JP2009173412A - Paper reversing device and image forming device having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paper reversing device capable of feeding paper to a desired conveying path without using a drive source. <P>SOLUTION: A switchback part 20 comprises a branched conveying path 21, and a paper reversing, discharging, and conveying path 22 and a paper resupplying conveying path 23 which are connected to the branched conveying path at different positions, respectively. When the paper is fed to the paper reversing, discharging, and conveying path 22, the paper is stopped when the drawn rear end of the paper reaches an upstream side paper stop position S1 at the intermediate flow part 212 of the branched conveying path 21. When the paper is fed to the resupplying and conveying path 23, the paper is stopped when the drawn end of the paper reaches a downstream side paper stop position S2 at the downstream part 213 of the branched conveying path 21. Guide means 40A, 50A for feeding the feeding front end of the paper to the conveying paths 22, 23 for receiving the paper when the paper is fed are installed in the branched conveying path 21 near converging points T1, T2. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a sheet reversing device that performs reversal processing on a sheet conveyed along a conveying path, and an image forming apparatus including the same.

  2. Description of the Related Art Conventionally, an image forming apparatus such as a copying machine provided with a switchback unit (paper reversing device) for performing reversal processing on paper conveyed along a conveyance path is known (Patent Document 1).

  Some of such image forming apparatuses are configured to send the paper reversed by the switchback unit to different transport paths according to the purpose.

  For example, in the image forming apparatus illustrated in FIG. 7, when the paper drawn through the branch conveyance path 121 is discharged immediately after the reversal process with the printing surface being the back side, the reverse discharge conveyance path 122. When the image forming process is also performed on the back side of the sheet after the reversing process, the sheet is sent to the refeed conveyance path 123.

  Specifically, a reverse discharge conveyance path 122 and a refeed conveyance path 123 are branched and extended immediately downstream of a switchback portion 30D having a reverse roller 32, and a sheet is located near the branch point. A switching member 70 for switching the transport direction is provided rotatably. The switching member 70 is controlled in posture by a control device (not shown) that determines which conveyance path the sheet should be directed to.

Then, the reversely discharged paper is guided by the switching member 70 toward the reverse paper discharge conveyance path 122, and the refeed paper is guided by the switching member 70 toward the refeed paper conveyance path 123. It is like that.
Japanese Patent Laid-Open No. 5-35018

  However, in the configuration as described above, a drive source such as a solenoid for switching the posture of the switching member 70 as necessary is required.

  The present invention has been made to solve the above-described problems, and provides a sheet reversing device and an image forming apparatus capable of directing a sheet to a desired conveyance path without using a driving source. With the goal.

  In order to achieve the above object, a paper reversing device according to claim 1 of the present invention includes a paper drawing portion provided on a paper conveyance path and a paper drawing portion that is provided in the paper drawing portion and rotates in both forward and reverse directions. Transporting means for pulling or feeding the paper to the section, and after feeding the paper transported along the transport path into the paper pulling section, the paper is fed so that the leading end of the paper becomes the rear end. A paper reversing device that performs reversal processing on the paper retraction unit, connected to the paper retraction unit, and connected to different positions on the retraction direction of the retraction direction of the retraction direction of the retraction direction of the retraction direction. The first feeding path and the second feeding path through which the reversed paper passes, and the paper drawn into the paper drawing section through the drawing path is sent out to the first sending path. In this case, the trailing edge of the paper reaches the first predetermined position between the first merging point with the first feeding path and the second merging point with the second feeding path. On the other hand, when the paper is sent out to the second sending path, the trailing edge of the paper is at the front side in the drawing direction from the second joining point with the second sending path of the drawing paths. When the sheet reaches the second predetermined position, the sheet is stopped when the sheet is fed to the vicinity of the confluence of the drawing path with each of the feeding paths. The guide means for making it go to the power delivery path | route is each provided, It is characterized by the above-mentioned.

  2. The paper reversing device according to claim 1, wherein at least one of the guide means is provided at a portion sandwiched between the drawing path and the sending path so as to be rotatable so as to indicate the drawing direction of the drawing path. And an urging means for urging the lever member in a direction to close the retracting path (claim 2).

  2. The sheet reversing device according to claim 1, wherein the pull-in path includes a pull-in side straight path portion extending in a pull-in direction from a merge point with the feed path, and the feed path is fed from the merge point with the pull-in path. A delivery-side straight path portion that extends in the vertical direction may be included, and at least one of the guide means may be configured by the pull-in-side straight path portion and the delivery-side straight path portion (Claim 3).

  An image forming apparatus according to a fourth aspect of the present invention is characterized in that the paper reversing apparatus according to any one of the first to third aspects is applied.

  According to the first and fourth aspects of the present invention, each feed path is connected to a different position of the pull-in path, and the sheet stop position is made different depending on the feed path to be used. Since the guide means for guiding the paper to the delivery path is provided in the vicinity of the junction with each delivery path, the paper delivery path can be selectively selected by a drive source that is driven and controlled by the control unit as in the prior art. Without providing a switching member that operates so as to switch to the sheet, it is possible to reliably feed the sheet to the feeding path to be used. Therefore, the sheet can be sent out to a desired delivery path without using a drive source.

  According to the invention of claim 2, the guide member is provided at a portion sandwiched between the drawing path and the sending path so as to be pivotable so as to indicate the drawing direction of the drawing path, and the lever member is And a biasing means that urges the pulling path in a direction to close the pulling path, so that when the paper is fed, a lever member arranged to block the pulling path in a posture pointing to the pulling direction is fed. The action from the leading edge of the paper transported in the direction does not rotate in the direction to open the pulling path, so that the paper is fed into the feeding path while reliably preventing the paper from being fed back to the pulling path. Can be directed towards. Further, the lever member configured as described above is rotated in a direction to easily open the drawing path against the urging force of the urging means by the force received from the leading end of the sheet conveyed in the drawing direction. Does not obstruct transport in the pull-in direction.

  According to the third aspect of the present invention, the guide means is arranged in the delivery direction from the joining point between the drawing-side straight path portion extending in the drawing direction from the joining point with the sending path of the drawing path and the drawing path of the sending path. If it is configured with an extended delivery-side straight path section, the paper transported in the pull-in path and the rear end of the pull-in reaches the merging point, the paper is restored to a straight line by the edge of the paper, and the rear end of the pull-in Since the (delivery tip) is directed to the delivery path, the sheet is naturally directed to the delivery path when the sheet is delivered. As a result, it is possible to prevent reverse feeding of the paper to the drawing-in route.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a front sectional view showing the overall configuration of the copier according to the first embodiment of the present invention, and FIG. 2 is a schematic explanatory diagram showing the configuration around the switchback portion of the copier shown in FIG. It is. FIG. 3 is a schematic explanatory diagram for explaining the sheet reversing operation at the first junction of the switchback unit shown in FIG. First, the overall configuration of the copying machine 10 will be described with reference to FIGS. 1 and 2. In the present embodiment, the copying machine 10 will be described as an example of the image forming apparatus.

  When the copying machine 10 performs a copying operation, in the image forming unit 11 in the apparatus main body 19, the photosensitive drum 112 that rotates in the arrow direction (clockwise direction) in the drawing is uniformly charged by the charging unit 111, and the document An electrostatic latent image is formed on the photosensitive drum 112 by a laser beam from the exposure unit 13 based on the document image data read by the reading unit 12, and a developer (hereinafter referred to as toner) is formed on the electrostatic latent image by the developing device 113. ) To form a toner image. The toner is supplied from the toner container 114 to the developing device 113.

  Then, toward the photosensitive drum 112 on which the toner image is formed, the paper P is conveyed from the paper feeding unit 17 to the image forming unit 11 via a paper feed conveyance path 14 including a plurality of conveyance roller pairs 141. In the image forming unit 11, the toner image on the surface of the photosensitive drum 112 is transferred onto the paper P by the transfer belt 15. Then, the sheet P on which the toner image has been transferred is separated from the photosensitive drum 112, and the fixing roller 161 and the peripheral surface in which a heating source such as a halogen lamp is provided are pressed against the peripheral surface of the fixing roller 161. Then, the toner image is conveyed to a fixing device 16 having a pressure roller 162, where the toner image is fixed by heating.

  A cleaning device 115 is provided on the peripheral surface of the photosensitive drum 112 upstream of the charging unit 111, and toner remaining on the peripheral surface of the photosensitive drum 112 after the transfer process is scraped off by the cleaning device 115. . In addition, a neutralization device 116 is provided between the charging unit 111 and the downstream side of the cleaning device 115 on the circumferential surface of the photosensitive drum 112, and the residual charge on the circumferential surface of the photosensitive drum 112 is neutralized by the neutralization device 116. The

  The paper P that has passed through the fixing device 16 is immediately discharged to the paper discharge tray 18 or sent to the switchback unit (paper reversing device) 30A according to the present invention and turned to the paper discharge tray 18 after the front and back are reversed. The sheet is discharged or sent to the switchback unit 30A, the front and back sides are reversed, returned to the image forming unit 11 again, double-sided copied, subjected to fixing processing by the fixing device 16, and then discharged to the sheet discharge tray 18. Is done.

  Specifically, a branch conveyance path 21 is provided in the middle of the paper discharge conveyance path 142 from the fixing device 16 to the paper discharge tray 18 toward the lower switchback unit 30A. A switching guide 144 that can be rotated around a predetermined horizontal axis is provided at the most upstream position of the branch conveyance path 21. The paper P sent out from the fixing device 16 is discharged to the paper discharge tray 18 through the paper discharge transport path 142 by the switching guide 144 when the paper P is discharged so that the print surface becomes the front side only by single-sided printing. . On the other hand, when the paper P is discharged so that only one side is printed and the printing surface is the reverse side, or when the paper P is to be printed on both sides, it is guided downward by the switching guide 144 to be branched and conveyed 21. To the switchback unit 30A.

  The paper feeding unit 17 includes a plurality of paper cartridges 171 that store a small amount of paper P, a stocker 172 that stocks a large amount of paper P, and the uppermost paper from a paper bundle stored in the paper cartridge 171 and the stocker 172. A pickup roller 173 for feeding P and feeding it to the image forming unit 11 through the paper feed conveyance path 14 is provided. The paper cartridge 171 and the stocker 172 are detachable from the apparatus main body 19. When the paper P is consumed and emptied, the paper cartridge 171 and the stocker 172 are pulled out from the apparatus main body 19 to be newly replenished and pushed into the apparatus main body 19.

  Next, the switchback unit 30A will be described in detail.

  As shown in FIGS. 1 and 2, the switchback unit 30 </ b> A is provided in the horizontally extending paper drawing unit 31 and the paper drawing unit 31, and rotates in both forward and reverse directions to draw paper into the paper drawing unit 31. Or it has the reverse roller pair (conveying means) 32 to send out.

  The reversing roller pair 32 is provided in the vicinity of the entrance of the paper drawing portion 31, and rotates forward while being in contact with the paper P to draw the paper P into the paper drawing portion 31 while being in contact with the paper P The paper P is rotated in reverse and is sent out from the paper drawing section 31.

  The reversing roller pair 32 includes a driven roller extending in the front-rear direction and a driving roller extending in the front-rear direction disposed opposite to the driven roller at the lower part. The drive roller is configured to rotate in both forward and reverse directions. As the drive roller rotates in both directions, the driven roller also rotates in both forward and reverse directions, causing the paper P to move in the forward direction (right direction) or the reverse direction ( It is transported in the left direction).

  Further, the switchback unit 30A is connected to the paper drawing unit 31 and is connected to the branch conveyance path (retraction path) 21 through which the sheet before reversal passes, and different positions on the base side and the front side of the branch conveyance path 21 in the drawing direction. Are connected to each other, and a paper transport path including a reverse paper discharge transport path (first sending path) 22 and a refeeding transport path (second sending path) 23 through which the reversed paper passes is provided. .

  The branch conveyance path 21 extends vertically downward from the switching guide 144, then extends obliquely downward to the right, further extends horizontally to the right, and is connected to the paper drawing portion 31.

  Further, the reverse paper discharge conveyance path 22 extends from the substantially central position of the vertically extending portion of the branch conveyance path 21 so as to branch obliquely upward to the left, and then extends vertically upward to be connected to the paper discharge conveyance path 142. It is a mode. A branch point between the branch conveyance path 21 and the reverse discharge conveyance path 22 is defined as a first junction T1 (see FIG. 2).

  Further, the re-feed conveyance path 23 extends from the left end of the horizontally extending portion of the branch conveyance path 21 so as to branch horizontally to the left, and then extends so as to wrap around downward and turn rightward. ing. A branch point between the branch conveyance path 21 and the refeed conveyance path 23 is defined as a second junction T2 (see FIG. 2).

  The branch conveyance path 21 includes an upstream portion 211 upstream from the first joining point T1, a midstream portion 212 between the first joining point T1 and the second joining point T2, and a downstream portion downstream from the second joining point T2. 213.

  In the present embodiment, when the paper P drawn into the paper drawing-in portion 31 through the branch conveyance path 21 is sent out to the reverse discharge conveyance path 22, the trailing edge of the paper (feeding out) The leading edge P1 (see FIG. 3) is stopped when it reaches the upstream sheet stop position (first predetermined position) S1 set in the midstream portion 212 of the branch conveyance path 21, while the sheet is re-feed conveyance path. In the case where the sheet is fed to the sheet 23, the sheet is stopped when the trailing end P1 of the sheet reaches the downstream sheet stop position (second predetermined position) S2 set in the downstream portion 213 of the branch conveyance path 21. ing. The sheet stopping operation is performed by driving control of the reverse roller pair 32 by a control device (not shown).

  Further, guide means 40A and 50A are provided in the vicinity of the junctions T1 and T2, respectively, for directing the leading edge of the paper toward the respective transport paths 22 and 23 to be sent when the paper is sent out. ing.

  In the present embodiment, the guide means 40A provided in the vicinity of the first junction T1 pulls the branch conveyance path 21 into a portion sandwiched between the upstream portion 211 of the branch conveyance path 21 and the reverse discharge conveyance path 22. An upstream guide lever (lever member) 41 that is rotatably provided so as to point in the direction (downward in the drawing) side, and this upstream guide lever 41 closes the upstream portion 211 of the branch conveyance path 21. It comprises a tension spring (biasing means) 43 that biases in the direction.

  The upstream guide lever 41 rotates about the fulcrum portion 42.

  The tension spring 43 is attached to a proper position of the apparatus main body 19, and the upstream guide lever 41 easily opens the upstream portion 211 of the branch transport path 21 by the force of the paper transported through the branch transport path 21. The upstream guide lever 41 is set to be urged with an urging force that is rotated in the clockwise direction. Note that a biasing means such as a plate spring other than the tension spring 43 or a torsion coil spring provided at the fulcrum portion 42 may be used.

  In the guide means 40A configured in this way, as shown in FIG. 3A, the upstream guide lever 41 simply opens the upstream portion 211 by the paper P that has been transported through the upstream portion 211 of the branch transport path 21. The paper P is transported sufficiently smoothly. Then, as shown in FIG. 3B, when the trailing end P1 of the sheet P has passed the front end of the upstream guide lever 41, the upstream guide lever 41 is biased by the tension spring 43 to cause the branch conveyance path 21. Is rotated in the direction of closing the upstream portion 211 (counterclockwise direction), and the upstream portion 211 is closed again. As a result, the sheet P sent out thereafter is not sent back toward the upstream portion 211 of the branch conveyance path 21 and is directed toward the reverse discharge conveyance path 22 as shown in FIG. .

  In addition, the guide means 50A provided in the vicinity of the second junction T2 is in the direction in which the branch conveyance path 21 is drawn in a portion sandwiched between the midstream portion 212 of the branch conveyance path 21 and the refeed conveyance path 23 (see FIG. In this case, the downstream guide lever (lever member) 51 is provided so as to be rotatable so as to point to the downstream portion 213 on the right side), and the downstream guide lever 51 is closed in the direction of closing the midstream portion 212 of the branch conveyance path 21. It comprises a tension spring (biasing means) 53 for biasing.

  The downstream guide lever 51 rotates around the fulcrum portion 52.

  The tension spring 53 is attached to an appropriate position of the apparatus main body 19, and the downstream guide lever 51 easily opens the midstream portion 212 of the branch conveyance path 21 by the force of the sheet conveyed through the branch conveyance path 21. The downstream guide lever 51 is set to be urged with an urging force that is rotated in the clockwise direction.

  The sheet guide operation by the guide means 50A configured as described above is substantially the same as that of the guide means 40A, and thus detailed description thereof is omitted.

  Further, an upstream sheet trailing edge detection sensor 61 for detecting the trailing end position of the sheet conveyed through the upstream portion 211 of the branch conveyance path 21 is provided above the upstream guide lever 41. Further, downstream sheet trailing edge detection for detecting the trailing end position of the sheet conveyed through the middle flow section 212 of the branch conveyance path 21 at the opposite portion sandwiching the middle flow section 212 above the downstream guide lever 51. A sensor 62 is provided. These sensors 61 and 62 detect the trailing edge of the paper, and the detection signal is transmitted to the control device, so that the control device grasps the position of the paper being conveyed, and the paper is in a predetermined stop position. The drive control of the reverse roller pair 32 is performed so as to be stopped.

  Then, the paper P that has been conveyed toward the paper drawing section 31 through the branch conveyance path 21 is stopped at the paper stop positions S1 and S2 corresponding to the desired conveyance paths 22 and 23 to be sent out, and the pair of reversing rollers At the time of delivery by the reversal drive of 32, it is reliably conveyed toward the desired conveyance paths 22 and 23 by being guided by the above-mentioned guide means 40A and 50A.

  In the first embodiment, as described above, the reverse paper discharge conveyance path 22 and the refeed paper conveyance path 23 (hereinafter, abbreviated as each delivery path) are connected to different positions of the branch conveyance path 21 and reversed. Guide means for differentiating the sheet stop positions S1 and S2 depending on each delivery path for delivering the sheet later, and for guiding the sheet to the delivery path in the vicinity of the junction T1 and T2 with each delivery path of the branch conveyance path 21. Since 40A and 50A are provided, the paper is sent out without providing a switching member that operates to selectively switch the paper delivery path by a drive source that is driven and controlled by the control unit, as in the prior art. The paper can be reliably sent out to the path. Therefore, the sheet can be sent out to a desired delivery path without using a drive source.

  In the first embodiment, as described above, the guide means 40A (50A) is branched and transported to a portion sandwiched between the branch transport path 21 and the reverse discharge transport path 22 (refeed paper transport path 23). A guide lever 41 (51) that is rotatably provided so as to indicate the retracting direction of the path 21, and a tension spring 43 (53) that urges the guide lever 41 (51) in a direction to close the branch conveyance path 21. With this configuration, when the paper is sent out, the guide lever 41 (51) arranged so as to close the branch transport path 21 in a posture pointing in the pull-in direction sends out the paper transported in the sending direction. However, since the action from the leading edge does not rotate in the direction to open the branch conveyance path 21, the sheet is reversed and the reverse discharge conveyance path 22 (re-started) while reliably preventing the paper from being fed back to the branch conveyance path 21. Guide toward the paper feed path 23) It can be.

  Further, the guide lever 41 (51) configured as described above easily opens the branch conveyance path 21 against the urging force of the tension spring 43 (53) by the force received from the leading end of the sheet conveyed in the drawing direction. Since it rotates in the direction, it does not hinder the conveyance of the paper in the drawing direction.

(Second Embodiment)
FIG. 4 is a schematic explanatory view showing the configuration around the switchback portion of the copying machine according to the second embodiment of the present invention, and FIG. 5 is a sheet inversion at the first junction point of the switchback portion shown in FIG. It is a schematic explanatory drawing for demonstrating operation | movement.

  In the switchback unit 30B of the second embodiment, the arrangement mode of the conveyance paths 21 to 23 constituting the conveyance path of the sheet and the configuration of the guide means 40B and 50B provided at the junctions T1 and T2 are as follows. This is different from the first embodiment.

  That is, the branch conveyance path 21 of the switchback portion 30B of the second embodiment extends from the switching guide 144 in an obliquely downward left direction, then extends vertically downward, and further inclines downward and obliquely downward to the right. It extends horizontally to the right and is connected to the paper pull-in portion 31.

  Further, the reverse discharge conveyance path 22 of the switchback portion 30B extends from the upper end of the vertically extending portion of the branch conveyance path 21 so as to branch vertically upward, and is connected to the discharge conveyance path 142. Yes. A branch point between the branch conveyance path 21 and the reverse discharge conveyance path 22 is defined as a first junction T1.

  Further, the re-feed conveyance path 23 of the switchback unit 30B extends linearly by a predetermined length so as to branch leftward from the left end of the horizontally extending portion of the branch conveyance path 21, and then rotates downward. It is an aspect that extends so as to be folded rightward. A branch point between the branch conveyance path 21 and the refeed conveyance path 23 is defined as a second junction T2.

  The branch conveyance path 21 includes an upstream portion 211 upstream from the first joining point T1, a midstream portion 212 between the first joining point T1 and the second joining point T2, and a downstream portion downstream from the second joining point T2. 213. Further, the straight portion extending vertically in the midstream portion 212 is a pull-in side straight path portion 214. The downstream portion 213 extending horizontally (straight) to the right corresponds to the “retraction-side straight path portion” of the present invention.

  Further, the straight portions extending in the feed direction from the junctions T1 and T2 of the reverse paper discharge conveyance path 22 and the refeed conveyance path 23 are the feed-side straight path portions 221 and 231 respectively.

  And in 2nd Embodiment, the guide means 40B is comprised by the said downstream part 213 and the said delivery side linear path | route part 221, and the guide means 50B is the said drawing-in side linear path | route part 214 and the said delivery side. And a straight path portion 231.

  In the guide means 40B configured in this way, as shown in FIG. 5A, the sheet conveyed in the upstream portion 211 of the branch conveyance path 21 is between the upstream portion 211 and the midstream portion 212 of the branch conveyance path 21. Due to the bent shape, the sheet is bent to resist the paper. Then, as shown in FIG. 5B, the paper P whose rear end P1 has reached the first joining point T1 is restored to a straight line by the paper scraping, and the rear end P1 is the reverse paper discharge conveyance path. 22 posture. As a result, as shown in FIG. 5C, the sheet P that is sent out thereafter is not sent back toward the upstream portion 211 of the branch conveyance path 21, but goes toward the reverse discharge conveyance path 22. .

  Further, since the operation of the sheet guiding operation by the guide means 50B is substantially the same as that of the guide means 40B, detailed description thereof is omitted.

  Then, the paper P that has been conveyed toward the paper drawing section 31 through the branch conveyance path 21 is reversed by a control device (not shown) that can receive detection signals from the sensors 61 and 62 as in the first embodiment. By the drive control of the roller pair 32, the guide means 40B described above is stopped at the sheet stop positions S1 and S2 corresponding to the desired transport paths 22 and 23 to be sent, and when the reverse roller pair 32 is fed by the reverse drive. , 50B, the sheet is reliably conveyed toward the desired conveyance paths 22, 23.

  In the second embodiment, as described above, the guide means 40B (50B) is moved in the pull-in direction from the junction T1 (T2) with the reverse discharge conveyance path 22 (re-feed conveyance path 23) of the branch conveyance path 21. A delivery side extending in the delivery direction from a junction T1 (T2) between the extended drawing-side straight path 214 (downstream part 213) and the branch conveyance path 21 of the reverse sheet delivery conveyance path 22 (refeed paper conveyance path 23). Since the straight path portion 221 (231) is configured, the sheet P conveyed in the pulling conveyance path 21 in the pulling direction and the trailing end P1 reaching the merging point is restored to a straight line by the paper strain, Since the rear end (feeding leading end) P1 of the drawing comes to face the reverse paper discharge conveyance path 22 (refeed paper conveyance path 23), the paper P is reversed reverse paper discharge conveyance path 22 when the paper is sent out. It naturally goes to (re-feed conveyance path 23). Thereby, it is possible to prevent the paper from being fed back to the branch conveyance path 21.

  The present invention is not limited to the above embodiment, and includes the following contents.

  In the above embodiment, the copying machine 10 has been described as an example of the image forming apparatus. However, the present invention is not limited to the copying machine 10 being an image forming apparatus, and may be a printer or a facsimile machine. There may be.

  Further, as shown in FIG. 6, the switch having a configuration in which the guide means 40A according to the first embodiment is provided in the vicinity of the first junction T1, and the guide means 50B according to the second embodiment is provided in the vicinity of the second junction T2. The back portion 30C may be used.

  Moreover, the guide means provided with the structure of both the guide means 40A by 1st Embodiment and the guide means 40B by 2nd Embodiment may be sufficient. That is, as shown in the second embodiment, in addition to providing each of the transport paths 21, 22 (23) with a drawing-side straight path portion and a sending-side straight path portion, as shown in the first embodiment, the merging A configuration in which a guide lever urged in a direction to close the branch conveyance path 21 by a tension spring is provided in the vicinity of the point. In this way, it becomes possible to more reliably prevent the paper from being reversely fed, and the paper can be reliably conveyed toward the desired conveyance paths 22 and 23.

1 is a front sectional view showing an overall configuration of a copying machine according to a first embodiment of the present invention. FIG. 2 is a schematic explanatory diagram illustrating a configuration around a switchback unit of the copier illustrated in FIG. 1. FIGS. 3A and 3B are schematic explanatory diagrams for explaining a sheet reversing operation at a first junction of the switchback unit illustrated in FIG. 2, in which FIG. FIG. 5C is a diagram showing a state immediately after the rear end of the sheet has passed the front end of the guide lever, and FIG. 5C is a diagram illustrating a state in which the sheet is being conveyed in the sending direction. FIG. 5 is a schematic explanatory diagram showing a configuration around a switchback unit of a copying machine according to a second embodiment of the present invention. 5A and 5B are schematic explanatory diagrams for explaining a sheet reversing operation at a first junction point of the switchback unit illustrated in FIG. 4, in which FIG. FIG. 10C is a diagram showing a state immediately after the trailing edge of the sheet reaches the first joining point, and FIG. 10C is a diagram illustrating a state in which the sheet is being conveyed in the sending direction. FIG. 6 is a schematic explanatory view showing a configuration around a switchback portion of a copying machine according to a modification of the present invention. It is a schematic explanatory view showing the configuration around the switchback unit of a conventional copying machine.

Explanation of symbols

10 Copying machine (image forming device)
21 Branch conveyance path (retraction path)
213 Downstream part (retraction side straight path part)
214 Pull-in side straight path portion 22 Reversed paper discharge conveyance path (first delivery path)
221 Sending-side straight path portion 23 Re-feed conveyance path (second sending path)
231 Delivery-side straight path sections 30A, 30B, 30C Switchback section (paper reversing device)
31 Paper pull-in part 32 Reverse roller pair (conveying means)
40A, 50A, 40B, 50B Guide means 41 Upstream guide lever (lever member)
43 Tension spring (biasing means)
51 Downstream guide lever (lever member)
53 Tension spring (biasing means)
P paper S1 upstream paper stop position (first predetermined position)
S2 downstream paper stop position (second predetermined position)
T1 first merge point T2 second merge point

Claims (4)

A paper drawing portion provided on the paper conveyance path and a conveyance means provided in the paper drawing portion and rotating in both forward and reverse directions to draw or send the paper to the paper drawing portion are conveyed along the conveyance path. A paper reversing device that applies a reversal process to the paper by feeding the paper so that the leading edge of the paper becomes the trailing edge after the paper is drawn into the paper drawing portion,
A retraction path connected to the paper retraction section, through which the paper before reversal passes, and a first delivery path connected to different positions on the base side and the front side of the retraction direction of the retraction path, and through which the paper after reversal passes; A second delivery path,
When the paper drawn into the paper drawing portion through the drawing path is sent to the first sending path, the trailing edge of the sheet is the first of the first sending paths out of the drawing paths. When the first predetermined position between the merging point and the second merging point with the second feeding path is reached, the sheet is stopped when the sheet is fed to the second feeding path. When the end reaches the second predetermined position on the front side in the retracting direction from the second joining point with the second delivery path of the retracting path, the end is stopped,
Guide means for directing the leading edge of the paper to the delivery path to be sent out when the paper is sent out is provided in the vicinity of the confluence of each drawing path with each delivery path. A paper reversing device characterized by the above.   At least one of the guide means includes a lever member provided at a portion sandwiched between the drawing path and the sending path so as to be rotatable so as to indicate the drawing direction of the drawing path, and the lever member closes the drawing path. 2. The sheet reversing device according to claim 1, further comprising an urging unit that urges the sheet in a direction. The pull-in path includes a pull-in side straight path portion extending in the pull-in direction from the junction with the delivery path,
The delivery path includes a delivery-side straight path portion extending in a delivery direction from a junction with the drawing-in path,
2. The sheet reversing device according to claim 1, wherein at least one of the guide means includes the pull-in side straight path portion and the delivery side straight path portion.   An image forming apparatus to which the sheet reversing device according to claim 1 is applied.

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