JP2010173811A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device capable of stably providing a high-quality double-sided image by preventing deflective deformation of a merging guide of a double-sided carrying unit. <P>SOLUTION: This image forming device includes a paper storage part, an image forming part, a paper ejecting means, a reversing means, a first carrying passage reaching the image forming part from the paper storage part, a second carrying passage reaching the paper ejecting means from the image forming part, a third carrying passage reaching the reversing means by branching off from the middle of the second carrying passage, a fourth carrying passage L4 merging with the first carrying passage by extending from the reversing means and the double-sided carrying unit 8 having the merging guide 44 arranged in a merging part of the first carrying passage of the fourth carrying passage L4, the reversing means and the fourth carrying passage L4, and is formed by slidably supporting the double-sided carrying unit 8 along a slider 45 arranged on the device body side. An installation member 47 for constituting a part of a frame body of the double-sided carrying unit 8, is fixed to the slider 45, and the guide end 44a of the merging guide 44 is fixed to the installation member 47. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus capable of forming images on both sides of a sheet.

  Some image forming apparatuses such as a copying machine, a printer, a facsimile, or a composite machine that forms an image on a sheet by an electrophotographic method can form an image on both sides of the sheet.

  Such an image forming apparatus includes a paper storage unit that stores paper, an image formation unit that forms an image on paper fed from the paper storage unit, and an image formed on one or both sides by the image forming unit. A paper discharge means for discharging the paper to the outside of the machine, a reversing means for reversing the front and back of the paper on which an image is formed on one side by the image forming section, and a first transport path from the paper storage section to the image forming section. A second transport path from the image forming unit to the paper discharge means, a third transport path that branches from the middle of the second transport path and reaches the reversing means, and extends from the reversing means to the first transport path. A double-sided conveyance unit having a fourth conveyance path that merges with the path, a merging guide provided at a merging portion of the first conveyance path of the fourth conveyance path, the reversing unit, and the fourth conveyance path;

  By the way, the double-sided conveyance unit is supported so as to be slidable along a slider provided on the apparatus main body side. For example, when maintenance such as jam processing is required, the double-sided conveyance unit is moved along the slider. It can be slid and pulled out to the near side.

  When forming an image on both sides of a sheet in the image forming apparatus having the above configuration, the sheet fed from the sheet storage unit is supplied to the image forming unit through the first conveyance path, and the image forming unit An image is formed on one side (first side). The sheet having an image formed on one side in this way is introduced from the second conveyance path through the third conveyance path to the reversing means, and after the front and back are reversed, the sheet passes through the fourth conveyance path of the duplex conveyance unit. Returned to one transport path. In this way, the sheet that has been turned upside down and returned to the first transport path is supplied again to the image forming unit and is on the opposite side (the second side opposite to the side on which the first image is formed). The sheet on which the image is formed on both sides and the image is formed on both sides is discharged from the second conveyance path to the outside of the apparatus by the discharge unit.

JP-A-10-026857 JP 2005-315920 A JP 2007-217126 A

  By the way, a merging guide for guiding the sheet conveyed through the fourth conveying path and guiding it to the first conveying path is provided at a portion where the fourth conveying path of the duplex conveying unit merges with the first conveying path. However, since the guide end of the merging guide is free and not fixed at all, when a stiff (high rigidity) sheet is conveyed, the sheet collides with the guide end of the merging guide and the merging guide is Due to the bending deformation, the fourth transport path is changed, which causes a problem that the optical axis is shifted and an image defect occurs when an image is formed on the second surface of the sheet.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an image forming apparatus capable of stably obtaining a high-quality double-sided image by preventing bending deformation of the merging guide of the double-sided conveyance unit. To rub.

  In order to achieve the above object, a first aspect of the present invention is a sheet storage section for storing sheets, an image forming section for forming an image on a sheet fed from the sheet storage section, and a single side by the image forming section. Alternatively, a paper discharge unit that discharges the paper on which the image is formed on both sides to the outside of the apparatus, a reversing unit that reverses the front and back of the paper on which the image is formed on one side by the image forming unit, and the image formation from the paper storage unit. A first conveyance path to the image forming section, a second conveyance path from the image forming section to the paper discharge means, a third conveyance path that branches from the middle of the second conveyance path to the reversing means, and the reversal A fourth conveyance path that extends from the means and merges with the first conveyance path, a merging guide provided at a merging portion of the first conveyance path of the fourth conveyance path, the reversing means, and the fourth conveyance path. A double-sided conveyance unit is provided. In the image forming apparatus, which is slidably supported along a slider provided on the apparatus main body side, an attachment member constituting a part of the frame of the double-sided conveyance unit is fixed to the slider, and the merging guide The guide end is fixed to the mounting member.

  According to a second aspect of the present invention, in the first aspect of the invention, the fourth transport path is formed in a substantially linear shape, and the merging guide extends along an extension line of the fourth transport path along the transport direction. And a shape having a curved portion which is adjacent to the downstream side of the straight portion and curves in a direction approaching the conveyance direction of the first conveyance path.

  According to a third aspect of the present invention, in the second aspect of the present invention, the fourth conveyance path that extends linearly adjacent to the upstream side of the merging guide is constituted by a conveyance guide that is provided facing each other. The conveyance guide has a guide surface opposed at a predetermined interval and one roller of a conveyance roller pair that conveys the sheet. In the state where the double-sided conveyance unit is pulled out from the apparatus main body, one of the conveyance guides is the other of the conveyance guides. The fourth moving path is opened by moving in a direction away from the guide.

  According to the first aspect of the present invention, the mounting member constituting a part of the frame of the double-sided conveyance unit is fixed to the slider provided on the apparatus main body side, and the guide end of the merging guide is fixed to the mounting member. Even if a stiff (high rigidity) paper collides with the merging guide, the merging guide is not bent and deformed, and the paper is guided to the merging guide and conveyed smoothly and accurately to the first conveying path. The optical axis does not vary during image formation on the second surface, and a high-quality double-sided image can be stably obtained.

  According to the second aspect of the present invention, since the fourth transport path is linear, the sheet is transported smoothly and with high accuracy along the fourth transport path. Further, since the linear portion is provided in the merge guide so as to extend on the extension line on the downstream side of the fourth conveyance path, the paper is smoothly conveyed to the merge guide. Further, the merging guide is provided with a curved portion that curves in a direction approaching the conveying direction of the first conveying path on the downstream side of the straight line portion, so that stiff sheets can be smoothly and highly accurately moved to the first conveying path. It is conveyed to.

  According to the third aspect of the present invention, one of the conveyance guides that are provided even if they face each other and that constitute the fourth conveyance path that extends linearly on the upstream side of the merging guide has pulled out the double-sided conveyance unit from the apparatus main body. In this case, it is possible to move away from the other conveyance guide together with one roller of the conveyance roller pair that conveys the sheet, so that the sheet can be easily removed when the sheet is jammed at the merging guide portion. is there. In addition, since the merging guide is not bent and deformed, and a large force does not act on the movable conveying guide, the merging guide is not bent and deformed even if the conveying guide is enlarged. The operation of removing the jammed paper becomes easy.

1 is a cross-sectional view of an image forming apparatus (multifunction machine) according to the present invention. FIG. 3 is a perspective view of a double-sided conveyance unit of the image forming apparatus according to the present invention. FIG. 4 is a partial perspective view illustrating a state in which the duplex conveyance unit of the image forming apparatus according to the invention is pulled out. It is a fracture | rupture perspective view of the confluence | merging guide part of a duplex conveying unit. It is a perspective view of a slider. It is a fragmentary sectional perspective view which shows the fixation structure of a confluence | merging guide. It is a fragmentary sectional perspective view which shows the fixation structure of a confluence | merging guide. It is a front view which shows the fixation structure to the attachment member of a confluence | merging guide. FIG. 4 is a perspective view of the double-sided conveyance unit of the image forming apparatus according to the present invention as viewed obliquely from below. It is the perspective view which looked at the conveyance guide of the double-sided conveyance unit from diagonally upward.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a cross-sectional view of an image forming apparatus according to the present invention. The illustrated image forming apparatus 1 is a multifunction device having both a copying function, a printer function, and a facsimile function, and forms images on both sides of a sheet. It is a device that can. The image forming apparatus includes an apparatus main body 2 and an automatic document feeder 3 and an original reading apparatus 4 disposed on the apparatus main body 2. An image forming unit 5 is disposed above the apparatus main body 2. A sheet storage unit 6 is arranged in the lower half of the inside 2. A transfer conveyance unit 7 and a double-sided conveyance unit 8 are disposed between the image forming unit 5 and the sheet storage unit 6 in the apparatus main body 2. The transfer conveyance unit 7 includes a reversing roller 36 that constitutes a reversing unit. A reversing roller 37 is provided.

  The image forming unit 5 forms an image by an electrophotographic method. The image forming unit 5 is a photosensitive drum 9 as an image carrier rotatably disposed, a charger 10 disposed around the photosensitive drum 9, a developing device 11, In addition to the transfer roller 12 and the cleaning device 13, the developing device 11 is provided with a toner hopper 14 for supplying toner as a developer. A laser scanner unit (LSU) 15 that is a scanning optical unit is disposed beside the image forming unit 5.

  The paper storage unit 6 includes four detachable paper feed cassettes 16, 17, 18, and 19 in which a plurality of paper sheets are stacked and accommodated. A pick roller 20 that picks up the sheets in the paper cassettes 16 to 19 one by one, a feed roller 21 that separates and feeds the picked-up sheets one by one, and a retard roller 22 are provided. In the vicinity of the bypass tray 23, a pick roller 20, a feed roller 21, a retard roller 22 and a transport roller 24 are provided as bypass transport means. In FIG. 1, reference numerals 25, 26 and 27 denote transport rollers.

  The transfer conveyance unit 7 conveys the sheet fed from the sheet storage unit 6 to the image forming unit 5 at an appropriate timing, and the sheet on which the image is formed in the image forming unit 5 to a paper discharge tray (not shown). The registration roller 28 disposed in the first conveyance path L1 from the paper storage unit 6 to the image forming unit 5, the transfer roller 12, and a later-described discharge unit serving as a discharge unit from the image forming unit 5. A fixing device 29, a conveyance roller 30, and a paper discharge roller 31 provided in the second conveyance path to the paper roller 31 are provided. The fixing device 29 includes a fixing roller 29a and a pressure roller 29b that rotate in a pressure contact state.

  The transfer conveyance unit 7 can be attached to and detached from the image forming apparatus main body 2, and the transfer conveyance unit 7 branches from the second conveyance path L <b> 2 and reverse rollers 36 and reverse rollers 37 of the duplex conveyance unit 8. A third U-shaped third conveying path L3 is provided, and a conveying roller 32 is provided in the middle. In addition to the third transport path L3, a reverse transport path L3 ′ branches from the second transport path L2 and extends downward in the transfer transport unit 7, and a transport roller 33 is provided in the middle. . A flapper 34 for switching the paper transport direction is rotatably provided at a branch portion between the second transport path L2 and the third transport path L3.

  The double-sided conveyance unit 8 reverses the front and back of the paper on which the image is formed in the image forming unit 5, and is arranged below the intermediate tray 35 connected to the third conveyance path L 3 and the reverse conveyance path L 3 ′. The intermediate tray 35 is provided with a reverse roller 36 that can be rotated forward and backward, and a reverse roller 37 that is pressed against / separated from the reverse roller 36.

  The double-sided conveyance unit 8 is provided with a large-diameter refeed roller 38 that is rotatable. Small-diameter rollers 39 and 40 are rotatably in contact with the outer periphery of the refeed roller 38. The refeed roller 38 is provided with a one-way clutch (not shown). A first transport path L4 extends from the reverse roller 36 and the reverse roller 37 constituting the reversing means, and the fourth transport path L4 joins the first transport path L1.

  In the fourth transport path L4, three sets of transport rollers 42 and transport rollers 41 that are in contact with each other are provided along the sheet transport direction. Further, in the vicinity of the refeed roller 38, a flapper 43 for switching the transport direction of the paper once drawn into the intermediate tray 35 is rotatably provided. In the present embodiment, the fourth transport path L4 of the duplex transport unit 8 is provided with two or more paper storage positions where two or more sheets can be stored.

  Next, an image forming operation of the image forming apparatus 1 having the above configuration will be described.

  For example, when a document set on the document tray 3a of the automatic document feeder 3 is automatically conveyed onto a contact glass 4a which is a document reading unit, and an image of the document is optically read by the document reader 4, In the image forming unit 5, the photosensitive drum 9 is rotationally driven in a direction indicated by an arrow (clockwise) in FIG. 1 by a driving unit (not shown), and the surface thereof is uniformly charged to a predetermined potential by the charger 10. When laser light based on image data transmitted from the document reading device 4 is output from the laser scanner unit 15 and irradiated onto the photosensitive drum 9, an electrostatic latent image is formed on the photosensitive drum 9. The electrostatic latent image formed on the photosensitive drum 9 is developed with toner by the developing device 11 to be visualized as a toner image.

  By the way, when cassette feeding is performed, the sheets stored in, for example, the sheet feeding cassette 16 of the sheet storage unit 6 are picked up one by one from the uppermost one by the pick roller 20 and are fed by the feed roller 21 and the retard roller 22. The sheets are separated one by one and conveyed by the conveying rollers 25 and 26 to the registration roller 28 through the first conveying path L1. In the registration roller 28, after the paper is temporarily in a standby state, the paper is supplied to the image forming unit 5 at a predetermined timing synchronized with the toner image on the photosensitive drum 9.

  In the image forming unit 5, the sheet supplied to the transfer nip between the photosensitive drum 9 and the transfer roller 12 is conveyed while being pressed against the photosensitive drum 9 by the transfer roller 12, so that the surface (first The toner image on the photosensitive drum 9 is transferred onto the surface. The sheet onto which the toner image has been transferred is conveyed to the fixing device 29, and is heated and pressed in the process of passing through the fixing nip between the fixing roller 29a and the pressure roller 29b of the fixing device 29, so that the toner image is transferred. Get fixed. The toner remaining on the surface of the photosensitive drum 9 (transfer residual toner) after the transfer of the toner image onto the paper is removed by the cleaning device 13.

  Thus, the paper whose toner image has been fixed on the surface by the fixing device 29 is determined by the flapper 34 when the face-up paper discharge (FU paper discharge) is selected. The paper is transported as it is toward the paper discharge roller 31 through the second transport path L2, and is discharged to a paper discharge tray (not shown) with the image surface facing up by the paper discharge roller 31.

  On the other hand, when face-down paper discharge (FD paper discharge) or double-sided image mode is selected, the flapper 34 is operated to switch the paper transport direction, and the paper that has passed through the fixing device 29 has a horizontal U-shape. It is conveyed to the duplex conveyance unit 8 through the third conveyance path L3.

  In the duplex conveying unit 8, the reversing roller 37 stands by in a state of being separated from the reversing roller 36, and when the sheet is fed to the duplex conveying unit 8 more than a certain amount, the reversing roller 37 is pressed against the reversing roller 36. . When the reversing roller 37 is pressed against the reversing roller 36 in this way, the reversing roller 36 is rotated forward and pulled in the direction in which the sheet is fed, and when the sheet is pulled more than a certain level, the reversing roller 36 is reversed. Thus, the sheet is switched back and sent to the reverse conveyance path L3 ′ or the fourth conveyance path L4.

  That is, when face-down paper discharge is selected, the paper transport direction is switched to the reverse transport path L3 ′ by the flapper 43, and the paper is not shown by the paper discharge roller 31 with the image side down. It is discharged to the paper discharge tray.

  When the double-sided image mode is selected, the conveyance direction of the paper is switched to the direction of the fourth surface conveyance path L4 by the flapper 43, and the paper is fed again by the refeed roller 38, the reverse roller 41, and the conveyance roller 42. Is transferred with the image surface facing up on the fourth transport path L4, and is transferred from the fourth transport path L4 to the first transport path L1 so that the front and back are reversed and the registration roller 28 is in a state where the image surface is face down. Sent to. Thereafter, a toner image is formed on the opposite surface (second surface) of the paper through the same process as described above, and the paper on which the toner image is formed is discharged after fixing the toner image by the fixing device 29. The paper is discharged to a paper discharge tray (not shown) by the paper roller pair 31, and images are formed on both sides of the paper.

  In the above description, the cassette feeding is described. However, when the manual feeding is performed, the sheets set on the bypass tray 23 are picked up one by one from the uppermost one by the pick roller 20, Each sheet is separated one by one by the feed roller 21 and the retard roller 22 and conveyed by the conveyance roller 24 to the registration roller 28 through the first conveyance path L1, and thereafter an image is formed on the sheet through the same process as described above.

  Next, details of the duplex conveying unit 8 will be described with reference to FIGS.

  2 is a perspective view of the double-sided conveyance unit, FIG. 3 is a partial perspective view showing a state in which the double-sided conveyance unit is pulled out, FIG. 4 is a broken perspective view of the merging guide portion of the double-sided conveyance unit, and FIG. 6 and 7 are partial cross-sectional perspective views showing the fixing structure of the merging guide, FIG. 8 is a front view showing the fixing structure of the merging guide to the mounting member, and FIG. 9 is a perspective view of the double-sided conveyance unit seen from obliquely below. FIG. 10 is a perspective view of the lower conveyance guide of the double-sided conveyance unit 8 as viewed obliquely from below.

  As shown in FIG. 4, in the double-sided conveyance unit 8, the fourth conveyance path L4, which is a double-sided conveyance path, is formed between the upper conveyance guide 8A and the lower conveyance guide 8B. Specifically, the fourth conveyance path L4 is formed by a sheet metal guide plate 8a constituting the lower surface of the upper conveyance guide 8A and a sheet metal guide plate 8b constituting the upper surface of the lower conveyance guide 8B. A merging guide 44 bent in an arc shape upward is formed at the merging portion that merges with the first conveyance path L1 at the downstream end of 8b, and a guide end (rear end) 44a of the merging guide 44 is formed. Is bent vertically downward. The guide surface of the merging guide 44 includes a straight guide portion 44b and a curved guide portion 44c. The straight guide portion 44b is configured to extend on an extension line in the transport direction of the fourth transport path L4 adjacent to the downstream end of the lower transport guide 8B. The curved guide portion 44c extends while curving upward from the direct portion 44b continuously, and guides the paper conveyance direction so as to approach the conveyance direction of the first conveyance path L1. Therefore, in the linear guide portion 44b and the curved guide portion 44c of the merging guide 44, a pressing force acts on the stiffness of the paper when the paper passes.

  Incidentally, the duplex conveying unit 8 shown in FIG. 2 has an upstream end and a downstream end (merging end) provided on the apparatus main body 2 side, and a width direction (perpendicular to the sheet conveying direction) by a slider 45 (only one is shown in the figure). The double-sided conveyance unit 8 can be slid along the slider 45 as shown in FIG. 3 and pulled out to the near side if necessary. Here, as shown in FIG. 5, the slider 45 includes a fixed guide 45 a having a C-shaped cross section attached to the frame body 2 </ b> A of the apparatus main body 2 via the bracket 46, and a cross section C attached to the duplex conveyance unit 8. And a guide rail 45c slidably held on the fixed guide 45a and the movable guide 45b via a ball (not shown).

  Thus, in the present embodiment, as shown in FIGS. 4, 6 and 7, the movable guide 45 b of the slider 45 has a Z-shaped cross section that constitutes a part of the frame of the double-sided conveyance unit 8. The mounting member 47 is fixed by a plurality of screws 48 (only one is shown in FIGS. 6 and 7). The flange portion 47a erected vertically on the upper surface of the mounting member 47 is disposed so as to overlap the inside of the vertical guide end 44a of the merge guide 44, and the vertical guide end 44a of the merge guide 44 is As shown in FIGS. 7 and 8, the three portions of the both ends in the width direction and the central portion are fixed to the flange portion 47 a of the mounting member 47 by screws 49.

  As described above, in the present embodiment, the mounting member 47 constituting a part of the frame of the duplex conveyance unit 8 is fixed to the movable guide 45b of the slider 45 provided on the apparatus main body 2 side by the screw 48. Since the guide end 44a of the merging guide 44 is fixed to the attachment member 47 with the screw 49, the merging guide 44 will not be bent and deformed even when a stiff (high rigidity) paper collides with the merging guide 44. For this reason, the sheet conveyed along the fourth conveyance path L4 toward the first conveyance path L1 is guided to the first conveyance path L1 by being guided by the merging guide 44 and smoothly and accurately to the second surface. The optical axis does not vary during image formation, and a high-quality double-sided image can be stably obtained.

  Further, the lower conveyance guide 8B of the duplex conveyance unit 8 will be described in detail. As shown in FIG. 2, the fourth transport path L4 extends from the downstream outlet of the refeed roller 38 to the merging guide 44 while being inclined slightly upward in a straight line, and the lower surface of the transport path therebetween As described above, the side is constituted by the lower conveyance guide 8B. As shown in FIGS. 9 and 10, the lower conveyance guide 8B has a guide plate 8b made of a rectangular sheet metal member, and a pair of left and right conveyance rollers 41 with respect to the conveyance direction is provided at the center in the width direction of the guide plate 8b. Three sets are provided at appropriate intervals along the sheet conveyance direction. The left and right two places where the conveying rollers 41 on the bottom surface of the guide plate 8b are provided are reinforced by two left and right first reinforcing plates 50 arranged in parallel along the sheet conveying direction. Further, two front and rear second reinforcing plates 51 arranged in parallel to the direction perpendicular to the paper transport direction are provided, and an opening / closing fulcrum 51a is provided at the back end of each reinforcing plate 51. Opening / closing hooks 51b are respectively formed on the front side end portions. Further, a handle 52 protruding forward is provided between the two opening / closing hooks 51b at the front end.

  The lower transport guide 8B is attached so as to be rotatable about the opening / closing fulcrum 51a, and the fourth transport path L4 can be opened by pushing down the handle 52. When a paper conveyance abnormality occurs, pulling out the duplex conveyance unit 8 to the front of the apparatus body and pressing down the lower conveyance guide 8B opens most of the fourth conveyance path L4. It is possible to easily remove the paper jammed at the position of the paper feed roller 38. The lower conveyance guide 8B is a flat plate having an area larger than two sheets of A4 size paper, but is reinforced by the first reinforcing plate 50 and the second reinforcing plate 51, and the paper is conveyed straight. Therefore, a large pressing force does not act during conveyance. Therefore, the lower conveyance guide 8B can appropriately convey the sheet without bending.

  In this embodiment, an example in which the present invention is applied to a multifunction machine has been described. However, the present invention can be similarly applied to a copying machine, a printer, a facsimile, etc. as a single unit. Of course.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Image forming apparatus main body 2A Image forming apparatus frame 3 Automatic document conveying device 3a Document tray 4 Document reading device 4a Contact glass 5 Image forming unit 6 Paper storage unit 7 Transfer conveying unit 8 Double-sided conveying unit 8A Double-sided conveying Upper conveyance guide of unit 8B Lower conveyance guide of double-sided conveyance unit 8a Guide plate of upper conveyance guide 8b Guide plate of lower conveyance guide 9 Photosensitive drum 10 Charger 11 Developing device 12 Transfer roller 13 Cleaning device 14 Toner hopper 15 Laser scanner unit ( LSU)
16 to 19 Paper feeding cassette 20 Pick roller 21 Feed roller 22 Retard roller 23 Bypass tray 24 to 27 Conveying roller 28 Registration roller 29 Fixing device 29a Fixing roller 29b Pressure roller 30 Conveying roller 31 Discharging roller 32, 33 Conveying roller 34 Flapper 35 Intermediate tray 36 Reverse roller 37 Reverse roller 38 Refeed roller 39, 40 Roller 41 Transport roller 42 Transport roller 43 Flapper 44 Merge guide 44a Guide end of merge guide 45 Slider 45a Slider fixed guide 45b Slider movable guide 45c Slider slide Guide rail 46 Bracket 47 Mounting member 47a Flange portion of mounting member 48, 49 Screw 50 First reinforcing plate 51 Second reinforcing plate 51a Opening / closing fulcrum 51b Opening / closing hook 52 Handle 1 the first transport path L2 the second transport path L3 third conveyance path L3 'reverse transport path L4 fourth transport path

Claims (3)

A paper storage unit that stores paper, an image forming unit that forms an image on paper fed from the paper storage unit, and a paper on which an image is formed on one or both sides by the image forming unit is discharged outside the apparatus. A paper discharge means, a reversing means for reversing the front and back of the paper on which the image is formed on one side by the image forming section, a first transport path from the paper storage section to the image forming section, and from the image forming section to the above-mentioned A second transport path that reaches the paper discharge means, a third transport path that branches from the middle of the second transport path and reaches the reversing means, and a fourth transport that extends from the reversing means and joins the first transport path. A double-sided conveyance unit having a path, a merging guide provided at a merging portion of the first conveyance path of the fourth conveyance path, the reversing unit, and the fourth conveyance path, and the double-sided conveyance unit on the apparatus main body side. Scan along the provided slider. In the image forming apparatus formed by Id rotatably supported,
An image forming apparatus, wherein an attachment member constituting a part of a frame of the double-sided conveyance unit is fixed to the slider, and a guide end of the merging guide is fixed to the attachment member.   The fourth transport path is formed in a substantially linear shape, and the merging guide is adjacent to the straight line portion extending on the extended line of the fourth transport path along the transport direction, and adjacent to the downstream side of the linear section. The image forming apparatus according to claim 1, further comprising a curved portion that curves in a direction approaching the conveyance direction of the road. The fourth conveyance path that extends linearly adjacent to the upstream side of the merging guide is configured by a conveyance guide that is provided to be opposed to each other, and each conveyance guide conveys a sheet and a guide surface facing each other at a predetermined interval. A structure having one roller of a pair of rollers, and in a state where the double-sided conveyance unit is pulled out from the apparatus main body, one of the conveyance guides moves away from the other conveyance guide to open the fourth conveyance path. The image forming apparatus according to claim 2, wherein the image forming apparatus is an image forming apparatus.

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