JP2014043338A - Sheet conveying device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet conveying device capable of further improving sheet retentivity, and an image forming apparatus comprising the sheet conveying device.SOLUTION: A sheet conveying device includes: rotary drive means for rotatively driving an inversion inlet roller pair 514, an inversion supply roller pair 301, an inversion roller pair 302, and a standby conveyance inlet roller pair 303; first contact/separation means for moving at least one of the inversion supply roller pair 301 so that the inversion supply roller pair 301 can be brought into a pressure contact state and a separation state; second contact/separation means for moving at least one of the inversion roller pair 302 so that the inversion roller pair 302 can be brought into the pressure contact state and the separation state; and a control unit 900 for controlling the rotary drive means, the first contact/separation and the second contact/separation means.

Description

  The present invention relates to a sheet conveying apparatus that conveys a sheet such as a document or a recording medium, and an image forming apparatus such as a copying machine, a printer, or a facsimile equipped with the sheet conveying apparatus.

  Conventionally, as this type of sheet conveying device, an image forming apparatus or the like is known which conveys a sheet such as a document or a recording sheet. The sheet conveying apparatus includes a guide plate as a conveying path forming member that forms a conveying path of the sheet, and a rotating body including a plurality of rollers or belts that can be driven to rotate so as to contact the sheet passing through the conveying path. The sheet is conveyed in the conveyance path.

Further, as an image forming apparatus provided with the sheet conveying apparatus, an apparatus that performs interleaf control as described below is known.
For example, Patent Document 1 discloses recording on the second surface (back surface) of a recording medium (double-sided processed sheet) that has been recorded on the first surface (front surface), and unrecorded recording medium (single-sided sheet). An interleaf control type double-sided image recording apparatus that alternately performs recording on the first side is disclosed. The double-sided image recording apparatus stores image information for each page of a document in page order, reads out each image information as necessary, and stores image information for two pages of the image information stored in the storage unit. Recording means for recording respectively on the first surface and the second surface of the recording medium. Further, the double-sided image recording apparatus includes a reversing unit for reversing the front and back sides to record image information on the second side of the recording medium, and a double-sided intermediate unit for guiding the reversed front and back sided recording medium to the recording unit again. A conveyance path. Then, recording is continuously performed on the first surface of the plurality of recording media at the beginning of recording, and the plurality of recording media on which recording is performed on the first surface is sequentially introduced into the double-sided intermediate conveyance path.

  Further, in Patent Document 1, a switchback conveyance path extending in the horizontal direction is provided above the double-sided intermediate conveyance path extending in the horizontal direction as the reversing means, and refeeding is performed on the switchback conveyance path. The structure which provided the return conveyance means (roller) which can be moved up and down is disclosed (refer to Claim 4, Paragraph 0034, 0060, FIG. 1 and FIG. 2 of Patent Document 1). In this configuration, the preceding sheet waiting in the switchback conveyance path is completely gripped by the reverse exit conveyance roller, and the subsequent conveyance sheet provided in the switchback conveyance path is retracted upward, Is fed into the switchback transport path by the reverse entrance transport roller. As a result, it is possible to reverse each other so that two sheets can be present in the switchback conveyance path.

  However, the double-sided image recording apparatus disclosed in Patent Document 1 can wait only for one or two sheets (paper as a recording medium) in the switchback conveyance path.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a sheet conveying apparatus that can further improve sheet retention and an image forming apparatus including the sheet conveying apparatus. is there.

  In order to achieve the above-mentioned object, the invention according to claim 1 is characterized in that the first surface of the main transport path is a main transport path for transporting the sheet so as to pass a sheet processing position for processing on one side of the sheet. A reversing path for reversing the traveling direction of the sheet to process the second surface of the processed sheet, a reversing conveyance path for conveying the sheet that has passed through the main conveyance path toward the reversing path, and the reversing path A conveyance path forming member that forms a standby conveyance path for waiting the sheet so that the sheet whose direction of movement has been reversed is reversed and fed back to the main conveyance path, and the traveling direction is reversed by the reversal path. Branching means for branching the sheet in the direction toward the standby conveyance path, and a rotation means provided at the entrance of the reverse conveyance path so as to convey the sheet that has entered the reverse conveyance path toward the reverse path A pair of reverse entrance rollers, A pair of reversing supply rollers provided at an outlet of the reversing conveyance path on the upstream side in the conveyance direction of the branching means and rotatable to convey the sheet in the reversing conveyance path toward the reversing path; A reversing roller pair that is provided so as to reverse the traveling direction of the sheet that has entered the reversing path, and a sheet that has been provided at the entrance of the standby conveying path and that has entered the standby conveying path is conveyed. A sheet conveying apparatus comprising: a pair of standby conveyance inlet rollers that are rotatable; and a rotation driving unit that rotationally drives the pair of reverse conveyance rollers, the pair of reverse supply rollers, the pair of reverse rollers, and the pair of standby conveyance rollers. A first contact / separation means for moving at least one roller of the pair of reverse supply rollers so that the pair of reverse supply rollers can be in a pressure contact state and a separated state; A second contact / separation means for moving at least one roller of the pair of reversing rollers so as to be able to take a pressure contact state and a separation state; the rotation driving means; the first contact / separation means; And a control means for controlling the separation means.

  According to the present invention, the preceding sheet and the succeeding sheet can be passed and the sheet retention can be further improved.

1 is a schematic configuration diagram illustrating an example of an overall configuration of a printer including a paper transport device according to an embodiment of the present invention. FIG. 3 is a block diagram illustrating an example of a main configuration of a control system of the sheet conveying apparatus according to the present embodiment. (A) And (b) is explanatory drawing which shows detailed operation | movement of recording paper S3, S4 continuously supplied following recording paper S1, S2 in the printer of this embodiment. (A) And (b) is explanatory drawing which shows the detailed operation | movement of the recording paper S5 fed continuously following recording paper S1-S4 in the printer of this embodiment. FIG. 10 is a schematic configuration diagram illustrating an example of an overall configuration of a printer including a sheet conveying device according to another embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram illustrating an example of the entire configuration of a full-color printer as an image forming apparatus including a sheet conveying apparatus according to an embodiment of the present invention. In FIG. 1, a full color printer (hereinafter referred to as “printer”) 100 as an image forming apparatus is an image on which toner images of four colors (Y: yellow, M: magenta, C: cyan, Bk: black) are formed. Photoreceptor drums 700Y, 700M, 700C, and 700Bk are provided as carriers. Further, the image forming apparatus 100 includes an intermediate transfer belt 601 as an intermediate transfer member and a secondary transfer unit 600 as a secondary transfer unit. The intermediate transfer belt 601 is spanned between a plurality of support rollers and rotated in the direction of the arrow in the figure.
The toner images on the photosensitive drums 700Y, 700M, 700C, and 700Bk are transferred. The secondary transfer unit 600 is configured such that the secondary transfer bias roller and the secondary transfer counter roller face each other with the intermediate transfer belt 601 interposed therebetween, and the superimposed toner image on the intermediate transfer belt 601 is transferred to a sheet (sheet-like recording). The image is transferred to a recording sheet S as a medium. The toner images of the respective colors formed on the photosensitive drums 700Y, 700M, 700C, and 700Bk are respectively transferred to an intermediate transfer belt by primary transfer units 602Y, 602M, 602C, and 602Bk as primary transfer units including primary transfer bias rollers. The images are sequentially transferred to 601.

  Although not shown in FIG. 1, around each of the plurality of photosensitive drums, a charging device that uniformly charges the surface of the photosensitive drum, and an electrostatic latent image on the photosensitive drum for each color ( The image forming apparatus includes a developing device that develops using toner of Y, M, C, and Bk) and a cleaning device that cleans the surface of the photosensitive drum. The surface of each photosensitive drum uniformly charged by the charging device is exposed based on an image signal by an optical writing device (not shown) as an exposure unit, so that an electrostatic latent image corresponding to each color is formed. The Image forming means for forming toner images of respective colors on the photosensitive drums 700Y, 700M, 700C, and 700Bk includes the charging device, the developing device, and the optical writing device. The transfer means for transferring the image (toner image) on the photosensitive drums 700Y, 700M, 700C, and 700Bk to one side (upper surface in FIG. 1) of the recording paper S includes the secondary transfer unit 600 and the intermediate transfer belt. 601, primary transfer portions 602Y, 602M, 602C, 602Bk, and the like.

  Further, the printer 100 fixes the toner image transferred on the recording paper by the sheet feeding devices 201 and 202 as the sheet supply unit, the skew correction device 400 that corrects the skew of the recording paper, and the secondary transfer unit 600. And a unit-shaped fixing device 800 as fixing means to be provided. The sheet feeding devices 201 and 202 feed one sheet at a time from a plurality of recording sheets stored in a sheet feeding cassette by a feeding roller, and are merged by a sheet feeding roller via a feeding conveyance path (vertical conveyance path) 501 described later. The unit 502 is configured to feed paper. The fixing device 800 is configured such that, for example, the heating roller and the pressure roller are in pressure contact with each other at a fixing position where the recording paper passes.

  The printer 100 also includes a sheet conveying device 500 as a sheet conveying device that conveys a recording sheet on which an image is formed on one side or both sides. The sheet conveying apparatus 500 includes a feeding conveyance path 501, a merging unit 502, a sheet feeding conveyance path 503, a belt conveyance path 504, a paper discharge conveyance path 505, a paper discharge section 506, a reverse conveyance path 507, A reversing path 508 extending in the vertical direction and a standby conveying path (double-sided conveying path) 509 extending in the horizontal direction are provided. Each transport path is formed by a guide member or a belt member (not shown) as a transport path forming member.

  In FIG. 1, a recording sheet whose processing target surface on which an image is to be formed is a first surface (front surface) is indicated by a symbol “S”, and a processing target surface on which an image is to be formed is a second surface (back surface). The recording paper is indicated by the symbol “D”. For each of the recording paper S and the recording paper D, the order in which the image forming unit processes the first side and the second side (the order in which the toner images are formed), that is, the order in which papers are fed from the paper feeding devices 201 and 202. The number which shows is attached | subjected suitably as a subscript. Here, the “first surface” of the recording paper is a surface on which an image is first formed, and the “second surface” is an image on which the recording paper is formed. This is the surface opposite to the first surface. The process of forming an image on the first side of the recording paper means a single-sided printing process or a printing process on the front side in double-sided printing, and the process of forming an image on the second side of the recording paper is on the back side in double-sided printing. Means the printing process. Further, in FIG. 1, the portions where the recording paper is present in each conveyance path are indicated by bold lines.

  The feeding conveyance path 501 is a conveyance path for conveying the recording sheet S fed from the sheet feeding device 201 or the sheet feeding device 202 to the merge unit 502. The merge unit 502 is a place where the recording sheet S from the sheet feeding devices 201 and 202 and the recording sheet D from the standby conveyance path 509 merge. A paper feed conveyance path 503 is a conveyance path that conveys the recording paper from the merging unit 502 to the secondary transfer unit 600. The belt conveyance path 504 includes an endless conveyance belt 515 and a belt roller pair 510 that are stretched over a plurality of support rollers, and serves as a branching unit from the secondary transfer unit 600 through a fixing position by the fixing device 80. This is a transport path for transporting the recording paper to the branch position by the first branch claw 530. The main transport path for transporting the recording paper so as to pass through the secondary transfer unit 600 as a sheet processing position for forming an image on one side of the recording paper is configured by the paper feed transport path 503 and the belt transport path 504. The

  A paper discharge conveyance path 505 is a conveyance path for conveying the recording paper from a branch position by the branch claw 530 to the paper discharge unit 506. The paper discharge unit 506 is a portion where the recording paper conveyed through the paper discharge conveyance path 505 is discharged out of the apparatus by the paper discharge roller pair 510.

  The reversing path 508 reverses the traveling direction of the recording paper on which the image is formed on the first surface in order to form an image on the second surface of the recording paper on which the image is formed on the first surface in the main conveyance path. It is a transport path. The reverse conveyance path 507 is a conveyance path from the branch position by the branch claw 530 to the third branch claw 304 as the branch means through the branch position by the second branch claw 305 as the branch means. In the reverse conveyance path 507, the recording paper that has passed through the main conveyance path (the paper feed conveyance path 503 and the belt conveyance path 504) is conveyed toward the reverse path 508.

  The standby conveyance path 509 is a conveyance path from the branching position by the branching claw 304 on the reversing path 508 to the junction unit 502. In this standby conveyance path 509, the recording paper whose traveling direction is reversed in the reversing path 508 is reversed, and the recording paper is put on standby so as to be re-supplied to the main conveyance path (the paper feeding conveyance path 503 and the belt conveyance path 504). be able to.

  A reversing device 300 for reversing the recording paper to form an image on the second surface of the recording paper on which the image is formed on the first surface includes a part on the downstream side of the reversing conveyance path 507, a reversing path 508, and a standby And a part on the upstream side of the conveyance path 509.

  The sheet conveying apparatus 500 includes a reverse supply roller pair 301, a reverse roller pair 302, a standby conveyance inlet roller pair (double-sided conveyance roller pair) 303, and a reverse inlet roller pair 514. The reverse supply roller pair 301 is provided at the exit of the reverse conveyance path 507 on the upstream side of the branch claw 304 in the conveyance direction, and is a roller pair that can rotate so as to convey the recording paper in the reverse conveyance path 507 toward the reverse path 508. It is. The reverse roller pair 302 is a roller pair that is provided in the reverse path 508 and is rotatable so as to reverse the traveling direction of the recording paper that has entered the reverse path 508. The standby conveyance entrance roller pair 303 is a roller pair that is provided at the entrance of the standby conveyance path 509 and is rotatable so as to convey the recording paper that has entered the standby conveyance path 509. The standby conveyance entrance roller pair 303 is desirably disposed immediately after the branching claw 304 at the entrance of the standby conveyance path 509 as shown in FIG. The branching claw 304 can branch the recording paper whose traveling direction is reversed in the reversing path 508 in the direction toward the standby transport path 508.

  Further, the sheet conveying device 500 is a roller pair rotation drive as a rotation driving means for rotating the reverse supply roller pair 301, the reverse roller pair 302, the standby conveyance inlet roller pair 303, and the reverse inlet roller pair 514 in a predetermined rotation direction. Department. The roller pair rotation drive unit can be configured using, for example, a drive source such as a motor (not shown) and a drive transmission mechanism such as a gear.

  The paper transport device 500 includes a branching claw swinging mechanism as a swinging unit that swings the branching claws 304, 305, and 530 so as to branch the recording paper in a predetermined direction on the transport path. This branch claw swing mechanism can be constituted by, for example, a cam mechanism, a stepping motor, a spring, a solenoid or the like.

  The sheet conveying apparatus 500 includes a first contact / separation unit that contacts and separates the reverse supply roller pair 301 and a second contact / separation unit that contacts and separates the reverse roller pair 302. The first contact / separation means moves at least one roller of the reverse supply roller pair 301 so that the reverse supply roller pair 301 can be in a pressure contact state and a separated state. The second contact / separation means moves at least one roller of the reverse roller pair 302 so that the reverse roller pair 302 can be in a pressure contact state and a separated state. These roller contact / separation mechanisms as the first contact / separation means and the second contact / separation means are actuators such as solenoids that move the bearing portions of the rollers constituting the reverse supply roller pair 301 and the reverse roller pair 302, for example. Can be configured.

  Further, the sheet conveying apparatus 500 is provided with a sheet sensor as a sheet detecting means for detecting a recording sheet at a predetermined position in each of the conveying paths. For example, a paper sensor 520 that detects the leading edge of the recording paper (preceding recording paper) that enters the standby conveyance path 509 is provided at a position downstream of the duplex conveyance roller pair 303 in the conveyance direction at the entrance of the standby conveyance path 509. It has been. In addition, a paper sensor 521 for detecting the rear end of the recording paper (first succeeding recording paper) conveyed to the reversing path 508 is provided on the upstream side of the reversing conveying path 507 in the conveying direction of the reverse discharge roller pair 301. ing. Further, the recording paper (second succeeding recording paper) that is about to enter the reversing path 508 is positioned at the upstream side of the reversing path 508 in the recording paper entering direction (position on the third branch claw 304 side). ) Is provided.

  FIG. 2 is a block diagram illustrating an example of a main configuration of a control system in the sheet conveying apparatus 500 according to the present embodiment. In FIG. 2, the control unit 900 as a control unit includes a CPU 901, a ROM 902 that stores a control program and various data, and a RAM 903 that temporarily stores various data. The control unit 900 includes sheet sensors 520, 521, and 522, a roller pair rotation driving unit 910, and a roller pair pressure contact / separation mechanism via an I / O interface 904 for exchanging signals with each peripheral control unit. 920, a branch claw drive unit 930, and the like are connected. The control unit 900 executes a predetermined control program incorporated in advance, and based on the detection results of the paper sensors 520, 521, and 522, the roller pair rotation drive unit 910, the roller pair pressure contact / separation mechanism 920, and the branch claw drive The part 930 can be controlled. This control makes it possible to rotate the roller pairs 301, 302, 303, 514, etc. in each conveyance path in a predetermined direction or turn the rotation on / off at a predetermined timing. Further, by the above control, the branching claws 304, 305, and 530 are swung so that the recording paper is branched in a predetermined direction at a predetermined timing, and the reverse discharge roller pair 301 and the reverse roller pair 302 are pressed and separated. You can make it.

  In the printer having the above-described configuration, the recording paper S to be image-formed is called from the paper feeding device 201 or the paper feeding device 202 one by one. The recording sheet S fed from the sheet feeding devices 201 and 202 is conveyed to the skew feeding correction device 400 via the feeding conveyance path 501 and the sheet feeding conveyance path 503. In the skew correction device 400, the leading edge of the recording paper S is abutted against the roller pair, so that the skew of the recording paper S is corrected and the recording paper S is aligned with the secondary transfer unit 600. Can do. The recording sheet S that has passed through the skew correction device 400 is transferred with the toner image on the intermediate transfer belt 601 by the secondary transfer unit 600 and conveyed to the fixing device 800 via the belt conveyance path 504.

  Next, a single-sided image forming operation (single-sided printing operation) in the printer having the above configuration will be described. In the case of single-sided printing, after fixing by the fixing device 800, the following face-up discharge or face-down discharge is performed.

  When performing face-up paper discharge, the recording paper S that has passed through the fixing device 800 is directly conveyed from the paper discharge roller pair 511 to the paper discharge unit 506 via the belt roller pair 510 and the paper discharge conveyance path 505 to be outside the apparatus. To be discharged. Here, the belt roller pair 510 and the paper discharge roller pair 511 are rotated at a constant speed by the same drive source (not shown).

  On the other hand, when performing face-down paper discharge, the recording paper S that has passed through the fixing device 800 is conveyed via a reverse path 507 to a reverse paper discharge roller pair 301 having a pressure contact / separation mechanism (not shown). The recording paper S is accelerated by the reverse discharge roller pair 301 from the timing when the trailing edge of the recording paper S passes through the belt roller pair 510, and the reverse discharge roller pair 301 performs normal rotation, stop, and reverse rotation. The recording paper S performs a switchback operation. The recording sheet S that has been switched back is conveyed to the paper discharge unit 506 via the paper discharge roller pair 511 and is discharged outside the apparatus.

  In the case of face-down paper discharge, the preceding recording sheet S passes the succeeding recording sheet S while being accelerated during the switchback operation. Therefore, as described above, the sheet conveying apparatus 500 according to the present embodiment includes the roller pair pressure contact / separation mechanism 920 that can press and separate the reverse discharge roller pair 301. Then, after the leading edge of the preceding recording paper S passes through the paper discharge roller pair 511, the reverse paper discharge roller pair 301 is controlled to be separated, and the subsequent recording paper S entering the reverse paper discharge roller pair 301 is received. . After that, the reverse sheet discharge roller pair 301 is again brought into pressure contact and the subsequent recording sheet S is switched back so that the face-down discharge can be continuously performed.

Next, a double-sided image forming operation (double-sided printing operation) in the image forming apparatus having the above configuration will be described. FIG. 1 shows a case where five recording sheets S1 to S5 continuously fed from the sheet feeding device 201 or the sheet feeding device 202 are fed as an interleaf at the start of printing.
In FIG. 1, in the case of duplex printing, the recording sheets S 1 (D 1) and S 2 (D 2) pass through the fixing device 800 and then enter the reverse conveyance path 507 and pass through the reverse discharge roller pair 301 and the reverse rollers. Reach pair 302. Then, the recording papers S1 and S2 are each reversed in the traveling direction by a switchback operation in the reversing device 300, and then pass through the double-sided conveyance roller pair 303 and before the junction unit 502 located on the downstream side of the standby conveyance path 509. It stops and waits for refeeding at the timing between the recording paper S5 and the preceding recording paper S5 that has been transported first to the paper feed transport path 503.

FIGS. 3A and 3B are diagrams illustrating detailed operations of the recording sheets S3 (D3) and S4 (D4) that are continuously fed after the recording sheets S1 and S2 in the printer of this embodiment. FIG. Here, the recording sheet S3 is a preceding sheet (recording sheet), and the recording sheet S4 is a first succeeding sheet (recording sheet).
First, when the preceding recording sheet S3 that has passed through the belt conveyance path 504 of the main conveyance path is conveyed toward the reversal path 508, the reversal inlet roller pair 514 is driven to rotate and the reversal supply roller pair 301 is rotated in a pressure contact state. Driven to control the pair of reversing rollers 302 to be in a separated state. As shown in FIG. 3A, the recording paper S <b> 3 stops when its rear end portion passes the branching position by the branching claw 304 and reaches the reversing roller pair 302. Thereafter, the recording paper S3 is conveyed toward the standby conveyance inlet roller pair 303 so as to be conveyed to the standby conveyance path 509, and the recording paper S4 that has passed through the belt conveyance path 504 of the main conveyance path is conveyed toward the reversing path 508. When it is controlled as follows. That is, the reverse inlet roller pair 514 is rotationally driven, the reverse supply roller pair 301 is rotationally driven in a pressure contact state, the reverse roller pair 302 is rotationally driven in a separated state, and the standby conveyance inlet roller pair 303 is rotationally driven. To do. As a result, a switchback operation is performed on the recording sheet S3, and the subsequent recording sheet S4 passes through the pair of reverse discharge rollers 301 and is conveyed toward the reverse path 508.

  Next, as shown in FIG. 3B, the recording paper S <b> 3 is switched back by the pair of reverse rollers 302 and then guided to the standby conveyance path (double-side conveyance path) 509 by the branching claw 304. When the leading edge of the recording sheet S3 passes through the standby conveyance inlet roller pair (double-sided conveyance roller pair) 303 (point A in FIG. 3B), control is performed to stop the rotation drive of the standby conveyance inlet roller pair 303. Is done. As a result, the recording sheet S3 is stopped in a state where the distance from the preceding recording sheet S2 is maintained. Immediately thereafter, the pair of reversing rollers 302 is separated by a roller pressure contact / separation mechanism to prepare for the entry of the recording sheet S4. The recording sheet S4 reaches the reversing path 508, and the conveyance of the recording sheet S4 is stopped just before the trailing edge reaches the pair of reversed discharging rollers 301 (point B in FIG. 3B).

  Note that the recording paper S5 as the second subsequent sheet shown in FIG. 1 is stopped by the skew feeding correction device 400, and the conveyance is started again after matching the timing with the toner image on the intermediate transfer belt 601, and the secondary transfer. Through the unit 600 and the fixing device 800, the paper is conveyed toward the reversing device 300 as double-sided refeeding.

  When the length of the recording sheet S is long as described above, the reversing roller pair 302 is separated, and at the same time, two sheets of recording sheet S are placed on standby on the reversing path 508, so that five sheets are waiting as an interleaf. This makes it possible to perform double-sided printing while maintaining productivity without increasing the conveyance speed of the recording paper S.

4A and 4B are explanatory diagrams showing detailed operations of the recording sheet S5 (D5) that is continuously fed after the recording sheets S1 to S4 in the printer of the present embodiment. Here, the recording sheet S5 is a second subsequent sheet (recording sheet).
FIG. 4A shows a state in which the recording sheets S3 and S4 are stopped on the reversing path 508 and are on standby, as in the state of FIG. 3B described above. Here, when the trailing edge of the recording paper S4 reaches the reverse supply roller pair 301, the rotation drive of the reverse supply roller pair 301 is stopped, and the rotation drive of the reverse roller pair 302 is stopped so that the reverse roller pair 302 is moved. Control to be in a pressure contact state. The recording sheets S3 and S4 are held by the pressure contact of the reverse roller pair 302.

  Next, when the succeeding recording sheet S5 that has passed through the belt conveying path 504 of the main conveying path is conveyed toward the reversing path 508, the reversing supply roller pair 301 is set in a separated state, and the leading end of the recording sheet S5 has a branching claw 304. The reversing inlet roller pair 514 is controlled to rotate until it passes through the branch position and reaches the upstream position in the conveying direction of the reversing roller pair 302. By this control, as shown in FIG. 4B, the recording paper S5 can be carried into the reversing device so as to overlap the recording paper S4 with the reversal supply roller pair 301 being separated. Thereafter, the recording sheets S4 and S5 can be held by pressing the reverse discharge roller pair 301 again.

  When double-sided re-feeding is started, first the recording paper S3 is first driven by rotating the standby conveyance inlet roller pair 303 that holds the leading edge of the recording paper S3 with the reversing roller pair 302 separated. Is carried out from the reversing device 300 toward the standby conveyance path (double-side conveyance path) 509. Then, after the trailing edge of the recording sheet S3 passes through the reversing roller pair 302, the reversing roller pair 302 is pressed against and rotated to perform the switchback operation of the recording sheet S4. Then, after the trailing edge of the recording paper S4 passes through the reverse supply roller pair 301, the reverse supply roller pair 301 is also pressed against and rotated, so that the recording paper S5 also enters the reverse path 508 and thereafter continuously. Then, the recording paper S is conveyed.

  As described above, when the back-side standby paper D is sequentially kept on the transport path by filling the gap between the recording sheets during double-sided printing, even if the stop portion cannot be secured, the three back-side standby paper D are simultaneously fed to the reverse transport path 307. And it can be made to stay in the inversion path 308, and can be made to stand by. Therefore, productivity can be ensured without increasing the recording paper conveyance speed.

  FIG. 5 is a schematic configuration diagram illustrating an example of the overall configuration of a printer as an image forming apparatus including a sheet conveying apparatus according to another embodiment of the present invention. The image forming apparatus 100 illustrated in FIG. 5 includes two structures 101 and 102. The first structure 101 includes an image carrier 700Y, 700M, 700C, and 700Bk, an intermediate transfer belt 601, a secondary transfer unit 600, a belt conveyance path 504 that is a part of the main conveyance path, and a standby conveyance path. And a part of (double-sided conveyance path). The second structure 102 is a fixing structure having a fixing device 800, a reversing device 300, and a part of a standby conveyance path (double-side conveyance path) 509. These structures 101 and 102 have a common structure with the same width, depth, and height, and have a structure in which a lot effect during production can be obtained. In addition, as the paper feeding device, large-sized paper feeding devices 201 and 202 that can load paper of a wide width or a long length are mounted, and the mounting positions on the respective structures 101 and 102 are also made common. . It is necessary to provide a feeding conveyance path (vertical conveyance path) 501 as shown in FIG. 1 by feeding recording paper from each of the paper feeding apparatuses 201 and 202 to the standby conveyance path (double-side conveyance path) 509. Disappears. Moreover, each structure 101,102 can be divided | segmented, and it can reduce cost by downsizing, and the convenience at the time of carrying in / out improves. Further, the recording paper transport direction when feeding from the paper feeding devices 201 and 202 is opposite to that in FIG. 1 for the following reason. That is, the image forming apparatus 100 main body and a preprocessing apparatus (not shown) share the common front and back setting directions when the user loads the recording paper S, and share the main configuration of the paper feeding apparatus with the preprocessing machine. This is because the cost reduction was considered by using. In the embodiment of FIG. 5, the belt roller pair 510, the paper discharge relay roller pairs 512 and 513, and the paper discharge roller pair 511 are configured to rotate at a constant speed by the same drive source (not shown).

  In the case of the configuration of FIG. 5, since the standby conveyance path (double-side conveyance path) 509 is long, it is possible to provide a plurality of recording paper stop locations (retention locations, standby locations). It is necessary to interrupt the recording sheet S6 from 202 into the standby conveyance path (double-side conveyance path) 509. For this reason, it is canceled out as the stop position of the recording paper D for double-sided refeeding. However, even in such a case, if the reversing roller pair 302 capable of being pressed and separated as described above is provided, the reversing path 508 is separated by separating the reversing roller pair 302 when the recording paper S enters the reversing device 300. The two sheets can be stopped simultaneously, and the standby position of the recording sheet S at the time of interleaf can be secured to ensure the productivity.

  In the above-described embodiment, the case where the predetermined target sheet is a paper conveyance device that conveys recording paper for image formation has been described. However, the present invention is not limited to recording paper, and conveys sheets other than recording paper. The present invention can also be applied to a sheet conveying apparatus. In the above embodiment, the case where the sheet processing position to be processed on one side of the sheet in the main transport paths 503 and 504 is the secondary transfer unit 600 of the printer, but the processing on one side of the sheet is as follows. It is not limited to the process of transferring the image to the sheet. The present invention can be similarly applied to a case where processing other than the image transfer processing is performed on the sheet at the sheet processing position.

What has been described above is merely an example, and the present invention has a specific effect for each of the following modes.
(Aspect A)
Main conveyance paths such as a sheet feeding conveyance path 503 and a belt conveyance path 504 for conveying a sheet so as to pass through a sheet processing position such as a secondary transfer unit 600 that processes one side of a sheet such as recording paper, and main conveyance In order to process the second surface of the sheet whose first surface has been processed in the path, the reversing path 508 that reverses the traveling direction of the sheet and the sheet that has passed through the main transport paths 503 and 504 are transported toward the reversing path 508. A conveyance path forming member that forms a reversal conveyance path 507 and a standby conveyance path 509 that waits for the sheet to be reversed and fed back to the main conveyance paths 503 and 504 by reversing the sheet whose direction of travel has been reversed on the reversal path 508. Branching means such as a branching claw 304 for branching the sheet whose traveling direction is reversed in the reversing path 508 in a direction toward the standby conveying path 509, and a reversing conveyance provided at the entrance of the reversing conveying path 507. A reversing entrance roller pair 514 that can be rotated so as to transport the sheet that has entered the path 507 toward the reversing path 508, and a reversing transport path provided at the exit of the reversing transport path 507 on the upstream side of the branching unit in the transporting direction. The reversal supply roller pair 301 that can be rotated so as to convey the sheet in the reversing path 508, and the reversing path 508 can be rotated so as to reverse the traveling direction of the sheet that has entered the reversing path 508. Reversing roller pair 302, standby transport inlet roller pair 303 that is provided at the entrance of standby transport path 509 and can be rotated so as to transport the sheet that has entered standby transport path 509, and reverse entrance roller pair 514 and reversal supply Rotation drive means such as a roller pair rotation drive unit 910 that rotationally drives the roller pair 301, the reverse roller pair 302, and the standby conveyance entrance roller pair 303; A sheet conveying device, such as a sheet conveying apparatus 500 that includes.
The sheet conveying apparatus includes a first contact / separation unit that moves at least one of the reverse supply roller pair 301 so that the reverse supply roller pair 301 can be in a pressure contact state and a separated state, and the reverse roller pair 302 is in pressure contact. Second contact / separation means for moving at least one roller of the reversing roller pair 302 so as to be able to take a state and a separation state, the rotation driving means, and a first contact / separation means such as a roller pair pressure contact / separation mechanism 920 And control means such as a controller 900 for controlling the second contact / separation means.
According to this, as described in the above embodiment, by controlling the contact and separation of the reversing supply roller pair 301 and the reversing roller pair 302, it becomes possible to pass the preceding sheet and the succeeding sheet, Sheet retention can be further improved.
(Aspect B)
In the above aspect A, when the control unit conveys a sheet such as the preceding recording sheet S3 that has passed through the main conveyance paths 503 and 504 toward the reversal path 508, the control unit rotates the reversal inlet roller pair 514 to perform reversal supply. The roller pair 301 is rotationally driven in a pressure contact state, and the reversing roller pair 302 is controlled to be in a separated state. Further, the control means conveys the preceding sheet toward the standby conveyance inlet roller pair 303 so as to convey the preceding sheet to the standby conveyance path 509 after the trailing edge of the preceding sheet has passed the branch position of the branching means. When the leading edge of the preceding sheet passes through the standby conveyance entrance roller pair 303, the rotation drive of the standby conveyance entrance roller pair 303 is controlled to stop, and the first recording sheet S4 or the like such as the recording paper S4 that has passed through the main conveyance paths 503 and 504 is controlled. When the succeeding sheet is conveyed toward the reversing path 508, the reversing entrance roller pair 514 is rotationally driven, the reversing supply roller pair 301 is rotationally driven in the pressure contact state, and the reversing roller pair 302 is controlled to be in the separated state. .
In addition, when the trailing edge of the first succeeding sheet reaches the reverse supply roller pair 301, the control unit stops the rotational drive of the reverse supply roller pair 301 and puts the reverse roller pair 302 into a pressure contact state. Control. In addition, when the control unit conveys the second succeeding sheet such as the recording sheet S5 that has passed through the main conveying paths 503 and 504 toward the reversing path 508, the control unit sets the reversing supply roller pair 301 in a separated state, and performs the second succeeding sheet. Control is performed so that the reverse entrance roller pair 514 is rotationally driven until the leading edge of the sheet passes through the branching position of the branching unit and reaches a position upstream of the reverse roller pair 302 in the conveying direction.
According to this, as described in the above embodiment, the preceding sheet and the succeeding sheet can be conveyed in two places, ie, the reversing supply roller pair 301 and the reversing roller pair 302, and the conveying path is lengthened. The three sheets processed for the first surface can stay in the reverse conveyance path and the reverse path without waiting. Thereby, without using a large motor for speeding up the conveyance speed of the sheet, it is possible to increase the productivity when re-supplying the processed sheet for the first surface and processing the second surface. it can. Accordingly, it is possible to further improve the productivity when processing the second surface by re-supplying the processed sheet for the first surface while suppressing an increase in size and cost.
(Aspect C)
In the above aspect A or B, the inversion path 508 extends in the vertical direction, and the standby conveyance path 509 extends in the horizontal direction. According to this, as described in the above embodiment, the inversion path 508 can be disposed on the side of the standby conveyance path 509, and the vertical size of the apparatus can be reduced. Further, the curvature of the sheet conveyance path from the reversing path 508 toward the standby conveying path 509 can be increased as compared with the configuration in which the reversing path extending in the horizontal direction is disposed above or below the standby conveying path 509. . Therefore, it is possible to suppress the occurrence of conveyance failure when the sheet is conveyed from the reverse path 508 to the standby conveyance path 509 while downsizing the apparatus.
(Aspect D)
Image bearing members such as photosensitive drums 700Y, 700M, 700C, and 700Bk, image forming means such as a charging device and a developing device that form an image on the image bearing member, and a sheet of recording paper or the like on the image bearing member Transfer means such as primary transfer portions 602Y, 602M, 602C, 602Bk, intermediate transfer belt 601 and secondary transfer portion 600 to be transferred onto the surface of the recording medium, and an image on the recording medium transferred by the transfer means. An image forming apparatus such as a printer 100 having a fixing unit such as a fixing device 800 for fixing, and a recording medium conveying unit for conveying a recording medium so as to pass through a transfer position of the transfer unit and a fixing position of the fixing unit. The sheet conveying apparatus according to the aspect A or B is provided as the recording medium conveying unit.
According to this, as described in the above embodiment, the image-formed recording medium is re-supplied with respect to the first surface without using a large motor for increasing the recording medium conveyance speed. Productivity when forming an image on the second surface can be increased. Accordingly, it is possible to further improve the productivity when an image is formed on the first surface and an image is formed on the second surface by suppressing the increase in size and cost. In addition, three recording media can be made to stand by at the same time in the reverse conveyance path 507 and the reverse path 508, and 100% productivity of the recording medium printed on both sides can be ensured without increasing the conveyance speed of the recording medium. Is possible.
(Aspect E)
In the above aspect D, the image forming structure 101 includes a first structure 101 such as an image forming structure 101 and a second structure such as a fixing structure 102, and the first structure includes the image forming unit and the transfer unit. And a part of the main transport paths 503 and 504 and a part of the standby transport path 509. The second structure includes the fixing unit, a part of the main transport paths 503 and 504, and a paper discharge. It has a discharge conveyance path such as the conveyance path 505, a reverse conveyance path 507, a reverse path 508, and a part of the standby conveyance path 509, and the standby conveyance path 509 in each of the first structure and the second structure. A sheet supply unit such as a sheet feeding device 201 or 202 that can store a sheet such as a recording sheet is provided below the sheet feeding unit.
According to this, as described in the above embodiment, by providing the sheet supply means below the standby conveyance path 509 of each of the first structure and the second structure, each structure can be reduced in size. Sharing is possible.
(Aspect F)
In aspect E, the sheet supplied from the sheet supply unit is conveyed to the standby conveyance path 509 of each of the first structure and the second structure. According to this, as described in the above embodiment, the standby conveyance path 509 and the sheet supply unit can be shared.

100 Image forming apparatus 101 First structure (image forming structure)
102 Second structure (fixing structure)
201, 202 Paper feeding device 300 Reverse device 301 Reverse feed roller pair 302 Reverse roller pair 303 Standby conveyance inlet roller pair (double-sided conveyance roller pair)
304 Third branch claw 305 Second branch claw 400 Skew correction device 500 Paper transport device 501 Feed transport path (vertical transport path)
502 Converging section 503 Paper feed transport path 504 Belt transport path 505 Paper discharge transport path 506 Paper discharge section 507 Reverse transport path 508 Reverse path 509 Standby transport path (double-side transport path)
510 Belt roller pair 511 Paper discharge roller pair 512, 513 Paper discharge relay roller pair 514 Reverse entrance roller pair 520-522 Paper sensor 530 First branching claw 600 Secondary transfer portion 601 Intermediate transfer belt 700 Image carrier 800 Fixing device 900 Control unit 910 Roller pair rotation drive unit 920 Roller pair pressure contact / separation mechanism 930 Separation claw swing mechanism S, D Recording paper

JP 2001-326785 A

Claims (6)

A main conveyance path for conveying the sheet, a reversing path for reversing the traveling direction of the sheet, a reversing conveying path for conveying the sheet that has passed through the main conveying path toward the reversing path, and a traveling direction in the reversing path. A conveyance path forming member that forms a standby conveyance path for waiting the sheet so that the reversed sheet is reversed and fed back to the main conveyance path;
Branching means for branching the sheet whose traveling direction is reversed in the reversing path in a direction toward the standby conveying path;
A pair of reversing entrance rollers that are provided at the entrance of the reversing conveyance path and are rotatable to convey the sheet that has entered the reversing conveyance path toward the reversing path;
A pair of reversing supply rollers provided at an outlet of the reversing conveyance path on the upstream side in the conveying direction of the branching means and rotatable to convey the sheet in the reversing conveyance path toward the reversing path;
A reversing roller pair that is provided in the reversing path and is rotatable to reverse the traveling direction of the sheet that has entered the reversing path;
A pair of standby conveyance inlet rollers provided at the entrance of the standby conveyance path and rotatable to convey a sheet that has entered the standby conveyance path;
A sheet conveying apparatus comprising: a reversing inlet roller pair; a reversing supply roller pair; a reversing roller pair; and a rotation conveying means that rotationally drives the standby conveying inlet roller pair;
First contact / separation means for moving at least one roller of the reverse supply roller pair so that the reverse supply roller pair can take a pressure contact state and a separated state;
Second contact / separation means for moving at least one roller of the reverse roller pair so that the reverse roller pair can be in a pressure contact state and a separated state;
A sheet conveying apparatus further comprising: a control unit that controls the rotation driving unit, the first contact / separation unit, and the second contact / separation unit. In the sheet conveying apparatus according to claim 1,
The control means includes
When conveying the preceding sheet that has passed through the main conveying path toward the reversing path, the reversing entrance roller pair is rotationally driven, the reversing supply roller pair is rotationally driven in a pressure contact state, and the reversing roller pair is separated. Control to state,
After the trailing edge of the preceding sheet has passed the branching position of the branching unit, the preceding sheet is conveyed toward the standby conveyance inlet roller pair so as to be conveyed to the standby conveyance path, When the front end passes through the standby conveyance inlet roller pair, control to stop the rotational drive of the standby conveyance inlet roller pair,
When the first succeeding sheet that has passed through the main conveying path is conveyed toward the reversing path, the reversing entrance roller pair is rotationally driven, the reversing supply roller pair is rotationally driven in a pressure contact state, and the reversing roller pair Is controlled to a separated state,
When the trailing edge of the first succeeding sheet reaches the reverse supply roller pair, the rotational drive of the reverse supply roller pair is stopped, and the reverse roller pair is controlled to be in a pressure contact state.
When the second succeeding sheet that has passed through the main transport path is transported toward the reversing path, the reversal supply roller pair is separated, and the leading edge of the second succeeding sheet passes through the branching position of the branching unit. Then, the sheet conveying apparatus is controlled so as to rotationally drive the pair of reversing entrance rollers until reaching a position upstream in the conveying direction of the pair of reversing rollers. In the sheet conveying apparatus according to claim 1 or 2,
The sheet conveying apparatus, wherein the reverse path extends in a vertical direction, and the standby conveyance path extends in a horizontal direction. An image carrier, an image forming unit that forms an image on the image carrier, a transfer unit that transfers an image on the image carrier to a surface of a sheet-like recording medium, and the image transferred by the transfer unit. An image forming apparatus comprising: a fixing unit that fixes an image on a recording medium; and a recording medium conveyance unit that conveys the recording medium so as to pass through a transfer position of the transfer unit and a fixing position of the fixing unit. And
An image forming apparatus comprising the sheet conveying apparatus according to claim 1, 2 or 3 as the recording medium conveying unit. The image forming apparatus according to claim 4.
A first structure and a second structure;
The first structure includes the image forming unit, the transfer unit, a part of the main conveyance path, and a part of the standby conveyance path.
The second structure includes the fixing unit, a part of the main transport path, the discharge transport path, the reverse transport path, the reverse path, and a part of the standby transport path. ,
An image forming apparatus comprising: a sheet supply unit capable of storing a sheet below the standby conveyance path in each of the first structure and the second structure. The image forming apparatus according to claim 5.
The image forming apparatus, wherein the sheet supplied from the sheet supply unit is conveyed to the standby conveying path of each of the first structure and the second structure.

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