JP2007045542A - Cleaning device and image formation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive inversion device having a simple structure, preventing unstable paper conveyance even when paper size is increased and preventing reduction of productivity. <P>SOLUTION: A stepping motor 28 is used for a contact/separation drive source of an intermediate tray 12. By rotating and driving the stepping motor 28, the intermediate tray 12 is moved and contacted/separated. Therefore, in accordance with paper types, movement amount of the intermediate tray 12 serving as a conveyance passage can be changed. In the case of paper with high stiffness, such as thick paper, increase in conveyance load during inversion may cause slip, and in the case of paper having special surface characteristics, such as surface-coated paper, decline in a friction coefficient between a roller and the paper may cause slip. In these cases, however, by increasing in rotating frequency of the stepping motor 28 compared with ordinary paper, conveyance force can be increased, variation of paper feeding amount during inversion can be reduced, and conveyance accuracy can be improved. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a recording medium reversing device used in a PPC, a laser printer, a facsimile, a scanner device, and the like, and an image forming apparatus using the same.

  In Patent Document 1, a conveying unit including a discharge roller that rotates in the forward direction and a reverse roller that rotates in the reverse direction, and either one of the rollers of the conveying unit is in pressure contact with either roller, And a reversing roller that can move the position so that it does not come into contact with the discharge roller or the reversing roller. A technique is disclosed in which a swingable document guide member is provided between the discharge roller and the discharge roller, and the sheet guide member is guarded against contact with the roller on which the press roller is not in contact with the document guide member. ing.

  In Patent Document 2, a forward conveyance path that guides a sheet in the forward direction, a switchback conveyance path that is continuous with the forward conveyance path, and a rear end portion of the sheet that is conveyed to the switchback conveyance path are provided with pressurizing means ( A reversing roller which is sandwiched between the pressure unit and the pressure roller and switched back in the reverse direction with the trailing edge as the leading edge, and when the paper is switched back, the paper enters the conveyance path and the paper is removed from the forward conveyance path. In a paper reversing apparatus including a branching claw for branching and a reversing conveyance path for guiding a paper branched by the branching claw, a technique is disclosed in which the pressurizing unit is provided integrally with the branching claw.

In Patent Document 3, in the image forming apparatus, the trailing edge separation unit is disposed on a slope-shaped conveyance guide that changes the traveling direction of the sheet and on the upstream side of the conveyance guide, and the sheet is pushed against the conveyance guide. There is disclosed an image forming apparatus characterized by comprising a flexible member to be hit.
JP 2002-128354 A Japanese Patent Laid-Open No. 06-127779 Japanese Patent Laid-Open No. 06-001495

  In the prior art as described above, the reverse conveyance path is configured such that the reverse conveyance of the paper is performed by the pair of normal and reverse rotation rollers, and one of the normal and reverse rotation rollers can be contacted / separated in order to improve productivity reduction. Since it is possible to allow the sheets to be conveyed while being overlapped, it is possible to reduce the interval between the continuously conveyed sheets.

  However, as the paper size increases, the distance that the sheets are overlapped and transported becomes longer, the transport of the sheets tends to become unstable, and there is a concern about the influence on the image because they are transported in an overlapping manner. It is necessary to keep the interval as small as small paper. For this reason, the larger the size paper, the lower the productivity.

  In order to improve this, it is necessary to increase the speed at the reversing section, and it is necessary to increase and decrease the speed of the motor with high accuracy. As a result, problems such as increased costs, noise, and increased power consumption are caused.

  Therefore, the present invention seeks to solve the above problem with a reversing device having a simple configuration and a low cost.

  The reversing device according to claim 1 of the present invention is a reversing device having a reversing means for reversing and reversing the recording paper to be transported, and is driven to rotate in opposite directions for reversing and transporting the recording paper. The recording paper transport path in which the driven roller is disposed at a position facing the pair of driving rollers has a recording paper transport path moving means that allows the driven roller and the driving roller to be brought into contact with and separated from each other, and the recording paper transport path moving means Means for changing the moving distance according to the type of recording paper to be conveyed.

  According to a second aspect of the present invention, in the reversing device according to the first aspect, a solenoid is provided as the moving means of the recording paper conveyance path.

  According to a third aspect of the present invention, in the reversing device according to the first aspect, the recording paper transport path includes means for holding the recording paper conveyance path at an intermediate position where the driving roller and the driven roller do not contact each other. Features.

  According to a fourth aspect of the present invention, in the reversing device according to the first or third aspect, a stepping motor is provided as the moving means of the recording paper conveyance path.

  According to the fifth aspect of the present invention, in the reversing device according to any one of the first to fourth aspects, the fixed conveyance path is provided upstream and downstream of the recording paper conveyance path, and the fixed conveyance path is formed of a flexible member. It is connected.

  According to a sixth aspect of the present invention, in the reversing device according to the fifth aspect, the flexible member is made of a conductive member.

  An image forming apparatus according to a seventh aspect of the present invention includes the reversing device according to any one of the first to sixth aspects.

  An electrophotographic copying machine according to an eighth aspect of the present invention includes the reversing device according to any one of the first to sixth aspects.

  A facsimile according to a ninth aspect of the present invention includes the reversing device according to any one of the first to sixth aspects.

  A printer according to a tenth aspect of the present invention includes the reversing device according to any one of the first to sixth aspects.

  A scanner according to an eleventh aspect of the present invention includes the reversing device according to any one of the first to sixth aspects.

  According to the present invention, by a reversing device having a simple configuration and low cost, even when the paper size becomes large, the paper conveyance is hardly unstable and the productivity is hardly lowered.

  The best mode for carrying out the present invention will be described below with reference to the embodiments shown in the drawings.

  FIG. 1 is an explanatory diagram illustrating a transfer material conveyance path of an image forming apparatus according to the present invention. FIG. 2 is an enlarged explanatory view of a reversing device portion of the image forming apparatus shown in FIG. In FIG. 1, the image forming apparatus according to the present embodiment has two stages of sheet cassettes 1a and 1b arranged in the lower part of the apparatus body. When a sheet feed command is issued, one sheet cassette 1 serves as a recording medium. The sheets are fed one by one by the separation feeding means 2. The fed paper passes through the grip roller pair 3 and reaches the registration roller pair 5 through the intermediate roller pair 4 at the junction with the refeed conveyance path. The separating / feeding means 2, the grip roller pair 3, the intermediate roller pair 4 and the registration roller pair 5 are each configured to be independently driven by a clutch, a stepping motor or the like.

  Reference numeral 6 in the drawing denotes a photosensitive drum as an image carrier. A toner image is formed on the photosensitive drum 6 by a known electrophotographic process. The toner image is transferred to the transfer position of the photosensitive drum 6 in synchronization with the image. After the transfer, the sheet is conveyed to the fixing device 7 where the toner image is fixed on the sheet.

  When the paper on which image formation has been completed is not reversed, it is conveyed straight to the paper discharge roller 9 and discharged outside the apparatus. When reverse paper discharge or double-sided copy is selected, the paper is conveyed to the reverse device 10 by switching the branching claw 8.

  As shown in FIG. 1, the reversing device 10 includes a reversing forward path 11 that communicates with the intermediate tray 12 as a switchback path, and a reversing backward path 13 that communicates from the intermediate tray 12 to the paper discharge roller 9. The sheet fed into the reverse path 11 is sandwiched between the reverse roller pairs 15 and 16 via the transport roller pair 14 and is sent to the intermediate tray 12 by the transport action.

  In this example, the reverse sensor 11 is provided with an inlet sensor 22 on the upstream side of the reverse roller pair 15 and 16, and when the inlet sensor 22 detects the leading edge of the paper, the switchback roller is triggered by the detection. Is rotated so as to receive the sheet, and the driving is stopped when the trailing edge of the sheet reaches a predetermined sheet stop position. Thereafter, the pair of switchback rollers 20 and 21 are driven in the reverse direction, and the sheet is conveyed in the direction opposite to the entering direction with the trailing edge as the leading edge.

  As shown in FIG. 2, the switchback roller pair 20, 21, the driving lower roller 26 and the driven upper roller 31 are urged by the spring 18 on the intermediate tray 12 so as to abut against each other. The sheet that has entered the intermediate tray 12 is conveyed into the intermediate tray 12 and is conveyed to a predetermined reversal position after the trailing edge of the sheet has passed through the reversing roller pairs 15 and 16. The upper switchback roller 20 can be brought into and out of contact with the lower switchback roller 21 using a solenoid (not shown) as a drive source.

  When the sheet is conveyed to a predetermined reversal position, the solenoid 19 as the contact / separation drive source of the member forming the intermediate guide 12 is driven to separate the switchback roller pairs 20 and 21 as shown in FIG. Then, the driving lower roller 26 and the driven upper roller 31 are brought into contact with each other. Since the driving lower roller 26 rotates in the direction opposite to that of the switchback roller 20 that is the driving upper roller, when the sheet is sandwiched between the driving lower roller 26 and the driven upper roller 31, the sheet is conveyed in the reverse direction and the intermediate tray. 12 is discharged.

  In the reverse return path 13, an exit sensor 27 is provided on the downstream side of the pair of reverse rollers 16 and 17, and a switchback roller 20 whose rear end is a driving upper roller triggered by detection of the front end of the paper by the outlet sensor 27. When the drive of the solenoid 19 is released after exiting the above, the intermediate tray 12 moves to the initial position shown in FIG. 2 and the next sheet can enter the intermediate tray 12.

  A switching claw 23 provided subsequent to the intermediate tray 12 switches the conveyance direction between reverse discharge and double-sided copying. When the switching claw 23 is in the position of the solid line in FIGS. 1, 2, and 3, the paper to be switched back is conveyed along the reverse return path 13 by the reverse roller pairs 16 and 17, and the transfer roller pairs 24 and 14 shown in FIG. 1. Then, the paper is conveyed to a paper discharge roller 9 and discharged outside the apparatus.

  When the switching claw 23 is in the position of the chain line in FIGS. 2 and 3, the sheet is fed by the reverse rollers 16 and 17, and is registered through the refeed conveyance path 25 and the intermediate roller pair provided below the intermediate tray 12. It is sent to the roller pair 4. When the image formation is completed on the back side of the sheet, the sheet is discharged outside the apparatus.

  It should be noted that a solenoid is used as a driving means for moving the constituent members of the intermediate tray 12, and an inexpensive motor such as a DC motor is used as a driving source of a driving roller for reversing the paper because there is no need for forward / reverse rotation driving. Therefore, the configuration is simple and the cost can be reduced.

  As shown in FIGS. 4, 5 and 6, a stepping motor 28 can be used as the contact / separation drive source for the intermediate tray 12. The rack 30 provided on the intermediate tray 12 and the gear 29 provided on the output shaft of the stepping motor 28 are attached so as to mesh with each other, and the intermediate tray 12 is moved by rotating the stepping motor 28, and the embodiment As in 1, the rollers are brought into contact with and separated from each other. When the paper is received, it is rotationally driven to the position shown in FIG. 4, and when the paper is reversed, it is rotationally driven to the position shown in FIG. When the inverted paper leading edge is detected by the exit sensor 27, the intermediate tray 12 is moved to the position shown in FIG.

  At this time, the switchback roller pair 20 and 21, the driving lower roller 26, and the driven upper roller 31 are held in a state where they are not in contact with the other party, so that the trailing edge of the sheet is completely removed from the driving lower roller 26. The next sheet can enter the intermediate tray 12. For this reason, even in a large-size sheet, the same sheet space as that of a small-size sheet can be maintained, and a reduction in productivity can be prevented.

  Further, by using an inexpensive stepping motor as a driving means for moving the constituent members of the intermediate tray 12, the transport path can be easily moved and held at the intermediate position without using a complicated mechanism.

  By using the stepping motor, it is possible to change the amount of movement of the intermediate tray 12 that is the conveyance path according to the type of paper. For example, in the case of stiff paper such as thick paper, slippage occurs due to an increase in the transport load during reversal, and in the case of paper with special surface properties such as surface-coated paper, slippage occurs due to a decrease in the friction coefficient between the roller and paper. May occur. In order to improve such a problem, it is preferable to increase the conveyance force by reducing the rotation amount of the stepping motor from that of plain paper, reduce variations in the paper feed amount during reversal, and improve the conveyance accuracy.

  The reverse feed path 11 provided on the upstream side in the paper transport direction of the intermediate tray 12 and the refeed transport path 25 provided on the downstream side are fixed to the reverse device. Since the intermediate tray 12 is configured to move up and down, it is necessary to consider the shape of the inlet guide of the intermediate tray 12 and the shape of the outlet to the refeed conveyance path 25 so that the conveyance margin is not affected. In FIG. 7, the connecting portion between the reverse going path 11 and the intermediate tray 12 and the connecting portion between the intermediate tray 12 and the refeed conveyance path 25 may be configured by flexible members 32 such as PET sheets. As a result, it is possible to save the space of the shape of the conveyance path and to stably convey the paper. Further, by configuring the connecting portion with a conductive flexible member, it is possible to prevent a conveyance failure such as sticking due to charging of the paper and an abnormal image during the second side printing. In addition, the lower member of the intermediate tray 12 is bent at the edge, and the flexible member 32 as a connecting member is positioned below the bent portion to prevent the paper from being caught.

  Needless to say, if such a reversing device is used in an electrophotographic copying machine, a facsimile machine, a printer, a scanner, or the like, the space can be reduced, the productivity can be increased, and the cost can be reduced.

Explanatory drawing which shows the conveyance path | route of the transfer material of the image forming apparatus which concerns on this invention. 1 is an enlarged explanatory view of a main part of a first embodiment of a reversing device according to the present invention used in the image forming apparatus shown in FIG. Expansion explanatory drawing which shows operation | movement of the inversion apparatus shown in FIG. Expansion explanatory drawing which shows operation | movement of the inversion apparatus shown in FIG. Expansion explanatory drawing which shows operation | movement of the inversion apparatus shown in FIG. Expansion explanatory drawing which shows operation | movement of the inversion apparatus shown in FIG. Enlarged explanatory view showing the connecting portion of the reversing forward path, the intermediate tray, and the refeed conveyance path

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a, 1b: Paper feeding cassette 2: Separation feeding means 3: Grip roller pair 4: Intermediate roller pair 5: Registration roller pair 6: Photosensitive drum 7: Fixing device 8: Branch claw 9: Paper discharge roller 10: Reversing device 11: Reverse path 12: Intermediate tray 13: Reverse return path 14, 24: Transport roller pair 15, 16, 17: Reverse roller 18: Spring 19: Solenoid 20, 21: Switchback roller pair 22: Entrance sensor 23: Switching claw 25 : Re-feed conveyance path 26: Driving lower roller 27: Exit sensor 28: Stepping motor 29: Gear 30: Rack 31: Followed upper roller 32: Flexible member

Claims (11)

A reversing device having a reversing means for reversing and reversing the recording paper to be transported, wherein a driven roller is disposed at a position facing a pair of driving rollers that are rotationally driven in opposite directions for reversing and transporting the recording paper. The provided recording paper transport path has a recording paper transport path moving means that enables the driven roller and the drive roller to contact and separate, and the moving distance of the recording paper transport path moving means depends on the type of recording paper to be transported A reversing device comprising means for changing. 2. The reversing device according to claim 1, further comprising a solenoid as a moving means of the recording paper transport path. 2. The reversing device according to claim 1, further comprising means for holding the recording paper conveyance path at an intermediate position where the driving roller and the driven roller do not contact each other. 4. The reversing device according to claim 1, further comprising a stepping motor as moving means for the recording paper transport path. 5. The reversing device according to claim 1, wherein the reversing device is provided in a fixed transport path upstream and downstream of the recording paper transport path, and the fixed transport path is connected by a flexible member. . 6. The reversing device according to claim 5, wherein the flexible member is made of a conductive member. An image forming apparatus comprising the reversing device according to claim 1. An electrophotographic copying machine comprising the reversing device according to claim 1. A facsimile comprising the reversing device according to claim 1. A printer comprising the reversing device according to claim 1. A scanner comprising the reversing device according to claim 1.