JP2006111390A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device of compact device structure capable of efficiently conveying paper sheets when recording in both surfaces of the paper sheets. <P>SOLUTION: A one-surface recording paper sheet P1 stopping at a waiting position in a reverse conveying path is conveyed into a paper sheet conveying path, and a paper sheet 2 recorded in one surface thereof is conveyed into the reverse conveying path by reverse rotation of an ejection roller 24. Recording is performed to a surface, to which recording is not performed yet, of the paper sheet P1 carried into the paper sheet conveying path, and at the same time, the paper sheet P2 is reversely conveyed and stopped at the waiting position. Reverse conveying operation is performed so that the paper sheet P1 and the paper sheet P2 are replaced with each other. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile machine.

  Conventionally, in an image forming apparatus, recording has been performed on both sides of a sheet of paper. However, if there is a recording unit on only one side of the sheet, the sheet is reversed after recording on one side of the sheet. Recording on the other side. Therefore, when performing such a double-sided recording operation, there is a problem of how to efficiently and accurately perform the reverse conveyance operation of the paper.

For example, in Patent Document 1, the sheet processing apparatus includes a sheet processing unit, a sheet processing transport path, and a sheet transport section including a sheet reversal transport path, and the sheet reversal transport path is a plurality of sheet standbys. Each of the sheet standby areas is provided with a control means for temporarily placing the sheets in a standby state in a controlled manner. One-surface continuous processing step, alternating processing step, and multi-surface continuous processing The point that a process is performed continuously is described.
JP 2002-323800 A

  In Patent Document 1, the sheet reversing and conveying operation forms a plurality of sheet reversing conveying paths in the apparatus and enables various reversing conveying processes. In addition, the transport rollers for reversal transport are required for each transport path, and it is necessary to design a drive transmission mechanism and drive mechanism including these transport rollers, which complicates drive control and increases costs. I must.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus capable of efficiently performing a sheet transport operation when performing a double-sided recording operation on a sheet with a compact apparatus configuration.

  In the image forming apparatus according to the present invention, the paper transported from the paper feeding unit is transported to the recording unit and carried to the paper discharge tray, and the paper transporting path is carried in from the downstream side of the recording unit. In an image forming apparatus provided with a reverse conveyance path for carrying out a sheet to the upstream side of the recording unit, a paper discharge operation is performed by rotating a discharge roller forward and a reverse conveyance operation is performed by reversing the discharge roller. A drive unit, and a conveyance control so that a double-sided recording operation is performed in the recording unit by carrying out the one-side recorded sheet from the standby position in the reverse conveyance path to the sheet conveyance path and controlling the drive unit Reversal conveyance control means for carrying the next one-side recorded paper by the discharge roller into the reverse conveyance path and conveying it to the standby position, and single-side recording conveyed to the standby position by the reverse conveyance control means Paper conveyance control means for carrying the paper so that the single-sided recording operation is performed in the recording unit after carrying out the paper discharge operation of the paper recorded on both sides with the received paper waiting And the reverse conveyance control means and the paper conveyance control means are alternately performed. Further, the drive means connects the first drive source used in the paper transport path, the second drive source used in the reverse transport path, and the discharge roller to the first drive source to perform normal rotation. And a drive transmission means for connecting the discharge roller to the second drive source and reversing it.

  By having the above configuration, a single-sided recording sheet (hereinafter referred to as “single-sided recording sheet”) is unloaded from the standby position, and the next single-sided recording sheet is reversed by a discharge roller during the recording operation on the unrecorded surface. Since the paper is carried into the conveyance path, the next paper comes in following the carry-out of the paper in the reverse conveyance path, so that the reverse conveyance of the paper can be performed efficiently and the time required for the conveyance operation can be reduced. It can be shortened. In addition, since a new sheet is loaded from the paper feed unit and recorded on a single side while the single-sided recording sheet is on standby, the single-sided recording sheet on which the standby has been performed immediately after the single-side recording is performed on the new sheet is not transferred. Recording is performed on the recording surface. Then, the reverse conveyance control means and the paper conveyance control means are alternately performed, so that the single-sided recording operation on the new paper and the unrecorded surface recording operation on the single-sided recording paper are alternately processed without interruption. The double-sided recording operation of the paper can be performed continuously and efficiently.

  In addition, since the discharge roller is rotated forward to perform the paper discharge operation and the discharge roller is reversely rotated to perform the reverse conveyance operation, the conveyance roller necessary for the reverse conveyance operation can be used as the discharge roller. Furthermore, since the paper discharge path also serves as the reverse conveyance path, the space required for the reverse conveyance path can be saved.

  Further, the discharge roller driving means connects the first drive source used in the paper conveyance path, the second drive source used in the reverse conveyance path, and the discharge roller to the first drive source for normal rotation and the discharge roller. And a drive transmission means for connecting to the second drive source to reversely rotate, the drive control of the discharge roller can be smoothly performed when the paper conveyance control means and the reverse conveyance control means are alternately performed.

  Hereinafter, embodiments according to the present invention will be described in detail. The embodiments described below are preferable specific examples for carrying out the present invention, and thus various technical limitations are made. However, the present invention is particularly limited in the following description. Unless otherwise specified, the present invention is not limited to these forms.

  FIG. 1 is a schematic cross-sectional view of the entire image forming apparatus according to the present invention. A paper discharge tray 10 is provided in the upper part of the image forming apparatus 1, and a recording unit 2 and a paper supply unit 3 are arranged in the lower part thereof.

  In the paper feed unit 3, a paper feed cassette 11 is arranged, and a plurality of sheets of a predetermined size are stacked on the flapper 12. A pickup roller 13 is disposed at the right end of the paper feed cassette 11. The flapper 12 is urged upward by a spring member (not shown) so that the upper surface of the stacked paper comes into pressure contact with the pickup roller 13. When the pickup roller 13 is rotationally driven in this state, the sheets are fed one by one to the sheet conveyance path by the frictional force.

  The fed paper is first conveyed to the recording unit 2 by the feed roller 14 and the press roller 15. The recording unit 2 includes a developing device 16, a cleaning mechanism 17, a corona charger 18, a photosensitive drum 19, a transfer roller 20, an exposure unit 21, and a fixing roller 22 for recording on the conveyed paper. The cleaning mechanism 17 cleans the surface of the photoconductive drum 19 by capturing foreign particles such as residual toner and paper dust attached to the surface of the photoconductive drum 19 after the transfer with a cleaning roller. The corona charger 18 uniformly charges the surface of the photosensitive drum 19 by corona discharge from the discharge wire. An electrostatic latent image is formed on the uniformly charged photosensitive drum 19 by exposing the photosensitive drum 19 in accordance with an image recording signal. Then, the toner in the developing device 16 is transferred to the electrostatic latent image formed on the photosensitive drum 19 to visualize the electrostatic latent image. The transfer roller 20 is installed at a position facing the photosensitive drum 19 with the paper interposed therebetween, and a toner image formed on the surface of the photosensitive drum 19 is transferred to the paper when a predetermined voltage is applied. The transferred toner image is sandwiched between the fixing roller 22 and the press roller 23 and heated and pressed to be fixed on the paper. The fixed sheet is sent to the discharge path by the feed roller 34 and the press roller 35, is sandwiched between the discharge roller 24 and the press roller 25, and is carried out to the sheet discharge tray 10.

  Further, a manual paper feed mechanism and a reverse conveyance mechanism are provided on the side surface of the apparatus main body, and when performing manual paper feed, the side cover 26 is opened and the paper is inserted into the paper feed roller 27. . The inserted paper is conveyed to the feed roller 14 and the press roller 15 by the paper feed roller 27 and recording operation is performed. Also, when performing reverse conveyance, the paper recorded on one side is once sandwiched between the discharge roller 24 and the press roller 25 and then conveyed, and then the discharge roller 24 is rotated in reverse and conveyed to the reverse conveyance path. The paper is conveyed downward by two pairs of conveying rollers, that is, a feed roller 28 and a press roller 29, a feed roller 30 and a press roller 31. Then, the sheet is conveyed upward by the feed roller 32 and the press roller 33 and is conveyed again to the feed roller 14 and the press roller 15 to perform the recording operation on the other surface, so that recording is performed on both surfaces of the sheet. Become. In addition, a toner cartridge 36 in which toner is stored is detachably attached to the central portion of the image forming apparatus 1, and the toner in the toner cartridge 36 passes through a path (not shown). The developing device 16 is appropriately replenished.

  FIG. 2 is a schematic diagram illustrating an example of a driving mechanism for the paper transport unit and the reverse transport unit. The sheet conveyance path is drawn with a solid line, and the drive transmission path is drawn with a dotted line. A main motor 50 is disposed as a first drive source on the paper transport unit 40 side. The driving force of the main motor 50 is a pickup roller 13 and a feed roller 14 functioning as a registration roller by a drive transmission mechanism (not shown). It is transmitted to a plurality of roller members such as the photosensitive drum 19 and the fixing roller 22 arranged in the recording unit 2, the feed roller 34 and the discharge roller 24. An electromagnetic clutch 51 is provided in the drive transmission path between the discharge roller 24 and the main motor 50, and between the electromagnetic clutch 52 and the pickup roller 13 in the drive transmission path between the feed roller 14. An electromagnetic clutch 53 is provided in the drive transmission path, and an electromagnetic clutch 54 is provided in the drive transmission path to the feed roller 34.

  Further, a sub motor 55 is disposed as a second drive source on the reverse conveying unit 41 side, and the driving force of the sub motor 55 is discharged by the drive transmission mechanism (not shown), the feed roller 28, and the feed roller 30. And transmitted to the feed roller 32. An electromagnetic clutch 56 is provided in the drive transmission path between the discharge roller 24 and the sub motor 55.

  A sheet detection sensor 57 is disposed between the discharge roller 24 and the fixing roller 22 of the recording unit 2 in the conveyance path on the sheet conveyance unit 40 side, and between the roller pairs 14 and 15 and the pickup roller 13. A paper detection sensor 58 is disposed.

  FIG. 3 is a circuit block diagram for driving and controlling the drive mechanism shown in FIG. On the paper transport unit 40 side, a CPU 60 that performs information processing related to drive control, a paper detection circuit 61 that detects signals from the paper detection sensors 57 and 58, a driver circuit 62 that drives the main motor 50, electromagnetic clutches 51 and 52, A driver circuit 63 for driving 53 and 54 is provided, and a driver circuit 64 for driving the sub motor 54 and a driver circuit 66 for driving the electromagnetic clutch 56 are provided on the reverse conveyance unit 41 side. Each circuit is connected to the CPU 60.

  FIGS. 4 to 6 are explanatory diagrams illustrating the sheet conveying operation in the sheet conveying path and the reverse conveying path in the present embodiment. In FIG. 4, when a command signal for the duplex recording mode is input, the CPU 60 starts driving the main motor 50 to connect the electromagnetic clutch 53, and the first sheet P <b> 1 is fed by the sheet feed roller 13. . Then, when the leading edge of the paper P1 passes the paper detection sensor 58, the paper detection sensor 58 is turned on, and the CPU 60 is connected to the electromagnetic clutches 51 to 54 as appropriate, and is arranged on the feed roller 14 and the recording unit 2 of the paper transport unit 40. A plurality of roller members such as the photosensitive drum 19, the fixing roller 22, the feed roller 34, and the discharge roller 24 are driven and controlled, and the recording unit 2 performs a recording operation on one side of the paper P1 while conveying the paper P1 ( (See FIG. 4 (a)). Such sheet conveyance control of the sheet P1 is known. 4 to 6, the sheets P1 to P3 are displayed with thick lines, and for easy understanding, the unrecorded part of the sheet is a dotted line, the single-sided recording part is a one-dot chain line, and the double-sided recording part is a solid line, respectively. It is trying to display.

  As the paper P1 recorded on one side is conveyed, the leading end is sandwiched between the discharge roller 24 and the press roller 25. Since the discharge roller 24 is connected to the main motor 50 via the electromagnetic clutch 51, the discharge roller 24 rotates forward and conveys the paper P1 in the paper discharge direction. When the paper detection sensor 57 detects the trailing edge of the paper P1, the CPU 60 starts driving the sub motor 55 after a predetermined time has elapsed, disconnects the electromagnetic clutch 51, and connects the electromagnetic clutch 56. When the discharge roller 24 is connected to the sub motor 55 via the electromagnetic clutch 56, the discharge roller 24 rotates in the reverse direction and transports the paper P1 in the direction opposite to the paper discharge direction. It will be carried in. In parallel with the reverse conveyance operation of the paper P1, the next paper P2 is carried by the paper feed roller 13 and the recording operation is started (see FIG. 4B). Then, the paper P1 is conveyed downward by two pairs of conveyance rollers, that is, a feed roller 28 and a press roller 29, and a feed roller 30 and a press roller 31 that are rotated by the rotation drive of the sub motor 55, and the rotation drive of the sub motor 55 is stopped. And stop at the standby position. During this time, the recording operation on one side of the paper P2 is continued (see FIG. 4C). In this case, since the reverse conveyance of the paper P1 can be performed only by the sub motor 55, the paper P1 can be promptly conveyed to the standby position by a high-speed conveyance operation. Further, the electromagnetic clutch 56 is disconnected at the timing when the sheet P1 is reversed and conveyed and leaves the discharge roller 24, the electromagnetic clutch 51 is connected, and the discharge roller 24 is in the forward rotation state. In this way, the duplex recording mode is started, and the sheets are arranged in the sheet conveyance path and the reverse conveyance path.

  FIG. 5 shows the reversal conveyance operation in a state where the sheets are respectively arranged on the sheet conveyance path and the reversal conveyance path. When the one-side recording operation of the paper P2 is completed, the sub motor 55 starts to drive and is on standby by the feed roller 28 and the press roller 29, the feed roller 30, the press roller 31, the feed roller 32, and the transport roller of the press roller 33. The paper P <b> 1 is carried into the paper transport unit and is sandwiched between the feed roller 14 and the press roller 15. On the other hand, after the sheet P2 is sandwiched between the discharge roller 24 and the press roller 25 and conveyed in the sheet discharge direction, the sheet discharge roller 24 is reversed by the disconnection of the electromagnetic clutch 51 and the connection of the electromagnetic clutch 56 as described above. Then, it is carried from the rear end to the reversing conveyance unit (see FIG. 5A).

  Then, the recording operation is performed on the unrecorded surface of the paper P1, the double-sided recording of the paper P1 is advanced, and the reverse conveyance operation of the paper P2 is performed and stopped at the standby position (see FIG. 5B). The electromagnetic clutch 56 is disengaged at the timing when the paper P2 is reversed and separated from the discharge roller 24, the electromagnetic clutch 51 is connected, and the discharge roller 24 is in the forward rotation state. In this way, the reverse conveying operation is performed so that the arrangement of the sheets P1 and P2 is changed from that in FIG.

  FIG. 6 shows a sheet conveying operation in a state where sheets are respectively arranged on the sheet conveying path and the reverse conveying path. When the recording operation on the unrecorded surface of the paper P1 is completed, the paper P1 is sandwiched between the discharge roller 24 and the press roller 25, conveyed in the paper discharge direction, and discharged to the paper discharge tray 10 as it is. Following the end of the operation, the next new sheet P3 is carried in by the sheet feed roller 13 (see FIG. 6A). While the paper P3 is being recorded by the recording unit 2, the paper P2 is in a standby state at the standby position in the reverse conveyance unit (see FIG. 6B). That is, as in FIG. 4C, the sheets are arranged on the sheet conveyance path and the reverse conveyance path.

  Next, the reverse conveyance operation described with reference to FIG. 5 is performed, and then the reverse conveyance operation and the paper conveyance operation shown in FIGS. 5 and 6 are alternately repeated so that the double-sided recording of the paper can be performed efficiently. Become. By performing such a transport operation, a sheet is placed in each of the sheet transport path and the reverse transport path, and immediately after the sheet recording operation, the next sheet recording operation is started. Further, since the sheets are transported in parallel so as to replace the sheets during the reverse transport operation, the transport time is shortened.

  In addition, by appropriately switching the rotation of the discharge rollers and performing the forward discharge operation and the reverse transfer operation by reverse rotation, the transfer operation can be performed while reducing the number of transfer rollers, and the drive transmission system is made compact accordingly. The

1 is a schematic sectional view of an entire image forming apparatus according to an embodiment of the present invention. It is the schematic which shows the example of the drive transmission mechanism of a paper conveyance part and a reverse conveyance part. It is a block diagram regarding drive control. FIG. 10 is an explanatory diagram illustrating a paper transport operation in a paper transport unit and a reverse transport unit. FIG. 10 is an explanatory diagram illustrating a paper transport operation in a paper transport unit and a reverse transport unit. FIG. 10 is an explanatory diagram illustrating a paper transport operation in a paper transport unit and a reverse transport unit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Recording part 3 Paper feeding part
24 Discharge roller
40 Paper transport section
41 Reverse transfer section
50 Main motor
51 Electromagnetic clutch
55 Secondary motor
56 Electromagnetic clutch

Claims (2)

  A paper transport path for transporting the paper transported from the paper feeding section to the recording section and transporting it to the paper discharge tray, and a paper transported from the downstream side of the recording section to the upstream side of the recording section in the paper transport path In an image forming apparatus having a reversing conveyance path for carrying out, a driving unit that performs a paper discharge operation by rotating a discharge roller forward and a reverse conveyance operation by reversing the discharge roller; The sheet is transported from the standby position in the reverse conveyance path to the sheet conveyance path, and the recording unit controls the conveyance so that the recording operation is performed on the unrecorded surface, and the drive unit is controlled to perform the next single-side recording by the discharge roller. Double-sided recording is performed in a state in which the reverse conveyance control means that carries the paper into the reverse conveyance path and conveys the paper to the standby position, and the single-sided recording paper that has been conveyed to the standby position by the reverse conveyance control means. A sheet conveyance control unit configured to carry a sheet so as to carry in a single-sided recording operation in the recording unit after carrying in the sheet from the sheet feeding unit following the sheet discharging operation, and the reverse conveyance control unit and the sheet conveyance An image forming apparatus characterized by alternately performing control means.   The drive means connects the first drive source used in the paper conveyance path, the second drive source used in the reverse conveyance path, and the discharge roller to the first drive source to rotate forward and discharge the discharge. The image forming apparatus according to claim 1, further comprising a drive transmission unit configured to connect a roller to the second drive source to reversely rotate the roller.

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