JP2012203389A - Transfer device, image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transfer device that allows entire transfer members to be directly transitioned to an evacuation state where the entire transfer members are evacuated from the rear surface of an endless belt from both of a multiple-color transfer state where the entire transfer members contact the rear surface of the endless belt and a single-color transfer state where one transfer member contacts the rear surface of the endless belt, as well as an image forming apparatus.SOLUTION: An image forming apparatus includes: a first switching mechanism 110 capable of switching from a multiple-color transfer state to a single-color transfer state; and a second switching mechanism 130 capable of evacuating one transfer member in the single-transfer state from the rear surface of an endless member so as to allow the entire transfer members to be switched to an evacuation state where the entire transfer members are evacuated from the rear surface of the endless member, and switching from the multiple-color transfer state to the evacuation state.

Description

  The present invention relates to a transfer device and an image forming apparatus.

  In the image forming apparatus described in Patent Document 1, the primary transfer roll can be moved to the retracted position and the tension adjusting roll can be moved to the tension relaxation position in consideration of the workability of replacing the photosensitive unit. Is provided.

JP 2007-93642 A

  The problem of the present invention is that all transfer members are directly endless from a multi-color transfer state where all transfer members are in contact with the back surface of the endless belt, and from a single color transfer state where one transfer member is in contact with the back surface of the endless belt. It is to shift to a retracted state where the belt is retracted from the back surface of the belt.

  In the transfer device according to the first aspect of the present invention, an endless member that circulates by a driving unit and a plurality of image holders that respectively hold images of different colors sandwich the endless member. A plurality of transfer members for transferring an image formed on the image holding member to the surface of the endless member, and a plurality of the transfer members coming into contact with the back surface of the endless member. The other transfer member is moved so that one of the transfer members comes into contact with the back surface of the endless member from a multi-color transfer state that enables transfer of the image from the image holding member to the surface of the endless member by the transfer member. A first switching mechanism that is retractable from the back surface of the endless member and is capable of switching to a single-color transfer state that enables transfer of an image from the image carrier to the surface of the endless member by the one transfer member; From a single color transfer state The transfer member is retracted from the back surface of the endless member to enable switching to a retracted state in which all the transfer members are retracted from the back surface of the endless member. And a second switching mechanism that is retracted from the back surface of the endless member and can be switched to the retracted state.

  The transfer device according to a second aspect of the present invention is the transfer device according to the first aspect, wherein a tension applying member that applies tension to the endless member is provided, and the second switching mechanism switches the transfer member to the retracted state. The second switching mechanism releases the tension of the endless member applied by the tension applying member.

  The transfer device according to claim 3 of the present invention is the transfer unit according to claim 1 or 2, wherein the transfer unit supports the back surface of the endless member and the image is transferred by the transfer member in the multi-color transfer state. A regulating member that regulates the circulation path of the endless member at the same time as the first switching mechanism switches from the multiple-color transfer state to the single-color transfer state, or the second switching mechanism includes the plurality of colors. In conjunction with switching from the transfer state to the retracted state, the first switching mechanism or the second switching mechanism retracts the regulating member from the back surface of the endless member.

  The transfer device according to a fourth aspect of the present invention is the transfer device according to any one of the first to third aspects, wherein the first switching mechanism includes a first position where the other transfer member contacts the back surface of the endless member. The other transfer member is in contact with the first support member that is movable between the second position where the other transfer member is retracted from the back surface of the endless member; The first moving member that moves from the first position to the second position and the first contact portion formed on the first moving member, and the other transfer members are moved to the first through the first moving member. A first switching member that switches from the second position to the second position, wherein the second switching mechanism includes a third position where one of the transfer members contacts the back surface of the endless member, and the first transfer. The member moves between the fourth position where the member retracts from the back surface of the endless member. Formed on the second moving member, the second moving member that makes contact with the second supporting member to be enabled and moves the one transfer member from the third position to the fourth position. A second switching member that hits the second contact portion and switches the one transfer member from the third position to the fourth position via the second moving member, and the second moving member In this case, as the one transfer member is moved from the third position to the fourth position, the second switch member is hit, and the other transfer members are moved from the first position to the first position. A third contact portion for switching to a second position, the other transfer member is disposed at the second position, and when the one transfer member is moved to the third position, the second switch member is The third contact portion is separated from the third contact portion.

  An image forming apparatus according to a fifth aspect of the present invention is provided in the transfer device with the transfer device according to any one of the first to fourth aspects and an endless member provided in the transfer device interposed therebetween. It is provided on the opposite side of the transfer member, and includes a plurality of image holding members that hold an image on the surface, and an image forming unit that forms an image on the image holding member.

  According to the transfer device of the first aspect of the present invention, it is possible to shift from the multi-color transfer state and the single-color transfer state directly to the retracted state in which all the transfer members are retracted from the back surface of the endless belt.

  According to the transfer device of the second aspect of the present invention, the life of the endless member can be extended as compared with the case where tension is always applied from the tension applying member to the endless member.

  According to the transfer device of claim 3 of the present invention, it is possible to suppress damage to the back surface of the endless member as compared with the case where the arrangement position of the regulating member that regulates the circulation path of the endless member is fixed. it can.

  According to the transfer device of the fourth aspect of the present invention, compared to a case where the first moving member that moves the other transfer member is not provided with a contact surface that contacts the second switching member, a plurality of configurations can be achieved with a simple configuration. It is possible to shift from the color transfer state to the retreat state where all transfer members retreat from the back surface of the endless belt directly from the single color transfer state.

  According to the image forming apparatus of the fifth aspect of the present invention, the transfer device can be easily attached and detached from the apparatus body as compared with the case where the transfer device according to any one of the first to fourth aspects is not provided. Can be made.

It is the side view which showed the primary transfer unit which concerns on embodiment of this invention. It is the side view which showed the primary transfer unit which concerns on embodiment of this invention. It is the side view which showed the primary transfer unit which concerns on embodiment of this invention. It is the side view which showed the primary transfer unit which concerns on embodiment of this invention. It is the perspective view which showed the primary transfer unit which concerns on embodiment of this invention. It is the perspective view which showed the primary transfer unit which concerns on embodiment of this invention. It is the perspective view which showed the primary transfer unit which concerns on embodiment of this invention. It is the perspective view which showed the primary transfer unit which concerns on embodiment of this invention. FIG. 2 is an enlarged perspective view showing a primary transfer unit according to an embodiment of the present invention. FIG. 2 is an enlarged perspective view showing a primary transfer unit according to an embodiment of the present invention. 1 is a perspective view illustrating an image forming apparatus according to an embodiment of the present invention. 1 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention.

  An example of a transfer device and an image forming apparatus according to an embodiment of the present invention will be described with reference to FIGS. In addition, arrow UP shown in a figure shows the vertical direction upper direction.

(overall structure)
As illustrated in FIG. 12, an image processing unit 12 that performs image processing on input image data is provided inside the apparatus main body 10 </ b> A of the image forming apparatus 10.

  The image processing unit 12 processes the input image data into gradation data of four colors of yellow (Y), magenta (M), cyan (C), and black (K). An exposure device 14 that receives the gradation data and performs image exposure with the laser beam LB is provided in the center of the apparatus main body 10A.

  Above the exposure device 14, four image forming units 16Y, 16M, 16C, and 16K of yellow (Y), magenta (M), cyan (C), and black (K) are inclined with respect to the horizontal direction. It is arranged at intervals in the direction to be. When there is no need to distinguish between Y, M, C, and K, Y, M, C, and K may be omitted.

  These four image forming units 16Y, 16M, 16C, and 16K are all configured in the same manner. A cylindrical image carrier 18 that is rotationally driven at a predetermined speed, and an outer periphery of the image carrier 18. Developing the electrostatic latent image formed on the outer peripheral surface of the charging member 20 for charging the surface and the image holding member 18 charged by the image exposure of the exposure device 14 with toner of a predetermined color. The developing member 22 is visualized as a toner image, and the cleaning blade 24 is used to clean the outer peripheral surface of the image carrier 18. A cleaning member 64 that cleans the outer peripheral surface of the charging member 20 in contact with the charging member 20 is provided below the charging member 20.

  In addition, the exposure apparatus 14 is provided with four semiconductor lasers (not shown) that are configured in common to the four image forming units 16Y, 16M, 16C, and 16K. From these semiconductor lasers, laser light LB-Y, LB-M, LB-C, and LB-K are emitted according to the gradation data.

  The laser beams LB-Y, LB-M, LB-C, and LB-K emitted from the semiconductor laser are irradiated to a polygon mirror 26 that is a rotary polygon mirror through a cylindrical lens (not shown). Are deflected and scanned. The laser beams LB-Y, LB-M, LB-C, and LB-K deflected and scanned by the polygon mirror 26 pass through the imaging lens (not shown) and a plurality of mirrors on the image carrier 18. The exposure point is scanned and exposed from obliquely below.

  Further, since this exposure device 14 scans and exposes an image on the image carrier 18 from below, this exposure device 14 includes four image forming units 16Y, 16M, 16C, and 16K positioned above. There is a risk that toner or the like may fall from the developing member 22 or the like. Therefore, the periphery of the exposure device 14 is sealed by a rectangular parallelepiped frame 28. In the upper part of the frame 28, four laser beams LB-Y, LB-M, LB-C, and LB-K are directed onto the image carriers 18 of the image forming units 16Y, 16M, 16C, and 16K. And transparent glass windows 30Y, 30M, 30C, and 30K are provided.

  On the other hand, a primary transfer unit 21 as an example of a transfer device is provided above the image forming units 16Y, 16M, 16C, and 16K. The primary transfer unit 21 includes an intermediate transfer belt 32 as an example of an endless endless member, and a driving roll 36 that rotates around the intermediate transfer belt 32 and rotates the intermediate transfer belt 32 in an arrow direction. The tension applying roller 40 as an example of a tension applying member for applying tension to the intermediate transfer belt 32 around which the intermediate transfer belt 32 is wound, and a driven member that is provided above the tension applying roller 40 and rotates with the intermediate transfer belt 32. And a primary transfer roll 34Y, 34M, 34C, 34K as an example of a transfer member disposed on the opposite side of the image carrier 18Y, 18M, 18C, 18K across the intermediate transfer belt 32. Has been.

  Then, yellow (Y), magenta (M), cyan (sequentially formed on the image carrier 18 of the image forming units 16Y, 16M, 16C, and 16K by the four primary transfer rolls 34Y, 34M, 34C, and 34K. C) and black (K) toner images are transferred onto the intermediate transfer belt 32 in a multiple manner.

  Further, a cleaning blade 38 for cleaning the outer peripheral surface of the intermediate transfer belt 32 is provided on the opposite side of the drive roll 36 with the intermediate transfer belt 32 interposed therebetween. Details of the primary transfer unit 21 will be described later.

  A secondary transfer roll 42 is provided on the opposite side of the driven roll 66 across the intermediate transfer belt 32. The yellow (Y), magenta (M), cyan (C), and black (K) toner images transferred onto the intermediate transfer belt 32 in a multiple manner are conveyed by the intermediate transfer belt 32 and are transferred to the driven roll 66 and the second transfer roller 66. The sheet is sandwiched between the next transfer rolls 42 and secondarily transferred to a sheet member P as a recording medium conveyed along the sheet conveyance path 56.

  Further, the toner image transferred to the sheet member P is fixed to the sheet member P by heat and pressure on the downstream side in the conveyance direction of the sheet member P with respect to the secondary transfer roll 42 (hereinafter simply referred to as the downstream side). A fixing device 44 is provided.

  Further, on the downstream side of the fixing device 44, a discharge roll 46 that discharges the sheet member P on which the toner image is fixed to a discharge portion 48 provided on the upper portion of the apparatus main body 10 </ b> A of the image forming apparatus 10 is provided.

  On the other hand, a sheet feeding member 50 on which the sheet members P are stacked is provided on the lower side in the apparatus main body 10A of the image forming apparatus 10. Further, a sheet feeding roll 52 for feeding the sheet members P stacked on the sheet feeding member 50 to the sheet conveying path 56 is provided, and the sheet members P are separated and conveyed one by one on the downstream side of the sheet feeding roll 52. A separation roll 54 is provided. Further, an alignment roll 58 for adjusting the conveyance timing is provided on the downstream side of the separation roll 54. Thus, the sheet member P supplied from the sheet feeding member 50 is moved to a position (secondary transfer position) where the intermediate transfer belt 32 and the secondary transfer roll 42 are in contact with each other by the alignment roll 58 that rotates at a predetermined timing. It is configured to be sent out.

  Further, next to the discharge roll 46, the sheet member P on which the toner image is fixed on one side by the fixing device 44 is transported to the double-side transport path 62 without being directly discharged onto the discharge portion 48 by the discharge roll 46. A transport roll 60 is provided. As a result, the sheet member P conveyed along the double-sided conveyance path 62 is conveyed again to the alignment roll 58 with the front and back sides reversed, and this time, the toner image is transferred to the back surface of the sheet member P. It is fixed and discharged onto the discharge unit 48.

  With this configuration, an image is formed on the sheet member P as follows.

  First, gradation data of each color is sequentially output from the image processing unit 12 to the exposure device 14, and the laser beams LB-Y, LB-M, LB-C, and LB emitted according to the gradation data from the exposure device 14 are output. -K is scanned and exposed on the outer peripheral surface of the image carrier 18 charged by the charging member 20, and an electrostatic latent image is formed on the outer peripheral surface of the image carrier 18. The electrostatic latent images formed on the image holding member 18 are yellow (Y), magenta (M), cyan (C), and black (K) toners by developing members 22Y, 22M, 22C, and 22K, respectively. Visualized as an image.

  Further, yellow (Y) and magenta (M) formed on the image carrier 18 by the primary transfer roll 34 of the primary transfer unit 21 disposed above the image forming units 16Y, 16M, 16C, and 16K. , Cyan (C), and black (K) toner images are transferred in multiple onto the rotating intermediate transfer belt 32.

  Further, the toner images of the respective colors transferred in multiple onto the circulating intermediate transfer belt 32 are transferred from the paper supply member 50 to the paper supply roll 52, the separation roll 54, and the alignment roll 58 by the secondary transfer roll 42, and the paper conveyance path. Then, the toner image is secondarily transferred to the sheet member P conveyed at 56 at a predetermined timing.

  Further, the sheet member P to which the toner image has been transferred is conveyed to the fixing device 44. The toner image transferred to the sheet member P is fixed on the sheet member P by the fixing device 44 and fixed, and then discharged to the discharge portion 48 provided on the upper portion of the apparatus main body 10A of the image forming apparatus 10 by the discharge roll 46. Is done.

  Further, when images are formed on both sides of the sheet member P, the sheet member P, on which the toner image is fixed on one side by the fixing device 44, is not discharged onto the discharge unit 48 as it is by the discharge roll 46, and the conveying direction is changed. It is switched and conveyed to the double-sided conveyance path 62 via the conveyance roll 60. Then, by conveying the sheet member P along the duplex conveyance path 62, the front and back of the sheet member P are reversed, and the sheet member P is conveyed again to the alignment roll 58. This time, the toner image is transferred / fixed on the back surface of the sheet member P, transferred and fixed, and then discharged onto the discharge portion 48 by the discharge roll 46.

(Main part configuration)
Next, the primary transfer unit 21 and the like will be described.

  As shown in FIGS. 1 and 5, the primary transfer roll 34 for each color for transferring the toner image of each color formed on the image carrier 18 onto the intermediate transfer belt 32 is made of metal (for example, stainless steel). .

  When the respective colors are transferred to the intermediate transfer belt 32 in a multiplex manner (during color printing), the primary transfer rolls 34 provided in the primary transfer unit 21 press the intermediate transfer belt 32 against the image carrier 18. It is like that. Thereby, the toner image formed on the image holding member 18 of each color is transferred to the intermediate transfer belt 32.

  Specifically, in the primary transfer unit 21, a pair of frame members 70 constituting the skeleton of the primary transfer unit 21 are provided on both sides in the rotational axis direction (hereinafter simply referred to as the axial direction) of the primary transfer roll 34. .

  Further, both end portions of the primary transfer rolls 34Y, 34M, and 34C are support members 72Y, 72M, and 72C as an example of a first support member that is bent at the center side when viewed from the axial direction and has an inverted L shape in FIG. It is rotatably attached to the tip side. Further, the bent portions of the support members 72Y, 72M, and 72C are provided with rotation shafts 74Y, 74M, and 74C that are rotatably attached to the frame member 70 and face the axial direction.

  In addition, coil springs 76Y, 76M as an example of biasing members that bias the primary transfer rolls 34Y, 34M, 34C toward the back surface of the intermediate transfer belt 32 are provided on the other ends of the support members 72Y, 72M, 72C. 76C is attached. Specifically, one end of the coil springs 76Y, 76M, and 76C is fixed to the other end side of the support members 72Y, 72M, and 72C, and the other end of the coil springs 76Y, 76M, and 76C is fixed to the frame member 70. Yes.

  Further, the back surface of the intermediate transfer belt 32 is supported between the drive roll 36 and the primary transfer roll 34Y, and when transferring the color toner images to the intermediate transfer belt 32, the color toner images are transferred to the intermediate transfer belt 32. A restricting roll 82 is provided as an example of a restricting member that restricts the circulation path of the intermediate transfer belt 32 in the transfer portion 80 to be transferred to 32.

  Both ends of the regulation roll 82 are rotatably attached to the distal end side of a support member 84 that is bent in the center side when viewed in the axial direction and has an inverted L shape. Further, the bent portion of the support member 84 is provided with a rotation shaft 86 that is rotatably attached to the frame member 70 and faces the axial direction.

  A coil spring 88 as an example of a biasing member that biases the regulating roll 82 toward the back surface of the intermediate transfer belt 32 is provided on the other end side of the support member 84. Specifically, one end of the coil spring 88 is fixed to the other end side of the support member 84, and the other end of the coil spring 88 is fixed to the frame member 70. The urging force of the coil spring 88 is stronger than the urging force of the coil spring 76 described above. The primary transfer rolls 34Y, 34M, and 34C press the intermediate transfer belt 32 against the image carrier 18.

  Further, the frame member 70 is provided with a protruding portion (not shown) that determines the position of the support member 84 when it contacts the support member 84 to which the urging force of the coil spring 88 is transmitted. As described above, the support member 84 comes into contact with the protruding portion by the urging force of the coil spring 88, so that the arrangement position of the regulating roll 82 is determined.

  On the other hand, both ends of the rotation shaft 40A of the tension applying roll 40 for applying tension to the intermediate transfer belt 32 are rotatably supported on one end side of the holding member 90 which is bent at the center side when viewed from the axial direction. Has been. Further, the bending portion of the holding member 90 is provided with a rotation shaft 92 that is rotatably attached to the frame member 70 and faces in the axial direction. That is, the holding member 90 rotates around the rotation shaft 92, and the tension applying roll 40 can move in an arc shape around the rotation shaft 92.

  Further, a distal end portion of a coil spring 94 as an example of an urging member is fixed to the other end side (an end portion extending upward) of the holding member 90, and a base end portion of the coil spring 94 is a frame. It is fixed to the member 70. Then, the coil spring 94 moves the other end side of the holding member 90 so that the holding member 90 rotates around the rotation shaft 92 and the tension applying roll 40 presses the back surface (inner peripheral surface) of the intermediate transfer belt 32. It comes to be energized. As a result, a predetermined range of tension is applied to the intermediate transfer belt 32.

  Further, a primary transfer roll 34K is provided between the tension applying roll 40 and the primary transfer roll 34C. Both end portions of the primary transfer roll 34K are rotatably attached to the front end side of a support member 98 as an example of a second support member that is bent at the center side when viewed in the axial direction and has an L shape. Further, the bent portion of the support member 98 is provided with a rotation shaft 102 that is rotatably attached to the frame member 70 and that faces in the axial direction.

  A coil spring 104 as an example of a biasing member that biases the primary transfer roll 34 </ b> K toward the back surface of the intermediate transfer belt 32 is attached to the other end side of the support member 98. Specifically, one end of the coil spring 104 is fixed to the other end side of the support member 98, and the other end of the coil spring 104 is fixed to the frame member 70. The urging force of the coil spring 104 is stronger than the urging force of the coil spring 76 described above.

  Further, the frame member 70 is provided with a protrusion 106 that contacts the support member 98 to which the urging force of the coil spring 104 is transmitted and determines the position of the support member 98. As described above, since the support member 98 abuts on the protrusion 106 by the urging force of the coil spring 104, the arrangement position of the primary transfer roll 34K can be determined.

  Then, as described above, the circulation path of the intermediate transfer belt 32 that circulates between the regulation roll 82 and the primary transfer roll 34K whose arrangement position is determined is regulated so as to pass through the determined position. That is, the circulation path of the intermediate transfer belt 32 in the transfer unit 80 for each color is regulated by the regulation roll 82 and the primary transfer roll 34K.

  On the other hand, when the primary transfer roll 34 of each color comes into contact with the back surface of the intermediate transfer belt 32, a multi-color transfer mode (a plurality of modes) that enables the transfer of the toner image onto the surface of the intermediate transfer belt 32 by the primary transfer roll 34 of each color. In the color transfer state, the primary transfer rolls 34Y, 34M, and 34C are retracted from the back surface of the intermediate transfer belt 32, and the toner image can be transferred to the surface of the intermediate transfer belt 32 by the primary transfer roll 34K (single color). A first switching mechanism 110 that can switch to a transfer state is provided.

  As shown in FIGS. 1 and 2, the first switching mechanism 110 has a first position where the regulating roll 82 and the primary transfer rolls 34 </ b> Y, 34 </ b> M, and 34 </ b> C are in contact with the back surface of the intermediate transfer belt 32 (FIGS. 1 and 2). 5) and a second position (see FIGS. 2 and 6) in which the regulating roll 82 and the primary transfer rolls 34Y, 34M, and 34C are retracted from the intermediate transfer belt 32 (see FIG. 2 and FIG. 6). Is provided.

  Specifically, the first moving member 112 is provided on the inner side in the axial direction (the side on which the primary transfer roll 34 is disposed) with respect to the frame member 70, and the first transfer rolls 34 of the respective colors are arranged side by side when viewed from the axial direction. The plate extends in one direction (the direction of arrow D shown in FIG. 1). Further, the first moving member 112 is formed with a long hole 112A and a long hole 112B extending in the first direction when viewed from the axial direction, and the long hole 112A and the long hole 112B are arranged side by side in the first direction.

  Further, a columnar rod 114 passing through the long hole 112 </ b> A and a columnar rod 116 passing through the long hole 112 </ b> B are suspended between the pair of frame members 70. The rod 114 and the rod 116 are movable in the long hole 112A and the long hole 112B. Thus, the first moving member 112 can reciprocate along the first direction.

  Further, when the first moving member 112 moves from one end portion to the other end portion, the first moving member 112 hits the support member 84 and the support member 72, and the regulation roll 82 and the primary transfer rolls 34Y, 34M, A protrusion 122 and protrusions 120Y, 120M, and 120C that move 34C from a first position (see FIG. 1) to a second position (see FIG. 2) are provided.

  Further, the first moving member 112 is formed with a contact surface 124 as an example of a first contact portion facing the drive roll 36 in the first direction. The contact surface 124 is then contacted, and the regulating roll 82 and the primary transfer rolls 34Y, 34M, 34C are moved from the first position (see FIG. 1) to the second position (see FIG. 2) via the first moving member 112. A cam member 126 as an example of the first switching member to be moved is provided.

  Specifically, as shown in FIG. 1, the cam member 126 is attached to the rod 116, and when the short diameter of the cam member 126 faces the contact surface 124, the protrusion 122 and the protrusion 120 are interposed. The pressing force is not transmitted to the support member 84 and the support member 72, and the regulation roll 82 and the primary transfer rolls 34 </ b> Y, 34 </ b> M, 34 </ b> C are arranged at the first position by the urging force of the coil spring 88 and the coil spring 76. It has become.

  On the other hand, as shown in FIG. 2, when the rod 116 rotates and the long diameter of the cam member 126 abuts against the contact surface 124, the contact surface 124 is pressed by the cam member 126 and the first moving member 112 moves in the first direction. It moves to the tension applying roll 40 side. As the first moving member 112 moves in the first direction, a pressing force is transmitted to the support member 84 and the support member 72 via the protrusion 122 and the protrusion 120. The support member 84 and the support member 72 rotate about the rotation shaft 86 and the rotation shaft 74, and the regulation roll 82 and the primary transfer rolls 34Y, 34M, and 34C are arranged at the second position. Yes.

  The rod 116 is driven by a driving source (not shown) provided outside the primary transfer unit 21 according to an instruction from the control unit, so that the driving force is transmitted to rotate the rod 116. When the pressing force by the first moving member 112 is released, the regulating roll 82 and the primary transfer rolls 34Y, 34M, 34C are moved from the second position to the first position by the urging force of the coil spring 88 and the coil spring 76. It is supposed to move.

  On the other hand, it is possible to switch from the single-color transfer mode shown in FIG. 2 to a retract mode (retracted state) in which the primary transfer roll 34K is retracted from the back surface of the intermediate transfer belt 32 and all the primary transfer rolls 34 are retracted from the intermediate transfer belt 32. In addition, a second switching mechanism 130 is provided that enables switching from the multi-color transfer mode shown in FIG. 1 to a retreat mode in which all the primary transfer rolls 34 are retreated from the intermediate transfer belt 32.

  As shown in FIGS. 1 and 2, the second switching mechanism 130 includes a third position where the primary transfer roll 34 </ b> K contacts and supports the back surface of the intermediate transfer belt 32, and the primary transfer roll 34 </ b> K includes the intermediate transfer belt 34. A second moving member 132 is provided that can move between a fourth position (see FIGS. 3 and 4) that retracts from the position 32.

  Specifically, as shown in FIGS. 1 and 5, the second moving member 132 is provided on the inner side in the axial direction with respect to the first moving member 112 and extends in the first direction when viewed from the axial direction. It has been. Further, the second moving member 132 is formed with a long hole 132A and a long hole 132B extending in the first direction when viewed from the axial direction, and the long hole 132A and the long hole 132B are arranged side by side in the first direction.

  Further, the first moving member 112 described above is formed with an emboss 134 extending in the axial direction through the elongated hole 132A. Further, a columnar rod 136 that passes through the long hole 132 </ b> B is spanned between the pair of frame members 70. The emboss 134 and the rod 136 are movable in the long hole 132A and the long hole 132B. Accordingly, the second moving member 132 can reciprocate along the first direction.

  As shown in FIGS. 1 and 3, when the second moving member 132 moves from one end to the other end, the second moving member 132 hits the support member 98 and hits the primary transfer roll 34 </ b> K. Is provided with a protrusion 146 that moves the first position from the third position (see FIG. 1) to the fourth position (see FIG. 3).

  Similarly, when the second moving member 132 moves from one end portion toward the other end portion, the second moving member 132 contacts the holding member 90 and rotates the holding member 90, and the tension applying roll 40 performs intermediate transfer. A protrusion 138 that releases the tension applied to the belt 32 is provided.

  Further, the second moving member 132 is formed with a contact surface 140 as an example of a second contact portion facing the tension applying roll 40 side in the first direction. An example of the second switching member that contacts the contact surface 140 and moves the primary transfer roll 34K from the third position (see FIG. 1) to the fourth position (see FIG. 3) via the second moving member 132. A cam member 142 is provided.

  Specifically, as shown in FIGS. 1 and 9, the cam member 142 is disposed between the first moving member 112 and the second moving member 132 in the axial direction. The cam member 142 is attached to the rod 136. When the short diameter of the cam member 142 faces the contact surface 140, the support member 98 and the holding member 90 are pressed against each other via the protrusion 146 and the protrusion 138. Is not transmitted. The primary transfer roll 34K is arranged at the third position by the biasing force of the coil spring 104, and the tension applying roll 40 applies tension to the intermediate transfer belt 32 by the biasing force of the coil spring 94. .

  On the other hand, as shown in FIGS. 3 and 10, when the rod 136 rotates and the long diameter of the cam member 142 hits the contact surface 140, the contact surface 140 is pressed by the cam member 126, and the second moving member 132 is It moves to the drive roll 36 side in one direction. As the second moving member 132 moves in the first direction, a pressing force is transmitted to the support member 98 and the holding member 90 via the protrusion 146 and the protrusion 138. The support member 98 rotates about the rotation shaft 102, the primary transfer roll 34K is disposed at the fourth position, and the holding member 90 rotates about the rotation shaft 92 and is applied to the intermediate transfer belt 32. Tension is released.

  Further, as shown in FIG. 1, the first moving member 112 has a contact surface 144 as an example of a third contact portion provided on the opposite side of the contact surface 140 with the cam member 142 interposed therebetween, on the drive roll 36 side. It is provided facing. As shown in FIGS. 1 and 4, with this configuration, when the primary transfer rolls 34 </ b> Y, 34 </ b> M, and 34 </ b> C are arranged at the first position, the rod 136 rotates and the major diameter of the cam member 142 becomes the contact surface 144. Then, the regulating roll 82 and the primary transfer rolls 34Y, 34M, 34C are moved from the first position (see FIG. 1) to the second position (see FIG. 4).

  Further, as shown in FIG. 5, one end portion of the rod 136 is provided with a handle 158 (see FIG. 11) described later or a meshing portion 148, and the rotation transmitted from the handle 158. Force is transmitted to the rod 136 via the meshing portion 148.

  As shown in FIG. 2, when the primary transfer rolls 34Y, 34M, and 34C are in the second position and the primary transfer roll 34K is in the third position, the cam member 142 and the contact surface 144 are The first moving member 112 does not move even when the cam member 142 is rotated because the cam member 142 is rotated.

  Also, as shown in FIGS. 11 and 12, a lid 150 is provided at the top in the vertical direction of the apparatus main body 10A so that the inside can be opened and the discharge part 48 is formed on the surface. Specifically, a rotation shaft 152 extending in the depth direction of the apparatus main body 10 </ b> A (the depth direction in FIG. 12) is provided at one end of the lid portion 150, and the lid portion 150 is rotated around the rotation shaft 152. Thus, the inside of the apparatus main body 10A is opened upward.

  Furthermore, a lid member 154 that opens the front surface of the apparatus main body 10A is provided on the front surface (the front surface in FIG. 12) of the apparatus main body 10A. Specifically, a rotation shaft 156 extending in the width direction of the apparatus main body 10A (left and right direction in FIG. 12) is provided at the lower end portion of the lid portion 154, and the lid portion 154 is rotated around the rotation shaft 156. Thus, the inside of the apparatus main body 10A is opened forward.

  Further, a rotational force can be applied via a meshing portion 148 (see FIG. 5) provided at one end of the rod 136, and a handle 158 that is detachable from the meshing portion 148 is provided. . The handle 158 is exposed to the outside by rotating the lid 154 to open the inside of the apparatus main body 10A forward.

(Effects of main components)
Next, the operation of the primary transfer unit 21 will be described.

  As shown in FIGS. 1 and 5, in the multi-color transfer mode in which an image is output in a plurality of colors (colors), the primary transfer roll 34 of each color is in contact with the back surface of the intermediate transfer belt 32.

  That is, the regulation roll 82 and the primary transfer rolls 34Y, 34M, and 34C are arranged at the first position, and the primary transfer roll 34K is arranged at the third position. A tension is applied to the intermediate transfer belt 32 by the tension applying roll 40.

  Further, the contact surface 124 of the first moving member 112 hits the short diameter of the cam member 126, and the contact surface 144 of the first moving member 112 and the contact surface 140 of the second moving member 132 hit the short diameter of the cam member 142. Yes.

  From this state, for example, when a user operates an operation panel (not shown) in order to shift to a monochrome transfer mode in which an image is output in a single color (black and white), the driving force from the drive source is controlled by an instruction from a control unit (not shown). 116. The cam member 126 rotates 180 degrees by the rotation of the rod 116 to which the driving force is transmitted.

  As shown in FIGS. 2 and 6, when the cam member 126 rotates 180 degrees, the outer peripheral surface of the cam member 126 presses the contact surface 124, and the long diameter of the cam member 126 hits the contact surface 124. 112 moves to the tension applying roll 40 side in the first direction.

  When the first moving member 112 moves in the first direction, the pressing force is transmitted to the support member 84 and the support member 72 of each color via the protrusion 122 and the protrusion 120 formed on the first movement member 112. The The support member 84 and the support member 72 of each color rotate around the rotation shaft 86 and the rotation shaft 74, and the regulation roll 82 and the primary transfer rolls 34 </ b> Y, 34 </ b> M, 34 </ b> C are retracted from the intermediate transfer belt 32. It is arranged at the position.

  In this state, a black and white image is formed on the sheet member P by outputting the image.

  Further, in order to take out the primary transfer unit 21 from the apparatus main body 10A from this state (single color transfer mode), as shown in FIG. 11, the user first opens the lid member 154 and rotates the handle 158. .

  As shown in FIGS. 3 and 7, the cam member 142 rotates 90 degrees by rotating the handle 158. When the cam member 142 rotates 90 degrees, the contact surface 140 is pressed by the outer peripheral surface of the cam member 142, the long diameter of the cam member 142 hits the contact surface 140, and the second moving member 132 moves toward the drive roll 36 in the first direction. Moving.

  When the second moving member 132 moves in the first direction, a pressing force is transmitted to the support member 98 and the holding member 90 via the protrusions 146 and the protrusions 138 formed on the second moving member 132. The support member 98 rotates about the rotation shaft 102, the primary transfer roll 34K is disposed at the fourth position, and the holding member 90 rotates about the rotation shaft 92 and is applied to the intermediate transfer belt 32. Tension is released.

  As described above, the multi-color transfer mode is shifted to the single-color transfer mode, and further, the single-color transfer mode is shifted to the retreat mode in which all the primary transfer rolls 34 are retracted from the intermediate transfer belt 32.

  On the other hand, as shown in FIG. 11, when the user directly shifts from the multi-color transfer mode to the retreat mode, first, the user opens the lid member 154 and rotates the handle 158.

  As shown in FIGS. 4 and 8, the cam member 142 rotates 90 degrees by rotating the handle 158. When the cam member 142 rotates 90 degrees, the contact surface 140 is pressed by the outer peripheral surface of the cam member 142, the long diameter of the cam member 142 hits the contact surface 140, and the second moving member 132 moves toward the drive roll 36 in the first direction. Moving.

  When the second moving member 132 moves in the first direction, a pressing force is transmitted to the support member 98 and the holding member 90 via the protrusions 146 and the protrusions 138 formed on the second moving member 132. The support member 98 rotates about the rotation shaft 102, the primary transfer roll 34K is disposed at the fourth position, and the holding member 90 rotates about the rotation shaft 92 and is applied to the intermediate transfer belt 32. Tension is released.

  When the cam member 142 rotates 90 degrees, the contact surface 144 is pressed by the outer peripheral surface of the cam member 142, the long diameter of the cam member 142 hits the contact surface 144, and the first moving member 112 is a tension applying roll in the first direction. Move to 40 side.

  When the first moving member 112 moves in the first direction, the pressing force is transmitted to the support member 84 and the support member 72 of each color via the protrusion 122 and the protrusion 120 formed on the first movement member 112. The The support member 84 and the support member 72 of each color rotate around the rotation shaft 86 and the rotation shaft 74, and the regulation roll 82 and the primary transfer rolls 34 </ b> Y, 34 </ b> M, 34 </ b> C are retracted from the intermediate transfer belt 32. It is arranged at the position.

  In this way, the multi-color transfer mode directly shifts to the save mode.

  Further, as shown in FIG. 11, the lid member 150 is opened in the state of shifting to the retreat mode, and the primary transfer unit 21 is taken out from the inside of the apparatus main body 10A.

  When the primary transfer unit 21 is attached to the apparatus main body 10A, the primary transfer unit 21 is attached to the apparatus main body 10A by performing a process reverse to the process described above.

  As described above, by providing the first switching mechanism 110 and the second switching mechanism 130, the primary transfer roll 34 is shifted from the multi-color transfer mode and the single-color transfer mode to the direct retraction mode.

  Further, when the primary transfer roll 34 is shifted to the retract mode, the tension applied to the intermediate transfer belt 32 by the tension applying roll 40 is released, so that curling of the intermediate transfer belt is suppressed and the intermediate transfer belt 32 is suppressed. The lifespan of is extended.

  In addition, the regulation roll 82 is linked with the switching of the first switching mechanism 110 from the multiple color transfer mode to the single color transfer mode, or in conjunction with the switching of the second switching mechanism 130 from the multiple color transfer mode to the withdrawal mode. Since the intermediate transfer belt 32 is retracted from the back surface, damage to the back surface of the intermediate transfer belt 32 is suppressed.

  Although the present invention has been described in detail with respect to specific embodiments, the present invention is not limited to such embodiments, and various other embodiments are possible within the scope of the present invention. It is clear to the contractor. For example, in the above-described embodiment, in the single-color transfer mode, the black primary transfer roll 34K is brought into contact with the intermediate transfer belt 32. However, the present invention is not limited to this, and other colors such as magenta are used. Also good. In the embodiment of the present invention, the electrophotographic image forming apparatus has been described. However, the image forming system is not limited to this, and other image forming apparatuses such as an ink jet system may be used.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 16 Image forming unit (an example of an image forming part)
18 Image carrier 21 Primary transfer unit (an example of a transfer device)
32 Intermediate transfer belt (an example of an endless member)
34Y primary transfer roll (an example of another transfer member)
34M primary transfer roll (an example of another transfer member)
34C primary transfer roll (an example of another transfer member)
34K primary transfer roll (an example of one transfer member)
40 Tension imparting roll (an example of a tension imparting member)
72 support member (an example of a first support member)
80 Transfer part 82 Restriction roll (an example of a restriction member)
98 support member (an example of a second support member)
110 First switching mechanism 112 First moving member 124 Contact surface (an example of a first contact portion)
126 cam member (an example of a first switching member)
130 2nd switching mechanism 132 2nd moving member 140 Contact surface (an example of a 2nd contact part)
142 cam member (example of second switching member)
144 Contact surface (example of third contact part)

Claims (5)

An endless endless member that circulates by driving means;
A plurality of image holders for holding images of different colors, provided on opposite sides of the endless member with respect to the plurality of image carriers, and transferring the image formed on the image holder to the surface of the endless member A transfer member of
A plurality of transfer members come into contact with the back surface of the endless member, and a plurality of transfer members can transfer an image from the image holding body to the surface of the endless member. The other transfer member is retracted from the back surface of the endless member so that the transfer member contacts the back surface of the endless member, and the image from the image carrier to the surface of the endless member by the one transfer member A first switching mechanism that enables switching to a single-color transfer state that enables transfer of
It is possible to switch from the single color transfer state to the retracted state in which one transfer member is retracted from the back surface of the endless member and all the transfer members are retracted from the back surface of the endless member. A second switching mechanism that retracts the transfer member from the back surface of the endless member and enables switching to the retracted state;
A transfer apparatus comprising: A tension applying member for applying tension to the endless member is provided,
The transfer according to claim 1, wherein the second switching mechanism interlocks with the switching of the transfer member to the retracted state, and the second switching mechanism releases the tension of the endless member applied by the tension applying member. apparatus. A regulating member is provided that supports a back surface of the endless member and regulates a circulation path of the endless member in a transfer portion where an image is transferred by the transfer member in the multi-color transfer state.
In conjunction with the first switching mechanism switching from the multiple color transfer state to the single color transfer state, or in conjunction with the second switching mechanism switching from the multiple color transfer state to the retracted state, the first switching mechanism. The transfer device according to claim 1, wherein the one switching mechanism or the second switching mechanism retracts the regulating member from the back surface of the endless member. The first switching mechanism is
A first support member that is movable between a first position where the other transfer member contacts the back surface of the endless member and a second position where the other transfer member retracts from the back surface of the endless member. When,
A first moving member that hits the first support member and moves the other transfer member from the first position to the second position;
A first switching member that contacts the first contact portion formed on the first moving member and switches the other transfer member from the first position to the second position via the first moving member; Prepared,
The second switching mechanism is
A second support member that is movable between a third position where one of the transfer members contacts the back surface of the endless member and a fourth position where the one transfer member retracts from the back surface of the endless member. When,
A second moving member that hits the second support member and moves one of the transfer members from the third position to the fourth position;
A second switching member that hits the second contact portion formed on the second moving member and switches one transfer member from the third position to the fourth position via the second moving member; Prepared,
The second moving member comes into contact with the second switching member as the one transfer member is moved from the third position to the fourth position, and the other transfer member is moved to the first position. A third contact portion for switching from the second position to the second position is provided,
The other transfer member is disposed at the second position, and when the one transfer member is moved to the third position, the second switching member is separated from the third contact portion. The transfer device according to any one of the above. A transfer device according to any one of claims 1 to 4;
A plurality of image carriers that are provided on the opposite side of the transfer member provided in the transfer device across an endless member provided in the transfer device, and that hold an image on the surface;
An image forming unit that forms an image on the image carrier;
An image forming apparatus comprising:

Images