter, the rotation of the conveyance belt 11 and the image writing position on the photosensitive drums 1 a, 1 b, 1 c, and 1 d are synchronized with each other and the sheet is supplied to the conveyance belt 11 by the registration roller pair 19. The transfer material P supplied toward the conveying belt 11 is adsorbed on the surface of the conveying belt 11 by an adsorbing roller 22 as an adsorbing member disposed further upstream than the photosensitive drum 1a on the most upstream side.

  A fixing device 20 is disposed further downstream (upward) of the most downstream image forming station Sd. The fixing device 20 fixes the toner images of a plurality of colors transferred onto the transfer material P, and includes a rotating fixing roller 23 and a pressure roller 24 that is pressed against the transfer roller P and applies heat and pressure to the transfer material P. have. That is, the transfer material P transferred so that the toner images of the respective colors on the photosensitive drums 1a, 1b, 1c, and 1d are sequentially overlapped is sandwiched between the fixing roller 23 and the pressure roller 24 when passing through the fixing device 20. While being conveyed, it is heated and pressurized to fix the toner images of a plurality of colors on the surface.

  The image forming operation in the above-described image forming apparatus is as follows. The photosensitive drums 1a, 1b, 1c, and 1d in the process cartridges 7a, 7b, 7c, and 7d are rotated counterclockwise in accordance with the image formation timing, and are uniformly charged by the charging devices 2a, 2b, 2c, and 2d. The The charged photosensitive drums 1a, 1b, 1c, and 1d are exposed according to image signals (image information) by the exposure devices 3a, 3b, 3c, and 3d to form an electrostatic latent image. At this time, a portion that is not exposed becomes a dark portion (high potential portion), and the potential (dark portion potential) is defined as VD. On the other hand, the exposed portion becomes a bright portion (low potential portion), and the potential (bright portion potential) is set to VL. The developing devices 4a, 4b, 4c, and 4d attach toner to the bright portions of the above-described electrostatic latent images, and cyan, yellow, magenta, and black toner images on the photosensitive drums 1a, 1b, 1c, and 1d, respectively. Form.

  On the other hand, the transfer material P supplied to the transport belt 11 from the paper feed cassette 17 by the paper feed roller 18, the registration roller pair 19 and the like is sandwiched between the suction roller 22 and the transport belt 11, and the surface of the transport belt 11 (outer periphery). And is electrostatically attracted to the surface of the conveyor belt 11 by applying a voltage between the conveyor belt 11 and the suction roller 22. At this time, a positive voltage is applied from the suction roller 22 side, and the roller (suction counter roller) 14 is grounded. As a result, the transfer material P is stably adsorbed to the transport belt 11 and is transported to the fourth transfer section on the most downstream side.

  The transfer material P adsorbed on the surface of the conveyance belt 11 in this way is sequentially conveyed to the first to fourth transfer portions of the respective colors by the rotation of the conveyance belt 11 in the direction of the arrow R11, and each photosensitive drum 1a, 1b, 1c. , 1d and the transfer rollers 12a, 12b, 12c, 12d, the toner images on the photosensitive drums 1a, 1b, 1c, 1d are sequentially transferred by an electric field (transfer electric field) formed between the transfer rollers 12a, 12b, 12c, 12d.

  The transfer material P onto which the four color toner images have been transferred is separated from the conveying belt 11 by the curvature of the roller (belt driving roller) 13 and is carried into the fixing device 20. The transfer material P is heated and pressed by the fixing roller 23 and the pressure roller 24 in the fixing device 20 to fix the toner images of four colors on the surface. After the toner image is fixed, the transfer material P is discharged by the paper discharge roller pair 25 onto the paper discharge tray 26 formed on the upper surface of the image forming apparatus main body 100 with the image surface facing downward. On the other hand, the residual toner remaining on the surface of the photosensitive drums 1a, 1b, 1c, and 1d after the toner image is fixed is removed by the cleaning devices 6a, 6b, 6c, and 6d, and used for the next image formation. Thus, the four-color full-color image formation is completed.

[Conveyor belt cleaning sequence]
The conveyance belt 11 intentionally transfers a toner image for density detection onto the conveyance belt 11 after image formation in a marginless mode, which will be described later, after a feeding jam of the transfer material P during image formation, or the like. Later, in order to prevent the transfer material P from being soiled, it is necessary to remove unnecessary toner on the conveyor belt 11.

  A toner removal method when toner adheres to the conveyor belt 11 will be described. In the present embodiment, a conveyor belt cleaning member (for example, a cleaning blade) dedicated to the conveyor belt 11 is not provided. The toner adhering to the conveyance belt 11 is reversely transferred onto the photosensitive drums 1a, 1b, 1c, and 1d, and collected using the cleaning devices 6a, 6b, 6c, and 6d in the photosensitive drum unit.

  First, in the first transfer portion of the image forming station Sa, an electric field having a polarity opposite to that of a normal transfer (when the toner image on the photosensitive drum 1a is transferred onto the transfer material P) is generated. The transfer bias and the surface potential of the photosensitive drum 1a are adjusted. The electric field adjusted in this way is hereinafter referred to as “transfer reverse electric field”. For example, the surface of the photosensitive drum 1a is set to the dark portion potential VD, and a negative bias having an absolute value larger than VD is applied to the transfer roller 12a as the transfer bias. Hereinafter, the negative transfer bias is referred to as a transfer reverse bias. Since the reverse transfer electric field is formed in the first transfer portion, the normally charged (negative charge) toner is reversely transferred to the photosensitive drum 1a, and is transferred to the waste toner chamber 53a by the photosensitive drum cleaning device 6a. To be recovered. In the configuration according to the present embodiment, when the dark portion potential VD on the surface of the photosensitive drum 1a is set to −700 V, about −1.5 kV is applied as the transfer reverse bias.

  Next, the transfer bias and the surface potential of the photosensitive drum 1b are adjusted so that an electric field having the same polarity as the electric field at the time of toner image transfer is generated in the second transfer portion of the image forming station Sb. The electric field adjusted in this way is hereinafter referred to as a “transfer positive electric field”. In order to realize this, the surface of the photosensitive drum 1b is set to the dark portion potential VD potential, and a bias having an absolute value of positive polarity is applied as the transfer bias. In the second transfer portion, by forming a transfer positive electric field, the toner whose polarity is reversed (positive charge) is reversely transferred to the photosensitive drum 1 b and discharge is caused between the photosensitive drum 1 b and the transport belt 11. Thus, the toner is recharged to a negative polarity. For example, in this embodiment, the dark portion potential VD on the surface of the photosensitive drum 1 is set to −700 V, and about +1.0 kV is applied as the second transfer bias.

  Next, a reverse transfer electric field similar to that of the first transfer portion was formed in the third transfer portion. The purpose and effect are the same as those of the first transfer portion.

  Next, a positive transfer electric field similar to that of the second transfer portion was formed in the fourth transfer portion. In the fourth transfer portion, the toner charged on the positive polarity is completely reversely transferred to the photosensitive drum 1 to complete the removal of the toner on the conveyance belt 11.

  Further, when the conveyor belt 11 is cleaned, that is, when the toner on the conveyor belt 11 is reversely transferred onto the photosensitive drums 1a, 1b, 1c, and 1d, the rotational speed of the photosensitive drums 1a, 1b, 1c, and 1d is determined. The toner on the conveyor belt 11 is also collected by the photosensitive drums 1a, 1b, 1c, and 1d by providing a significant peripheral speed difference between positive and negative in the moving speed (rotational speed) of the conveyor belt 11. In the present embodiment, the moving speed of the conveyor belt 11 is increased by about 50% with respect to the rotational speed of the photosensitive drums 1a, 1b, 1c, and 1d.

  A series of sequence operations relating to the cleaning of the transport belt 11 described above will be collectively referred to as “transport belt cleaning”. In this embodiment, the conveyance belt cleaning is mainly performed after the image formation in the marginless mode, but other than this, for example, a toner image for detection purposely for the purpose of density control or registration (registration) control. Is formed on the conveying belt 11 or after the toner is inevitably transferred onto the conveying belt 11 due to a feeding jam of the transfer material P at the time of image formation. To run.

[Image formation mode]
In the image forming apparatus of the present invention, as an image forming mode, a margin mode in which a margin portion is provided at an end portion on a transfer material P and an image is printed as usual, and an image without a margin portion is provided on the transfer material P. Has no margin mode to print.

  FIG. 3 is a schematic diagram showing the relationship between the size of the printing area M and the transfer material P of the image forming apparatus. In the margin mode, as shown in FIG. 3A, by setting the printing area M smaller than the size of the transfer material P, margins are secured at the end portions of the four sides on the transfer material P. Yes. The size of the margin is set as appropriate. In this embodiment, a margin area of 3 mm at least on the transfer material P is ensured by setting the print area M in the margin mode to the inside 3 mm from the end portions of the four sides of the transfer material P.

  On the other hand, in the case of no margin mode, as shown in FIG. 3B, by setting the printing area M larger than the size of the transfer material P, there are no margin portions at the ends of the four sides of the transfer material P. Images can be printed. That is, by allowing the toner image to protrude from the transfer material, the toner image can be placed up to the end of the transfer material P even if the transfer material P is slightly displaced. In this embodiment, the printing area M in the marginless mode is set to be 2 mm outside from the end portions of the four sides of the transfer material P. Therefore, in the no margin mode, when the toner image is transferred from the photosensitive drum 1 to the transfer material P, the toner image located outside the transfer material P is directly transferred onto the conveying belt 11 and remains. This is removed by executing the conveyor belt cleaning. The printing area M for the transfer material P in the marginless mode is not limited to the set value of the present embodiment, and may be any size as long as an image without a margin can be completely formed on the transfer material P. In this embodiment, all four sides have no margin, but the present invention is not limited to all four sides.

[Conveyor belt circumference]
FIG. 4 is a schematic diagram showing the relationship between the circumferential length of the conveyance belt 11 and the length of the printing area M in the sheet passing direction. L _B represents the circumferential length of the conveyor belt 11, and L _M represents the length of the print region M in the sheet passing direction. Circumferential length L _B of the conveyor belt 11 of the image forming apparatus is set to be more than at least the feed direction length of the print area M of the no-margin mode L _M. If the circumferential length L _B of the conveyor belt 11 is less than L _M in marginless mode, the region where the transfer is performed toner image by the transfer material P carried and conveyed to the transfer device in a region on the conveyor belt 11 It is used for carrying the transfer material P or transferring the toner image twice during one image formation. At this time, there is a possibility that the transfer material P may be stained with toner due to unnecessary toner directly transferred onto the conveyance belt 11.

The image forming apparatus of this embodiment is a color LBP corresponding to A4 size, and has a specification in which the marginless mode can be applied to the transfer material P up to the maximum A4 size. Therefore, the maximum length of length L _M in the feed direction of the print area M of the marginless mode is a feed direction length of the print area M at A4 size. As described with reference to FIG. 3B, since the printing area M is set to be 2 mm outside the end of the four sides of the transfer material P, the length of the A4 size in the sheet passing direction is 210 mm. The print area M in the marginless mode is 214 mm. And the circumference of the conveyance belt 11 of a present Example is set to 675 mm which exceeds this.

[Conveyor belt cleaning execution control]
FIG. 5 is a diagram illustrating a control flow for determining the execution timing of the conveyor belt cleaning during image formation.

  After receiving the image formation signal (S1), the image forming apparatus starts image formation in the no margin mode or the margin mode according to the image formation signal (S2). Then, the toner image formed on the photosensitive drum 1 is sequentially transferred to the transferred transfer material P (S3).

  Next, the image forming mode at this time is confirmed (S4). If the image formation in S2 is the marginless mode, the conveyor belt cleaning is executed after the transfer of the toner image (S5). In the marginless mode, the toner is directly transferred onto the conveyor belt 11, so that it is necessary to always carry out the conveyor belt cleaning.

  When the image forming mode in S2 is not the marginless mode (S4), that is, in the margin mode, the toner is not directly transferred to the conveyor belt 11, and the conveyor belt cleaning is not performed.

  Finally, the presence or absence of the next image formation is confirmed (S6). If the next image formation is not reserved, the image formation ends (S7) as it is, and if the next image formation is reserved, the subsequent control steps from the start of image formation in S2 are repeated again.

  To summarize the above control flow, the conveyance belt cleaning sequence is not performed in the margin mode, and the conveyance belt cleaning is performed every time image formation is performed on the transfer material P in the marginless mode.

  However, even when the image is formed in the margin mode, if there is a possibility that the conveyance belt 11 becomes dirty due to toner fogging on the photosensitive drum 1 or the like, the conveyance belt cleaning is executed at a predetermined timing. You may let them.

  By the configuration of the image forming apparatus and the conveyance belt cleaning described above, unnecessary toner transferred on the conveyance belt generated during printing without margins can be satisfactorily removed, and transfer material contamination caused by the unnecessary toner can be prevented. Can be prevented.

<Second Embodiment>
A second embodiment will be described. Note that the schematic configuration of the image forming apparatus, the conveying belt cleaning sequence, the image forming mode, and the circumference of the conveying belt 11 are the same as those in the first embodiment described above, and a description thereof will be omitted.

  In the first embodiment, in the marginless mode, the conveyance belt cleaning sequence is performed every time image formation is performed regardless of the size of the transfer material P, whereas in this embodiment, continuous image formation is performed. By controlling the execution timing of the conveyor belt cleaning according to the length of the area on the conveyor belt 11 that is sometimes required, the number of executions of the conveyor belt cleaning during image formation is minimized. As a result, the downtime due to the execution of the conveyor belt cleaning can be minimized, and a decrease in the throughput number of the transfer material P can be suppressed.

[Relationship between the circumference of the conveyor belt and the length of the transfer material P in the sheet passing direction]
FIG. 6 is a schematic diagram showing the relationship between the circumferential length of the conveyance belt 11 and the lengths of the printing region M and the transfer material P in the sheet passing direction during continuous image formation in the marginless mode.

L _B indicates the circumferential length of the conveyor belt 11. In this embodiment, the circumferential length L _B of the conveyor belt 11 of the image forming apparatus, as in the first embodiment, set to be not less than the maximum length of length L _M in the feed direction of the print area M of the marginless mode doing. L _P (n) indicates the length (in the following, referred to as “transfer material length”) of the transfer material P used when the nth image is formed in the case of continuous printing in the marginless mode. n is a natural number excluding 0. L _INT (n) is the length in the sheet passing direction between the transfer material P used for n-th image formation and the transfer material P used for n + 1-th image formation (hereinafter referred to as “inter-sheet length”). ). L _H indicates the length in the sheet passing direction of the area that protrudes from the upstream side of the transfer material P in the print area M in the first marginless mode.

FIG. 6 shows a state before image formation of the (n + 1) th image is performed after image formation is continuously performed up to the nth image in the marginless mode. Here, the length in the sheet passing direction on the conveying belt 11 necessary for the image formation from the first sheet to the (n + 1) th sheet is the print area L _H that protrudes upstream from the transfer material P and the first sheet to the nth sheet. The total length of the transfer material length and the inter-paper length up to and the (n + 1) th transfer material length are added. If the length obtained by adding these is L _T (n), L _T (n) can be expressed by the following equation.
L _T (n) = L _H + ΣN = 1 to n {L _P (N) + L _INT (N)} + L _P (n + 1) (1)

If L _T (n) is shorter than the circumferential length L _{B of} the conveyor belt 11, the conveyor belt 11 is transported within the printing area M for image formation on one side as long as the conveyor belt cleaning is executed every time the conveyor belt 11 makes one round. direct toner is transferred area belt 11 (e.g., the region of L _H) is not able to carry again the transfer material P without being conveyor belt cleaning, stain the transfer material P with the toner adhering to the conveyor belt 11 There is no fear. That is, if L _T (n) satisfies the following expression (2), the (n + 1) th image can be continuously formed without carrying out the conveyor belt cleaning.
L _B > L _T (n) (2)

By setting the conditions as described above and controlling the execution timing of the conveyor belt cleaning, the number of conveyor belt cleanings during continuous printing can be minimized, and a decrease in the number of throughputs can be suppressed. The configuration of the present embodiment is particularly effective when continuously forming images on a transfer material P having a small size. For example, the size of the L-plate size transfer material P is 127 mm long × 89 mm wide, which is a relatively small size. When continuously imaging the transfer material P of the L-size at longitudinal feed in marginless mode, them to _{L H} 2 mm, the recording material length _L P of the (N) 127 mm, the sheet interval length _{L INT} (N) and 30mm For example, since the conveyance belt length L _B is 675 mm, it is possible to form four continuous images without performing the conveyance belt cleaning from the equations (1) and (2). That is, the conveyor belt cleaning may be executed every time four consecutive sheets are printed.

[Conveyance belt cleaning execution timing control]
Here, the conveyance belt cleaning execution timing control will be described only in the marginless mode. In the margin mode, there is no need to execute the conveyor belt cleaning, and thus the description thereof is omitted here.

  FIG. 7 is a diagram showing a control flow for determining the execution timing of the conveyor belt cleaning in the marginless mode.

  After receiving the image forming signal (S11), the image forming apparatus starts image formation in the marginless mode (S12). The toner images formed on the photosensitive drum are sequentially transferred onto the transported transfer material P (S13).

After the toner image is transferred, it is confirmed whether the next image formation is refrained (S14). If the next image formation is not reserved, the conveyance belt cleaning is executed (S15), the image formation is ended (S16), and the next image formation signal is received. When the next image formation is refrained, the image for which the next image formation is refrained, that is, the (n + 1) th transfer material length is confirmed when the nth image is already formed. As described in the section “Relationship between the circumference of the conveyor belt and the length of the transfer material P in the sheet passing direction”, the sheet passing on the conveyor belt 11 necessary for image formation from the first sheet to the (n + 1) th sheet is performed. It is confirmed whether or not the direction length L _T (n) satisfies the above-described expression (2) (S17). If the expression (2) is satisfied, the n + 1th image is continuously formed without performing the conveyor belt cleaning (S12), and the subsequent control steps are repeated again. If the expression (2) is not satisfied, after carrying belt cleaning is performed (S18), the n + 1th image is continuously formed (S12), and the subsequent control steps are repeated again.

  By the configuration of the image forming apparatus and the conveyance belt cleaning described above, unnecessary toner transferred on the conveyance belt generated when printing images without margins is removed well, and occurrence of image contamination due to the unnecessary toner is prevented. can do. In addition, it is possible to minimize the downtime due to the execution of the conveyance belt cleaning, and to suppress a decrease in the throughput number of the transfer material P during continuous image formation.

<Third Embodiment>
In the above embodiment, the image forming apparatus that directly transfers the toner image from the photosensitive drum 1 to the transfer material P has been described as an example. However, the present invention is not limited to this, and the present invention is not limited thereto. The present invention can also be applied to an image forming apparatus that transfers a toner image to a transfer material P.

[Schematic configuration of image forming apparatus]
FIG. 8 shows an image forming apparatus of this embodiment. The image forming apparatus shown in the figure is an electrophotographic four-color full-color laser printer using a four-pass intermediate transfer member, and the figure is a longitudinal sectional view showing a schematic configuration thereof. As the first and second embodiments, the image forming mode has a margin mode and a marginless mode.

  In such an image forming apparatus, first, the photosensitive drum 1 which is a latent image carrier formed of an organic photoreceptor or an amorphous silicon photoreceptor rotates at a predetermined conveyance speed (circumferential speed) in the counterclockwise direction indicated by an arrow. Driven. The photosensitive drum 1 is subjected to a charging process with a predetermined polarity and a uniform potential by a charging device 2 such as a charging roller in the course of rotation.

  Next, the charged surface is subjected to a scanning exposure process according to target image information by a laser beam 103 output from a laser optical box (laser scanner) 3. The laser optical box 3 outputs a modulated laser beam 103 that is switched on or off in response to a time-series electric digital pixel signal of target image information from an image signal generator such as an image reading device (not shown), The surface of the drum 1 is scanned and exposed. Thereby, an electrostatic latent image corresponding to the target image information is formed on the surface of the photosensitive drum 1. At this time, the output laser light from the laser optical box 3 is deflected to the exposure position of the photosensitive drum 1 by the mirror 109.

  In the case of full-color image formation, scanning exposure and latent image formation are performed on a first color separation component image, for example, a cyan component image in a target full-color image, and the latent image is cyan among the four color developing devices 4a to 4d. The cyan toner image is developed by the operation of the developing device 4a. The cyan toner image is transferred onto the surface of the intermediate transfer drum 105 at a primary transfer portion T1 which is a contact portion or a proximity portion between the photosensitive drum 1 and the intermediate transfer drum 105 (intermediate transfer body). The surface of the photosensitive drum 1 after the toner image is transferred to the surface of the intermediate transfer drum 105 is cleaned by the cleaning device 6 after removal of adhered residues such as transfer residual toner.

  The process cycle of charging, scanning exposure, development, primary transfer, and cleaning as described above is the second color separation component image of the target full-color image (for example, the yellow component image, the yellow developing device 4b is activated), the third color The intermediate transfer drum is sequentially executed for each color separation component image of the separation component image (for example, magenta component image, magenta developing device 4c is activated) and the fourth color separation component image (for example, black component image, black developing device 4d is activated). Four color toner images of a cyan toner image, a yellow toner image, a magenta toner image, and a black toner image are sequentially superimposed and transferred onto the surface 105, and a color toner image corresponding to the target full-color image is synthesized and formed.

  The intermediate transfer drum 105 is provided with a middle resistance elastic layer and a high resistance surface layer on a metal drum. The intermediate transfer drum 105 contacts or is close to the photosensitive drum 1 at the same peripheral speed as the photosensitive drum 1 in the clockwise direction. And a bias potential is applied to the metal drum of the intermediate transfer drum 105, and the toner image on the photosensitive drum 1 side is transferred to the surface of the intermediate transfer drum 105 by the potential difference with the photosensitive drum 1.

  The conveyor belt 11 is stretched between a transfer roller 12 and a roller 106. The color toner image formed on the surface of the intermediate transfer drum 105 is transferred to the secondary transfer portion T2 in the secondary transfer portion T2 which is a nip portion between the intermediate transfer drum 105 and the transfer roller 12 via the conveyor belt 11. The image is transferred onto the surface of the transfer material P fed from a paper supply unit (not shown) at a predetermined timing. The transfer roller 12 supplies a charge opposite in polarity to the toner from the back side of the transfer material P via the conveyor belt 11, thereby sequentially transferring the combined color toner images sequentially from the intermediate transfer drum 105 surface side to the transfer material P side. .

  The transfer material P that has passed through the secondary transfer portion T2 is separated from the surface of the intermediate transfer drum 105 and introduced into the fixing device 20 as a heating device. The transfer material P is heated and pressed while being nipped and conveyed by the fixing roller 23 and the pressure roller 24 when passing through the fixing device 20, and a toner image of a plurality of colors is fixed on the surface.

  After the color toner image is transferred to the transfer material P, the intermediate transfer drum 105 is cleaned by the intermediate transfer body cleaning device 108 after removal of the adhering residue such as transfer residual toner and paper dust.

[Conveyor belt cleaning sequence]
A method for removing toner when toner adheres to the conveyor belt 11 in this embodiment will be described. In the present embodiment, a conveyor belt cleaning member (for example, a cleaning blade) dedicated to the conveyor belt 11 is not provided. The toner adhering to the conveying belt 11 is reversely transferred onto the intermediate transfer drum 105 and collected using the intermediate transfer member cleaning device 108.

  First, when the conveyance belt 11 is driven to rotate, in the first transfer, the electric field is opposite to the electric field at the time of normal transfer (when the toner image on the intermediate transfer drum 105 is transferred onto the transfer material P) in the secondary transfer portion T2. The transfer bias of the secondary transfer portion T2 is adjusted so that a polar transfer reverse electric field is generated. In order to realize this, for example, a negative bias is applied to the transfer roller 12. By forming a reverse transfer electric field at the secondary transfer portion T2, the normally charged toner (negative polarity) is reversely transferred to the intermediate transfer drum 105 and collected by the intermediate transfer drum cleaning device.

  Next, the transfer belt 11 is rotated to adjust the transfer bias of the secondary transfer portion T2 so that a positive transfer electric field having the same polarity as the electric field at the time of toner image transfer is generated in the second turn. In order to realize this, for example, a positive bias is applied to the transfer roller 12. In the secondary transfer portion T2, by forming a transfer positive electric field, the toner whose polarity is reversed (positive charge) is reversely transferred to the intermediate transfer drum 105 and collected by the intermediate transfer drum cleaning device.

  Further, when the transport belt 11 is cleaned, that is, when the toner on the transport belt 11 is reversely transferred onto the intermediate transfer drum 105, the moving speed (rotational speed) of the transport belt 11 with respect to the rotational speed of the intermediate transfer drum 105 is determined. ) Is used in combination with causing the intermediate transfer drum 105 to collect the toner on the conveyor belt 11 by providing a significant difference between the positive and negative peripheral speeds.

  For the conveyance belt cleaning execution timing control, the first embodiment or the second embodiment may be applied.

  In the above embodiment, the belt-shaped conveyance belt 11 has been described as an example of the transfer material conveyance member. However, the present invention is not limited to this, and the member that conveys the transfer material P is a drum-shaped conveyance drum. It can also be applied to cases.

  Further, the example in which the present invention is applied to an electrophotographic image forming apparatus has been described. However, the present invention is not limited to an electrophotographic image forming apparatus, but other image forming apparatuses such as an electrostatic recording system. The present invention can also be applied to an image forming apparatus. However, in this case, instead of the photosensitive drum, a toner image carrier is used, and an electrostatic latent image is directly formed on the toner image carrier to develop the electrostatic latent image. Good.

1 is a longitudinal sectional view illustrating a schematic configuration of an image forming apparatus according to a first embodiment. FIG. 2 is an enlarged view of a cyan process cartridge in FIG. 1. FIG. 4 is a schematic diagram illustrating a relationship between a printing area and a transfer material size. FIG. 6 is a schematic diagram illustrating a relationship between a circumferential length of a conveyance belt and a length of a printing area in a sheet passing direction. It is a figure which shows the control flow which determines the execution timing of conveyance belt cleaning. FIG. 10 is a schematic diagram illustrating a relationship between a circumferential length of a conveyance belt, a printing area, and a length in a sheet passing direction of a transfer material during continuous image formation in a marginless mode in the second embodiment. It is a figure which shows the control flow which determines the execution timing of the conveyance belt cleaning at the time of no margin mode. It is a longitudinal cross-sectional view which shows schematic structure of the image forming apparatus of 3rd Embodiment. It is a longitudinal cross-sectional view which shows schematic structure of the conventional image forming apparatus.

Explanation of symbols

1, 1a, 1b, 1c, 1d Photoconductor (photosensitive drum)
2, 2a, 2b, 2c, 2d Charging device 3 Laser optical box (laser scanner)
3a, 3b, 3c, 3d Exposure devices 4, 4a, 4b, 4c, 4d Developing devices 6, 6a, 6b, 6c, 6d Photoconductor cleaning devices 7a, 7b, 7c, 7d Process cartridge 11 Transfer material conveying member (conveying belt) )
12a, 12b, 12c, 12d Transfer device (transfer roller)
100 Image forming apparatus main body 106 Intermediate transfer body (intermediate transfer drum)
108 Intermediate transfer member cleaning device P Transfer material Sa, Sb, Sc, Sd Image forming station

Claims (7)

A photosensitive member having a movable surface, a charging device for charging the surface of the photosensitive member, an exposure device for exposing the charged surface of the photosensitive member to form an electrostatic latent image, and toner on the electrostatic latent image. A developing device that adheres and develops as a toner image, a transfer material conveyance member that carries and conveys a transfer material onto which the toner image is transferred, and a toner image on the photoconductor on the transfer material carried on the transfer material conveyance member An image forming apparatus that can form an image with no margin at at least one of the leading edge, the trailing edge, the left edge, and the right edge of the transfer material. In the device
Of the area on the transfer material conveying member, the surface of the transfer material conveying member before the area where the transfer material is carried and conveyed and the toner image is transferred by the transfer device is carried and conveyed again. An image forming apparatus, wherein the transfer material conveying member cleaning for removing the toner adhering to the toner is performed at least once.   The image forming apparatus includes a photoconductor cleaning device that cleans the surface of the photoconductor after transfer of a toner image, and the transfer material transport member cleaning electrostatically removes unnecessary toner adhering to the transfer material transport member. The image forming apparatus according to claim 1, wherein the image forming apparatus is reversely transferred to a body and removed by the photoconductor cleaning device. A photosensitive member having a movable surface, a charging device for charging the surface of the photosensitive member, an exposure device for exposing the charged surface of the photosensitive member to form an electrostatic latent image, and toner on the electrostatic latent image. A developing device that adheres and develops as a toner image, an intermediate transfer member to which the toner image is transferred, a first transfer device that transfers a toner image on the photosensitive member to the intermediate transfer member, and the intermediate transfer member A transfer material conveying member that carries and conveys the transfer material onto which the toner image is transferred, and a second transfer device that transfers the toner image on the intermediate transfer member to the transfer material. In the image forming apparatus capable of forming an image without a margin in at least one of the rear end, the left end, and the right end,
Of the area on the transfer material conveying member, the surface of the transfer material conveying member before the area where the transfer material is carried and conveyed and the toner image is transferred by the transfer device is carried and conveyed again. An image forming apparatus, wherein the transfer material conveying member cleaning for removing the toner adhering to the toner is performed at least once.   The image forming apparatus includes an intermediate transfer body cleaning device that cleans the surface of the intermediate transfer body after transferring a toner image, and the transfer material transport member cleaning electrostatically removes unnecessary toner adhering to the transfer material transport member. The image forming apparatus according to claim 3, wherein the intermediate transfer member is reversely transferred to the intermediate transfer member and removed by the intermediate transfer member cleaning device.   The image forming apparatus forms an image so that a toner image print area is outside the transfer material at at least one of the front end, rear end, left end, and right end of the transfer material. 4. The image forming apparatus according to claim 1, wherein a marginless image is formed on the transfer material.   The image forming apparatus includes a first image forming mode for forming an image having a blank portion at all of a front end portion, a rear end portion, a left end portion, and a right end portion of a transfer material, and a front end portion, a rear end portion, A second image forming mode for forming an image having no margin at at least one of the left end and the right end, and in the first image forming mode, the transfer material conveying member cleaning is executed. 4. The image forming apparatus according to claim 1, wherein cleaning of the transfer material conveying member is executed in the second image forming mode. 5.   4. The image forming apparatus according to claim 1, wherein the transfer material conveying member has a circumferential length equal to or longer than a length in a sheet passing direction of a printing area for forming a marginless image. .

Images