JP4463022B2 - Paper reversing device and image forming apparatus equipped with the same - Google Patents

Description

  The present invention relates to a sheet reversing apparatus that reverses the front and back of a sheet, and an image forming apparatus equipped with the sheet reversing apparatus.

  Some image forming apparatuses such as copying machines and printers have a duplex printing function. The double-sided printing function enables printing on the other side of the paper on which the toner image is transferred to one side in the image forming unit and the paper is passed through the fixing unit by switching the paper transport direction. Conventionally, a switchback method has been proposed as a general method of switching the paper transport direction. In the switchback method, a sheet of paper with an image printed on one side is conveyed to a predetermined sheet conveyance path, where the conveyance of the sheet is temporarily stopped, and then the direction of sheet conveyance is determined when entering the sheet conveyance path. The paper conveyance is resumed by reversing the rotation. Various configurations have been put to practical use as the configuration of the switchback type paper transport path.

However, when switching the paper transport direction by the switchback method, there is a problem that the top and bottom of the printed images on both sides are reversed when printing one side of the paper and when printing the other side. there were. Thus, in order to realize double-sided printing with the top and bottom aligned, a paper rotation device that reverses the top and bottom of the paper has been disclosed and proposed (see, for example, Patent Documents 1 to 3).
JP-A-5-301659 (page 4, FIG. 1) Japanese Patent Laid-Open No. 7-112852 (page 3, FIG. 6) JP-A-8-143185 (page 5, FIG. 1)

  Certainly, a paper reversing device that is a combination of a conventional switchback device and a paper rotating device can perform double-sided printing with the top and bottom of a double-sided printed image on an image forming apparatus equipped with it. is there.

  However, in the conventional paper reversing device, since the paper is directly carried into the switchback device and the paper rotating device, the next paper can be newly carried in as long as the first paper remains in the mechanism. could not. Further, in the conventional paper reversing device, it is necessary to perform a two-stage process of paper reversal processing and top / bottom reversal processing when realizing the paper reversal in which the top and bottom of the double-sided printed image are aligned. For this reason, the productivity of the paper reversing process by the conventional paper reversing device, that is, the double-sided productivity of the image forming apparatus equipped with the paper reversing device is not necessarily high.

  In addition, since the conventional paper reversing device is configured to switch the paper transport direction by the switchback method, an extra paper transport path is required, and a paper rotating device is additionally required in addition to the switchback device. there were. Therefore, in the conventional paper reversing device, the increase in the device scale and the accompanying increase in the installation floor area have been problems. Further, in the conventional sheet reversing device, the mechanism and control are complicated, and the cost is increased due to the increase in the number of parts.

  SUMMARY An advantage of some aspects of the invention is that it provides a paper reversing apparatus capable of improving the productivity of paper reversing processing and an image forming apparatus equipped with the paper reversing apparatus.

  In order to achieve the above object, a sheet reversing device according to the present invention includes a plurality of reversing front bases for temporarily placing sheets before reversing, and a refeed for temporarily placing reversed sheets. A paper front table, a paper reversing mechanism for reversing the front and back of the paper placed on the reversing front table and transporting it to the refeeding front table, and the carried paper before the reversing And a separation mechanism that separates and conveys to any one of the tables. With such a configuration, it is possible to newly carry in the next sheet without waiting for completion of the reversal of the starting sheet, and it is possible to improve the productivity of the sheet reversing process.

  In the sheet reversing apparatus having the above-described configuration, the reversing front stage and the refeeding front stage are arranged side by side in the vertical direction, and the paper reversing mechanism includes the reversing mechanism. A reversing roller that is provided adjacent to one side edge of the front table and the refeeding front table and rotates about the paper conveyance direction, and a sheet placed on the reversing front table is used as the reversing roller. It is preferable to have a configuration including a sheet slide mechanism that horizontally moves the sheet and a curved member that reversely guides the sheet fed by the reversing roller to the refeeding front table. By adopting such a configuration, it is possible to realize paper reversal in which the top and bottom of the double-sided printed image are aligned in a single process, and it is possible to improve the productivity of the paper reversal process. Also, with this configuration, no switchback device or device rotation device is required to realize paper reversal with the top and bottom of the double-sided printed image. Therefore, the device scale can be reduced, the installation floor area can be reduced, the reversing mechanism and control can be performed. It is possible to reduce costs by simplifying and reducing the number of parts.

  In the sheet reversing apparatus having the above-described configuration, the sheet sliding mechanism may be configured to include a separate and independent sheet abutting plate for each of the plurality of reversing front stands. By adopting such a configuration, while the starting sheet placed on a certain reversing front stage is being slid, or the sheet abutting plate that has finished sliding movement of the starting sheet reaches its standby position. While the sheet is being returned, the next sheet can be carried into another reversing stage, so that the productivity of the sheet reversing process can be further improved.

  The paper reversing device having the above-described configuration includes a plurality of the refeeding front tables, and the paper whose front and back are reversed by the paper reversing mechanism is set to any one of the refeeding front tables. A second sorting mechanism for sorting and transporting may be used. With such a configuration, the next inverted sheet is transported to the refeed front stage without waiting for completion of refeeding of the first sheet (that is, completion of emptying of the refeed stage). Therefore, the productivity of the paper reversing process can be further improved.

  In addition, an image forming apparatus according to the present invention is configured to include any one of the above sheet reversing devices. With this configuration, it is possible to improve the double-sided productivity of the image forming apparatus.

  As described above, the paper reversing apparatus according to the present invention and the image forming apparatus equipped with the paper reversing apparatus can improve the paper reversing process productivity (and thus improve the double-sided productivity of the image forming process). It becomes.

  Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS.

  First, an image output operation of an image forming apparatus equipped with a sheet reversing device according to the present invention will be described with reference to FIG. FIG. 1 is a vertical sectional front view schematically showing a configuration example of an image forming apparatus equipped with a sheet reversing device according to the present invention. In the following description, “front side” means the front side of the image forming apparatus and the side where the user stands for operating the apparatus.

  As shown in the figure, an image forming apparatus 100 according to the present invention includes a cassette type paper feeding unit 101, a manual paper feeding unit 102, a paper transport unit 103, a document feeding unit 104, an optical unit 105, and image formation. The image forming apparatus includes a unit 106, a transfer unit 107, a fixing unit 108, a discharge / branching unit 109, and a sheet reversing unit 1. In addition, the solid line arrow in the drawing indicates the conveyance path of the paper P.

  Although not shown in the figure, the image forming apparatus 100 according to the present invention includes a control unit (CPU [Central Processing Unit] and the like) that controls each unit of the apparatus, various information in addition to the above-described components. A display unit for displaying a user, an operation unit for accepting user operations, a memory unit used as a storage area for control programs, a storage area for image data, and a development area, and an information processing apparatus connected via a network Various circuit elements such as a communication unit and a network control unit for establishing a connection with a public telephone line or a modem for performing mutual conversion between image data and a facsimile signal are provided.

  In the cassette type paper supply unit 101, sheets P (cut paper or the like) before printing are stacked and stored, and the sheets P are separated and sent out one by one. The manual paper feed unit 102 is loaded with paper P having a size that is not in the cassette type paper feed unit 101, or an OHP sheet that is to be fed one by one. The paper P sent out from the cassette type paper supply unit 101 is vertically conveyed along the side surface of the main body of the image forming apparatus 100 by the paper conveyance unit 103, and the paper P sent out from the manual paper supply unit 102 is conveyed horizontally and transferred. Part 107 is reached.

  When the user copies an original, an original on which images such as characters, graphics, and patterns are drawn is loaded on the original feeding unit 104. The document feeding unit 104 separates the documents one by one and feeds the document, and the optical unit 105 reads the image data. The image forming unit 106 creates an electrostatic latent image of the document image. A toner image is formed from the electrostatic latent image, and the toner image is transferred by the transfer unit 107 to the pre-printing paper P sent in synchronization by the paper transport unit 103.

  Thereafter, the paper P carrying the unfixed toner image is sent to the fixing unit 108 and the toner image is fixed by the heat roller. The sheet P discharged from the fixing unit 108 is discharged from the discharge / branch unit 109 to a sheet receiving tray outside the apparatus. When performing duplex printing, the paper P discharged from the fixing unit 108 is sent to the paper reversing unit 1 via the discharge / branching unit 109, and the paper reversing device 10 provided in the paper reversing unit 1. As a result, the front and back sides of the paper P are reversed and sent again from the paper transport unit 103 to the transfer unit 107.

  Next, the structure of the first embodiment of the sheet reversing device 10 which is a characteristic part of the present invention will be described with reference to FIGS. FIG. 2 is a vertical sectional front view (Z sectional view of FIGS. 3 and 4) schematically showing the first embodiment of the sheet inverting device 10, and FIG. 3 shows the first embodiment of the sheet inverting device 10. FIG. It is a horizontal section top view (Y sectional view of Drawing 2 and Drawing 4) showing typically. FIG. 4 is a vertical cross-sectional side view (X cross-sectional view of FIGS. 2 and 3) schematically showing the first embodiment of the sheet reversing device 10. A thick two-dot line in each drawing indicates the paper P.

  As shown in FIG. 2, the sheet reversing device 10 of the present embodiment includes first and second reversing heads 11 and 12 for temporarily placing the sheet P conveyed from the fixing unit 108 before reversing. , And a refeed front stage 13 for temporarily placing the inverted paper P before refeeding. In addition, each front stand 11-13 is arranged in parallel by shifting the position in the vertical direction in the illustrated order. FIG. 2 shows a configuration in the case where the paper P is transported (carrying-in / re-feeding) horizontally from the left side of the paper surface to the right side of the paper surface. The length is designed to be longer than the maximum conveyance direction length of the paper P that can be reversed by the paper reversing device 10.

  Further, a flap plate 12x for separating the paper P into the first and second reversing front bases 11 and 12 is provided at the front edge (left end of the paper surface) of the second reversing front base 12. It has been. The flap plate 12x has a rotation shaft at its rear end (right end on the paper surface), and its front end (left end on the paper surface) is rotated around the rotation shaft. More specifically, the front end portion of the flap plate 12x is based on a position that is substantially horizontal with a paper insertion surface of an upstream nip 14 to be described later. In order to block the conveyance path to the second reversing front stage 12, it is tilted upward, and conversely, when carrying paper into the second reversing front stage 12, the transport path to the first reversing front stage 11. It is tilted down to shut off.

  An upstream conveying roller 14 a is provided on the upstream side of the first and second reversing heads 11 and 12 in the sheet conveying direction. The upstream transport roller 14a is in contact with the upstream pinch roller 14b at the uppermost portion thereof, and an upstream nip 14 is formed by both rollers. The upstream conveyance roller 14a is rotated clockwise by the motor (not shown), and the upstream pinch roller 14b is rotated counterclockwise according to the rotation of the upstream conveyance roller 14a. By such rotational driving, the sheet P inserted through the upstream nip 14 is fed from the left side of the sheet to the right side of the sheet. Although not shown in the drawing, the upstream-side transport roller 14a is provided with a paper position detection actuator that detects the arrival and passage of the paper P.

  On the other hand, a downstream side conveyance roller 15a is provided on the downstream side of the sheet refeeding stage 13 in the sheet conveyance direction. The downstream conveying roller 15a is in contact with the downstream pinch roller 15b at the uppermost portion, and a downstream nip 15 is formed by both rollers. The downstream conveying roller 15a is rotated clockwise by the motor (not shown), and the downstream pinch roller 15b is rotated counterclockwise according to the rotation of the downstream conveying roller 15a. By such rotational driving, the paper P inserted into the downstream nip 15 is fed from the left side of the paper surface to the right side of the paper surface. Although not shown in the drawing, the downstream transport roller 15a is provided with a paper position detection actuator for detecting the arrival and passage of the paper P.

  Further, the downstream side pinch roller 15 b is provided with a forward feed device 20 including a forward feed roller 21 and a rotating arm 22. The front feed roller 21 is rotated counterclockwise by a motor (not shown), and feeds the paper P on the refeeding front table 13 that is in contact with the lowermost portion thereof toward the downstream nip 15. The rotating arm 22 supports the forward feed roller 21 and is rotated around the axis of the pinch roller 16 by a motor (not shown). By this turning operation, the turning arm 22 causes the forward feed roller 21 to abut against or separate from the paper P on the paper re-feeding base 13.

  On the other hand, as shown in FIGS. 3 and 4, the front side edges of the first and second reversing front stands 11 and 12 are notched in the center in the sheet conveyance direction, and the center notches A paper slide device 30 is provided in the sections 11a and 12a. The paper slide device 30 includes a paper abutting plate 31, a rack 32, a pinion 33, and a motor 34.

  The sheet abutting plate 31 has an L-shaped vertical cross section, and includes a horizontal portion 31a corresponding to the bottom of the L shape and an abutting portion 31b corresponding to the vertical side wall portion. The paper abutting plate 31 is formed and arranged so that the horizontal portion 31a is located below the first reversing front base 11 and the abutting portion 31b is located inside the central notches 11a and 12a. . The sheet abutting plate 31 is supported by a slide guide (not shown) so as to be horizontally movable in a direction perpendicular to the sheet conveying direction.

  The rack 32 is fixed to the bottom surface of the horizontal portion 31 a of the paper abutting plate 31 from the front side to the back side of the paper reversing device 10. A pinion 33 is engaged with the rack 32 to constitute a rack and pinion mechanism. The pinion 33 is fixed to a rotating shaft of a motor 34 provided on the bottom surface of the first reversing head 11 and is rotated by the motor 34. The sheet abutting plate 31 is horizontally moved back and forth by the horizontal movement mechanism including the rack 32, the pinion 33, and the motor 34. Therefore, when the paper abutting plate 31 is moved horizontally to the back side of the apparatus, the abutting portion 31b is brought into contact with the front side edge of the paper P at a certain time, and thereafter, the paper P is brought into contact with the abutting portion 31b. It is pushed and slid to the back side of the device.

  Further, as shown in FIG. 4, a reverse roller 40 is provided on the back surface of the paper reversing device 10. The reversing roller 40 is further on the back side than the first and second reversing front stands 11, 12, and the uppermost portion thereof is substantially the same height as the top surface of the refeeding front stand 13, and The lowermost portion is disposed so as to be at a height located between the first and second reversing heads 11 and 12. The reversing roller 40 is in contact with the upper pinch roller 41 and the lower pinch roller 42 at the uppermost part and the lowermost part, respectively, and upper and lower nips are formed between the pinch rollers. . Further, a curved guide plate 43 is provided on the back side of the reverse roller 40. The curved guide plate 43 is a curved member for reversely guiding the paper P conveyed by the reverse roller 40 from the lower nip to the upper nip, and is arranged along the outer periphery of the reverse roller 40 according to the curvature of the reverse roller 40. Has been.

  Here, the reverse roller 40 is rotated counterclockwise by a motor (not shown), and the upper and lower pinch rollers 41 and 42 are both rotated clockwise according to the rotation of the reverse roller 40. By such rotational driving, the paper P inserted into the lower nip is sent to the upper nip along the curved guide plate 43, and the paper P inserted into the upper nip is sent to the refeed front stage 13. Sent. Although not shown in the drawing, the reverse roller 40 is provided with a paper position detection actuator for detecting the arrival and passage of the paper P.

  Further, regarding the radius R of the reversing roller 40, the vertical distance between the contact point of the paper P conveyed from the second reversing front table 12 and the lowermost end (the paper insertion surface of the lower nip) is R /. It may be designed to be within 2 (preferably R / 3). Similarly, with respect to the radius r of the lower pinch roller 42, the vertical distance between the contact point of the paper P conveyed from the first reversing head 11 and its uppermost end (paper insertion surface of the lower nip). May be designed to fall within r / 2 (preferably r / 3).

  In addition, the rear side edge (the reverse roller 40 side end) of the second reversing front stage 12 may be subjected to a rounding process or the like so that the paper can be smoothly inserted into the lower nip.

  Next, the operation of the sheet reversing apparatus 10 having the above configuration will be described in detail with reference to FIG. 5 together with FIGS. FIG. 5 is a diagram for explaining the reversing operation of the paper P. Similar to FIG. 4, the schematic vertical sectional side view of the paper reversing device 10 (X sectional view of FIGS. 2 and 3). It represents. A thick two-dot chain line in the drawing indicates the paper P. Hereinafter, for convenience of explanation, the paper P is referred to as paper P1, P2, and P3 in the order of conveyance.

  First, when the paper P1 is carried in, if both the first and second reversing heads 11 and 12 are vacant, the paper reversing device 10 raises the tip of the flap plate 12x (see FIG. 2) upward. Tilt to block the conveyance path to the second reversing head 12. As a result, the sheet P1 fed by the upstream nip 14 (see FIG. 2) is conveyed to the first reversing front table 11 as shown in FIG. 5A. At this time, the sheet abutting plate 31 is in a standby state on the forefront side of the apparatus that does not interfere with sheet conveyance. The completion of the sheet conveyance is detected by using a sheet position detection actuator (not shown) of the upstream conveyance roller 14a (see FIG. 2).

  When the completion of conveyance of the sheet P1 with respect to the first reversing head 11 is detected, the sheet reversing device 10 starts the horizontal movement of the sheet abutting plate 31. When the paper abutting plate 31 is horizontally moved to the back side of the apparatus in this way, the abutting portion 31b is brought into contact with the front side end portion of the paper P1 at a certain point in time, and thereafter, the paper P1 is shown in FIG. As shown in b), it is pushed by the abutting portion 31b and slid to the back side of the apparatus. As a result, the rear side edge of the paper P1 is brought into contact with the lower nip at a certain time, and thereafter, the paper P1 is fed to the rear side of the apparatus by the rotational driving of the reverse roller 40 and the lower pinch roller 42. Given. On the other hand, the sheet abutting plate 31 finishes the operation of pushing the sheet P1 toward the rear side of the apparatus when the sheet P1 is caught in the lower nip, and waits for the previous state (non-interference that does not interfere with sheet conveyance). In order to return to the state, the horizontal movement direction is changed from the back side of the apparatus to the front side of the apparatus. During this time, new paper loading into the paper reversing device 10 is prohibited.

  The sheet P1 inserted into the lower nip by the above operation is sent to the upper nip along the curved guide plate 43 as shown in FIG. The sheet P1 inserted into the upper nip is fed to the front side of the apparatus by the rotational driving of the reverse roller 40 and the upper pinch roller 41. As a result, as shown in FIG. 5 (d), the sheet P1 is rotated about the sheet conveyance direction of the sheet reversing device 10, and is placed on the refeeding pre-stage 13 with its front and back reversed. Placed. The completion of the paper reversal placement is detected by using a paper position detection actuator (not shown) of the reversing roller 40. When the reverse placement completion of the paper P1 is detected, the paper reversing device 10 drives the downstream side conveyance roller 15a and the forward feeding device 20 (see FIG. 2), and starts refeeding the paper P1.

  On the other hand, the sheet reversing device 10 permits the transfer of a new sheet P2 without waiting for the completion of the reversal of the sheet P1 when the transition of the sheet abutting plate 31 that has finished the sliding operation of the sheet P1 is detected. To do. At that time, the sheet reversing device 10 inclines the front end portion of the flap plate 12x (see FIG. 2) downward to block the conveyance path to the first reversing stage 11. As a result, the sheet P2 fed by the upstream nip 14 (see FIG. 2) is conveyed to the second reversing front stage 12 as shown in FIG. 5C. The completion of the sheet conveyance is detected by using a sheet position detection actuator (not shown) of the upstream conveyance roller 14a (see FIG. 2).

  When the completion of the conveyance of the paper P2 to the second reversing stage 12 is detected, the paper reversing device 10 determines the time required for the slide movement of the paper P2, the time required for the reversal of the paper P1, P2, and the re-use of the paper P1. Considering the time required for paper feeding, the horizontal movement of the paper abutting plate 31 is started at the timing when the paper P2 does not interfere with the first paper P1. When the paper abutting plate 31 is horizontally moved to the back side of the apparatus in this way, the abutting portion 31b is brought into contact with the front side end portion of the paper P2 at a certain point in time, and thereafter, the paper P2 is shown in FIG. As shown in d), it is pushed by the abutting portion 31b and slid to the back side of the apparatus. As a result, the rear side edge of the paper P2 is brought into contact with the lower nip at a certain point, and thereafter, the paper P2 is fed to the rear side of the apparatus by the rotational driving of the reverse roller 40 and the lower pinch roller 42. Given. On the other hand, the sheet abutting plate 31 finishes the operation of pushing the sheet P2 toward the rear side of the apparatus when the sheet P2 is caught in the lower nip, and changes its horizontal movement direction so as to return to the previous standby state. Turn from the back of the device to the front of the device. During this time, new paper loading into the paper reversing device 10 is prohibited.

  The sheet P2 inserted into the lower nip by the above operation is sent to the upper nip along the curved guide plate 43 as shown in FIG. The sheet P2 inserted through the upper nip is fed to the front side of the apparatus by the rotational drive of the reverse roller 40 and the upper pinch roller 41. At this time, since the refeeding of the paper P1 has already been completed and the refeeding front stage 13 is empty, there is no problem in the reverse placement operation of the paper P2.

  Thereafter, by the same operation as described above, the paper reversing device 10 places the first paper without waiting for completion of reversal of the first paper when the standby state transition of the paper abutting plate 31 is detected. A new sheet is transported to the reversing head that is not turned on (see the sheet P3 in FIG. 5E).

  As described above, the sheet reversing device 10 of the present embodiment is configured to temporarily place the first and second reversing heads 11 and 12 for temporarily placing the unreversed sheets and the reversed sheets. Sheet feeding mechanism 13 and a sheet reversing mechanism that reverses the front and back of the paper placed on the first and second reversing heads 11 and 12 and transports the paper to the refeeding stage 13. 30 to 43, and a flap plate 12x that separates and conveys the loaded paper to any one of the first and second reversing heads 11 and 12. By adopting such a configuration, it is possible to newly carry in the next sheet without waiting for completion of the reversal of the first sheet, so that the productivity of the sheet reversal process is improved, and further, the double-sided production of the image forming apparatus 100 is achieved. It becomes possible to improve the property.

  Further, in the paper reversing device 10 of the present embodiment, the first and second reversing front bases 11 and 12 and the refeed front base 13 are arranged side by side in the vertical direction. The sheet reversing mechanism includes a reversing roller 40 and an upper side that are arranged adjacent to one side edge side of the first and second reversing front bases 11 and 12 and the refeed front stage 13 and rotate around the paper transport direction. Lower pinch rollers 41, 42, a sheet slide device 30 that horizontally moves the sheets placed on the first and second reversing heads 11, 12 toward the reversing roller 40, the reversing roller 40 and the upper side, A curved guide plate 43 that reversely guides the sheet fed by the lower side pinch rollers 41 and 42 to the refeed front stage 13 is provided. By adopting such a configuration, it is possible to realize sheet reversal in which the top and bottom of the double-sided printed image are aligned in a single process, and thus it is possible to improve the productivity of the sheet reversal process. Also, with this configuration, no switchback device or device rotation device is required to realize sheet reversal with the top and bottom of the double-sided printed image aligned, so the device scale can be reduced, the installation floor area can be reduced, and the mechanism and control can be reduced. It is possible to reduce the cost by simplifying and reducing the number of parts.

  In the above paper reversing operation, the forward speed of the paper slide device 30 (the horizontal movement speed toward the back side of the device) is the paper carry-in speed (that is, the image forming speed) to the paper reversing device 10 from the viewpoint of preventing jamming. It is better to set later than). On the other hand, the reverse speed of the paper slide device 30 (the horizontal movement speed toward the front side of the device) should be set as fast as possible in order to open the first and second reversing heads 11 and 12 early. Good. In addition, the refeed speed of the reversed paper (the transport speed from the refeed to the registration) is set higher than the paper carry-in speed to the paper reversing device 10 in order to open the refeed pre-stage 13 early. It is good to keep. Further, the reverse conveyance speed by the reverse roller 40 may be appropriately set in consideration of prevention of interference between the first sheet and the second sheet.

  Next, the structure and operation of the second embodiment of the sheet reversing device 10 according to the present invention will be described with reference to FIG. FIG. 6 is a vertical cross-sectional side view schematically showing the second embodiment of the paper reversing device 10. Note that the basic configuration of the present embodiment is the same as that of the first embodiment described above, and therefore, the same components as those described above are denoted by the same reference numerals and description thereof is omitted.

As shown in the figure, the sheet reversing device 10 according to the present embodiment includes separate and independent sheet abutting plates 31-1 and 31-2 for the first and second reversing heads 11 and 12, respectively. It is configured.
By adopting such a configuration, the paper abutting plate 31 while the first paper P1 placed on the first reversing front table 11 is being slid, or after the sliding movement of the paper P1 has been completed. While −1 is returned to the standby position, the next sheet P2 can be carried into the second reversing front stage 12. Although not shown in the figure, contrary to the above, while the first paper placed on the second reversing head 12 is being slid, or the paper is slid. Of course, the next sheet can be carried into the first reversing stage 11 while the finished sheet abutting plate 31-2 is returned to its standby position. Therefore, the sheet reversing device 10 of the present embodiment can further improve the double-sided productivity of the image forming apparatus 100 as compared to the first embodiment.

  Next, the structure and operation of the third embodiment of the sheet reversing device 10 according to the present invention will be described with reference to FIG. FIG. 7 is a vertical sectional front view (a) and a vertical sectional side view (b) schematically showing the third embodiment of the sheet reversing device 10. Note that the basic configuration of the present embodiment is the same as that of the first embodiment described above, and therefore, the same components as those described above are denoted by the same reference numerals and description thereof is omitted.

  As shown in the figure, the sheet reversing device 10 of the present embodiment has two stages of the refeeding front stage 13 and includes first and second refeeding front stages 13-1 and 13-2. It has been configured. In addition, each front stand 13-1 and 13-2 are arranged in parallel in the order shown in figure in the position shifted in the vertical direction.

  As shown in FIG. 7 (a), the downstream side end of the second refeeding front stage 13-2 has a central portion cut out in a rectangular shape. It is installed so as to be rotatable via the downstream notch 13-2a. With this configuration, the rotating arm 22 causes the front feed roller 21 to move to the front bases 13-1, 13- according to the presence / absence of a sheet on the second refeed front 13-2. 2 can be brought into contact with or separated from the paper P1, P2.

  Further, as shown in FIG. 7B, the first and second refeeding front bases 13-1 and 13 are placed on the rear surface of the second refeeding front base 13-2. -2 is provided with a flap plate 13-2b. The flap plate 13-2b has a rotation shaft at the front side end portion (left end portion on the paper surface) of the apparatus, and the tip end portion (right end portion on the paper surface) is rotated around the rotation shaft. More specifically, the front end of the flap plate 13-2b is based on a position that is substantially horizontal to the sheet insertion surface of the upper nip formed by the reversing roller 40 and the upper pinch roller 41. When the paper is carried into the paper pre-stage 13-1, it is tilted upward so as to block the conveyance path to the second re-feed pre-stage 13-2. When the paper is carried into the placing table 13-2, it is tilted downward so as to cut off the conveyance path to the first refeeding placing table 13-1.

  By adopting such a configuration, it is possible to wait for completion of re-feeding of the preceding paper (that is, completion of emptying of the re-feeding placement table), and the re-feeding front stand on which the preceding paper is not placed. It is possible to transport a new sheet. Accordingly, it is possible to further improve the double-sided productivity of the image forming apparatus 100 as compared to the first embodiment.

  In the above-described embodiment, the case where the present invention is applied to a paper reversing device of a right angle reversing method that rotates the paper around the paper conveyance direction and reverses the front and back has been described as an example. The application target of the invention is not limited to this, and the invention can be widely applied to a sheet reversing apparatus having a switchback method and other reversing mechanisms.

  Further, in the above-described embodiment, the description has been given by taking as an example the configuration in which the re-feeding front table is disposed above the reversing front table, but the configuration of the present invention is not limited thereto. Instead of the above, each position may be reversed upside down.

  Further, in the above embodiment, the description is given by taking as an example a configuration in which the reversing front stage is configured in two stages, or a configuration in which the reversing front stage and the refeeding front stage are each two stages. However, the configuration of the present invention is not limited to this, and the number of stages may be three or more.

  Further, in the above embodiment, the separation mechanism that separates and conveys the carried-in paper to any one of the first and second reversing heads 11 and 12, and the first and second refeeds of the reversed paper. Although the second sorting mechanism that sorts and transports the paper to the paper table 13-1 or 13-2 has been described as an example, a configuration in which flap plates 12x and 13-2b are provided, respectively. The configuration of the present invention is not limited to this, and any separation mechanism may be used as long as it can perform the same separation process as described above.

  The configuration of the present invention can be variously modified within the scope of the present invention in addition to the above embodiment.

  The present invention is a technique useful for improving the productivity of paper reversal processing, and is particularly suitable for a paper reversing apparatus mounted on an image forming apparatus that is required to improve double-sided productivity.

1 is a vertical sectional front view schematically showing a configuration example of an image forming apparatus equipped with a sheet reversing device according to the present invention. FIG. 2 is a vertical sectional front view schematically showing the first embodiment of the sheet reversing device 10. FIG. 2 is a horizontal sectional top view schematically showing the first embodiment of the sheet reversing device 10. FIG. 3 is a vertical cross-sectional side view schematically showing the first embodiment of the sheet reversing device 10. FIG. 5 is a diagram for explaining a reversing operation of the paper P. These are the vertical cross-section side views which show typically 2nd Embodiment of the paper inversion apparatus 10. FIG. These are the vertical cross section front view and vertical cross section side view which show typically 3rd Embodiment of the paper inversion apparatus 10. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Paper reversing part 10 Paper reversing apparatus 11, 12 1st, 2nd reversing front stand 11a, 12a Center notch part 12x Flap board 13 (13-1, 13-2) (1st, 2nd) Refeed Front stage 13-2a Downstream notch 13-2b Flap plate 14, 15 (Upstream / Downstream) Nip 14a, 15a (Upstream / Downstream) Conveying rollers 14b, 15b (Upstream / Downstream) Pinch Roller 20 Forward feed device 21 Forward feed roller 22 Rotating arm 30 Paper slide device 31, 31-1, 31-2 Paper abutting plate 31a Horizontal portion 31b Abutting portion 32 Rack 33 Pinion 34 Motor 40 Reverse roller 41, 42 ( Upper and lower) Pinch roller 43 Curved guide plate 100 Image forming apparatus 101 Cassette type paper feed unit 102 Manual paper feed unit 103 Paper transport unit 104 Original Ri 105 optical unit 106 the image forming unit 107 the transfer unit 108 fixing portion 109 releases and bifurcation P (P1 to P3) Paper

Claims (4)

A plurality of reversing heads for temporarily placing the paper before reversing, a refeeding front table for temporarily placing the reversed paper, and the reversing head. A sheet reversing mechanism for reversing the front and back of the conveyed paper and transporting it to the refeeding front table, and a separation mechanism for separating and transporting the loaded paper to any one of the reversing front table. adult Te is,
The reversing front stage and the refeeding front stage are arranged side by side in the vertical direction,
The sheet reversing mechanism is mounted on the reversing front table and a reversing roller that is provided adjacent to one side edge of the reversing front table and the refeeding front table and rotates about the paper transport direction. A paper slide mechanism that horizontally moves the placed paper toward the reversing roller, and a curved member that reversely guides the paper fed by the reversing roller to the refeeding front table. A sheet reversing device characterized by comprising:   2. The paper reversing device according to claim 1, wherein the paper sliding mechanism includes a separate paper abutting plate for each of the plurality of reversing front stands.   A plurality of the refeeding pre-stages, and a second sorting mechanism that separates and conveys the paper whose front and back are reversed by the paper reversing mechanism to any one of the refeeding pre-stages. The sheet reversing device according to claim 1, wherein the sheet reversing device is provided.   An image forming apparatus comprising the sheet reversing device according to claim 1.

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