JP2007078795A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve the simplification of the constitution of an image forming apparatus and the reduction of cost by obtaining a means for peeling a foreign matter adhering to the edge part of a cleaner blade with simple constitution. <P>SOLUTION: In the image forming apparatus, a driven roller 83 on which the cleaner blade 711 abuts is energized in an energizing direction D83, and a plurality of transfer members 85 are positioned relative to image forming stations Y, M, C and K, whereby a transfer belt 81 is pressed to abut on the image forming stations Y, M, C and K, while N transfer members from the one on an upstream side in the conveying direction D81 to the N-th one out of a plurality of transfer members are moved to be separated from the image forming stations as necessary. By such separating movement, the transfer belt 81 moves in a reverse direction to the conveying direction at a position where the cleaner blade 711 abuts on the transfer belt 81. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a tandem-type image forming apparatus provided with a cleaner blade that cleans the surface of a transfer belt by bringing its tip into contact with the surface of a moving transfer belt.

  As an image forming apparatus such as a copying machine, a printer, or a facsimile, for example, an image forming station that forms toner images of different colors along a transfer belt conveyed in a predetermined direction as disclosed in Patent Document 1 below. There is known a so-called tandem type image forming apparatus in which a plurality of image forming devices are arranged. In such an image forming apparatus, a color image is formed by superimposing toner images of different colors formed by a plurality of image forming stations on the surface of a transfer belt. The color image formed on the belt surface is transferred to a transfer medium such as paper.

  In such an image forming apparatus, a cleaner blade may be provided to remove toner remaining on the surface of the transfer belt. The cleaner blade removes residual toner from the surface of the transfer belt by bringing its tip into contact with the surface of the transfer belt conveyed in a predetermined direction.

  However, there are cases where foreign matters such as paper dust adhere to the transfer belt surface in addition to the residual toner. Most of such foreign matter is removed from the transfer belt surface by the cleaner blade in the same manner as the residual toner. However, some foreign matter adheres to the tip of the cleaner blade and is between the tip of the cleaner blade and the transfer belt surface. It may get caught. As a result, a gap is formed between the cleaner blade and the surface of the transfer belt, and the residual toner may slip through the gap, so that the residual toner may not be removed satisfactorily.

  The above-described problem in the configuration in which the cleaner blade is brought into contact with an image carrier that moves in a predetermined direction such as a transfer belt to clean the surface of the image carrier is also pointed out in, for example, Patent Document 2 below. Yes. For this problem, for example, in the invention described in Patent Document 2, the rotation direction of the image carrier is controlled. That is, the image carrier is driven to rotate in the opposite direction to the rotation direction of the image carrier during image formation. By this reverse driving, the foreign matter sandwiched between the surface of the image carrier and the tip of the cleaner blade is moved upstream in the rotation direction during image formation, and the foreign matter is peeled off from the tip of the cleaner blade. .

JP 2003-015378 A (paragraph 0022, FIG. 1) Japanese Patent Laying-Open No. 2004-102178 (paragraphs 0005, 0011, 0012)

  However, when the invention described in Patent Document 2 is applied to an apparatus that cleans the transfer belt surface with a cleaner blade, it is necessary to newly provide a reverse rotation mechanism in the drive system of the transfer belt, which complicates the configuration of the drive system. Invite. As a result, there arises a problem that the cost is increased and the size of the apparatus is increased.

  The present invention has been made in view of the above problems, and it is possible to effectively remove a foreign matter adhering to a cleaner blade with a simpler configuration, and to realize a technique for realizing cost reduction and downsizing of an apparatus. It is intended to provide.

  A first aspect of the image forming apparatus according to the present invention includes a transfer belt that is stretched around at least two rollers, that is, a driving roller and a blade rotating roller that is driven to rotate, and is rotated and conveyed in a predetermined conveying direction, and a conveying direction of the blade facing roller. M images that are arranged downstream in the transport direction upstream of the drive roller in the transport direction and that are superimposed on each other by primary transfer of toner images of different colors to the transfer belt surface. In an image forming apparatus having a forming station (M ≧ 2), in order to achieve the above object, the transfer belt is opposed to each of the M image forming stations on a one-to-one basis inside the transfer belt. By positioning the M transfer members arranged and the M transfer members on the image forming station side, the transfer belt is moved to the image forming station. The toner image can be primarily transferred at all the image forming stations by pushing and abutting, while the N-th (M ≧ N ≧ 1) from the upstream side in the transport direction among the M transfer members as necessary. The N transfer members are moved away from the image forming station to release the pushing state of the transfer belt by the N transfer members, and the leading end of the transfer member is brought into contact with the blade facing roller via the transfer belt. A cleaner blade that contacts and cleans the surface of the transfer belt; and a biasing means that biases the blade facing roller away from the driving roller. The blade facing roller is biased by the biasing means integrally with the cleaner blade. In accordance with the fact that the N transfer members are moved away from the image forming station by the separating contact means and the pushing state of the transfer belt is resolved, It is characterized in that rotationally driven in the direction opposite to the conveying direction while moving in the biasing direction by the biasing force from the energizing means.

  In the invention configured as described above, the transfer belt is stretched around at least two rollers, that is, the driving roller and the blade rotating roller that is driven to rotate, and the transfer belt is rotated and conveyed in a predetermined conveyance direction. Then, the tip of the cleaner blade is brought into contact with the surface of the cleaner facing blade via the transfer belt to clean the surface of the transfer belt. Therefore, as described above, foreign matters such as paper dust adhere to the tip of the cleaner blade, and as a result, there may be a cleaning failure in which residual toner cannot be removed satisfactorily.

  In order to solve such a problem, the present invention pushes the transfer belt to the image forming station by positioning the M transfer members, which are arranged to face the M image forming station in a one-to-one relationship, on the image forming station side. The toner images can be primarily transferred at all the image forming stations by making contact with each other. On the other hand, from the M transfer members, the Nth (M ≧ N ≧ 1) from the upstream side in the transport direction, if necessary. A separation contact means for moving the N transfer members away from the image forming station to eliminate the pushing state of the transfer belt by the N transfer members, and a biasing force for urging the blade facing roller away from the drive roller And the blade-opposing roller is reciprocally movable in the urging direction of the urging unit integrally with the cleaner blade, and the N transfer members are moved by the separating / contacting unit. As the transfer belt is moved away from the transfer belt and the pushing state of the transfer belt is released, the transfer belt is moved in the urging direction by the urging force from the urging means and is driven to rotate in the direction opposite to the conveying direction. Yes. In other words, by providing an urging means for urging the blade facing roller away from the driving roller, the blade facing roller is configured to reciprocate in the urging direction so that the blade facing roller functions as a so-called tension roller. Tension is applied to the transfer belt. The transfer belt thus tensioned by the blade facing roller is positioned on the image forming station side against the urging means of the urging force, thereby positioning the transfer belt on the image forming station side. We are going to push it.

  The N transfer members up to the Nth (M ≧ N ≧ 1) from the upstream side in the transport direction among the M transfer members are moved away from the image forming station by the separation contact means, and transferred by the N transfer members. When the belt pushing state is canceled, the blade facing roller moves while pulling the transfer belt in the urging direction by the urging force from the urging means in accordance with the cancellation of the pushing state. Therefore, the transfer belt from which the pushing state is eliminated is separated from the image forming station. Since the moving direction of the blade facing roller is a direction away from the driving roller, the circumferential length of the transfer belt from the driving roller to the blade facing roller in the transfer belt conveying direction (the circumferential length opposite to the image forming station) is increased. Thus, the circumference of the transfer belt (image formation station side circumference) from the drive roller to the blade-facing roller is reduced in the direction opposite to the transfer belt conveyance direction. At this time, since the driving roller is stationary and a relatively high frictional force exists between the driving roller and the transfer belt, the transfer belt does not move with respect to the driving roller. On the other hand, since the blade-opposing roller is a driven roller, the blade is rotated by being pulled by the transfer belt in the direction opposite to the transfer belt conveyance direction by the length of the circumference on the opposite side of the image forming station. In addition, the cleaner blade is configured integrally with the blade facing roller, and the cleaner blade moves together with the movement of the blade facing roller. Therefore, the relative positions of the blade facing roller and the cleaner blade are the same. The relationship does not change. Therefore, when the blade facing roller rotates in the direction opposite to the conveyance direction by the variation in the peripheral length on the image forming station side, the transfer belt is moved by the variation in the circumferential length at the contact position where the tip of the cleaner blade contacts the transfer belt. It moves in the direction opposite to the transport direction. Therefore, when foreign matter such as paper dust adheres to the tip of the cleaner blade, the foreign matter can be peeled from the tip of the cleaner blade as the transfer belt moves in the reverse direction. As described above, according to the present invention, the N-th (M ≧ N ≧ 1) N transfer members from the upstream side in the transport direction are moved away from the image forming station by the separation contact unit, so that the tip of the cleaner blade The transfer belt moves in the direction opposite to the conveying direction at the contact position where it contacts the transfer belt, so that the foreign matter adhering to the tip of the cleaner blade can be removed. Therefore, for example, unlike the invention described in Patent Document 2, it is not necessary to separately receive a drive mechanism for rotating the transfer belt in the reverse direction, and the drive system is simplified. That is, according to the present invention, the foreign matter adhering to the tip of the cleaner blade can be effectively peeled off with a simpler configuration, and the cost and size of the apparatus can be reduced.

  When the foreign matter is peeled off from the cleaner blade tip by the separation contact means as described above, the larger the moving amount of the transfer belt in the reverse direction of the transfer belt at the contact position where the cleaner blade tip contacts the transfer belt, the more Foreign substances can be effectively peeled off. In the above-described invention, as the transfer member moves away, the peripheral length on the opposite side of the image forming station becomes longer, while the peripheral length on the side of the image forming station becomes shorter. That is, the peripheral length on the opposite side of the image forming station is increased by the amount that the peripheral length on the image forming station side is shortened. The variation in the circumferential length is the amount of movement of the transfer belt in the direction opposite to the conveyance direction at the contact position where the cleaner blade tip contacts the transfer belt. Therefore, the larger the amount of variation in the peripheral length of the image forming station, the greater the amount of movement of the transfer belt in the direction opposite to the conveyance direction. On the other hand, the fluctuation amount of the peripheral length on the image forming station depends on the degree to which the transfer belt is separated from the image forming station.

  Accordingly, the separation contact unit is configured to move all of the M transfer members away from the image forming station as necessary to eliminate the pushing state of the transfer belt by the M transfer members, and the blade The opposing roller is energized by the energizing force from the energizing unit in response to all of the M transfer members being moved away from the image forming station by the separating / contacting unit and the pushing state of the transfer belt is eliminated. You may comprise so that it may follow and rotate in the direction opposite to a conveyance direction, moving to a direction. Thus, in the constructed invention, all the transfer members are moved away from the image forming station by the separation contact means. Therefore, the transfer belt is separated from all M image forming stations. As a result, it is possible to increase the fluctuation amount of the peripheral length on the image forming station side. Accordingly, it is possible to increase the amount of movement of the transfer belt in the direction opposite to the conveyance direction at the contact position where the cleaner blade tip is in contact with the transfer belt.

  Further, among the M transfer members, the most downstream transfer member disposed between the most downstream transfer member and the driving roller on the most downstream side in the transport direction and inside the transfer belt, and the most downstream transfer member is positioned on the image forming station side In the image forming apparatus further comprising a downstream guide roller that contacts the transfer belt on a common inscribed line between the most downstream transfer member and the image forming station facing the most downstream transfer member, the following configuration may be adopted. good. That is, the separation and abutting means is first set to the most upstream in the transport direction with respect to the L transfer members from the upstream in the transport direction to the Lth (M ≧ L ≧ 2) of the M transfer members as necessary. The (L-1) transfer members excluding the most upstream transfer member positioned are moved away from the image forming station, and then the uppermost transfer member is moved away from the image forming station to transfer the transfer belt by the L transfer members. The configuration is made to eliminate the pushing state, and the blade facing roller is moved away from the image forming station by the separating contact means, and the pushing state of the transfer belt is eliminated. You may comprise so that it may follow and rotate in the direction opposite to a conveyance direction, moving in a biasing direction with the biasing force from a biasing means.

  In the invention configured in this way, among the M transfer members, the L transfer members from the upstream side in the transport direction to the Lth (M ≧ L ≧ 2) L transfer members are first positioned at the most upstream position in the transport direction. After the (L-1) transfer members excluding the upstream transfer member are moved away from the image forming station, the most upstream transfer member is moved away from the image forming station. At this time, in a state where (L-1) transfer members are merely moved away from the image forming station, the transfer belt is still pushed to the image forming station by the most upstream transfer member and the downstream guide roller. Only when the most upstream transfer member is moved away from the image forming station from such a state, the pushing state of the transfer belt to the image forming station is eliminated. Accordingly, the transfer belt can be quickly separated from the image forming station when the pushing state is canceled. This is because when the transfer belt performs the separating operation, the (L-1) transfer members excluding the most upstream transfer member are already separated from the image forming station. 1) It is not limited by a single transfer member. As a result, the transfer belt moves in the reverse direction in the conveying direction at the contact position of the transfer blade at the tip of the cleaner blade, and foreign matter adhering to the tip of the cleaner blade can be peeled off more effectively. Is preferred.

  Further, the separation contact means moves all the transfer members excluding the most upstream transfer member located at the most upstream in the transport direction among the M transfer members as necessary, and then moves the separation contact means away from the image forming station. The member is moved away from the image forming station to eliminate the pushing state of the transfer belt by the M transfer members, and the most opposed transfer member is moved away from the image forming station by the blade contact roller. In response to the movement of the transfer belt being released by being moved away from the transfer belt, the transfer belt may be driven to rotate in the direction opposite to the conveyance direction while being moved in the biasing direction by the biasing force from the biasing means. . In such a configuration, since all of the M transfer members are separated from the image forming station, the amount of fluctuation in the peripheral length of the image forming station can be increased. Therefore, the movement amount of the transfer belt in the direction opposite to the conveyance direction at the contact position where the tip of the cleaner blade contacts the transfer belt can be increased.

  Further, the downstream guide roller may be moved inward of the transfer belt as the most upstream transfer member moves away. In such a configuration, the downstream guide roller is also moved inwardly of the transfer belt by the separation and contact operation, so that the fluctuation amount of the peripheral length on the image forming station side can be further increased. Therefore, the movement amount of the transfer belt in the direction opposite to the conveyance direction at the contact position where the tip of the cleaner blade contacts the transfer belt can be increased.

  Further, among the M transfer members, the M transfer members are disposed between the most upstream transfer member positioned at the most upstream in the transport direction and the blade-facing roller and inside the transfer member, and the M transfer members are disposed on the image forming station side. An image forming apparatus that further includes an upstream guide roller that stretches the transfer belt in a positioned state may be configured as follows. That is, the separation contact means moves the N transfer members up to the Nth (M ≧ N ≧ 1) from the upstream side in the transport direction out of the M transfer members as necessary, and moves upstream from the image forming station. The guide roller is moved inwardly of the transfer belt to eliminate the pushing state of the transfer belt by the N transfer members, and the blade facing roller is moved by the separating and contacting means so that the N transfer members are moved. When the upstream guide roller is moved inward of the transfer belt by moving away from the image forming station and the pushing state of the transfer belt is canceled, the biasing force from the urging means moves in the urging direction. However, it may be configured to follow and rotate in the direction opposite to the conveyance direction.

  In the invention configured as described above, the N transfer members are moved away from the image forming station by the separation contact means, and the upstream guide roller is moved inward of the transfer belt. The pushing state of the transfer belt is eliminated. Then, in response to the cancellation of the pushing state of the transfer belt, the blade facing roller is driven to rotate in the direction opposite to the conveying direction while moving in the urging direction by the urging force from the urging means. As a result, the transfer belt moves in the direction opposite to the conveying direction at the contact position where the cleaner blade tip contacts the transfer belt, and foreign matter adhering to the cleaner blade tip can be removed. Therefore, for example, unlike the invention described in Patent Document 2, it is not necessary to separately receive a mechanism for reversely rotating the transfer belt, and the drive system is simplified. That is, according to the present invention, the foreign matter adhering to the tip of the cleaner blade can be effectively peeled off with a simpler configuration, and the cost and size of the apparatus can be reduced.

  A second aspect of the image forming apparatus according to the present invention includes a transfer belt that is stretched between at least two rollers, that is, a driving roller and a driven blade-opposing roller, and is rotated and conveyed in a predetermined conveying direction. K pieces which are arranged side by side in the conveyance direction downstream in the conveyance direction and upstream in the conveyance direction of the driving roller and form a color image by superimposing toner images of different colors on the transfer belt surface by primary transfer. In order to achieve the above object, the image forming apparatus having the image forming stations (K ≧ 3) sandwiches the transfer belt on the inner side of the transfer belt in a one-to-one relationship with each of the K image forming stations. The K transfer members disposed opposite to each other and the K transfer members are positioned on the image forming station side to thereby position the transfer belt on the image forming station. The toner image is pushed and brought into contact with each other to enable primary transfer of the toner image at all the image forming stations, and, if necessary, of the K transfer members, the Jth (K ≧ J ≧≧) from the upstream side in the transport direction. For the J transfer members up to 3), first, except for the most upstream transfer member and the most downstream transfer member located at the most upstream and downstream in the transport direction, (J-2) transfer members are transferred to the image forming station. Separating the uppermost stream transfer member from the image forming station and releasing the pushing state of the transfer belt by the (J-2) transfer members and the uppermost stream transfer member. A cleaner blade for cleaning the surface of the transfer belt by bringing its tip into contact with the blade facing roller via the transfer belt, and a biasing hand for biasing the blade facing roller away from the drive roller The blade-opposing roller is provided so as to be able to reciprocate in the urging direction of the urging means integrally with the cleaner blade, and the most upstream transfer member and the most downstream transfer member are moved away from the image forming station by the separation contact means. Then, as the pushing state of the transfer belt is canceled, the transfer belt is driven to rotate in the direction opposite to the conveying direction while moving in the urging direction by the urging force from the urging means.

  In the invention configured as described above, first, the most upstream and the most downstream in the transport direction with respect to the J transfer members from the upstream in the transport direction to the Jth (K ≧ J ≧ 3) among the K transfer members. After the (J-2) transfer members excluding the most upstream transfer member and the most downstream transfer member located at each position are moved away from the image forming station, the most upstream transfer member and the most downstream transfer member are separated from the image forming station. Move. At this time, in a state where (J-2) transfer members are merely moved away from the image forming station, the transfer belt is still pushed to the image forming station by the most upstream transfer member and the most downstream transfer member. Only when the most upstream transfer member is moved away from the image forming station from such a state, the pushing state of the transfer belt to the image forming station is eliminated. Accordingly, the transfer belt can be quickly separated from the image forming station when the pushing state is canceled. This is because when the transfer belt performs the separation operation, since the (J-2) transfer members excluding the most upstream transfer member and the most downstream transfer member are already separated from the image forming station, the transfer belt separation operation is performed. This is because (J-2) transfer members are not limited. As a result, the transfer belt moves in the reverse direction in the conveying direction at the contact position of the transfer blade at the tip of the cleaner blade, and foreign matter adhering to the tip of the cleaner blade can be peeled off more effectively. Is preferred.

  Further, the most downstream transfer member and the most downstream transfer member may be separated from the image forming station by the separation contact means. In such a configuration, the most downstream transfer member is also moved inward of the transfer belt by the separation and contact operation, so that the fluctuation amount of the peripheral length on the image forming station side can be further increased. Therefore, the movement amount of the transfer belt in the direction opposite to the conveyance direction at the contact position where the tip of the cleaner blade contacts the transfer belt can be increased.

  Further, the transfer member may be a transfer roller that is driven to rotate. In such a configuration, friction between the transfer belt and the transfer member (transfer roller) when the transfer belt is separated from the image forming station in accordance with the cancellation of the belt pushing state by the separation contact means is reduced. Can do. As a result, the separating operation of the transfer belt can be performed quickly, and the foreign matter adhering to the tip of the cleaner blade can be peeled off more effectively.

<First Embodiment>
FIG. 1 is a diagram showing a first embodiment of an image forming apparatus according to the present invention. FIG. 2 is a diagram showing an electrical configuration of the image forming apparatus of FIG. This apparatus is an image forming apparatus that forms a color image by superposing four color toners of black (K), cyan (C), magenta (M), and yellow (Y). In this image forming apparatus, when an image forming command (printing command) is given to the main controller 510 from an external device such as a host computer, the engine controller 520 controls each part of the engine unit EG in accordance with the command from the main controller 510. Then, a predetermined image forming operation is executed, and an image corresponding to the image forming command is formed on a sheet such as copy paper, transfer paper, paper, and an OHP transparent sheet.

  In the housing main body 3 of the image forming apparatus according to the first embodiment, an electrical component box 5 that houses a power circuit board, a main controller 510 and an engine controller 520 is provided. An image forming unit 7, a transfer belt unit 8, and a paper feeding unit 11 are also disposed in the housing body 3. In FIG. 1, a secondary transfer unit 12, a fixing unit 13, and a sheet guide member 15 are disposed on the right side in the housing body 3. The paper feeding unit 11 is configured to be detachable from the apparatus main body 1. The paper feed unit 11 and the transfer belt unit 8 can be removed and repaired or exchanged.

  The image forming unit 7 includes four image forming stations Y (for yellow), M (for magenta), C (for cyan), and K (for black) that form a plurality of images of different colors. Each of the image forming stations Y, M, C, and K is provided with a photosensitive drum 21 on which a toner image of each color is formed. Each photosensitive drum 21 is connected to a dedicated drive motor and is driven to rotate at a predetermined speed in the direction of arrow D21 in the figure. A charging unit 23, an image writing unit 29, a developing unit 25, and a photoconductor cleaner 27 are disposed around the photoconductive drum 21 along the rotation direction. Then, a charging operation, a latent image forming operation, and a toner developing operation are executed by these functional units. In FIG. 1, the image forming stations of the image forming unit 7 have the same configuration, and therefore, for convenience of illustration, only some image forming stations are denoted by reference numerals, and the other image forming stations are omitted. .

  The charging unit 23 includes a charging roller whose surface is made of elastic rubber. The charging roller is configured to rotate in contact with the surface of the photosensitive drum 21 at the charging position, and at a peripheral speed in the driven direction with respect to the photosensitive drum 21 as the photosensitive drum 21 rotates. Followed rotation. The charging roller is connected to a charging bias generator (not shown). The charging roller is supplied with the charging bias from the charging bias generator and is charged at the charging position where the charging unit 23 and the photosensitive drum 21 come into contact with each other. The surface of 21 is charged.

  The image writing unit 29 is an array writing in which elements such as a liquid crystal shutter including a light emitting diode and a backlight are arranged in a line in the axial direction of the photosensitive drum 21 (direction perpendicular to the paper surface of FIG. 1). The head is used and is spaced from the photosensitive drum 21. From such an element, the surface of the photosensitive drum 21 charged by the charging unit 23 is irradiated with light to form a latent image on the surface. The array-like writing head has a shorter optical path length and is more compact than the laser scanning optical system. Therefore, it can be disposed close to the photosensitive drum 21 and has the advantage that the entire apparatus can be reduced in size.

  In the first embodiment, the photosensitive drum 21, the charging unit 23, the developing unit 25, and the photosensitive cleaner 27 of each of the image forming stations Y, M, C, and K are combined with the photosensitive cartridges 17Y, 17M, 17C, and 17K ( It is unitized as FIG. Each of the photoconductor cartridges 17Y, 17M, 17C, and 17K is provided with nonvolatile memories 910, 920, 930, and 940 for storing information related to the photoconductor cartridge. The transmission / reception units 530Y, 530M, 530C, and 530K provided on the respective photosensitive cartridges and the transmission / reception units 5220Y, 5220M, 5220C, and 5220K provided on the main body side are arranged close to each other, and Wireless communication is performed with the memories 910, 920, 930, and 940. In this way, information on each photoconductor cartridge is transmitted to the CPU 5210, and information in each memory 910, 920, 930, 940 is updated and stored.

  The developing unit 25 has a developing roller 251 on which toner is carried. The charged toner is developed at a developing position where the developing roller 251 and the photosensitive drum 21 come into contact with each other by a developing bias applied to the developing roller 251 from a developing bias generator (not shown) electrically connected to the developing roller 251. Is moved from the developing roller 251 to the photosensitive drum 21, and the electrostatic latent image formed by the image writing unit 29 becomes obvious.

  The toner image that has been made visible at the development position in this way is conveyed in the rotational direction D21 of the photosensitive drum 21, and then the primary transfer position TR1 where the transfer belt 81, which will be described in detail later, and each photosensitive drum 21 come into contact with each other. 1 is primarily transferred to the transfer belt 53.

  In this embodiment, a photoreceptor cleaner 27 is provided in contact with the surface of the photoreceptor drum 21 on the downstream side of the primary transfer position TR1 in the rotation direction D21 of the photoreceptor drum 21 and on the upstream side of the charging unit 23. It has been. The photoconductor cleaner 27 abuts on the surface of the photoconductor drum to remove the toner remaining on the surface of the photoconductor drum 21 after the primary transfer.

  The transfer belt unit 9 includes a driving roller 82, a driven roller 83 (blade facing roller) disposed on the left side of the driving roller 82 in FIG. 1, and a stretched direction of these rollers in the direction indicated by an arrow D81 (conveying direction). And a transfer belt 81 that is driven to circulate. Further, the transfer belt unit 8 is disposed on the inner side of the transfer belt 81 so as to be opposed to each of the photosensitive drums 21 included in the image forming stations Y, M, C, and K when the photosensitive cartridge is mounted. Four primary transfer rollers 85Y, 85M, 85C, and 85K (transfer members) are provided. Then, as shown in FIG. 1, these primary transfer rollers 85 are positioned on the opposing image forming stations Y, M, C, and K sides, so that the transfer belt 81 is moved to the image forming stations Y, M, and so on. , C, and K are pushed and brought into contact with the photosensitive drum 21. As a result, a primary transfer position TR 1 is formed between each photosensitive drum 21 and the transfer belt 81. The primary transfer rollers 85 are electrically connected to the primary transfer bias generator 5250, respectively. The primary transfer rollers 85 are brought into contact with the photosensitive drums 21 facing each other with the transfer belt 81 interposed therebetween, and the primary transfer bias is applied from the primary transfer bias generator 5250 at an appropriate timing. Thus, the toner image formed on the surface of each photoconductive drum 21 can be transferred onto the transfer belt 81 at the primary transfer position TR1 where the photoconductive drum 21 and the transfer belt 81 contact each other. Each primary transfer roller 85 and driven roller 83 (blade facing roller) each have a moving mechanism, which will be described in detail later.

  Further, the transfer belt unit 8 is driven on the downstream side of the primary transfer roller 85K (the most downstream transfer member) located on the most downstream side in the transport direction D81 among the four primary transfer rollers 85Y, 85M, 85C, and 85K. A guide roller 86 (downstream guide roller) disposed on the upstream side of the roller 82 is provided. Further, the downstream guide roller 86 is common to the primary transfer roller 85K and the photosensitive drum 21 at the primary transfer position TR1 formed by the primary transfer roller 85K contacting the photosensitive drum 21 of the image forming station K. It is configured to contact the transfer belt 81 on the inscribed line.

  The drive roller 82 circulates and drives the transfer belt 81 in the direction of the arrow D81 in the figure, and also serves as a backup roller for the secondary transfer roller 121. A rubber layer having a thickness of about 3 mm and a volume resistivity of 1000 kΩ · cm or less is formed on the peripheral surface of the driving roller 82, and secondary transfer is omitted by grounding through a metal shaft. The conductive path of the secondary transfer bias supplied from the bias generation unit via the secondary transfer roller 121 is used. When the rubber layer having high friction and shock absorption is provided on the driving roller 82 in this way, the sheet enters the contact portion (secondary transfer position TR2) between the driving roller 82 and the secondary transfer roller 121. Is difficult to be transmitted to the transfer belt 81, and image quality deterioration can be prevented.

  The paper feed unit 11 includes a paper feed unit having a paper feed cassette 77 capable of stacking and holding sheets and a pickup roller 79 for feeding sheets one by one from the paper feed cassette 77. The sheet fed from the sheet feeding unit by the pickup roller 79 is fed to the secondary transfer position TR2 along the sheet guide member 15 after the sheet feeding timing is adjusted by the registration roller pair 80.

  The secondary transfer roller 121 is provided so as to be able to come into contact with and separate from the transfer belt 81 and is driven to come into contact with and separate from a secondary transfer roller drive mechanism (not shown). The fixing unit 13 includes a heating roller 131 that includes a heating element such as a halogen heater and is rotatable, and a pressure unit 132 that presses and biases the heating roller 131. The sheet on which the image has been secondarily transferred is guided to a nip formed by the heating roller 131 and the pressure belt 1323 of the pressure unit 132 by the sheet guide member 15, and in the nip, a predetermined value is formed. The image is heat-fixed at temperature. The pressure unit 132 includes two rollers 1321 and 1322 and a pressure belt 1323 stretched between them. A nip portion formed by the heating roller 131 and the pressure belt 1323 is formed by pressing the belt tension surface stretched by the two rollers 1321 and 1322 out of the surface of the pressure belt 1323 against the peripheral surface of the heating roller 131. Is configured to be widely taken. Further, the sheet thus subjected to the fixing process is conveyed to a paper discharge tray 4 provided on the upper surface portion of the housing body 3.

  Moreover, in this apparatus, the cleaner part 71 is arrange | positioned facing the blade facing roller. The cleaner unit 71 includes a cleaner blade 711 and a waste toner box 713. The cleaner blade 711 removes foreign matters such as toner and paper dust remaining on the transfer belt remaining after the secondary transfer by contacting the tip of the cleaner blade 711 with the blade facing roller 83 via the transfer belt 81. The foreign matter removed in this way is collected in a waste toner box 713. Further, the cleaner blade 711 and the waste toner box 713 are integrally formed with the blade facing roller 83. Therefore, when the blade facing roller 83 moves as will be described in detail later, the cleaner blade 711 and the waste toner box 713 also move together with the blade facing roller 83.

  Further, as shown in FIG. 2, the apparatus includes a display unit 540 that is controlled by the CPU 5110 of the main controller 510. This display unit 540 is configured by, for example, a liquid crystal display, and in accordance with a control command from the CPU 5110, the operation guidance to the user, the progress of the image forming operation, the occurrence of an abnormality in the apparatus, the replacement timing of any unit, etc. A predetermined message for notification is displayed.

  In FIG. 2, reference numeral 5130 denotes an image memory provided in the main controller 510 for storing an image given from an external device such as a host computer via the interface 5120. Reference numeral 5230 is a ROM for storing a calculation program executed by the CPU 5210, control data for controlling the engine unit EG, and the like. Reference numeral 5240 is a RAM for temporarily storing a calculation result in the CPU 5210 and other data. is there.

  3 and 4 are views showing a moving mechanism of the blade facing roller 83 and the primary transfer rollers 85Y, 85M, 85C, and 85K in the first embodiment. In the first embodiment, the blade facing roller 83 is urged in the direction D83 away from the driving roller 82 by the urging means 99 and is configured to reciprocate in the urging direction D83. Further, the three primary transfer rollers 85Y, 85M, and 85C from the upstream side in the transport direction D81 to the third are rotatably supported by the first support member 95, and the first support member 95 is It is fixedly supported by the first solenoid S1. Further, the first solenoid S1 is electrically connected to the first solenoid control unit 5260 of FIG. Accordingly, by giving an appropriate signal from the first solenoid control unit 5260 to the first solenoid S1, the first support member 95 and the primary transfer rollers 85Y, 85M, and 85C are moved in the stroke direction D (S1) of the first solenoid S1. Can be moved back and forth. The primary transfer roller 85K located on the most downstream side in the transport direction D81 is rotatably supported by a second support member 97, and the second support member 97 is fixedly supported by a second solenoid S2. Yes. Further, the second solenoid S2 is electrically connected to the second solenoid control unit 5270 of FIG. Therefore, by giving an appropriate signal to the second solenoid S2 from the second solenoid controller 5270, the second support member 97 and the primary transfer roller 85K are reciprocated in the stroke direction D (S2) of the second solenoid S2. be able to.

  As shown in FIG. 3, in the first embodiment, the four primary transfer rollers 85Y, 85M, 85C, and 85K are positioned on the four image forming stations Y, M, C, and K, thereby transferring the transfer belt. The primary transfer position TR1 is formed by pushing 81 against and in contact with the photosensitive drum 21 of the image forming stations Y, M, C, and K.

  From such a state of FIG. 3, the first solenoid control unit 5260 transmits a separation signal to the solenoid S1, and the three primary transfer rollers 85Y, 85M, 85C are separated from the image forming station from the upstream side in the transport direction D81. FIG. 4 shows the state that has been achieved. Thus, in the first embodiment, the first solenoid control unit 5260, the first solenoid S1, and the first support member 95 function as the “separation means” in the present invention. Further, as described above, the blade facing roller 83 is urged by the urging means 99 in the direction D81 away from the driving roller 82, and is configured to reciprocate in the urging direction D81. Therefore, the blade facing roller functions as a so-called tension roller that applies tension to the transfer belt 81.

  Therefore, as shown in FIG. 4, the three primary transfer rollers 85Y, 85M, 85C are separated from the image forming stations Y, M, C by the solenoid S1, and the three primary transfer rollers 85Y, 85M are separated. , 85C, when the pushing state of the transfer belt 81 is canceled, the blade facing roller 83 pulls the transfer belt 81 in the biasing direction D83 by the biasing force from the biasing means 99 in response to the cancellation of the pushing state. However, it is separated from the image forming stations Y, M, and C. Therefore, the transfer belt 81 from which the pushing state has been eliminated is separated from the photosensitive drum 21 of the image forming stations Y, M, and C. Since the moving direction of the blade facing roller 83 is a direction away from the driving roller 82, the transfer belt moving from the driving roller 82 toward the blade facing roller in the transport direction D81 of the transfer belt 81 with the separation operation of the transfer belt 81. While the peripheral length L1 of 81a (the peripheral length L1 opposite to the image forming station) is increased, the peripheral length L2 of the transfer belt 81b from the drive roller 82 toward the blade facing roller 83 in the direction opposite to the transfer direction D81 of the transfer belt 81 ( The peripheral length L2) on the image forming station side is shortened.

  At this time, the driving roller 82 is stationary, and the surface of the driving roller 82 has a high frictional force as described above, so that the transfer belt 81 does not move with respect to the driving roller 82. On the other hand, since the blade facing roller 83 is a driven roller, it is pulled and rotated by the transfer belt 81 in the direction opposite to the transfer direction D81 of the transfer belt 81 by the length of the circumference L1 on the opposite side of the image forming station. Become. Further, as described above, the cleaner blade 711 is formed integrally with the blade facing roller 83, and the cleaner blade 711 moves together with the movement of the blade facing roller 83. Therefore, the relative position of the cleaner blade 711 and the blade facing roller 83 does not change. Therefore, when the blade facing roller 83 rotates in the direction opposite to the conveyance direction D81 by the variation ΔL2 of the image forming station side circumferential length L2, the peripheral edge is at the contact position where the tip of the cleaner blade 711 contacts the transfer belt 81. The transfer belt 81 moves in the direction opposite to the conveyance direction D81 by the length variation ΔL2. Therefore, in the state of FIG. 3, the foreign matter adhering to the tip of the cleaner blade 711 causes the primary transfer rollers 85Y, 85M, and 85C to be separated from the image forming stations Y, M, and C by the “separation contact means”. Thus, as shown in FIG. 4, it moves in the direction opposite to the conveyance direction D81 by the circumference variation ΔL2, and the foreign matter adhering to the tip of the cleaner blade 711 can be peeled off.

  As described above, in the apparatus according to the first embodiment, the front end portion of the cleaner blade 711 can be obtained simply by separating the primary transfer rollers 85Y, 85M, and 85C from the image forming stations Y, M, and C by the “separation contact means”. Foreign matter adhering to can be removed. Therefore, it is not necessary to separately receive a mechanism for driving the transfer belt 81 in a reverse rotation, and the drive system is simplified. In other words, according to the apparatus according to the first embodiment, the foreign matter attached to the tip of the cleaner blade 711 can be effectively peeled off with a simpler configuration, and the cost and size of the apparatus can be reduced.

  In the first embodiment, a moving mechanism (second solenoid S2, second support member 97) is also provided for the black (K) primary transfer roller 85K. Therefore, after the primary transfer rollers 85Y, 85M, 85C are separated from the image forming station by the “separation contact means”, a separation signal is further sent from the second solenoid control unit 5270 (FIG. 2) to the second solenoid S2. By transmitting and separating the primary transfer roller 85K, the transfer belt 81 can be separated from all the image forming stations Y, M, C, and K.

  As described above, in the first embodiment, the photosensitive drum 21, the charging unit 23, the developing unit 25, and the photosensitive cleaner 27 of the image forming stations Y, M, C, and K are used as the photosensitive cartridges 17Y, 17M, 17C, and 17K. It is unitized and can be removed from the image forming apparatus main body 3. However, when the transfer belt 81 is in contact with the photosensitive drum 21 of the image forming stations Y, M, C, and K at the time of removal, the photosensitive drum 21 and the transfer belt 81 interfere with each other. The problem of hurting may occur. In contrast, in the apparatus according to the first embodiment, since the transfer belt 81 can be separated from the photosensitive drums 21 of all the image forming stations Y, M, C, and K as described above, the occurrence of such a problem is suppressed. can do.

Second Embodiment
When the foreign matter is peeled off from the tip portion of the cleaner blade 711 by the “separating means” as in the first embodiment, the transfer belt is conveyed in the reverse direction at the contact position where the tip portion of the cleaner blade 711 contacts the transfer belt 81. The larger the amount of movement, the more effectively the foreign matter can be peeled off. In the above-described embodiment, as the primary transfer roller 85 moves away, the peripheral length L1 on the opposite side of the image forming station becomes longer, while the peripheral length L2 on the side of the image forming station becomes shorter. That is, the peripheral length on the opposite side of the image forming station is increased by the amount (ΔL2) of the peripheral length on the image forming station side. Such a circumferential variation ΔL2 is the amount of movement of the transfer belt 81 in the direction opposite to the conveyance direction at the contact position where the tip of the cleaner blade 711 contacts the transfer belt. Therefore, as the fluctuation amount ΔL2 of the peripheral length on the image forming station side is increased, the movement amount of the transfer belt 81 in the direction opposite to the conveyance direction D81 is increased. On the other hand, the fluctuation amount ΔL2 of the image forming station side circumference depends on the degree to which the transfer belt 81 is separated from the image forming stations Y, M, C, and K.

  Therefore, an image forming apparatus may be configured as in a second embodiment described below. Since the basic configuration of the apparatus is the same as that of the first embodiment, only the characteristic parts of the second embodiment will be described here, and the other components are denoted by the same reference numerals as those of the first embodiment and the description thereof is omitted. To do.

  In the first embodiment, among the four primary transfer rollers, the three primary transfer rollers 85Y, 85M, and 85C that are third from the upstream side in the transport direction are connected to the image forming stations Y and M by the first solenoid S1. , C. In contrast, in the second embodiment, as shown in FIG. 5, the primary transfer roller 85K is separated from the image forming station K by the second solenoid simultaneously with the separation operation by the first solenoid S1. That is, the first solenoid control unit 5260 (FIG. 2) issues a separation signal to the first solenoid S1, and at the same time, the second solenoid control unit 5270 (FIG. 2) issues a separation signal to the second solenoid S2. The primary transfer rollers 85Y, 85M, 85C, and 85K are separated from the image forming stations Y, M, C, and K. Thus, in the present embodiment, the first solenoid control unit 5260, the first solenoid S1, the first support member 95, the second solenoid control unit 5270, the second solenoid S2, and the second support member 97 are “ It functions as a “separating means”. Therefore, the fluctuation amount ΔL2 of the peripheral length L2 on the image forming station is larger than when only the three primary transfer rollers 85Y, 85M, and 85C are separated from the image forming stations Y, M, and C from the upstream side in the transport direction. I can take it. As a result, it is possible to increase the amount of movement of the transfer belt 81 in the direction opposite to the conveyance direction at the contact position where the tip of the cleaner blade 711 contacts the transfer belt. Therefore, the foreign matter adhering to the tip of the cleaner blade 711 can be more reliably removed, which is preferable.

<Third Embodiment>
Next, a third embodiment of the apparatus according to the present invention will be described. Since the basic configuration of the apparatus is the same as that of the first embodiment, only the features of the third embodiment will be described here, and the other components will be denoted by the same reference numerals as those of the first embodiment and description thereof will be omitted. To do.

  6-8 is a figure which shows operation | movement of the apparatus in 3rd Embodiment. Also in the third embodiment, the blade facing roller 83 is urged in the direction D83 away from the drive roller 82 by the urging means 99, and is configured to reciprocate in the urging direction D83. Further, the cleaner blade 711 is formed integrally with the blade facing roller 83 and can reciprocate along with the blade facing roller 83. A primary transfer roller 85Y (most upstream transfer member) positioned at the most upstream in the transport direction D81 is rotatably supported by a first support member 95, and the first support member 95 is a first solenoid. It is fixedly supported by S1. Further, the first solenoid S1 is electrically connected to the first solenoid control unit 5260 of FIG. Accordingly, by giving an appropriate signal from the first solenoid controller 5260 to the first solenoid S1, the first support member 95 and the primary transfer roller 85Y are reciprocated in the stroke direction D (S1) of the first solenoid S1. be able to. The three primary transfer rollers 85M, 85C, and 85K located at the second to fourth positions from the upstream side in the transport direction D81 are rotatably supported by the second support member 97 and the second support member. 97 is fixedly supported by the second solenoid S2. Further, the second solenoid S2 is electrically connected to the second solenoid control unit 5270 of FIG. Accordingly, by giving an appropriate signal from the second solenoid control unit 5270 to the second solenoid S2, the second support member 97 and the primary transfer rollers 85M, 85C, 85K are moved in the stroke direction D (S2) of the second solenoid S2. Can be moved back and forth.

  As shown in FIG. 6, also in the third embodiment, the four primary transfer rollers 85Y, 85M, 85C, and 85K are positioned on the four image forming stations Y, M, C, and K, thereby transferring. The belt 81 is pushed and brought into contact with the photosensitive drum 21 of the image forming stations Y, M, C, and K to form the primary transfer position TR1.

  In the third embodiment, the primary transfer roller 85Y (the most upstream transfer) located in the most upstream in the transport direction D81 out of the four primary transfer rollers 85Y, 85M, 85C, and 85K from the state shown in FIG. The three primary transfer rollers 85M, 85C, and 85K except the member are separated from the image forming stations M, C, and K by the second solenoid S2. That is, the second solenoid control unit 5270 (FIG. 2) issues a separation signal to the second solenoid S2 to separate the three primary transfer rollers 85M, 85C, 85K from the image forming stations M, C, K. . At this time, as shown in FIG. 7, if the three primary transfer rollers 85M, 85C, and 85K are separated from the image forming stations M, C, and K, the transfer belt 81 is still connected to the primary transfer roller 85Y. The image forming stations Y, M, C, and K are pushed by the downstream guide roller 86.

  Next, in the third embodiment, from the state shown in FIG. 7, the first solenoid controller 5260 (FIG. 2) issues a separation signal to the first solenoid S1 to separate the primary transfer roller 85Y from the image forming station K (see FIG. 7). FIG. 8). The pushing state of the transfer belt 81 to the image forming stations Y, M, C, and K is canceled only by the separation of the primary transfer roller 85Y. As described above, in the third embodiment, the first solenoid control unit 5260, the first solenoid S1, the first support member 95, the second solenoid control unit 5270, the second solenoid S2, and the second support member 97 of the present invention. It functions as a “separating means”.

  As described above, in the apparatus according to the third embodiment, the cleaner blade can be obtained simply by separating the primary transfer rollers 85Y, 85M, 85C, and 85K from the image forming stations Y, M, C, and K by the “separation contact means”. Foreign matter adhering to the tip of 711 can be removed. Therefore, it is not necessary to separately receive a mechanism for driving the transfer belt 81 in a reverse rotation, and the drive system is simplified. That is, according to the apparatus according to the third embodiment, the foreign matter attached to the tip of the cleaner blade 711 can be effectively peeled off with a simpler configuration, and the cost and size of the apparatus can be reduced.

  In the third embodiment, first, the three primary transfer rollers 85M, 85C, and 85K except the primary transfer roller 85Y (the most upstream transfer member) are separated from the image forming stations M, C, and K, and then the 1 The next transfer roller 85Y is separated from the image forming station Y. Therefore, the pushing state of the transfer belt 81 to the image forming stations Y, M, C, and K is first canceled by the separation of the primary transfer roller 85Y, and the blade facing roller 83 accompanying the removal of the pushing state. When the transfer belt 81 is separated from the image forming stations Y, M, C, and K by the movement of the primary transfer rollers 85M, 85C, and 85K, the primary transfer rollers 85M, 85C, and 85K are already separated from the image forming stations M, C, and K. Therefore, the separation operation of the transfer belt 81 is not limited by the primary transfer rollers 85M, 85C, and 85K, and the separation operation of the transfer belt 81 can be performed quickly. As a result, the transfer belt 81 moves quickly in the direction opposite to the conveyance direction D81 at the contact position where the tip of the cleaner blade 711 contacts the transfer belt 81, and more reliably adheres to the tip of the cleaner blade 711. It is preferable that the foreign matter can be peeled off.

  Also in the third embodiment, since the transfer belt 81 can be separated from the photosensitive drums 21 of all the image forming stations Y, M, C, and K, as described above, from the image forming apparatus main body 3. When removing the photosensitive cartridge 17 from the apparatus main body 3, it is possible to suppress the occurrence of a problem that the photosensitive cartridge 17 and the transfer belt 81 interfere with each other.

<Fourth embodiment>
As described in the second embodiment, the larger the fluctuation amount ΔL2 of the circumferential length L2 (image forming station side circumferential length L2) of the transfer belt 81b when the transfer belt 81 is apart from the image forming station, the more reliably. In addition, the foreign matter attached to the tip of the cleaner blade 711 can be peeled off. Here, the transfer belt 81b indicates the circumferential length of the transfer belt from the driving roller 82 toward the blade facing roller 83 in the reverse direction of the conveyance direction D81. Therefore, in the fourth embodiment, the apparatus is configured as follows in order to increase the fluctuation amount ΔL2. Since the basic configuration of the apparatus is the same as that of the first embodiment, only the features of the fourth embodiment will be described here, and the other components will be denoted by the same reference numerals as those of the first embodiment and description thereof will be omitted. To do.

  9-11 is a figure which shows operation | movement of the apparatus in 4th Embodiment. Also in the fourth embodiment, the blade facing roller 83 is urged in the direction D83 away from the drive roller 82 by the urging means 99 and is configured to reciprocate in the urging direction D83. Further, the cleaner blade 711 is formed integrally with the blade facing roller 83 and can reciprocate along with the blade facing roller 83. Further, a primary transfer roller 85Y (most upstream transfer member) and a downstream guide roller 86 positioned on the most upstream side in the transport direction D81 are rotatably supported by a first support member 95, and the first support member is also supported. 95 is fixedly supported by the first solenoid S1. Further, the first solenoid S1 is electrically connected to the first solenoid control unit 5260 of FIG. Accordingly, by giving an appropriate signal from the first solenoid controller 5260 to the first solenoid S1, the first support member 95 and the primary transfer roller 85Y are reciprocated in the stroke direction D (S1) of the first solenoid S1. be able to. The three primary transfer rollers 85M, 85C, and 85K located at the second to fourth positions from the upstream side in the transport direction D81 are rotatably supported by the second support member 97 and the second support member. 97 is fixedly supported by the second solenoid S2. Further, the second solenoid S2 is electrically connected to the second solenoid control unit 5270 of FIG. Accordingly, by giving an appropriate signal from the second solenoid control unit 5270 to the second solenoid S2, the second support member 97 and the primary transfer rollers 85M, 85C, 85K are moved in the stroke direction D (S2) of the second solenoid S2. Can be moved back and forth.

  As shown in FIG. 9, also in the fourth embodiment, the four primary transfer rollers 85Y, 85M, 85C, and 85K are positioned on the four image forming stations Y, M, C, and K, thereby transferring. The belt 81 is pushed and brought into contact with the photosensitive drum 21 of the image forming stations Y, M, C, and K to form the primary transfer position TR1.

  In the fourth embodiment, from the state shown in FIG. 9, the primary transfer roller 85Y (the most upstream transfer) located in the uppermost stream in the transport direction D81 among the four primary transfer rollers 85Y, 85M, 85C, and 85K. The three primary transfer rollers 85M, 85C, and 85K except the member are separated from the image forming stations M, C, and K by the second solenoid S2. That is, the second solenoid control unit 5270 (FIG. 2) issues a separation signal to the second solenoid S2 to separate the three primary transfer rollers 85M, 85C, 85K from the image forming stations M, C, K. . At this time, as shown in FIG. 10, if the three primary transfer rollers 85M, 85C, and 85K are merely separated from the image forming stations M, C, and K, the transfer belt 81 still has the primary transfer roller 85Y. The image forming stations Y, M, C, and K are pushed by the downstream guide roller 86.

  Next, in the fourth embodiment, from the state of FIG. 10, the first solenoid controller 5260 (FIG. 2) issues a separation signal to the first solenoid S1 to separate the primary transfer roller 85Y from the image forming station K. The downstream guide roller 86 is moved inward of the transfer belt 81 (FIG. 8). Only when the primary transfer roller 85Y is separated and the downstream guide roller 86 is moved, the pushing state of the transfer belt 81 to the image forming stations Y, M, C, and K is eliminated. Thus, in the fourth embodiment, the first solenoid control unit 5260, the first solenoid S1, the first support member 95, the second solenoid control unit 5270, the second solenoid S2, and the second support member 97 are “ It functions as a “separating means”.

  As described above, in the apparatus according to the fourth embodiment, the primary transfer rollers 85Y, 85M, 85C, and 85K are separated from the image forming stations Y, M, C, and K by the “separating contact means” and the downstream guide roller 86 is separated. The foreign matter adhering to the tip of the cleaner blade 711 can be removed simply by moving inward of the transfer belt. Therefore, it is not necessary to separately receive a mechanism for driving the transfer belt 81 in a reverse rotation, and the drive system is simplified. That is, according to the apparatus according to the fourth embodiment, the foreign matter attached to the tip of the cleaner blade 711 can be effectively peeled off with a simpler configuration, and the cost and size of the apparatus can be reduced.

  In the fourth embodiment, not only the primary transfer roller 85Y is separated from the image forming station Y but also the downstream guide roller 86 is moved to the inside of the transfer belt 81 to eliminate the pushing state of the transfer belt. . Therefore, as compared with the third embodiment in which only the primary transfer roller 85Y is separated from the image forming station Y and the pushing state of the transfer belt 81 is eliminated, the drive roller is driven in the direction opposite to the transfer direction D81 of the transfer belt 81. The variation ΔL2 of the circumferential length L2 (image forming station side circumferential length L2) of the transfer belt 81b from the blade 82 toward the blade facing roller 83 can be made larger. As a result, it is possible to increase the amount of movement of the transfer belt 81 in the direction opposite to the conveyance direction at the contact position where the tip of the cleaner blade 711 contacts the transfer belt. Therefore, the foreign matter adhering to the tip of the cleaner blade 711 can be more reliably removed, which is preferable.

  In the fourth embodiment, first, the three primary transfer rollers 85M, 85C, and 85K except the primary transfer roller 85Y (the most upstream transfer member) are separated from the image forming stations M, C, and K, and then the 1 The next transfer roller 85Y is separated from the image forming station Y. Therefore, the pushing state of the transfer belt 81 to the image forming stations Y, M, C, and K is first canceled by the separation of the primary transfer roller 85Y and the movement of the downstream guide roller 86, and the pushing state of the pushing state is also reduced. When the transfer belt 81 moves away from the image forming stations Y, M, C, and K due to the movement of the blade facing roller 83 accompanying the cancellation, the primary transfer rollers 85M, 85C, and 85K have already been moved to the image forming stations M, C, and K. Separated from K. Therefore, the separation operation of the transfer belt 81 is not limited by the primary transfer rollers 85M, 85C, and 85K, and the separation operation of the transfer belt 81 can be performed quickly. As a result, the transfer belt 81 moves quickly in the direction opposite to the conveyance direction D81 at the contact position where the tip of the cleaner blade 711 contacts the transfer belt 81, and more reliably adheres to the tip of the cleaner blade 711. It is preferable that the foreign matter can be peeled off.

  Also in the fourth embodiment, since the transfer belt 81 can be separated from the photosensitive drums 21 of all the image forming stations Y, M, C, and K, as described above, from the image forming apparatus main body 3. When removing the photosensitive cartridge 17 from the apparatus main body 3, it is possible to suppress the occurrence of a problem that the photosensitive cartridge 17 and the transfer belt 81 interfere with each other.

<Fifth Embodiment>
Next, a fifth embodiment of the image forming apparatus according to the present invention will be described. Since the basic configuration of the apparatus is the same as that of the first embodiment, only the characteristic parts of the fifth embodiment will be described here, and the other components are denoted by the same reference numerals as those of the first embodiment and the description thereof is omitted. To do.

  12-13 is a figure which shows operation | movement of the apparatus in 5th Embodiment. Also in the fifth embodiment, the blade facing roller 83 is urged in the direction D83 away from the driving roller 82 by the urging means 99 and is configured to reciprocate in the urging direction D83. Further, the cleaner blade 711 is formed integrally with the blade facing roller 83 and can reciprocate along with the blade facing roller 83. Moreover, the apparatus in 5th Embodiment becomes a structure which does not have the downstream guide roller 86 in the said 1st-4th embodiment. Further, four primary transfer rollers 85Y, 85M, 85C, and 85K (transfer members) are arranged so as to face each of the four image forming stations Y, M, C, and K in a one-to-one relationship. A primary transfer roller 85Y (most upstream transfer member) positioned at the most upstream in the transport direction D81 is rotatably supported by a first support member 95, and the first support member 95 is a first solenoid. It is fixedly supported by S1. Further, the first solenoid S1 is electrically connected to the first solenoid control unit 5260 of FIG. Accordingly, by giving an appropriate signal from the first solenoid controller 5260 to the first solenoid S1, the first support member 95 and the primary transfer roller 85Y are reciprocated in the stroke direction D (S1) of the first solenoid S1. be able to. Of the four primary transfer rollers 85Y, 85M, 85C, and 85K, the primary transfer roller 85Y (most upstream transfer member) positioned at the most upstream position in the transport direction D81 and the primary transfer roller 85K positioned at the most downstream position. The two primary transfer rollers 85M and 85C excluding (the most downstream transfer member) are rotatably supported by a second support member 97, and the second support member 97 is supported by a second solenoid S2. Fixedly supported. Further, the second solenoid S2 is electrically connected to the second solenoid control unit 5270 of FIG. Therefore, by giving an appropriate signal from the second solenoid control unit 5270 to the second solenoid S2, the second support member 97 and the primary transfer rollers 85M and 85C are reciprocated in the stroke direction D (S2) of the second solenoid S2. Can be made. The primary transfer roller 85K is rotatably supported by the apparatus main body 3.

  As shown in FIG. 12, also in the fifth embodiment, the four primary transfer rollers 85Y, 85M, 85C, and 85K are positioned on the four image forming stations Y, M, C, and K, thereby transferring. The belt 81 is pushed and brought into contact with the photosensitive drum 21 of the image forming stations Y, M, C, and K to form the primary transfer position TR1.

  In the fifth embodiment, from the state shown in FIG. 12, the primary transfer roller 85Y (the most upstream transfer) located in the most upstream in the transport direction D81 among the four primary transfer rollers 85Y, 85M, 85C, and 85K. Two primary transfer rollers 85M and 85C except for the primary transfer roller 85K (most downstream transfer member) located on the most downstream side are separated from the image forming stations M and C by the second solenoid S2. That is, the second solenoid control unit 5270 (FIG. 2) issues a separation signal to the second solenoid S2 to separate the two primary transfer rollers 85M and 85C from the image forming stations M and C. At this time, as shown in FIG. 13, if the two primary transfer rollers 85M and 85C are merely separated from the image forming stations M and C, the transfer belt 81 still forms images by the primary transfer rollers 85Y and 85K. It is pushed to stations Y, M, C, K.

  Next, in the fifth embodiment, from the state shown in FIG. 13, the first solenoid controller 5260 (FIG. 2) issues a separation signal to the first solenoid S1 to separate the primary transfer roller 85Y from the image forming station K (see FIG. 13). FIG. 14). The pushing state of the transfer belt 81 to the image forming stations Y, M, C, and K is canceled only by the separation of the primary transfer roller 85Y. As described above, in the fifth embodiment, the first solenoid control unit 5260, the first solenoid S1, the first support member 95, the second solenoid control unit 5270, the second solenoid S2, and the second support member 97 of the present invention are used. It functions as a “separating means”.

  As described above, in the apparatus according to the fifth embodiment, the front end portion of the cleaner blade 711 can be obtained simply by separating the primary transfer rollers 85Y, 85M, and 85C from the image forming stations Y, M, and C by the “separation contact means”. Foreign matter adhering to can be removed. Therefore, it is not necessary to separately receive a mechanism for driving the transfer belt 81 in a reverse rotation, and the drive system is simplified. That is, according to the apparatus according to the fifth embodiment, the foreign matter attached to the tip of the cleaner blade 711 can be effectively peeled off with a simpler configuration, and the cost and size of the apparatus can be reduced.

  In the fifth embodiment, among the four primary transfer rollers 85Y, 85M, 85C, and 85K, first, the primary transfer roller 85Y (the most upstream transfer member) and the primary transfer roller 85K (the most downstream transfer member) are used. The other two primary transfer rollers 85M and 85C are separated from the image forming stations M and C, and then the primary transfer roller 85Y is separated from the image forming station Y. Therefore, the pushing state of the transfer belt 81 to the image forming stations Y, M, C, and K is first canceled by the separation of the primary transfer roller 85Y, and the blade facing roller 83 accompanying the removal of the pushing state. When the transfer belt 81 is separated from the image forming stations Y, M, and C by the movement of the primary transfer rollers 85M and 85C, the primary transfer rollers 85M and 85C are already separated from the image forming stations M and C. Accordingly, the separation operation of the transfer belt 81 is not limited by the primary transfer rollers 85M and 85C, and the separation operation of the transfer belt 81 can be performed quickly. As a result, the transfer belt 81 moves quickly in the direction opposite to the conveyance direction D81 at the contact position of the transfer belt 81 at the tip of the cleaner blade 711, and the foreign matter attached to the tip of the cleaner blade 711 more reliably. Can be peeled off.

<Sixth Embodiment>
As described in the second embodiment, the larger the fluctuation amount ΔL2 of the circumferential length L2 (image forming station side circumferential length L2) of the transfer belt 81b when the transfer belt 81 is apart from the image forming station, the more reliably. In addition, the foreign matter attached to the tip of the cleaner blade 711 can be peeled off. Here, the transfer belt 81b indicates the circumferential length of the transfer belt from the driving roller 82 toward the blade facing roller 83 in the reverse direction of the conveyance direction D81. Therefore, in the sixth embodiment, the apparatus is configured as follows in order to increase the fluctuation amount ΔL2. Since the basic configuration of the apparatus is the same as that of the first embodiment, only the features of the sixth embodiment will be described here, and the other components will be denoted by the same reference numerals as those of the first embodiment and description thereof will be omitted. To do.

  15-17 is a figure which shows operation | movement of the apparatus in 6th Embodiment. Also in the sixth embodiment, the blade facing roller 83 is urged in the direction D83 away from the drive roller 82 by the urging means 99, and is configured to reciprocate in the urging direction D83. Further, the cleaner blade 711 is formed integrally with the blade facing roller 83 and can reciprocate along with the blade facing roller 83. Moreover, the apparatus in 6th Embodiment becomes a structure which does not have the downstream guide roller 86 which existed in the said 1st-4th embodiment. Further, a primary transfer roller 85Y (most upstream transfer member) positioned at the uppermost stream in the transport direction D81 and a primary transfer roller 85K positioned at the uppermost stream are rotatably supported by the first support member 95. The first support member 95 is fixedly supported by a first solenoid S1. Further, the first solenoid S1 is electrically connected to the first solenoid control unit 5260 of FIG. Accordingly, by giving an appropriate signal from the first solenoid controller 5260 to the first solenoid S1, the first support member 95 and the primary transfer roller 85Y are reciprocated in the stroke direction D (S1) of the first solenoid S1. be able to. Of the four primary transfer rollers 85Y, 85M, 85C, and 85K, the primary transfer roller 85Y (most upstream transfer member) positioned at the most upstream position in the transport direction D81 and the primary transfer roller 85K positioned at the most downstream position. The two primary transfer rollers 85M and 85C excluding (the most downstream transfer member) are rotatably supported by a second support member 97, and the second support member 97 is supported by a second solenoid S2. Fixedly supported. Further, the second solenoid S2 is electrically connected to the second solenoid control unit 5270 of FIG. Therefore, by giving an appropriate signal from the second solenoid control unit 5270 to the second solenoid S2, the second support member 97 and the primary transfer rollers 85M and 85C are reciprocated in the stroke direction D (S2) of the second solenoid S2. Can be made.

  As shown in FIG. 15, also in the sixth embodiment, the four primary transfer rollers 85Y, 85M, 85C, and 85K are positioned on the four image forming stations Y, M, C, and K, thereby transferring the image. The belt 81 is pushed and brought into contact with the photosensitive drum 21 of the image forming stations Y, M, C, and K to form the primary transfer position TR1.

  In the sixth embodiment, from the state shown in FIG. 15, the primary transfer roller 85Y (the most upstream transfer) located in the most upstream in the transport direction D81 among the four primary transfer rollers 85Y, 85M, 85C, and 85K. Members) and two primary transfer rollers 85M and 85C excluding the primary transfer roller 85K (most downstream transfer member) located on the most downstream side are separated from the image forming stations M and C by the second solenoid S2. That is, the second solenoid control unit 5270 (FIG. 2) issues a separation signal to the second solenoid S2 to separate the two primary transfer rollers 85M and 85C from the image forming stations M and C. At this time, as shown in FIG. 16, the transfer belt 81 still forms an image from the primary transfer rollers 85Y and 85K only by separating the two primary transfer rollers 85M and 85C from the image forming stations M and C. It is pushed to stations Y, M, C, K.

  Next, in the sixth embodiment, from the state of FIG. 16, the first solenoid controller 5260 (FIG. 2) issues a separation signal to the first solenoid S 1 to separate the primary transfer rollers 85Y and 85K from the image forming station K. (FIG. 17). Only when the primary transfer rollers 85Y and 85K are separated from each other, the pushing state of the transfer belt 81 to the image forming stations Y, M, C, and K is eliminated. Thus, in the sixth embodiment, the first solenoid control unit 5260, the first solenoid S1, the first support member 95, the second solenoid control unit 5270, the second solenoid S2, and the second support member 97 are the “ It functions as a “separating means”.

  As described above, in the apparatus according to the sixth embodiment, only the primary transfer rollers 85Y, 85M, 85C, and 85K are separated from the image forming stations Y, M, C, and K by the “separating and abutting means”. Foreign matter adhering to the tip of 711 can be removed. Therefore, it is not necessary to separately receive a mechanism for driving the transfer belt 81 in a reverse rotation, and the drive system is simplified. That is, according to the apparatus according to the sixth embodiment, the foreign matter attached to the tip of the cleaner blade 711 can be effectively peeled off with a simpler configuration, and the cost and size of the apparatus can be reduced.

  As described above, in the sixth embodiment, not only the primary transfer roller 85Y but also the primary transfer roller 85Y is separated from the image forming station Y to eliminate the pushing state of the transfer belt. Therefore, as compared with the fifth embodiment in which only the primary transfer roller 85Y is separated from the image forming station Y and the pushing state of the transfer belt 81 is eliminated, the driving roller is driven in the direction opposite to the transfer direction D81 of the transfer belt 81. The variation ΔL2 of the circumferential length L2 (image forming station side circumferential length L2) of the transfer belt 81b from the blade 82 toward the blade facing roller 83 can be made larger. As a result, it is possible to increase the amount of movement of the transfer belt 81 in the direction opposite to the conveyance direction at the contact position where the tip of the cleaner blade 711 contacts the transfer belt 81. Therefore, the foreign matter adhering to the tip of the cleaner blade 711 can be more reliably removed, which is preferable.

  In the sixth embodiment, first, the two primary transfer rollers 85M and 85C except the primary transfer rollers 85Y and 85K are separated from the image forming stations M and C, and then the primary transfer rollers 85Y and 85K are moved to the image. Separated from the forming station Y. Therefore, the pushing state of the transfer belt 81 to the image forming stations Y, M, C, and K is first canceled by the separation of the primary transfer rollers 85Y and 85K, and the blades are opposed to each other when the pushing state is eliminated. When the transfer belt 81 is separated from the image forming stations Y, M, C, and K by the movement of the roller 83, the primary transfer rollers 85M and 85C are already separated from the image forming stations M and C. Accordingly, the separation operation of the transfer belt 81 is not limited by the primary transfer rollers 85M and 85C, and the separation operation of the transfer belt 81 can be performed quickly. As a result, the transfer belt 81 moves quickly in the direction opposite to the conveyance direction D81 at the contact position of the transfer belt 81 at the tip of the cleaner blade 711, and the foreign matter attached to the tip of the cleaner blade 711 more reliably. Can be peeled off.

  Also in the sixth embodiment, since the transfer belt 81 can be separated from the photosensitive drums 21 of all the image forming stations Y, M, C, and K, as described above, from the image forming apparatus main body 3. When removing the photosensitive cartridge 17 from the apparatus main body 3, it is possible to suppress the occurrence of a problem that the photosensitive cartridge 17 and the transfer belt 81 interfere with each other.

<Seventh embodiment>
Next, a seventh embodiment of the image forming apparatus according to the present invention will be described. Since the basic configuration of the apparatus is the same as that of the first embodiment, only the features of the seventh embodiment will be described here, and the other components will be denoted by the same reference numerals as those of the first embodiment and description thereof will be omitted. To do.

  18 and 19 are diagrams illustrating the operation of the apparatus according to the seventh embodiment. In the seventh embodiment, the blade facing roller 83 is urged in the direction D83 away from the driving roller 82 by the urging means 99, and is configured to reciprocate in the urging direction D83. Further, the cleaner blade 711 is formed integrally with the blade facing roller 83 and can reciprocate along with the blade facing roller 83. Further, the apparatus in the seventh embodiment does not have the downstream guide roller 86 existing in the first to fourth embodiments, but on the downstream side in the conveyance direction D81 of the blade facing roller 83 and the conveyance of the primary transfer roller 85Y. An upstream guide roller 87 is disposed upstream in the direction D81. The upstream guide roller 87 is positioned inside the transfer belt 81, and the four primary transfer rollers 85Y, 85M, 85C, and 85K are positioned on the image forming stations Y, M, C, and K, and are transferred. The belt 81 is stretched.

  The upstream guide roller 87 and the three primary transfer rollers 85Y, 85M, and 85C from the upstream side in the transport direction D81 are rotatably supported by a first support member 95 and are also supported by the first support member 95. The member 95 is fixedly supported by the first solenoid S1. Further, the first solenoid S1 is electrically connected to the first solenoid control unit 5260 of FIG. Accordingly, by giving an appropriate signal from the first solenoid control unit 5260 to the first solenoid S1, the first support member 95 and the primary transfer rollers 85Y, 85M, and 85C are moved in the stroke direction D (S1) of the first solenoid S1. Can be moved back and forth. The primary transfer roller 85K located on the most downstream side in the transport direction D81 is rotatably supported by a second support member 97, and the second support member 97 is fixedly supported by a second solenoid S2. Yes. Further, the second solenoid S2 is electrically connected to the second solenoid control unit 5270 of FIG. Therefore, by giving an appropriate signal to the second solenoid S2 from the second solenoid controller 5270, the second support member 97 and the primary transfer roller 85K are reciprocated in the stroke direction D (S2) of the second solenoid S2. be able to.

  As shown in FIG. 18, in the seventh embodiment, the four primary transfer rollers 85Y, 85M, 85C, and 85K are positioned on the four image forming stations Y, M, C, and K, and the upstream guide rollers. 87, the transfer belt 81 is stretched, and the transfer belt 81 is pushed and brought into contact with the photosensitive drum 21 of the image forming stations Y, M, C, K to form the primary transfer position TR1.

  From such a state of FIG. 18, the first solenoid control unit 5260 transmits a separation signal to the solenoid S1, moves the upstream guide roller 87 inward of the transfer belt 81, and three from the upstream side in the transport direction D81. FIG. 19 shows a state in which the primary transfer rollers 85Y, 85M, and 85C are separated from the image forming station. Thus, in the seventh embodiment, the first solenoid control unit 5260, the first solenoid S1, and the first support member 95 function as the “separating and contacting means” in the present invention. Further, as described above, the blade facing roller 83 is urged by the urging means 99 in the direction D83 away from the driving roller 82, and is configured to reciprocate in the urging direction D83. Therefore, the blade facing roller functions as a so-called tension roller that applies tension to the transfer belt 81.

  Accordingly, as shown in FIG. 18, the upstream guide roller 87 is moved inward of the transfer belt 81, and the three primary transfer rollers 85Y, 85M, 85C are moved to the image forming stations Y, M, C by the solenoid S1. When the pushing state of the transfer belt 81 is released away from the blade, the blade facing roller 83 is moved in the urging direction D83 by the urging force from the urging means 99 according to the elimination of the pushing state. Is separated from the image forming stations Y, M, and C. Therefore, the transfer belt 81 from which the pushing state has been eliminated is separated from the photosensitive drum 21 of the image forming stations Y, M, and C. Since the moving direction of the blade facing roller 83 is a direction away from the driving roller 82, the transfer belt moving from the driving roller 82 toward the blade facing roller in the transport direction D81 of the transfer belt 81 with the separation operation of the transfer belt 81. While the peripheral length L1 of 81a (the peripheral length L1 opposite to the image forming station) is increased, the peripheral length L2 of the transfer belt 81b from the drive roller 82 toward the blade facing roller 83 in the direction opposite to the transfer direction D81 of the transfer belt 81 ( The peripheral length L2) on the image forming station side is shortened. As a result, at the contact position where the tip of the cleaner blade 711 contacts the transfer belt 81, the transfer belt 81 moves in the direction opposite to the conveyance direction D81 by the variation ΔL2 of the circumferential length L2. Therefore, in the state of FIG. 3, the foreign matter adhering to the tip of the cleaner blade 711 causes the primary transfer rollers 85Y, 85M, and 85C to be separated from the image forming stations Y, M, and C by the “separation contact means”. Thus, as shown in FIG. 4, it moves in the direction opposite to the conveyance direction D81 by the circumference variation ΔL2, and the foreign matter adhering to the tip of the cleaner blade 711 can be peeled off.

  As described above, in the apparatus according to the seventh embodiment, the front end portion of the cleaner blade 711 can be obtained simply by separating the primary transfer rollers 85Y, 85M, and 85C from the image forming stations Y, M, and C by the “separation contact means”. Foreign matter adhering to can be removed. Therefore, it is not necessary to separately receive a mechanism for driving the transfer belt 81 in a reverse rotation, and the drive system is simplified. That is, according to the apparatus according to the seventh embodiment, the foreign matter adhering to the tip of the cleaner blade 711 can be effectively peeled off with a simpler configuration, and the cost and size of the apparatus can be reduced.

  In the seventh embodiment, a moving mechanism (second solenoid S2, second support member 97) is also provided for the black (K) primary transfer roller 85K. Therefore, after the primary transfer rollers 85Y, 85M, 85C are separated from the image forming station by the “separation contact means”, a separation signal is further sent from the second solenoid control unit 5270 (FIG. 2) to the second solenoid S2. By transmitting and separating the primary transfer roller 85K, the transfer belt 81 can be separated from all the image forming stations Y, M, C, and K. Therefore, as described above, it is possible to suppress the occurrence of the problem that the photosensitive cartridge 17 and the transfer belt 81 interfere when the photosensitive cartridge 17 is detached from the apparatus main body 3 from the image forming apparatus main body 3. .

<Others>
The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention. For example, in the above embodiment, the image forming stations Y, M, C, and K are arranged in this order from the upstream side in the transport direction D81. However, the arrangement order of the image forming stations is not limited to this and can be changed as appropriate. is there.

  In the first to fourth embodiments and the seventh embodiment, four image forming stations Y, M, C, and K are used. However, the number of image forming stations is not limited to this, and the number is two or more. If it is. In the fifth and sixth embodiments, four image forming stations Y, M, C, and K are used. However, the number of image forming stations is not limited to this, and may be three or more.

  In the first embodiment, the three primary transfer rollers 85Y, 85M, and 85C from the upstream side in the transport direction D81 to the third side are separated from the image forming station, but from the upstream side in the transport direction D81. It is possible to arbitrarily select how many primary transfer rollers are separated from the image forming station. For example, two primary transfer rollers 85Y and 85M up to the second from the upstream side in the transport direction D81 can be arbitrarily selected. It can be set.

  In the second embodiment, two solenoids S1 and S2 are used to separate all the primary transfer rollers 85Y, 85M, 85C, and 85K from the image forming stations Y, M, C, and K. The separation method is not limited to this. For example, all the primary transfer rollers 85Y, 85M, 85C, and 85K are separated from the image forming stations Y, M, C, and K by a single solenoid. You may comprise.

  In the third embodiment, the three primary transfer rollers 85M, 85C, and 85K are separated from the image forming station by the solenoid S2, but the method of selecting the primary transfer roller to be separated by the solenoid S2 is not limited to this. For example, only the primary transfer roller 85M may be used, or two of the primary transfer rollers 85M and 85C may be selected. However, in order to increase the amount of movement of the transfer belt 81 in the reverse direction of the conveyance direction D81 at the contact position of the cleaner blade 711 with the transfer belt 81, as many primary transfer rollers 85 as possible are separated from the image forming station. It is suitable to make it.

  In the fifth embodiment, the two primary transfer rollers 85M and 85C are separated from the image forming stations M and C by the solenoid S2, but the primary transfer roller to be separated by the solenoid S2 is selected. For example, only the primary transfer roller 85M may be used. However, in order to increase the amount of movement of the transfer belt 81 in the reverse direction of the conveyance direction D81 at the contact position of the cleaner blade 711 with the transfer belt 81, as many primary transfer rollers 85 as possible are separated from the image forming station. It is suitable to make it.

  In the seventh embodiment, the three primary transfer rollers 85Y, 85M, and 85C are separated from the image forming stations Y, M, and C by the solenoid S1, but the primary transfer roller that is separated by the solenoid S1 is used. The selection method is not limited to this. For example, only the primary transfer roller 85Y positioned at the uppermost stream in the transport direction D81 may be used, or the first primary transfer rollers 85Y and 85M from the upstream side in the transport direction D81 may be selected. . However, in order to increase the amount of movement of the transfer belt 81 in the reverse direction of the conveyance direction D81 at the contact position of the cleaner blade 711 with the transfer belt 81, as many primary transfer rollers 85 as possible are separated from the image forming station. It is suitable to make it.

  In the above embodiment, the primary transfer roller that is driven and rotated is used as the transfer member. However, the usable transfer member is not limited to this, and a transfer member that is not driven and rotated, for example, may be used. However, when the transfer member is a driven roller, the friction between the transfer belt and the transfer member (transfer roller) when the transfer belt is separated from the image forming station with the cancellation of the belt pushing state by the separation contact means. Can be reduced. As a result, the separating operation of the transfer belt can be performed quickly, and the foreign matter adhering to the tip of the cleaner blade can be peeled off more effectively.

1 is a diagram illustrating a first embodiment of an image forming apparatus according to the present invention. FIG. 2 is a block diagram showing an electrical configuration of the image forming apparatus in FIG. 1. The figure which shows operation | movement of the apparatus in 1st Embodiment of this invention. The figure which shows operation | movement of the apparatus in 1st Embodiment of this invention. The figure which shows operation | movement of the apparatus in 2nd Embodiment of this invention. The figure which shows operation | movement of the apparatus in 3rd Embodiment of this invention. The figure which shows operation | movement of the apparatus in 3rd Embodiment of this invention. The figure which shows operation | movement of the apparatus in 3rd Embodiment of this invention. The figure which shows operation | movement of the apparatus in 4th Embodiment of this invention. The figure which shows operation | movement of the apparatus in 4th Embodiment of this invention. The figure which shows operation | movement of the apparatus in 4th Embodiment of this invention. The figure which shows operation | movement of the apparatus in 5th Embodiment of this invention. The figure which shows operation | movement of the apparatus in 5th Embodiment of this invention. The figure which shows operation | movement of the apparatus in 5th Embodiment of this invention. The figure which shows operation | movement of the apparatus in 6th Embodiment of this invention. The figure which shows operation | movement of the apparatus in 6th Embodiment of this invention. The figure which shows operation | movement of the apparatus in 6th Embodiment of this invention. The figure which shows operation | movement of the apparatus in 7th Embodiment of this invention. The figure which shows operation | movement of the apparatus in 7th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 ... Housing box main body, 5 ... Electrical component box, 7 ... Image forming unit, 8 ... Transfer belt unit, 21 ... Photosensitive drum, 71 ... Cleaner part, 711 ... Cleaner blade, 81 ... Transfer belt, 82 ... Drive roller, 83: driven roller (blade facing roller), 85, 85Y, 85M, 85C, 85K ... primary transfer roller, 86 ... downstream guide roller, 87 ... upstream guide roller, 95 ... first support member, 97 ... second support member 99, biasing means, Y, M, C, K, image forming station, D21, photosensitive drum rotation direction, TR1, primary transfer position, D81, transport direction, D83, biasing direction, D (S1), D (S2): Stroke direction, ΔL2: Fluctuation amount of transfer belt circumference, S1, S2: Solenoid

Claims (9)

A transfer belt that is stretched over at least two rollers, a driving roller and a driven blade-opposing roller, and rotated and conveyed in a predetermined conveying direction; a downstream side of the blade-facing roller in the conveying direction and the conveying direction of the driving roller M image forming stations (M ≧ 2) that are arranged side by side in the transport direction on the upstream side, and form color images by superimposing toner images of different colors on the transfer belt surface by primary transfer. In an image forming apparatus comprising:
M transfer members disposed on the inner side of the transfer belt so as to face each of the M image forming stations in a one-to-one relationship with the transfer belt interposed therebetween;
While positioning the M transfer members on the image forming station side, the transfer belt is pushed and brought into contact with the image forming station to enable primary transfer of toner images in all the image forming stations. If necessary, N transfer members of the M transfer members up to the Nth (M ≧ N ≧ 1) from the upstream side in the transport direction are moved away from the image forming station to move the N transfer members. Separation contact means for eliminating the pushing state of the transfer belt by
A cleaner blade that cleans the surface of the transfer belt by bringing its tip into contact with the blade-opposing roller via the transfer belt;
Urging means for urging the blade facing roller in a direction away from the driving roller;
The blade-opposing roller is provided integrally with the cleaner blade so as to reciprocate in the urging direction of the urging unit, and the N transfer members are moved away from the image forming station by the separating and contacting unit. In accordance with the cancellation of the pushing state of the transfer belt, image formation is characterized in that it is driven to rotate in the direction opposite to the conveying direction while moving in the urging direction by the urging force from the urging means. apparatus. The separation contact means moves all of the M transfer members away from the image forming station as necessary to eliminate the pushing state of the transfer belt by the M transfer members,
The blade-opposing roller is configured such that the urging unit is urged in response to all of the M transfer members being moved away from the image forming station by the separating and contacting unit and the pushing state of the transfer belt is eliminated. The image forming apparatus according to claim 1, wherein the image forming apparatus is driven to rotate in a direction opposite to the conveyance direction while moving in the urging direction by an urging force from the image forming apparatus. Among the M transfer members, the transfer member is disposed between the most downstream transfer member on the most downstream side in the transport direction and the driving roller and inside the transfer belt, and the most downstream transfer member is located on the image forming station side. The image forming apparatus according to claim 1, further comprising a downstream guide roller that contacts the transfer belt on a common inscribed line between the most downstream transfer member in the positioned state and the image forming station facing the most downstream transfer member. A device,
If necessary, the separation and abutment means first applies the L transfer members up to the Lth (M ≧ L ≧ 2) from the upstream side in the transport direction among the M transfer members. (L-1) transfer members excluding the most upstream transfer member located upstream are moved away from the image forming station, and then the most upstream transfer member is moved away from the image forming station. Eliminate the pushing state of the transfer belt by the transfer member,
The blade facing roller is urged by the urging unit when the uppermost transfer member is moved away from the image forming station by the separating and contacting unit and the pushing state of the transfer belt is released. An image forming apparatus that rotates in a direction opposite to the conveying direction while moving in the urging direction by force. The separation contact means moves all the transfer members excluding the most upstream transfer member located at the most upstream in the transport direction from the image forming station among the M transfer members, if necessary, Moving the most upstream transfer member away from the image forming station to eliminate the pushing state of the transfer belt by the M transfer members;
The blade facing roller is urged by the urging unit when the uppermost transfer member is moved away from the image forming station by the separating and contacting unit and the pushing state of the transfer belt is released. The image forming apparatus according to claim 3, wherein the image forming apparatus is driven to rotate in a direction opposite to the conveyance direction while being moved in the urging direction by force. The separation contact means moves the most upstream transfer member away from the image forming station and moves the downstream guide roller inward of the transfer belt to push the transfer belt by the M transfer members. Cancel the condition,
In the blade facing roller, the uppermost transfer member is moved away from the image forming station by the separation and contact means, and the downstream guide roller is moved inward of the transfer belt to push the transfer belt. 5. The image forming apparatus according to claim 4, wherein in response to the cancellation, the image forming apparatus is driven to rotate in a direction opposite to the conveying direction while moving in the urging direction by an urging force from the urging unit. Among the M transfer members, the M transfer members are disposed between the most upstream transfer member positioned on the most upstream side in the transport direction and the blade facing roller and inside the transfer member, and the M transfer members are the images. The image forming apparatus according to claim 1, further comprising an upstream guide roller that stretches the transfer belt while being positioned on the forming station side.
The separation contact unit moves, as necessary, the N transfer members up to the Nth (M ≧ N ≧ 1) from the upstream side in the transport direction among the M transfer members away from the image forming station. And the upstream guide roller is moved inward of the transfer belt to eliminate the pushing state of the transfer belt by the N transfer members,
The blade facing roller moves the N transfer members away from the image forming station by the separating and contacting means, and the upstream guide roller is moved inward of the transfer belt to push the transfer belt. An image forming apparatus that is driven to rotate in a direction opposite to the conveying direction while moving in the urging direction by an urging force from the urging unit in response to the cancellation of the state. A transfer belt that is stretched over at least two rollers, a driving roller and a driven blade-opposing roller, and rotated and conveyed in a predetermined conveying direction; a downstream side of the blade-facing roller in the conveying direction and the conveying direction of the driving roller K image forming stations (K ≧ 3) which are arranged side by side in the conveying direction on the upstream side and form a color image by superimposing the toner images of different colors on the transfer belt surface by primary transfer. In an image forming apparatus comprising:
K transfer members disposed on the inner side of the transfer belt so as to face each of the K image forming stations in a one-to-one relationship with the transfer belt interposed therebetween;
While the K transfer members are positioned on the image forming station side, the transfer belt is pushed against and brought into contact with the image forming station to enable primary transfer of toner images in all the image forming stations. If necessary, among the K transfer members, the J-th transfer member from the upstream side in the transport direction to the Jth (K ≧ J ≧ 3) J-th transfer members, first in the upstream and downstream in the transport direction. After the (J-2) transfer members excluding the most upstream transfer member and the most downstream transfer member located are moved away from the image forming station, the uppermost transfer member is moved away from the image forming station to move the transfer member. (J-2) separation contact means for eliminating the pushing state of the transfer belt by the individual transfer members and the most upstream transfer member;
A cleaner blade that cleans the surface of the transfer belt by bringing its tip into contact with the blade-opposing roller via the transfer belt;
Urging means for urging the blade facing roller in a direction away from the driving roller;
The blade-opposing roller is provided so as to reciprocate in the urging direction of the urging unit integrally with the cleaner blade, and the most upstream transfer member is moved away from the image forming station by the separating and contacting unit. An image forming apparatus that is driven to rotate in a direction opposite to the conveying direction while being moved in the urging direction by an urging force from the urging unit in response to cancellation of the pushing state of the transfer belt. . The separation contact means positions the K transfer members on the image forming station side to push the transfer belt against the image forming station so as to contact the primary image of the toner image at all the image forming stations. While making transfer possible, among the K transfer members, the J transfer members up to the Jth (K ≧ J ≧ 3) from the upstream side in the transport direction are first transferred in the transport direction first. After the (J-2) transfer members excluding the most upstream transfer member and the most downstream transfer member positioned on the upstream and the most downstream side are moved away from the image forming station, the most upstream transfer member and the most downstream transfer member are moved. Moving the transfer member away from the image forming station to eliminate the pushing state of the transfer belt by the J transfer members;
The blade-opposing roller is provided so as to reciprocate in the urging direction of the urging unit integrally with the cleaner blade, and the most downstream transfer member and the most downstream transfer member are moved to the image forming station by the separation and abutment unit. And moving in the urging direction by the urging force from the urging means and being driven to rotate in the direction opposite to the conveying direction in response to the release of the pushing state of the transfer belt. 8. The image forming apparatus according to 7.   The image forming apparatus according to claim 1, wherein the transfer member is a transfer roller that is driven to rotate.

Images