JP2005067776A - Recording sheet transport device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the producibility in double-side recording without bringing about a large-sized construction of a device even if the device is equipped with a plurality of sheet ejection trays for distributing to different destinations, for example in a complex machine. <P>SOLUTION: The device is furnished with a first paper path 3 and a third paper path 5 for recording in the route leading from a sheet feed cassette 2 to an external sheet ejection tray 25, and a second paper path 4 is provided parallel with the first paper path, and between the first and third paper paths, a two-direction transport roller 11 and a first 13 and a second path changeover guide piece 14 are installed. At the time of double-side recording, recording sheets with one side having undergone recording are once transported to the third paper path and ejected. Because the third paper path is used as common passage to serve both for the transport for ejection and the transport for inversion, the device can be made compact, and the ejection and inverting motions are overlapped to enhance the producibility at the time of continuous double-side recording. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a recording paper transport device and an image forming apparatus in a facsimile / copy multifunction peripheral capable of double-sided recording, and in particular, to improve productivity in double-sided recording processing.

  Conventionally, in a double-sided image recording apparatus capable of recording on both sides of a recording sheet, the recording sheet (recording sheet) supplied from the sheet supply unit is reversed after being conveyed to the image forming unit, and the inverted recording sheet is imaged again. A sheet conveying system for double-sided recording that is discharged to the sheet discharging unit after being conveyed to the forming unit is provided, and the recording sheet is reversed in the return conveying path of the recording sheet from the image forming unit in the sheet conveying system for double-sided recording By providing a plurality of sheet reversing portions, there is one that improves the productivity of a double-sided recording apparatus without unnecessarily increasing the length of the recording sheet conveyance path (see, for example, Patent Document 1).

A main conveying path for conveying a sheet on which an image is formed by the image forming means; a plurality of discharging means for discharging and stacking the sheets; and a guiding means for selectively guiding the sheet from the main conveying path to the plurality of discharging means. And at least one of the plurality of discharge means also serves as a sheet reversing means for reversing the sheet conveying direction, and the production of a double-sided image recording apparatus without incurring production costs or increasing the size of the apparatus. Some have improved properties (for example, see Patent Document 2).
Japanese Patent Laid-Open No. 11-133679 JP 2002-3059 A

  In the above-described conventional technique, in the configuration in which the recording paper conveyance paths to the plurality of paper discharge trays are independent, it is possible to improve the productivity at the time of double-sided recording without increasing the size of the apparatus. However, in a configuration in which the external paper discharge tray is disposed on the extension line of the internal paper discharge tray, it is difficult to improve productivity during double-sided recording by simply applying the conventional technique. There was a problem.

  To solve these problems and provide a plurality of paper discharge trays to divide the paper discharge destination as in the case of a multifunction machine, productivity for double-sided recording can be improved without increasing the size of the apparatus. An object of the present invention is to provide a recording paper conveyance device and an image forming apparatus that can be improved, and in order to realize this, in the present invention, an image is formed on both sides of the recording paper conveyance device or the recording paper. An image forming apparatus comprising: an image forming unit disposed between a paper feed cassette and a paper discharge tray; and a transport control unit configured to control the transport of the recording paper so that the recording sheet passes twice through the image forming unit. A first paper path for feeding recording paper fed from a paper cassette through the image forming means to the discharge tray side, and the first paper path from the discharge tray side of the first paper path to the first paper path. Second for transporting recording paper to the paper cassette A paper path, a third paper path provided between the first and second paper paths and the paper discharge tray, and the recording paper from the first paper path to the third paper path. The first and second paper paths and the third paper so that the recording paper conveyed to the third paper path can be reversed toward the second paper path. It has conveyance reversing means provided between the paths.

  In particular, a second paper discharge tray is provided in parallel with the third paper path, and the recording is discharged from the first paper path between the first paper path and the third paper path. It is preferable to provide a switching means for switching the paper discharge destination to either the third paper path or the second paper discharge tray. The conveyance reversing means includes three rollers including two rollers disposed with a common roller interposed therebetween, and the recording paper fed from the first paper path between one pair of rollers. The recording paper conveyed in the discharge direction and conveyed to the third paper path between the other pair of rollers may be conveyed toward the second paper path.

  As described above, according to the present invention, the third paper path is provided between the first and second paper paths and the paper discharge tray, and between the first and second paper paths and the third paper path. Since the conveyance reversing means is provided, the recording paper is conveyed to the discharge tray via the third paper path, and the conveyance reversing operation for returning to the second paper path in order to perform double-sided recording on the one-side recorded recording paper is performed. It can be performed simultaneously by the conveyance reversing means. Since the third paper path can be used as a path for performing both the transport for discharging and the transport for reversing, the apparatus can be made compact, and the recording paper discharged on both sides and the single-side recording can be recorded. Since the operations of reversing the used recording paper can be overlapped, productivity during continuous duplex recording can be improved.

  In particular, the third paper path is provided by providing a second paper discharge tray in parallel with the third paper path and switching means for switching to either the third paper path or the second paper discharge tray. Can be switched between the case of discharging to the paper discharge tray and the case of discharging to the second paper discharge tray, for example, it is possible to discharge separately for double-sided recording and for single-sided recording. In this case, the third paper path provided in parallel with the second paper discharge tray can be used for both the reversing of the recording paper on one side and the conveyance for discharging the recording paper. For example, since it is not necessary to provide a separate path for reversal, the size of the apparatus can be prevented, and the single-sided recording paper is not once exposed to the outside (on the paper discharge tray), thereby improving the aesthetics. obtain.

  In addition, by configuring the conveyance reversing means with three rollers, the recording paper is conveyed to the third paper path side between the intermediate common roller and one roller while the rotation direction of each roller remains constant. However, since the recording paper can be returned to the second paper pass side between the common roller and the other roller, there is no useless part when returning the recording paper on which one side has been recorded in the third paper pass, and both sides recording is performed. The productivity of time can be improved.

  By providing the first to third paper paths, the purpose of improving the productivity at the time of double-sided recording is realized without causing an increase in the size of the apparatus.

  FIG. 1 is a side view showing a schematic configuration of, for example, a facsimile / copy multifunction peripheral as an image forming apparatus to which the present invention is applied. The recording paper conveyance device or the image forming apparatus according to the present invention is not limited to the application to the above-mentioned multifunction peripheral, and can be applied to various devices that record on both sides of the recording paper.

  In the MFP shown in the drawing, a sheet feeding cassette 2 that accommodates a bundle of recording sheets PP and is disposed at the lower part of the main body 1 and a recording sheet fed from the sheet feeding cassette 2 are moved upward in the figure. A first paper path 3 serving as a path for transporting the recording paper, and a path for transporting the recording paper from the discharge side of the first paper path 3 to the paper feeding side, provided alongside the outer portion of the first paper path 3. A second paper path 4, and a third paper path 5 serving as a path for conveying the recording paper in a substantially horizontal state from the discharge side of the first paper path toward the side opposite to the first paper path side; Is provided. Each of the paper paths 3 to 5 includes a plurality of pairs of rollers arranged at appropriate positions so as to convey the recording paper while sandwiching the recording paper, and a guide surface that forms a conveyance path between the pair of rollers. ing. Each pair of rollers may be a combination of a driving roller and a driven roller, and at least one of them is coated with a rubber material to generate a frictional force between the recording paper and the recording paper. For example, a driven roller is elastically urged against the drive roller so that the two are pressed against each other.

  In the main body 1, an intermediate transfer body 6 is provided for transferring an image to one side of the recording paper passing through the first paper path 3. The intermediate transfer body 6 has a configuration in which the transfer belt 8 is stretched between a pair of rollers 7 a and 7 b that are spaced apart from each other and provided in parallel, with one roller 7 a facing the intermediate portion of the first paper path 3. It is set so that you can. Below the intermediate transfer member 6 in the illustrated example, four developing units 9 including three primary colors and black OPCs and developing units are arranged, and an LSU (laser) is provided on each OPC of each developing unit 9. A latent image exposed by the scanning unit 10 is formed and developed by each developing device.

  The first paper path 3 includes a third paper path from a first paper feed roller 3a provided at an adjacent position so as to face a pickup roller 2a provided at a recording paper feed port of the paper feed cassette 2. Via a first paper discharge roller 3 b provided on the side 5, a two-way conveyance roller 11 as a conveyance reversing means provided between the first paper discharge roller 3 b and the third paper path 5 is provided. It is provided to reach. The two-way transport roller 11 is composed of three rollers, an intermediate drive roller 11a and two driven rollers 11b and 11c arranged so as to sandwich the intermediate drive roller 11a. Further, in the path of the first paper path 3, one roller 7a of the intermediate transfer body 6 and a corresponding driven roller are provided, and a fixing device 12 is provided on the recording paper discharge side. Each pair of transport rollers is provided at an appropriate position according to the specification of the length in the transport direction of the recording paper.

  The second paper path 4 is supplied from the two-way transport roller 11 via the second paper feed roller 4a provided at a position adjacent to the first paper discharge roller 3b of the first paper path 3. It is provided so as to reach the second paper discharge roller 4b provided at a position adjacent to the paper feed roller 3a. Also in the path of the second paper path 4, a pair of transport rollers are disposed at appropriate positions according to the specification of the length in the transport direction of the recording paper.

  The third paper path 5 is provided in a range from the two-way conveyance roller 11 to a position facing the outside of the main body 1. In the path of the third paper path 5, a plurality of transport rollers 5a are disposed at a predetermined pitch according to the specification of the length in the transport direction of the recording paper.

  Further, between the first paper discharge roller 3 b and the second paper feed roller 4 a and the two-way conveyance roller 11, the recording paper discharged from the first paper path 3 is placed at the center of the two-way conveyance roller 11. A first path switching guide piece 13 is provided as switching means that can be selectively guided between the lower roller and the upper driven roller in the drawing relative to the common roller. Between the two-way transport roller 11 and the third paper feed roller 5a, the recording paper transported from the first paper path 3 through the lower rollers of the two-way transport roller 11 is transferred to the third paper path. And a position for guiding the recording paper fed to the third paper path 5 toward the second paper path 4 between the upper rollers of the two-way conveyance roller 11. A second path switching guide piece 14 that tilts so as to be able to selectively take two positions is provided. These two path switching guide pieces 13 and 14 also constitute a conveyance reversing means. These paper paths 3 to 5 and both switching guide pieces 13 and 14 constitute a recording paper transport device.

  The portions forming the first and second paper paths 3 and 4 are arranged on the side of the main body 1 so that the recording paper can be removed when a paper jam occurs in the middle of each paper path 3 and 4. A plurality of opening / closing bodies that can be freely opened and closed are provided. In the illustrated example, a plurality of opening / closing bodies are provided so that the paper paths 3 and 4 are divided into an upper half including the fixing device 12 and a lower half thereof so that the paper paths 3 and 4 can be exposed. Yes.

  Here, it shows about the structure of each said opening-closing body. In addition, the guide surface of each paper path 3-5 is formed by the surface which mutually opposes in the main body 1 and each opening / closing body, and the drive roller and driven roller which make each pair are separated from each other in the door open state of the opening / closing body. It is provided in each member. Between the first paper feed roller 3 a and the fixing device 12 in the first paper path 3, a first opening / closing body 15 that forms a guide surface in the front and rear range of one roller 7 a of the intermediate transfer body 6 is provided. And an auxiliary opening / closing body 16 that forms a guide surface between the end of the first opening / closing body 15 on the side of the sheet feeding cassette 2 and the first sheet feeding roller 3a (sheet feeding port). Yes. In addition, a second opening / closing body 17 is provided between the fixing device 12 and the first path switching guide piece 13 in the first paper path 3 together with the fixing device 12 to form a guide surface in the range. . The upper guide surface including the fixing device 12 in the second paper path 4 is also formed by the second opening / closing body 17 together with the fixing device 12.

  On the lower half side of the second paper path 4, a third opening / closing that forms a guide surface extending from the boundary with the second opening / closing body 17 in the second paper path 4 to the vicinity of the second paper discharge roller 4 b. A body 19 is provided. The third opening / closing body 19 is tiltably attached to the first opening / closing body 15 with the lower end portion in the drawing supported by the lower end portion of the first opening / closing body 15 so as to be tiltable. The auxiliary opening / closing body 16 is further attached to the first opening / closing body 15 so as to be tiltable.

    In each of the first to third opening / closing bodies 15, 17, 19, the first and second opening / closing bodies 15, 17 are pivotally supported with respect to the main body, and the third opening / closing body 19 is As described above, the lower end portion is pivotally supported by the first opening / closing body. Further, the first and second opening / closing bodies 15 and 17 are locked by latch means (not shown) having an upper end portion provided between the main body 1 and the third opening / closing body 19 has the upper end portion of the first opening / closing body 15, 17. It is locked by a latch means (not shown) provided between the opening / closing body 15.

  The lower guide surface in the third paper path 5 that extends horizontally to the main body 1 is formed by a corresponding portion of the main body 1 and is provided so as to cover the lower guide surface from above. An upper guide surface is formed by the five opening / closing bodies 20. The fifth opening / closing body 20 may be tiltable upward or detachable upward. Thereby, a paper jam in the third paper path 5 can be dealt with.

  In addition, although the manual feed tray 21 is provided below the third opening / closing body 19, the manual feed tray 21 is optional and may not be attached. Further, an upper part of the main body 1 is provided with a document placing table 22, a document cover 23, an optical image reading device (not shown), and the like, which are not different from a known copying machine. Therefore, explanation here is omitted.

  An external paper discharge tray 25 is attached to the side surface of the main body 1 opposite to the open / close bodies 15, 17, and 19. An internal paper discharge tray 24 as a second paper discharge tray is formed in a portion below the third paper path 5 in the main body 1, which is recessed with respect to the side surface (the front surface of the main body 1). Is provided.

  Next, the operation procedure at the time of double-sided recording of the apparatus of the present invention will be described below with reference to FIGS. 2A to 2G schematically showing the main part of FIG.

  First, the first recording paper P1 is pulled out from the paper feed cassette 2 as shown in FIG. 2A, and is transported through the first paper path 3 by the first paper feed roller 3a and other transport rollers. In the meantime, the image is recorded on one side (surface) by passing through the intermediate transfer member 6 and the fixing device 12. When the recording paper P1 is discharged from the first paper path 3, the first path switching guide piece 13 is positioned on the side facing the first paper path 3 and discharged from the first paper path 3. The one-side recorded recording paper P1 is guided between the intermediate driving roller 11a and the upper driven roller 11b of the two-way conveying roller 11. The second path switching guide piece 14 is positioned on the side facing the intermediate driving roller 11a and the upper driven roller 11b of the direction conveying roller 11 as shown by the solid line in the figure.

  The state of each of the path switching guide pieces 13 and 14 is shown enlarged in FIG. As shown in FIG. 3A, when the first recording paper P1 is discharged from the first paper path 3, the rotation direction of the intermediate drive roller 11a of the two-way transport roller 11 is as shown in FIG. It is counterclockwise as indicated by the arrow. In this way, the first sheet of recording paper P1 is sent to the third paper path 5. When recording on both sides, the recording paper P1 is reversed from the third paper path 5 to the second paper path 4 in order to record on the other side (back side) of the recording paper P1.

  When the recording paper P1 is reversed, as shown in FIG. 3B, the intermediate drive roller 11a is moved in the clockwise direction indicated by the arrow in the figure before the trailing end of the recording paper P1 passes through the two-way conveyance roller 11. Reverse. This reverse rotation control is possible by providing a paper detection sensor 26 at a predetermined position on the first path switching guide piece 13 side of the two-way transport roller 11 and performing reverse control when the passage of the recording paper is detected. It is. At the time of reverse rotation, the first path switching guide piece 13 is switched to the side facing the second paper path 4 as shown in FIG. As a result, the recording paper P1 is fed by the two-way transport roller 11 toward the second paper path 4 as indicated by an arrow A in FIG.

  At this time, as shown in FIG. 2B, the second recording paper P2 is taken out from the paper feed cassette 2 in the same manner as in FIG. When the trailing edge of the first recording paper P1 starts to be conveyed through the second paper path 4, the first path switching guide piece 13 is switched to the first paper path 3 side, as shown in FIG. In this way, the second recording paper P2 is conveyed toward the third paper path 5 by the two-direction conveyance roller 11.

  Next, as shown in FIG. 2 (d), the first path switching guide piece 13 is switched to the second paper path 4 side as in FIG. The paper is conveyed toward the second paper path 4. At this time, the third recording paper P3 is taken out from the paper feed cassette 2 and started to be conveyed to the first paper path 3, and is returned from the second paper path 4 to the first paper path 3. If there is a possibility of interference between the recording paper P1 and the recording paper P3, the first recording is performed when the recording paper conveyed through the first paper path 3 is detected by a paper detection sensor (not shown). The paper P1 is stopped before the discharge end of the second paper path 4. This stop control may not be necessary depending on the relationship between the path length of each paper path 3 and 4 and the length in the conveyance direction of the recording paper.

  When the passage of the third recording paper P3 is detected by the paper detection sensor, the first recording paper P1 is conveyed to the first paper path 3. In this state, as shown in FIG. 2 (e), the second recording is performed on the first recording paper P1, and the second recording paper P2 is conveyed through the second paper path 4 to obtain three sheets. The recording paper P3 on which one side of the eyes has been recorded is conveyed to the third paper path 5.

  When the one-side recorded recording paper P3 and the double-side recorded recording paper P1 pass each other by the two-way conveyance roller 11, as shown in FIG. Positioned as shown in (b), the first recording sheet P1 is guided under the first switching guide piece 13, and the intermediate driving roller 11a and the lower driven roller 11c of the two-way conveying roller 11 are guided. The third recording paper P3 that is conveyed toward the middle and reversed from between the intermediate driving roller 11a and the upper driven roller 11b is guided on the upper side of the first switching guide piece 13, and the second paper path 4 is reached. Transport toward Further, the second switching guide piece 14 is switched to the side facing the intermediate drive roller 11a and the lower driven roller 11c, and the first recording paper P1 is transferred from the two-way conveyance roller 11 to the third paper path 5. To guide. In the state of FIG. 2F, the fourth recording paper P4 is taken out from the paper feed cassette 2, and the second single-side recorded recording paper P2 transported through the second paper path 4 is the above-mentioned. It has stopped like FIG.2 (d).

  Next, as shown in FIG. 2G, the first double-side recorded recording paper P1 is discharged to the external paper discharge tray 25 through the third paper path 5, and the second recording paper P2 is printed. Moves from the second paper path 4 to the first paper path 3, the third recording paper P 3 is conveyed through the second paper path 4, and the fourth recording paper P 4 is transferred from the first paper path 3. Guided toward the third paper path 5. Thereafter, the first recording sheet P1 on which double-sided recording has been performed is discharged to the external discharge tray 25, and each recording sheet is in the state shown in FIG. ) Will be repeated.

  In the illustrated example, the recording paper on which double-side recording has been performed is discharged to the external paper discharge tray 25 via the third paper path 5, but it can also be discharged to the internal paper discharge tray 24. In this case, the second path switching guide piece 14 is positioned as shown by the imaginary line in FIG. 2F, and the recording paper is placed under the second switching guide piece 14 in the internal paper discharge tray 24. Guide to the side. This selection may be arbitrarily set by the user.

  Further, when the recording is finished only on one side, the two-way conveyance roller 11 is not reversed when the recording paper on which one side has been recorded passes through the first paper path 3 and is sent to the third paper path 5. By continuing to drive in the direction of conveyance toward the discharge side, the sheet can be discharged to the external discharge tray 25 as it is. When discharging to the internal paper discharge tray 24, when the one-side recorded recording paper passes through the first paper path 3 and is sent to the third paper path 5, the second path switching guide is the same as described above. The piece 14 may be placed at the position indicated by the imaginary line in FIG. As described above, the recording paper can be freely distributed to any one of the internal paper discharge tray 24 and the external paper discharge tray 25 by the switching control of the path switching guide pieces 13 and 14.

  2A to 2G are steps a to g, and FIG. 4 shows an operation process for the recording paper. In the figure, the recording operation on one side (front / back) of each recording paper P1 to P5 and the conveying operation (reversing operation or passing through the reversing part) of each recording paper P1 to P5 are shown in a convex shape. Yes. In the drawing, it is shown that the reversing operation of the recording paper P3 can be performed almost in a superimposed manner as described above during the recording operation on the back surface of the recording paper P1 in the first step f. Similarly, in the second step f, it is shown that the reversing operation of the recording paper P4 can be substantially overlapped during the recording operation on the back surface of the recording paper P2. Specifically, during the recording operation in which the recording paper passes through the intermediate transfer member 6 and the fixing device 12, the front end of the recording paper conveyed while being recorded and the recording paper that is reversed by the third paper path 5 are recorded. Interference with the rear end portion is prevented by the switching operation of the two path switching guide pieces 13 and 14, and both recording sheets can be moved over and under the two-way transport roller 11, so that the above operation is repeated. The combination is realized. Thereby, the productivity at the time of double-sided recording can be improved.

  The productivity is shown below in comparison with continuous single-sided recording. 2 (f), the recording paper P1 is a recording paper that is ejected as recorded, and the recording paper P4 is taken out from the paper feed cassette 2 to be recorded next. This corresponds to recording paper conveyed to one paper path 3. At the time of continuous single-sided recording, there is no recording paper P3 to be reversed toward the second paper path 4 shown in FIG. 2 (f), so the recording paper ejected by the two-way conveyance roller 11 and the recording paper to be reversed Mutual interference can be ignored, and continuous recording paper can be conveyed as close as possible.

  On the other hand, in the conveyance of the recording paper at the time of continuous double-sided recording according to the present invention, double-sided recording can be performed continuously to the same extent as at the time of continuous single-sided recording. Specifically, after the recording paper P3 to be reversed toward the second paper path 4 shown in FIG. 2 (f) is discharged from the third paper path 5, the double-side recorded recording paper P1 is transferred to the third paper path P3. Since it is transported to the paper path 5, it takes more time to discharge the paper than the continuous single-sided recording because of the margin. However, assuming that the productivity when performing single-sided recording on 10 sheets of recording paper is 100%, the productivity when performing double-sided recording on 10 sheets of recording paper as described above is 85%. The productivity at the time of continuous double-sided writing could be increased.

  The control in the reverse conveyance can be improved, and the operation procedure is shown with reference to FIG. In FIG. 5, the double-sided recorded recording paper P1 is conveyed from the first paper path 3 toward the third paper path 5, and the single-sided recorded recording paper P3 is transferred from the third paper path 5 to the second paper. The state conveyed toward the path 4 is shown. In this case, both the single-side recorded recording paper P3 and the double-side recorded recording paper P1 use the third paper path 5 as a common transport path. However, as shown in FIG. The rear end portion of P3 and the front end portion of the double-side recorded recording paper P1 may be rubbed. In this way, the recording paper P1 and P3 can be efficiently transported to the third paper path 5, and productivity during continuous recording can be improved. The productivity value can be 95%, and the productivity is comparable to continuous single-sided recording.

  INDUSTRIAL APPLICABILITY The recording paper transport apparatus and the image forming apparatus according to the present invention have the effect of improving the productivity at the time of double-sided recording while reducing the size of the apparatus, and transporting the recording paper in a facsimile / copy multifunction machine capable of double-sided recording. It is useful as an apparatus and an image forming apparatus.

1 is a side view illustrating a schematic configuration of a multifunction machine to which the present invention is applied. (Example 1) It is explanatory drawing which shows the operation | movement point at the time of double-sided recording. (Example 1) It is explanatory drawing which shows the operation | movement point at the time of double-sided recording. (Example 1) It is explanatory drawing which shows the operation | movement point at the time of double-sided recording. (Example 1) It is explanatory drawing which shows the operation | movement point at the time of double-sided recording. (Example 1) It is explanatory drawing which shows the operation | movement point at the time of double-sided recording. (Example 1) It is explanatory drawing which shows the operation | movement point at the time of double-sided recording. (Example 1) It is explanatory drawing which shows the operation | movement point at the time of double-sided recording. (Example 1) It is explanatory drawing which shows the conveyance point in an inversion part. (Example 1) It is explanatory drawing which shows the conveyance point in an inversion part. (Example 1) It is a time chart which shows the operation timing at the time of double-sided recording. (Example 1) It is explanatory drawing which shows the conveyance point in an inversion part. (Example 2)

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main body 2 Paper feed cassette 3 1st paper path 4 2nd paper path 5 3rd paper path 6 Intermediate transfer body 9 Development unit 11 Two-way conveyance roller 12 Fixing device 13 1st path switching guide piece 14 2nd Path switching guide piece 24 Internal discharge tray 25 External discharge tray

Claims (6)

  A first paper path for feeding recording paper fed from the paper feed cassette to the paper discharge tray side through the image forming means, and a first paper path from the paper discharge tray side of the first paper path. A second paper path for conveying recording paper to the paper feed cassette side, a third paper path provided between the first and second paper paths and the paper discharge tray, The recording paper can be transported from the first paper path toward the third paper path, and the recording paper transported to the third paper path can be reversed toward the second paper path. A recording paper transporting apparatus comprising transporting and reversing means provided between the first and second paper paths and the third paper path. A second paper discharge tray is provided in parallel with the third paper path;
Between the first paper path and the third paper path, the discharge destination of the recording paper discharged from the first paper path is either the third paper path or the second paper discharge tray. 2. A recording paper conveying apparatus according to claim 1, further comprising a switching means for switching to the above.   The conveyance reversing unit includes three rollers including two rollers arranged with a common roller interposed therebetween, and discharges the recording paper sent from the first paper path between one pair of rollers. The recording paper conveyed in the direction and conveyed to the third paper path between the other pair of rollers is conveyed toward the second paper path. Recording paper transport device.   Image forming means disposed between a paper feed cassette and a paper discharge tray to form images on both sides of the recording paper, and transport control means for controlling the transport so that the recording paper passes through the image forming means twice. A first paper path for feeding recording paper fed from the paper feed cassette to the paper discharge tray side through the image forming means, and the first paper from the paper discharge tray side of the first paper path. A second paper path for conveying recording paper to the paper feed cassette side of the path, and a third paper path provided between the first and second paper paths and the paper discharge tray The recording paper can be transported from the first paper path toward the third paper path, and the recording paper transported to the third paper path can be reversed toward the second paper path. As described above, the conveyance reversing means provided between the first and second paper paths and the third paper path An image forming apparatus, comprising a.   A second paper discharge tray is provided in parallel with the third paper path, and the recording paper discharged from the first paper path is between the first paper path and the third paper path. 5. The image forming apparatus according to claim 4, further comprising switching means for switching a discharge destination to either the third paper path or the second paper discharge tray. The conveyance reversing unit includes three rollers including two rollers arranged with a common roller interposed therebetween, and discharges the recording paper sent from the first paper path between one pair of rollers. 6. The recording paper transported in the direction and transported to the third paper path between the other pair of rollers is transported toward the second paper path. Image forming apparatus.

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