JP2012203387A - Guide mechanism for recording medium, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a guide mechanism for a recording medium able to bring the conveyance position of a recording medium with respect to the position of an intermediate transfer belt into a predetermined range, and an image forming apparatus.SOLUTION: A tension application roll 40 moves in circular arc when shifted between a multi-color transfer mode and a monochrome transfer mode. As a result, the position of an intermediate transfer belt 32 changes and a support member 162 moves. A second guide part 182 and a third guide part 184 are moved by the movement of the support member 162. That is, the second guide part 182 and the third guide part 184 are moved by linking the change in the position of the intermediate transfer belt 32 in the contact part of the intermediate transfer belt 32 and the leading end of a sheet member P. This makes it possible to bring the conveyance position of a recording medium with respect to the position of the intermediate transfer belt into the predetermined range.

Description

  The present invention relates to a recording medium guide mechanism and an image forming apparatus.

  Patent Document 1 describes a movable guide that guides a recording sheet to a position just before a transfer area in an intermediate transfer belt.

JP 2006-11044 A

  An object of the present invention is to set the conveying posture of the recording medium with respect to the posture of the intermediate transfer belt within a predetermined range.

  The recording medium guiding mechanism according to claim 1 of the present invention is a recording medium in which an image formed on the endless member is transferred toward an endless endless member on which an image is formed on the surface while being rotated by a driving unit. The guide member is moved in conjunction with a change in the attitude of the endless member at a guide member that guides the medium, and a contact portion where the leading end portion of the recording medium and the endless member contact each other, and is guided by the guide member. And a moving means for changing the conveying posture of the recording medium.

  A recording medium guiding mechanism according to a second aspect of the present invention is the recording medium guiding mechanism according to the first aspect, wherein the moving means presses the back surface of the endless member and changes the posture of the endless member at the contact portion. The guide member is moved in conjunction with movement of a tension applying member that applies tension to the endless member.

  According to a third aspect of the present invention, there is provided the recording medium guiding mechanism according to the first or second aspect, wherein the moving means includes the endless member in the transfer unit that transfers the image formed on the endless member to the recording medium. The guide member is moved so that an angle formed with the recording medium falls within a predetermined range.

  A recording medium guide mechanism according to a fourth aspect of the present invention is the recording medium guiding mechanism according to the third aspect, wherein the guide member is sent out from a conveying member provided upstream of the guiding member in the conveying direction of the recording medium. The front end of the recording medium hits, the front end of the recording medium hits the contact portion of the endless member on the upstream side in the circumferential direction of the endless member with respect to the transfer portion, and is fixed to the apparatus main body. The recording medium in which the leading end abuts against the endless member by the first guide so that the angle formed by the endless member and the recording medium in the guide portion and the transfer portion is within a predetermined range. The second guide portion that is moved by the moving means and the angle formed by the endless member and the recording medium in the transfer portion is within a predetermined range. Out With hits the rear end of the recording medium, characterized in that it and a third guide portion moved by the moving means.

  According to a fifth aspect of the present invention, there is provided an image forming apparatus comprising: an endless endless member that is circulated by a driving unit; and a plurality of image holding members that are in contact with the back surface of the endless member and that hold images of different colors, respectively. A plurality of transfer members that are provided on the opposite side of the endless member and transfer the image formed on the image holding member to the surface of the endless member, and the endless member toward the endless member that circulates. The recording medium guide mechanism according to any one of claims 1 to 4 for guiding a recording medium onto which an image formed on the recording medium is transferred, and the recording medium guided by the recording medium guide mechanism, Transfer means for transferring an image formed on the endless member.

  According to the recording medium guiding mechanism of the first aspect of the present invention, it is possible to make the conveying posture of the recording medium within a predetermined range with respect to the posture of the endless member.

  According to the recording medium guide mechanism of the second aspect of the present invention, the guide member can be moved.

  According to the recording medium guiding mechanism of the third aspect of the present invention, the angle between the endless member and the recording medium at the transfer portion is larger than the predetermined range between the recording medium and the endless member. The generated discharge can be suppressed.

  According to the recording medium guiding mechanism of the present invention, the conveying posture of the recording medium with respect to the posture of the endless member can be determined with a simple configuration as compared with the case where the guiding member is not divided into a plurality of pieces. Range.

  According to the image forming apparatus of the fifth aspect of the present invention, the quality of the output image is improved as compared with the case where the recording medium guiding mechanism according to any one of the first to fourth aspects is not provided. Can do.

It is the side view which showed the guide mechanism of the recording medium which concerns on embodiment of this invention. (A) (B) It is the side view which showed the guide mechanism of the recording medium based on embodiment of this invention. (A) (B) It is the side view which showed the guide mechanism of the recording medium based on embodiment of this invention. (A) (B) It is the side view which showed the guide mechanism of the recording medium based on embodiment of this invention. (A) (B) It is the side view which showed the guide mechanism of the recording medium based on embodiment of this invention. 1 is a side view showing a primary transfer unit used in an image forming apparatus according to an embodiment of the present invention. 1 is a side view showing a primary transfer unit used in an image forming apparatus according to an embodiment of the present invention. 1 is a side view showing a primary transfer unit used in an image forming apparatus according to an embodiment of the present invention. 1 is a side view showing a primary transfer unit used in an image forming apparatus according to an embodiment of the present invention. 1 is a perspective view showing a primary transfer unit used in an image forming apparatus according to an embodiment of the present invention. 1 is a perspective view showing a primary transfer unit used in an image forming apparatus according to an embodiment of the present invention. 1 is a perspective view showing a primary transfer unit used in an image forming apparatus according to an embodiment of the present invention. 1 is a perspective view showing a primary transfer unit used in an image forming apparatus according to an embodiment of the present invention. FIG. 3 is an enlarged perspective view showing a primary transfer unit used in the image forming apparatus according to the embodiment of the present invention. FIG. 3 is an enlarged perspective view showing a primary transfer unit used in the image forming apparatus according to the 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 recording medium guide mechanism 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 shown in FIG. 17, 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. A support member 162 to which a detection member 160 (see FIG. 1) for detecting a toner image transferred to the intermediate transfer belt 32 is attached is provided at a position facing the tension applying roll 40 with the intermediate transfer belt 32 interposed therebetween. It has been. Details of the primary transfer unit 21 and the detection member 160 will be described later.

  A secondary transfer roll 42 as an example of a transfer unit is provided on the opposite side of the driven roll 66 with the intermediate transfer belt 32 interposed therebetween. 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. In addition, an alignment roll 58 as an example of a transport member that matches the transport timing is provided on the downstream side of the separation roll 54.

  Further, on the downstream side of the alignment roll 58, a recording medium guide mechanism 164 (hereinafter simply referred to as a guide) that guides the sheet member P onto which the toner image is transferred toward the intermediate transfer belt 32 on which the toner image is formed. A mechanism 164).

  As a result, the sheet member P supplied from the sheet feeding member 50 and fed out by the alignment roll 58 is guided by the guide mechanism 164 to a position where the intermediate transfer belt 32 and the secondary transfer roll 42 are in contact (secondary transfer position). H). Details of the guide mechanism 164 will be described later.

  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.

(Configuration of primary transfer unit and guide mechanism)
Next, the primary transfer unit 21 and the guide mechanism 164 will be described.

  As shown in FIGS. 6 and 10, the primary transfer rolls 34 for the respective colors for transferring the toner images of the respective colors formed on the image carrier 18 onto the intermediate transfer belt 32 are formed 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 rotatably attached to the front end sides of the support members 72Y, 72M, and 72C that are bent in the center side in the axial direction in FIG. It has been. 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 which is bent at the center side when viewed from the axial direction and is L-shaped. 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, since the primary transfer roll 34 of each color is in contact with the back surface of the intermediate transfer belt 32, the toner image can be transferred to the surface of the intermediate transfer belt 32 by the primary transfer roll 34 of each color. First switching that enables the primary transfer rolls 34Y, 34M, and 34C to be retracted from the back surface of the intermediate transfer belt 32 and to be switched to a single-color transfer mode that enables the transfer of the toner image onto the surface of the intermediate transfer belt 32 by the primary transfer roll 34K. A mechanism 110 is provided.

  As shown in FIGS. 6 and 7, 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, 34 </ b> C come into contact with the back surface of the intermediate transfer belt 32 (FIGS. 10) and a first moving member 112 that enables movement between the regulating roll 82 and the primary transfer rolls 34Y, 34M, and 34C from the second position (see FIGS. 7 and 11) where they are retracted from the intermediate transfer belt 32. 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. 6). 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 the first position (see FIG. 6) to the second position (see FIG. 7) 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, and 34C are moved from the first position (see FIG. 6) to the second position (see FIG. 7) 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. 6, 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. 7, 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.

  In contrast, the primary transfer roll 34K can be retracted from the back surface of the intermediate transfer belt 32 from the single-color transfer mode shown in FIG. 7 and can be switched to a retract mode in which all the primary transfer rolls 34 are retracted from the intermediate transfer belt 32. A second switching mechanism 130 is provided that enables switching from the multi-color transfer mode shown in FIG. 6 to a retract mode in which all the primary transfer rolls 34 are retracted from the intermediate transfer belt 32.

  As shown in FIGS. 6 and 7, 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. 8 and 9) retracted from the position 32.

  Specifically, as shown in FIGS. 6 and 10, 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.

  Further, as shown in FIGS. 6 and 8, 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 34K. Is provided with a protrusion 146 that moves the first position from the third position (see FIG. 6) to the fourth position (see FIGS. 8 and 12).

  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. 6) to the fourth position (see FIG. 8) via the second moving member 132. A cam member 142 is provided.

  Specifically, as shown in FIGS. 6 and 14, 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. 8 and 15, when the rod 136 rotates and the long diameter of the cam member 142 contacts 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. 6, 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. 6 and 9, 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 regulation roll 82 and the primary transfer rolls 34Y, 34M, and 34C are moved from the first position (see FIG. 6) to the second position (see FIGS. 9 and 13).

  Further, as shown in FIG. 10, one end of the rod 136 is provided with a handle 158 (see FIG. 16) which will be 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. 7, 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.

  On the other hand, as shown in FIG. 1, a detection member 160 that detects a toner image transferred to the intermediate transfer belt 32 is provided at a position facing the tension applying roll 40 with the intermediate transfer belt 32 interposed therebetween. The member 160 is attached to the support member 162.

  Specifically, the support member 162 includes a pair of support portions 166 disposed on both sides in the axial direction of the tension applying roll 40 and a pair of support portions 166 having a groove portion 166A into which the rotation shaft 40A of the tension applying roll 40 is fitted. The base portion of the support portion 166 is fixed, and a rectangular parallelepiped housing portion 168 to which the detection member 160 is attached is provided.

  Furthermore, the base end surface of the housing portion 168 (the surface opposite to the side on which the support portion 166 is fixed) is placed on a flat support plate 170. In addition, the support plate 170 is provided with a rail member (not shown) that allows the casing 168 mounted on the support plate 170 to move along an orthogonal direction (arrow J direction shown in FIG. 1) orthogonal to the axial direction. It has been.

  Further, the support plate 170 is supported so as to be movable in a direction (arrow K direction shown in FIG. 1) for urging the groove portion 166A to the rotating shaft 40A, and the groove portion 166A is provided below the support plate 170 in the vertical direction. A coil spring 172 is provided as an example of a biasing member that biases the rotary shaft 40A.

  With these configurations, even when the support member 162 moves, the angle (M degrees shown in FIG. 1) formed between the support member 162 and the vertical direction is always constant. That is, even when the arrangement position of the support member 162 moves following the movement of the tension applying roll 40, the posture of the support member 162 does not change.

  Further, adjacent to the detection member 160 (right adjacent in FIG. 1) and downstream of the alignment roll 58, the above-described guide mechanism 164 is formed, and the sheet member P toward the intermediate transfer belt 32 is formed. A guide member 174 for guiding the above is provided.

  And this guide member 174 contacts the front-end | tip part of the sheet | seat member P sent out from the alignment roll 58, and the 1st guide part 180 fixed to the apparatus main body 10A and the conveyance surface of the sheet | seat member P conveyed are used. A third guide portion 182 that moves in conjunction with the movement of the tension applying roll 40 and a rear end portion of the conveyed sheet member P and a third portion that moves in conjunction with the movement of the tension applying roll 40 as well. And a guide unit 184. Here, the conveyance surface of the sheet member P is a surface opposite to the surface facing the intermediate transfer belt 32.

  Specifically, as shown in FIGS. 2A and 4A, the first guide portion 180 is formed by bending a plate member and is disposed on the downstream side of the alignment roll 58. The first guide unit 180 is located between the leading end of the conveyed sheet member P and the leading end of the contact sheet member P from the position where the intermediate transfer belt 32 and the secondary transfer roll 42 are in contact (secondary transfer position H). The transfer belt 32 contacts the intermediate transfer belt 32 on the upstream side in the circumferential direction. That is, the contact portion T where the leading end portion of the sheet member P and the intermediate transfer belt 32 come into contact is upstream of the secondary transfer position H in the circumferential direction of the intermediate transfer belt 32.

  2B and 4B, the second guide portion 182 is formed by bending a plate member and is disposed on the downstream side with respect to the first guide portion 180. A space between the intermediate transfer belt 32 and the second guide portion 182 is a sheet conveyance path 56 (see FIG. 17) of the conveyed sheet member P. The second guide portion 182 is fixed to the support member 162 with a bracket (not shown), and moves with the movement of the support member 162.

  That is, in order to apply the determined tension to the intermediate transfer belt 32, the single-color transfer mode (see FIGS. 4 and 5) is compared with the multi-color transfer mode (see FIGS. 2 and 3). Thus, the tension applying roll 40 is rotationally moved about the rotation shaft 92 (see FIG. 6) and is disposed on the lower side in the vertical direction. As a result, the support member 162 also moves. However, since the support member 162 moves while maintaining the posture, when the support member 162 moves to the lower left side of the page, the second guide portion 182 also moves to the lower left side of the page. It has become.

  Further, the second guide portion 182 comes into contact with the conveyance surface of the sheet member P to be conveyed, and falls within a predetermined range in the angle formed by the intermediate transfer belt 32 and the sheet member P at the secondary transfer position H. ing.

  Here, as shown in FIG. 1, the formed angle E is a line connecting the secondary transfer position H and a point on the intermediate transfer belt 32 side in the second guide portion 182, and the surface of the intermediate transfer belt 32. Is the angle formed by The determined range is 10 degrees as an example.

  Further, as shown in FIGS. 3A and 5A, the conveyance speed of the sheet member P in the alignment roll 58 is higher than the conveyance speed of the sheet member P in the secondary transfer position H. For this reason, after the sheet member P is sandwiched between the intermediate transfer belt 32 and the secondary transfer roll 42 at the secondary transfer position H, the conveyance surface of the sheet member P is separated from the second guide portion 182, and the sheet member P Is designed to draw a loop.

  Further, as shown in FIGS. 3B and 5B, the third guide portion 184 has a flat plate shape and is disposed so as to face the first guide portion 180. A space between the first guide unit 180 and the third guide unit 184 is a sheet transport path 56 (see FIG. 17) of the sheet member P to be transported. Further, the third guide portion 184 is fixed to the support member 162 by a bracket 188, and moves with the movement of the support member 162.

  That is, in order to apply the determined tension to the intermediate transfer belt 32, the single-color transfer mode (see FIGS. 4 and 5) is compared with the multi-color transfer mode (see FIGS. 2 and 3). Thus, the tension applying roll 40 is rotationally moved about the rotation shaft 92 (see FIG. 6) and is disposed on the lower side in the vertical direction. As a result, the support member 162 also moves. However, since the support member 162 moves while maintaining the posture, when the support member 162 moves to the lower left side of the page, the third guide portion 184 also moves to the lower left side of the page. It has become.

  Further, the third guide portion 184 comes into contact with the rear end of the conveyed sheet member P after the rear end of the sheet member P depicting the loop is released from the nipping by the alignment roll 58. Since the angle formed between the intermediate transfer belt 32 and the sheet member P at the secondary transfer position H is smaller than the angle E (see FIG. 1) described above, it falls within a predetermined range.

  As described above, the moving means 178 for moving the second guide portion 182 and the third guide portion 184 in accordance with the movement of the tension applying roll 40 (change in the posture of the intermediate transfer belt 32) is shown as the support member 162 and the bracket 188. And includes a bracket.

(Effects of main components)
Next, the operation of the guide mechanism 164 and the like will be described.

  As shown in FIGS. 6 and 10, 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.

  As shown in FIG. 2A, when an image is to be output in this state, the conveyed sheet member P is conveyed to the downstream side after the conveyance timing is adjusted by the alignment roll 58.

  The leading edge of the sheet member P fed from the alignment roll 58 is guided by the first guide portion 180 and contacts the intermediate transfer belt 32 on the upstream side in the circumferential direction of the intermediate transfer belt 32 from the secondary transfer position H.

  As shown in FIG. 2B, the leading edge of the sheet member P moves toward the secondary transfer position H by the intermediate transfer belt 32 that circulates. As the leading end of the sheet member P moves toward the secondary transfer position H, the conveyance surface of the sheet member P hits the second guide portion 182.

  The leading end portion of the sheet member P is sandwiched between the intermediate transfer belt 32 and the secondary transfer roll 42 at the secondary transfer position H while the conveyance surface of the sheet member P is in contact with the second guide portion 182. That is, since the leading end portion of the sheet member P is sandwiched between the intermediate transfer belt 32 and the secondary transfer roll 42 while the conveyance surface of the sheet member P is in contact with the second guide portion 182, the secondary transfer position H The angle θ1 formed by the intermediate transfer belt 32 and the sheet member P falls within a predetermined range.

  As shown in FIG. 3A, after the leading end of the sheet member P is sandwiched between the intermediate transfer belt 32 and the secondary transfer roll 42, the position is determined by the conveyance speed of the sheet member P at the secondary transfer position H. Since the conveying speed of the sheet member P by the alignment roll 58 is increased, the conveying surface of the sheet member P is separated from the second guide portion 182 and the first guide portion 180. Then, the sheet member P draws a loop. Since the sheet member P draws a loop when the conveying surface of the sheet member P is separated from the second guide portion 182 and swells toward the intermediate transfer belt 32, the intermediate transfer belt 32 and the sheet member P at the secondary transfer position H are drawn. The angle θ2 formed by and falls within a predetermined range.

  As shown in FIG. 3B, when the rear end of the sheet member P depicting a loop is released from the nipping by the alignment roll 58, the released rear end of the sheet member P is connected to the third guide portion 184. Hit it. Therefore, the angle θ3 formed by the intermediate transfer belt 32 and the sheet member P at the secondary transfer position H falls within a predetermined range.

  On the other hand, as shown in FIGS. 6 and 10, for example, when a user operates an operation panel (not shown) to shift to a single color transfer mode in which an image is output in a single color (monochrome), a control unit (not shown) The driving force is transmitted from the driving source to the rod 116 by the instruction. 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. 7 and 11, 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.

  When the regulating roll 82 and the primary transfer rolls 34Y, 34M, and 34C are retracted from the intermediate transfer belt 32, the tension applied to the intermediate transfer belt 32 is weakened. However, the tension applying roll 40 is rotated in an arc shape around the rotation shaft 92 by the urging force of the coil spring 94 and presses the back surface of the intermediate transfer belt 32, so that a predetermined tension is applied to the intermediate transfer belt 32. Is done.

  Here, as shown in FIG. 4 (A), since the tension applying roll 40 around which the intermediate transfer belt 32 is wound moves in an arc shape, the intermediate transfer at the contact portion T (see FIG. 2 (A)). As the posture of the belt 32 changes, the support member 162 also moves (see the two-dot chain line).

  Furthermore, the second guide portion 182 and the third guide portion 184 move as the support member 162 moves. That is, the second guide portion 182 and the third guide portion 184 move in conjunction with the change in the posture of the intermediate transfer belt 32 at the contact portion T.

  Here, as described above, since the support member 162 moves while maintaining the posture, when the support member 162 moves to the lower left side of the drawing, the second guide portion 182 and the third guide portion 184 also move to the lower left side of the drawing. To do. That is, since the intermediate transfer belt 32 that circulates between the secondary transfer position H and the tension applying roll 40 is shifted to the left side of the paper surface, the second guide portion 182 and the third guide portion 184 also move to the left side of the paper surface.

  If an image is to be output in this state, the transported sheet member P is transported to the downstream side after the transport timing is adjusted by the alignment roll 58.

  The leading edge of the sheet member P fed from the alignment roll 58 is guided by the first guide portion 180 and contacts the intermediate transfer belt 32 on the upstream side in the circumferential direction of the intermediate transfer belt 32 from the secondary transfer position H.

  As shown in FIG. 4B, the leading end of the sheet member P moves toward the secondary transfer position H by the intermediate transfer belt 32 that circulates. As the leading end of the sheet member P moves toward the secondary transfer position H, the conveyance surface of the sheet member P hits the second guide portion 182.

  Then, the leading end portion of the sheet member P is sandwiched between the intermediate transfer belt 32 and the secondary transfer roll 42 at the secondary transfer position H while the conveyance surface of the sheet member P is in contact with the second guide portion 182. . That is, the leading end portion of the sheet member P is sandwiched between the intermediate transfer belt 32 and the secondary transfer roll 42 while the conveyance surface of the sheet member P is in contact with the second guide portion 182.

  Here, as described above, since the second guide portion 182 is moved in conjunction with the change in the posture of the intermediate transfer belt 32, the angle formed between the intermediate transfer belt 32 and the sheet member P at the secondary transfer position H. θ4 falls within a predetermined range.

  As shown in FIG. 5A, after the leading end of the sheet member P is sandwiched between the intermediate transfer belt 32 and the secondary transfer roll 42, the position is determined by the conveyance speed of the sheet member P at the secondary transfer position H. Since the conveying speed of the sheet member P by the alignment roll 58 is increased, the conveying surface of the sheet member P is separated from the second guide portion 182 and the first guide portion 180. Then, the sheet member P draws a loop. Since the sheet member P draws a loop when the conveying surface of the sheet member P is separated from the second guide portion 182 and swells toward the intermediate transfer belt 32, the intermediate transfer belt 32 and the sheet member P at the secondary transfer position H are drawn. The angle θ5 formed by lies within a predetermined range.

  As shown in FIG. 5B, when the rear end of the sheet member P depicting a loop is released from clamping by the alignment roll 58, the rear end of the sheet member P hits the third guide portion 184.

  Here, as described above, since the third guide portion 184 is moved in conjunction with the change in the posture of the intermediate transfer belt 32, the angle formed between the intermediate transfer belt 32 and the sheet member P at the secondary transfer position H. θ6 falls within a predetermined range.

  As described above, since the second guide portion 182 and the third guide portion 184 move in conjunction with the posture of the intermediate transfer belt 32, the angle formed between the intermediate transfer belt 32 and the sheet member P at the secondary transfer position H. Falls within the determined range.

  Further, since the angle formed by the intermediate transfer belt 32 and the sheet member P at the secondary transfer position H falls within a predetermined range, 2 on the upstream side (secondary transfer Pre nip side) with respect to the secondary transfer position H. The discharge due to the next transfer electric field suppresses the occurrence of white spots during the transfer of the toner image and the deterioration of the quality of the output image.

  In addition, since the first guide portion 180 is fixed to the apparatus main body 10A, the load applied to the sheet member P fed from the alignment roll 58 is constant.

  Further, since the second guide portion 182 and the third guide portion 184 are moved in conjunction with the movement of the tension applying roll 40, the second guide portion 182 and the third guide portion 184 move with a simple configuration.

  Further, since the guide member 174 of the guide mechanism 164 is divided into the first guide portion 180, the second guide portion 182 and the third guide portion 184, the sheet member P can be easily conveyed with respect to the posture of the intermediate transfer belt 32. The posture is within the determined range.

  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 embodiment, the moving force of the tension applying roll 40 is transmitted to the second guide portion 182 and the third guide portion 184 via the support member 162, but the tension is not particularly required via the support member 162. The moving force may be directly transmitted to the second guide part 182 and the third guide part 184 from the rotating shaft or the like of the applying roll.

  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 10A Apparatus main body 32 Intermediate transfer belt (an example of an endless member)
34 Primary transfer roll (an example of a transfer member)
40 Tension imparting roll (an example of a tension imparting member)
42 Secondary transfer roll (an example of transfer means)
58 Positioning roll (an example of a conveying member)
164 Guide mechanism (recording medium guide mechanism)
174 Guide member 178 Moving means 180 First guide part 182 Second guide part 184 Third guide part

Claims (5)

A guide member that guides a recording medium on which an image formed on the endless member is transferred toward an endless endless member that is circulated by a driving unit and has an image formed on a surface thereof;
The guide member is moved in conjunction with the change in the attitude of the endless member at the contact portion where the leading end of the recording medium and the endless member are in contact with each other, and the conveying attitude of the recording medium guided by the guide member is changed. Transportation means;
A recording medium guiding mechanism.   The moving means moves the guide member in conjunction with the movement of the tension applying member that applies tension to the endless member while pressing the back surface of the endless member to change the attitude of the endless member at the contact portion. The recording medium guiding mechanism according to claim 1.   The moving means moves the guide member so that an angle formed by the endless member and the recording medium is within a predetermined range in a transfer portion that transfers an image formed on the endless member to the recording medium. The recording medium guiding mechanism according to claim 1. The guide member is
The leading end of the recording medium delivered from the conveying member provided on the upstream side in the conveying direction of the recording medium hits the guide member, and the leading end of the recording medium hits the transfer portion in the circumferential direction of the endless member A first guide portion that is applied to the contact portion of the endless member on the upstream side and fixed to the apparatus main body,
A conveyance surface of the recording medium in which the leading end abuts against the endless member by the first guide portion so that an angle formed by the endless member and the recording medium in the transfer portion is within a predetermined range. A second guide part that is moved by the moving means,
The transfer unit contacts the rear end of the recording medium fed from the conveying member and moves by the moving means so that an angle formed by the endless member and the recording medium falls within a predetermined range. The third guide,
A recording medium guiding mechanism according to claim 3. An endless endless member that circulates by driving means;
A toner image formed on the image holding member that is provided on the opposite side of the endless member with respect to a plurality of image holding members that are in contact with the back surface of the endless member and hold images of different colors. A plurality of transfer members that transfer the surface to the surface of the endless member;
The recording medium guiding mechanism according to any one of claims 1 to 4, which guides a recording medium onto which an image formed on the endless member is transferred toward the endless member that circulates;
Transfer means for transferring the toner image formed on the endless member to the recording medium guided by the recording medium guiding mechanism;
An image forming apparatus comprising:

Images