JP2018203386A - Sheet conveyance device and image formation apparatus - Google Patents

Abstract

To provide a sheet conveyance device which has simple constitution and is compact, and an image formation apparatus.SOLUTION: A sheet conveyance device comprises a before-registration roller pair 62 upstream from a skew correction device in a sheet conveyance direction, and the before-registration roller pair 62 comprises a before-registration drive roller 62a and a before-registration driven roller 62b. Further, the sheet conveyance device comprises a separation plate 117 which is driven by a before-registration motor M2 to move, and then move the before-registration driven roller 62b to separate from the before-registration driving roller 62a. Then the separation plate 117 is provided with a guide surface 117a and a guide surface 117b forming a sheet conveyance path P for guiding a sheet on the side of the before-registration drive roller 62b.SELECTED DRAWING: Figure 11

Description

  The present invention relates to a sheet conveying apparatus and an image forming apparatus.

  A sheet conveying apparatus applied to an image forming apparatus such as a printer, a facsimile, a copying machine, or an image reading apparatus has been proposed in which a pair of conveying rollers are separated (see Patent Document 1). In addition, this Patent Document 1 also drives a movable guide plate that forms a sheet conveyance path when separating the above-described upstream roller pair, and further increases the width of the sheet conveyance path. It is comprised so that conveyance resistance may be reduced.

JP 2013-1547 A

  In Patent Document 1, an arm portion for separating the roller pair is disposed on the outer side in the sheet width direction with respect to the sheet conveyance path. For this reason, there exists a problem that an apparatus will enlarge.

  SUMMARY An advantage of some aspects of the invention is that it provides a sheet conveying apparatus and an image forming apparatus that can be downsized with a simple configuration.

  A sheet conveying apparatus according to the present invention includes a first roller and a second roller that abuts against the first roller to form a nip and is separable from the first roller, and conveys the sheet. Means, a driving means for outputting a driving force, a moving member that moves by being driven by the driving means to move away from the first roller, and a moving member. And a guide surface for guiding the sheet conveyed by the conveying means.

  According to the present invention, since the moving member that separates the second roller from the first roller has the guide surface that forms the sheet conveyance path for guiding the sheet on the second roller side, the apparatus can be miniaturized. be able to.

1 is a schematic diagram illustrating a configuration of an image forming apparatus according to an embodiment. The schematic diagram which shows the manual feeding apparatus and skew feeding correction apparatus which concern on this embodiment. The block diagram which shows the transmission path and control part of the driving force of a manual feeding apparatus and a skew feeding correction apparatus. (A) is a schematic diagram showing a state in which the skewed sheet is conveyed to the registration roller pair, (b) is a schematic diagram showing a state in which the skewed sheet abuts against the registration roller pair, and (c) is a registration roller. The schematic diagram which shows the state which started conveyance of the sheet | seat by a pair. FIG. 4 is a schematic diagram illustrating a state in which a pair of pre-registration rollers is separated when the conveyance of a sheet by a registration roller pair is started. (A) is a schematic diagram showing a state in which the pre-registration roller pair is kept in pressure contact when the conveyance of the sheet by the registration roller pair is started, and (b) is a state in which the pre-registration roller pair is kept in pressure contact. The schematic diagram which shows the position of a sheet | seat. The perspective view which shows the state which looked at the pre-registration driven guide unit from the opposite side of the sheet conveyance path. The perspective view which shows the state which looked at the pre-registration driven guide unit which removed the guide reinforcement board from the other side of the sheet conveyance path. The expansion perspective view which shows the separation | spacing mechanism in a pre-registration driven guide unit. The perspective view which shows the state which looked at the pre-registration driven guide unit from the sheet conveyance path side. Sectional drawing which shows the pre-registration driven guide unit in a state in which the pair of pre-registration rollers is pressed. Sectional drawing which shows the pre-registration driven guide unit in a state where the pair of pre-registration rollers is separated. Sectional drawing for demonstrating the arrangement | positioning space of the separation plate in the pre-registration driven guide unit.

[Configuration of Image Forming Apparatus]
Hereinafter, a sheet conveying apparatus and an image forming apparatus according to the present embodiment will be described with reference to the drawings. The image forming apparatus 1 according to the present embodiment is a full-color laser beam printer that forms an image on a sheet S based on image information input from an external device such as a personal computer. However, the sheet S refers to a thin-layer recording medium such as paper including plain paper, cardboard, envelope, and the like, a plastic film such as an overhead projector sheet (OHT), and cloth.

  As shown in FIG. 1, the image forming apparatus 1 includes an image forming unit 1B that forms an image on a sheet S, a fixing unit 20 that fixes an image on the sheet S, and the like inside the apparatus main body 1A. Above the apparatus main body 1A, an image reading device 2 that reads image data of a document is disposed in a posture in which the document placement surface is substantially horizontal. A discharge tray 23 is provided in a sheet discharge space formed between the image reading apparatus 2 and the apparatus main body 1A. Further, the apparatus main body 1A is provided with a sheet feeding unit 30 that feeds the sheet S to the image forming unit 1B. The sheet feeding unit 30 includes one or a plurality (four in the illustrated example) of sheet feeding devices 31, 32, 33, and 34 and a manual feeding device 35 disposed at the lower portion of the apparatus main body 1 </ b> A. Each of the sheet feeding apparatuses 31, 32, 33, and 34 has cassettes 41, 42, 43, and 44 that store a sheet bundle composed of a plurality of sheets S. Each of the sheet feeding devices 31, 32, 33, and 34 includes a pickup roller 5a, a feed roller 5b, and a retard for feeding the uppermost sheet of the sheet bundle of the cassettes 41, 42, 43, and 44 one by one. It has a roller 5c. The manual feeding device 35 includes a feeding tray 45 on which sheets can be stacked, a pickup roller 65 for feeding the uppermost sheets of the stacked sheet bundle one by one, and a feeding separation roller pair 64. ing. The configuration of the manual feeding device 35 will be described later in detail.

  The image forming unit 1B as an image forming unit has a so-called four-drum full-color configuration including a laser scanner 10, four process cartridges 1a, 1b, 1c, and 1d, and an intermediate transfer unit 1C. These cartridges form yellow, magenta, cyan, and black toner images, respectively. Each process cartridge 1a, 1b, 1c, 1d includes a photosensitive drum 12, which is a photosensitive member, a charger 13, a developing device 14, a cleaner (not shown), and the like. A toner cartridge 15 containing toner of each color is detachably mounted on the apparatus main body 1A above the image forming unit 1B.

  The intermediate transfer unit 1C is configured by winding an intermediate transfer belt 16 as an intermediate transfer member around a driving roller 16a, a tension roller 16b, and the like, and is disposed above the four process cartridges 1a, 1b, 1c, and 1d. . The intermediate transfer belt 16 is rotated in the counterclockwise direction in the figure by a driving roller 16a driven by a driving unit (not shown) while being in contact with the photosensitive drums 12 of the process cartridges 1a, 1b, 1c, and 1d. The intermediate transfer unit 1 </ b> C includes a primary transfer roller 17 that is in contact with the inner peripheral surface of the intermediate transfer belt 16 at a position facing each photosensitive drum 12. Further, the image forming unit 1B includes a secondary transfer roller 19 that contacts the outer peripheral surface of the intermediate transfer belt 16 at a position facing the drive roller 16a.

  In each of the above-described process cartridges 1a, 1b, 1c, and 1d, an electrostatic latent image is drawn on the surface of the photosensitive drum 12 by the laser scanner 10, and then toner is supplied from the developing unit 14, thereby negative polarity. A toner image of each color charged is formed. These toner images are subjected to multiple transfer (primary transfer) to the intermediate transfer belt 16 by applying a positive transfer bias voltage to the primary transfer roller 17 to form a full color toner image on the intermediate transfer belt 16. Is done.

  In parallel with the toner image forming process, the sheet S fed from the sheet feeding unit 30 serves as a skew feeding correction unit having a drawing roller pair 63, a pre-registration roller pair 62, and a registration roller pair 61. It is transported toward the skew correction device 60. The skew correction device 60 corrects the skew of the sheet. The registration roller pair 61 puts the sheet S on the secondary transfer portion formed between the intermediate transfer belt 16 and the secondary transfer roller 19 in accordance with the transfer timing of the full-color toner image formed on the intermediate transfer belt 16. Transport. The toner image carried on the intermediate transfer belt 16 is secondarily transferred to the sheet S by applying a positive transfer bias voltage to the secondary transfer roller 19. The configuration of the skew feeding correction device 60 will be described later in detail.

  When the sheet S to which the toner image has been transferred is heated and pressed in the fixing unit 20, the toner image is fixed on the sheet S as a color image. The sheet S on which the image is fixed is discharged and stacked on the discharge tray 23 by the discharge roller pair 25a. When images are formed on both sides of the sheet S, the sheet S that has passed through the fixing unit 20 is switched back by a pair of reversing rollers 25b that can be rotated in the normal direction. Then, when the sheet S is conveyed again to the image forming unit 1B via the reconveying path R1, an image is formed on the back surface of the sheet S and is discharged to the discharge tray 23 to complete the duplex printing.

[Configuration of sheet conveying apparatus]
Next, a sheet conveying device 90 including the manual feeding device 35 and the skew feeding correction device 60 will be described with reference to FIGS. Note that, in a broad sense, the sheet conveying device 90 in the image forming apparatus 1 of the present embodiment conveys a sheet set in the sheet feeding unit 30 including the manual feeding device 35 to the image forming unit 1B, and further performs image formation. This refers to a device that conveys the used sheet to the discharge tray 23. However, in a narrow sense, the sheet conveying device 90 may be a device that conveys the sheet fed from the manual feeding device 35 to the image forming unit 1B by correcting the skew by the skew feeding correcting device 60.

  As shown in FIG. 2, the manual feeding device 35 includes a feeding tray 45, a pickup roller 65, and a feeding separation roller pair 64. The pickup roller 65 is supported by a pick arm 66 included in the pickup roller lifting mechanism 300 so as to be slidable in the vertical direction. The retard roller 64b is pressed against the feed roller 64a by a spring (not shown) across the sheet conveyance path P.

  Further, the skew feeding correction device 60 includes a drawing roller pair 63, a pre-registration roller pair 62 as a conveying unit, and a registration roller pair 61. The drawing roller pair 63 includes a drawing driving roller 63a and a drawing driven roller 63b. The drawing driven roller 63b is pressed against the drawing driving roller 63a by a spring (not shown) with the sheet conveying path P interposed therebetween. Similarly, the pre-registration roller pair 62 includes a pre-registration driving roller 62a as a first roller or a driving roller and a pre-registration driven roller 62b as a second roller or a driven roller. The pre-registration driven roller 62b is pressed against the pre-registration drive roller 62a by a spring (not shown) across the sheet conveyance path P. A detailed configuration of the registration roller pair 61 including the registration driving roller 61a and the registration driven roller 61b will be described later.

  The various rollers described above are housed in the respective guide units, the guide units are arranged to face each other, and each has a guide surface for guiding the sheet, whereby a sheet transport path P as a path for transporting the sheet is formed. Is formed. That is, the feed roller 64 a and the pulling driven roller 63 b are accommodated in the feed roller guide unit 75. The retard roller 64 b and the extraction drive roller 63 a are accommodated in an extraction drive guide unit 76 that is disposed to face the feed roller guide unit 75. The pre-registration driving roller 62 a is accommodated in the pre-registration driving guide unit 74, and the pre-registration driven roller 62 b is accommodated in the pre-registration driven guide unit 73 disposed to face the pre-registration driving guide unit 74. The registration driving roller 61 a is accommodated in the registration driving guide unit 72, and the registration driven roller 61 b is accommodated in a registration driven guide unit 71 disposed opposite to the registration driving guide unit 72.

  Next, drive paths in the manual feeding device 35 and the skew feeding correction device 60 will be described. As shown in FIG. 3, the manual feed device 35 is provided with a feed motor M3 that outputs a driving force, and the skew correction device 60 has a pre-registration motor that outputs a driving force as a driving means. M2 and a registration motor M1 that outputs a driving force are provided. Each of these motors is connected to the control unit 100 and driven and controlled in the forward direction or the reverse direction. In addition, although the control part 100 has illustrated what is provided with CPU101, RAM102, ROM103, HDD104, etc., it is not limited to these structures in particular.

  The division of the drive path is important because it is directly linked to the skew correction ability when the skew correction of the sheet is performed. In the present embodiment, the arrangement is as follows. The registration driving roller 61a is driven by a single registration motor M1, and the pre-registration driving roller 62a and the extraction driving roller 63a are driven in the same way by the pre-registration motor M2. The pickup roller 65, the feed roller 64a, and the retard roller 64b are driven by the same feeding motor M3.

  Specifically, the feed motor M3 is connected to the pickup roller 65, the feed roller 64a, and the retard roller 64b via a one-way clutch (not shown) that transmits forward rotation, and the feed motor M3 is driven to rotate forward. Thus, it is driven to rotate synchronously. The retard roller 64b is rotated in the reverse direction toward the opposite side to the sheet conveying direction via a gear or the like. The feed motor M3 is connected to a pickup roller lifting mechanism via a one-way clutch (not shown) that transmits reverse rotation, and when the feed motor M3 is driven in reverse, the pick arm 66 and the pickup roller 65 are moved in the vertical direction. Driven, that is, moved up and down. Further, the pre-registration motor M2 is connected to the pre-registration drive roller 62a and the pull-out drive roller 63a via a one-way clutch (not shown) that transmits normal rotation, and is synchronized with the pre-registration motor M2 being driven to rotate forward. And is driven to rotate. The pre-registration motor M2 is connected to the pre-registration driven roller contact / separation mechanism 200 via a one-way clutch (not shown) that transmits reverse rotation. As the pre-registration motor M2 is driven in reverse, the pre-registration driven roller 62b is brought into contact with and separated from the pre-registration drive roller 62a as described in detail later. The pre-registration motor M2 is disposed on the same side as the pre-registration driven roller contact / separation mechanism 200 with respect to the sheet conveyance path. The registration driving roller 61a is connected to the registration motor M1 and is driven to rotate forward or reversely.

  Here, an operation of rough sheet feeding and skew feeding correction will be described. When feeding the sheets stacked on the feeding tray 45, first, the feeding motor M3 is rotated in the reverse direction, the pickup roller lifting mechanism 300 is driven, and the pickup roller 65 is brought into contact with the uppermost sheet. Thereafter, the feed motor M3 is rotated forward, the pickup roller 65, the feed roller 64a, and the retard roller 64b are rotated, and the pickup roller 65 feeds the sheet to the feed separation roller pair 64. At this time, for example, when a plurality of sheets are fed to the feed separation roller pair 64, the feed roller 64a conveys the upper sheet, and the retard roller 64b pushes the lower sheet back to the feed tray 45, thereby Sheets are separated one by one and fed. Further, the pre-registration motor M2 is rotated forward to rotate the pulling driving roller 63a and the pre-registration driving roller 62a, and the sheet fed separated from the feed roller 64a is pulled by the pulling roller pair 63, and the register It is conveyed to the front roller pair 62. Then, the sheet is conveyed to the registration roller pair 61 by the pre-registration roller pair 62.

  On the other hand, the registration motor M1 is stopped, and the sheet conveyed by the pre-registration roller pair 62 hits the stopped registration roller pair 61. As a result, the skew of the sheet is corrected so that the skew of the leading edge of the sheet follows the registration roller pair 61 while the sheet is bent. At this time, by causing the registration motor M1 to rotate in the reverse direction, biting of the leading edge of the sheet into the registration roller pair 61 can be eliminated, and the sheet can be easily rotated in the sheet width direction. Further, as will be described in detail later, the pre-registration motor M2 is rotated in the reverse direction, the pre-registration driven roller contact / separation mechanism 200 is driven, and the pre-registration driven roller 62b is separated from the pre-registration drive roller 62a, thereby conveying the sheet. Resistance can be reduced. Thereafter, by rotating the registration motor M1 in the normal direction, the sheet conveyance by the registration roller pair 61 is resumed, and the sheet whose skew has been corrected is conveyed toward the image forming unit 1B.

  Next, details of the skew correction operation in the skew correction device 60 will be described with reference to FIGS. 4 to 6, the solid line indicates the sheet that is conveyed while being skewed, and the dotted line is the sheet that is conveyed without being skewed. The design center in the sheet width direction in the sheet conveyance path P is indicated as a sheet conveyance center CT, and the sheet conveyance direction is indicated by an arrow A. Further, in each of the roller pairs shown in FIGS. 4 to 6, the roller pairs indicated by shading are in a pressure contact state, and the roller pairs not shaded are in a separated state. A registration sensor SN1 is provided near the sheet conveyance center CT between the registration roller pair 61 and the pre-registration roller pair 62, and a pull-out sensor is provided near the sheet conveyance center CT between the pre-registration roller pair 62 and the drawing roller pair 63. SN2 is respectively arranged. By detecting the presence or absence of a sheet by the registration sensor SN1 and the pull-out sensor SN2, it is possible to determine the delay or stay of the sheet conveyance, and it is possible to determine the amount of bending of the sheet based on the detected timing.

  As shown in FIG. 4A, first, the skewed sheet S is conveyed by the pre-registration roller pair 62 and the drawing roller pair 63. As an example of the skewed sheet S at this time, the sheet S is skewed so that the left side in FIG. Thereafter, as shown in FIG. 4B, the leading edge of the sheet S is abutted against the stopped pair of registration rollers 61, and the skew of the leading edge of the sheet S is corrected. At this time, the skew of the leading edge of the sheet S is corrected by bending the sheet S between the registration roller pair 61 and the pre-registration roller pair 62. The amount of bending of the sheet S is controlled at the timing when the sheet S is detected by the registration sensor SN1. Thereafter, as shown in FIG. 4C, the registration roller pair 61 is rotated so that the leading edge of the sheet S is conveyed in a corrected state.

  Here, as shown in FIG. 6A, when the registration roller pair 61 is rotated and the sheet S with the skew at the leading end is conveyed, if it is nipped by the pre-registration roller pair 62 and is conveyed, The rear end of the sheet S is restrained. Then, as shown in FIG. 6B, it can be seen that the position of the solid line has moved to the left as compared with the position of the broken line. That is, when the trailing edge of the sheet S is restrained by the pre-registration roller pair 62, the amount of deviation t increases. In the schematic diagram, although it is extremely displayed for easy understanding, the positional deviation of the sheet S occurs particularly when the sheet is conveyed after the registration roller pair 61 of FIG. This is due to the bending shape of the sheet S formed between the registration roller pair 61 and the pre-registration roller pair 62. That is, the rear end of the sheet S is restrained by the pre-registration roller pair 62 that is an upstream roller in the sheet conveyance direction, and thus the sheet cannot be rotated in the direction indicated by the arrow B.

  On the other hand, as shown in FIG. 5, if the pre-registration roller pair 62 is separated after the rotation of the registration roller pair 61 is started, the sheet easily turns in the direction indicated by the arrow B, and the above-described misalignment amount t is also shown in FIG. Smaller than (b). This is because the skew feeding section of the sheet S is reduced by making the trailing edge of the sheet free as early as possible during conveyance after correction of the leading edge of the sheet S. Further, bending the sheet S between the registration roller pair 61 and the pre-registration roller pair 62 may cause the sheet to buckle, particularly with respect to a sheet having low rigidity such as thin paper, and a paper jam occurs. There is also a fear. Accordingly, by separating the pair of pre-registration rollers 62 in this way, it is possible to eliminate excessive sheet deflection and stabilize the sheet behavior.

[Details of pre-registration driven guide unit]
First, as a method of separating the roller pair, three methods of separating the driving roller, separating the driven roller, and separating both rollers can be considered. However, the method of separating the drive rollers or separating both rollers is complicated in construction. That is, the mechanism for driving the drive roller includes a gear, and the driving force is transmitted from the motor via the gear. Therefore, in the method of separating the drive roller, it is necessary to move the drive roller including the gear, and parts such as a link and a coupling are required. Therefore, the configuration is complicated and the cost is increased. Therefore, since the method of separating the driven roller has a simple configuration and can prevent an increase in cost, the structure of separating the pre-registration driven roller 62b is also adopted for the pre-registration roller pair 62 in the present embodiment.

  As shown in FIGS. 7 to 12, the pre-registration driven guide unit 73 includes a housing 112 that is immovably disposed in the image forming apparatus 1 as a guide member, and a reinforcement that is attached to reinforce the housing 112. A plate 116 is provided. Inside the housing 112 and the reinforcing plate 116, as shown in FIG. 8 with the reinforcing plate 116 removed, the pre-registration driven roller 62b, the support shaft 114, the compression spring 115, the pre-registration driven roller contact / separation mechanism 200, etc. Is built-in.

  The pre-registration driven roller 62b is rotatably supported by a support shaft 114 that can move with respect to the housing 112 in a direction opposite to the pre-registration drive roller 62a. The support shaft 114 is urged toward the pre-registration drive roller 62a with respect to the casing 112 by a compression spring 115 as urging means. That is, the seating surface of the compression spring 115 is positioned and held by the reinforcing plate 116, and the compression spring 115 presses the pre-registration driven roller 62b toward the pre-registration drive roller 62a via the support shaft 114 so as to be separated.

  As shown in FIGS. 8 and 9, the pre-registration driven roller contact / separation mechanism 200 includes a separation plate 117, a separation shaft 118, a separation arm 119, a separation gear 120, and a biasing spring 121 as moving members. ing. The separation plate 117 is fixed to one end portion of the separation shaft 118 with a screw or the like, and a separation arm 119 is fixed to the other end portion of the separation shaft 118 with a screw or the like. The separation arm 119 fixed to the separation shaft 118 is always in contact with the surface of the separation cam 122 whose arm portion 119 a is interlocked with the separation gear 120 by a biasing spring 121. Therefore, when the separation gear 120 rotates together with the separation cam 122 by the pre-registration motor M2, the arm portion 119a of the separation arm 119 moves along the surface shape of the separation cam 122, and the arm portion 119a of the separation arm 119 moves the separation shaft 118. Swings as the center of rotation. Then, when the separating arm 119 is swung, the separating plate 117 is also swung through the separating shaft 118, and the support shaft 114 engaged with the separating plate 117 is moved against the urging force of the compression spring 115. Then, the pre-registration driven roller 62b is moved to separate the nip of the pre-registration roller pair 62. The contact position and separation position of the pre-registration driven roller 62b with respect to the pre-registration drive roller 62a are determined by detecting the position of the separation arm 119 using a photosensor 123 attached in the vicinity of the separation arm 119.

  In the present embodiment, as shown in FIGS. 7, 8, and 10, the separation plate 117 is disposed at the center in the sheet width direction orthogonal to the sheet conveyance direction, that is, at the sheet conveyance center CT. ing. The pre-registration driven rollers 62b are plural, and are arranged at a plurality of locations (two locations in the present embodiment) in the axial direction, that is, the sheet width direction, with the sheet conveyance center CT as a line target. That is, when the sheet is conveyed by the two pre-registration driven rollers 62b in the sheet width direction, the sheet is restrained and supported at two locations, so that the sheet can be fed diagonally less than when conveyed by one roller, for example. It is difficult to turn. In this configuration, when the pre-registration driven roller 62b supported by the support shaft 114 is separated, the support shaft 114 at the center of the two pre-registration driven rollers 62b in the sheet width direction is supported by the separation plate 117. It is considered optimal for reducing the number of parts. For example, the spacing plate 117 is not supported at the center of the two pre-registration driven rollers 62b but on the opposite side of the pre-registration driven roller 62b from the sheet conveyance center CT. Then, in order to separate the two pre-registration driven rollers 62b with high accuracy, it is necessary to provide separation plates 117 at two positions, such as position C and position D shown in FIG. In this case, it is necessary to add parts of the separation plate 117, and the number of parts is increased, resulting in an increase in cost. For this reason, in the present embodiment, the optimal position of the separation plate 117 is arranged at a position perpendicular to the sheet thickness direction, that is, the thickness direction of the sheet conveyance path, with respect to the sheet conveyance center CT, and the center in the sheet width direction is It contacts with the separation plate 117.

  As described above, the components of the pre-registration driven roller contact / separation mechanism 200 are disposed only on the pre-registration driven roller 62b side with respect to the sheet conveyance path P, and the support shaft 114 can be moved by the separation plate 117. Is possible. Accordingly, since there is no need for parts that straddle the sheet conveyance path P, it is not necessary to make the pre-registration driven guide unit 73 significantly longer than the sheet conveyance path P in the sheet width direction, and the configuration is simple and the size is reduced. Can be planned.

[About the separation plate]
As described above, the first function of the separation plate 117 is to move the support shaft 114 and move the pre-registration driven roller 62b to the separation position or the contact position. A second function of the separation plate 117 is to have a guide surface 117a that forms the sheet conveyance path P and to guide the sheet. In general, it is desirable that the guide member for guiding the sheet is not movable except for example a flapper. This is to cope with various sheet states (so-called curled paper or the like), and because the guide member moves, the guide position of the sheet varies, which may cause a paper jam. However, the spacer plate 117 is configured to have the second function for the following reason.

  As shown in FIG. 10, the pre-registration driven guide unit 73 has a guide surface 112 a that forms the sheet conveyance path P of the housing 112. In part of the guide surface 112a, a sensor for detecting a delay or stay of the conveyed sheet is disposed in the vicinity of the sheet conveyance center CT. Therefore, an opening 112c for securing the detection region is provided. Is formed. That is, the sensor detects the sheet conveyed through the opening 112c. For example, when the separation plate 117 does not serve as a sheet guide member, as shown in FIG. 13, a guide member 212 having a guide surface forming the sheet conveyance path P bent as shown by a solid line is disposed, and the opening 112c is arranged. It is necessary to form a guide surface. That is, if a guide surface is formed like the virtual guide surface 112v shown by the dotted line in FIG. 13, the region X is lost, and the sensor detection region is lost. Here, if the guide member 212 that forms the bent guide surface as shown by the solid line in FIG. 13 is disposed, the distance d3 from the support shaft 114 is small, and the gap for storing the separation plate 117 is small. There is a problem that a gap for inserting the separation plate 117 cannot be secured. As means for solving this problem, it is conceivable to increase the outer diameter of the pre-registration driven roller 62b or to arrange the separation plate 117 at a position offset in the sheet width direction. However, in any case, the cost increases. Arise.

  In the present embodiment, as shown in FIGS. 10 to 12, since the separation plate 117 has the guide surface 117a and the guide surface 117b, another guide member is provided on the sheet conveyance path P side of the separation plate 117. Arrangement can be made unnecessary. In other words, the spacing plate 117 also serves as the guide surface of the sheet directly, so that the sheet guide surface can be considered by the thickness of the spacing plate 117. Further, when configuring the pre-registration driven roller contact / separation mechanism 200, the distance between the sheet conveyance path P and the support shaft 114 can be reduced, and the apparatus can be downsized. Further, the guide surface 117 a and the guide surface 117 b of the separation plate 117 are located at positions offset toward the support shaft 114 with respect to the guide surface 112 a on the pre-registration drive roller 62 a side of the housing 112. Thereby, a recessed part is formed and the detection area | region of the sensor mentioned above is ensured.

  A detailed configuration of the separation plate 117 configured as described above will be described with reference to FIGS. 10, 11, and 12. As shown in FIGS. 10 and 11, an opening 112 c that exposes the separation plate 117 is formed in the housing 112. Further, a guide surface 112b as a downstream guide surface formed integrally with the housing 112 is provided on the downstream side of the opening 112c in the sheet conveyance direction. The connecting portion between the leading end 112d of the guide surface 112b of the casing 112 on the downstream side in the sheet conveying direction and the leading end 117c on the upstream side of the separating plate 117 in the sheet conveying direction is closer to the sheet than the nip N of the pre-registration roller pair 62. Located downstream in the transport direction.

  A line passing through the center of the nip N is a nip line NL, that is, a common tangent line between the pre-registration driving roller 62a and the pre-registration driven roller 62b is a nip line NL. In a state where the pre-registration driven roller 62b is in contact with the pre-registration drive roller 62a, the distance d1 between the tip 117c of the separation plate 117 and the nip line NL is equal to the tip 112d of the guide surface 112b of the housing 112 and the nip line NL. The distance d2 is smaller than the distance d2. That is, the separation plate 117 is disposed so as to satisfy the relationship of distance d2> distance d1> 0. Therefore, the front end 117 c of the separation plate 117 is located closer to the nip line NL than the front end 112 d of the guide surface 112 b of the housing 112. By disposing the separation plate 117 in this way, the sheet can be stably conveyed without being caught when passing the connecting portion after the sheet is nipped and conveyed by the pair of pre-registration rollers 62. Further, as shown in FIG. 12, even when the pre-registration driven roller 62b is separated from the pre-registration drive roller 62a, the sheet is caught because it is configured to satisfy the relationship of distance d2> distance d1> 0. And can be transported stably.

  Also, as shown in FIG. 12, in the state where the pre-registration driven roller 62b is separated from the pre-registration drive roller 62a, the angle θa formed by the guide surface 117a of the separation plate 117 and the nip line NL is 45 degrees or less. The spacing plate 117 is configured and arranged so as to be. By achieving this positional relationship, even when the sheet is conveyed, for example, a sheet with a curled end portion can be prevented from being caught when coming into contact with the guide surface 117a, and is not affected by the state of the sheet. Transport is possible. In addition, since the resistance that the sheet receives from the guide surface 117a during conveyance of the sheet can be reduced, the conveyance efficiency of the sheet can be improved, and skew feeding of the sheet can be reduced.

  As described above, the separation plate 117 that separates the pre-registration driven roller 62b from the pre-registration drive roller 62a forms the guide surface 117a and the guide surface that form the sheet conveyance path P that guides the sheet on the pre-registration driven roller 62b side. 117b. Accordingly, it is not necessary to dispose a component that drives the separation plate 117 outside the sheet conveyance path P in the sheet width direction. As a result, the structure for reducing the sheet conveyance resistance at the time of skew correction can be simplified, and the size can be reduced.

  In the present embodiment, the sheet conveying device 90 including the skew feeding correcting device 60 has been described as correcting the skew feeding to the image forming unit 1B and feeding the sheet. However, the present invention is not limited to this. For example, in an automatic document feeder that automatically conveys a sheet as a document to the image reading unit, the sheet may be conveyed by correcting skew feeding to the image reading unit.

  Further, in the present embodiment, the guide surface 117a and the guide surface 117b of the separation plate 117 are described as being recessed from the guide surface 112a of the housing 112, that is, on the side opposite to the sheet conveyance path P. . However, the guide surface 117a and the guide surface 117b of the separation plate 117 may be in the same position as the guide surface 112a of the housing 112 in a state where the pre-registration driven roller 62b is in contact with the pre-registration drive roller 62a.

  In the present embodiment, the pre-registration driven roller 62b and the single separation plate 117 are described. However, the present invention is not limited to this, and there may be a plurality of pre-registration driven rollers 62b and a plurality of separation plates 117, a single pre-registration driven roller 62b and a plurality of separation plates 117.

  In the present embodiment, the pre-registration roller pair 62 has been described as a roller pair that is separated when the registration roller pair 61 starts to be transported on the upstream side of the registration roller pair 61 in the sheet transport direction. However, the present invention is not limited to this, and any pair of rollers may be used as long as they can be separated at the start of conveyance of the registration roller pair 61 and the restraint of the trailing edge of the sheet can be released.

  In the present embodiment, the pre-registration roller pair 62 is illustrated as the pair of rollers that are separated from each other. However, the present invention can be applied to any pair of rollers in the conveyance path.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus: 1B ... Image forming part: 60 ... Skew correction means (skew correction apparatus): 62 ... Conveyance means (pre-registration roller pair): 62a ... First roller, drive roller (pre-registration drive roller) : 62b ... second roller, driven roller (pre-registration driven roller): 90 ... sheet conveying device: 112 ... guide member (housing): 112c ... opening: 112b ... downstream guide surface: 112d ... tip: 114 ... support Axis: 115 ... biasing means (compression spring): 117 ... moving member (separating plate): 117a, 117b ... guide surface: 117c ... tip: M2 ... driving means (motor before registration): N ... nip: NL ... nip line : P ... Sheet conveyance path: S ... Sheet: SN1 ... Sensor (registration sensor): X ... Detection area

Claims (10)

A first roller and a second roller that forms a nip in contact with the first roller and is separable from the first roller;
Driving means for outputting a driving force;
A moving member that moves by being driven by the driving means to move the second roller away from the first roller;
A guide surface provided on the moving member and guiding a sheet conveyed by the conveying unit.
A sheet conveying apparatus. A guide member that is disposed so as not to move so as to be positioned in the sheet width direction perpendicular to the sheet conveyance direction with respect to the nip, and forms a sheet conveyance path;
The guide member has an opening in a part in the sheet width direction,
The moving member is arranged so that the guide surface corresponds to the opening.
The sheet conveying apparatus according to claim 1. The second roller is a plurality of rollers arranged at a plurality of positions in the axial direction with the sheet conveyance center as a line target,
The opening of the moving member and the guide member is arranged so that the guide surface of the moving member is in contact with the center in the width direction of the conveyed sheet.
The sheet conveying apparatus according to claim 2. The transport means includes a support shaft that rotatably supports the second roller,
The moving member engages with the support shaft to move the second roller,
The guide surface of the moving member is offset to the support shaft side with respect to the first roller side surface of the guide member in a state where the second roller is in contact with the first roller. To position,
The sheet conveying apparatus according to claim 2, wherein the sheet conveying apparatus is a sheet conveying apparatus. It has a sensor that detects the conveyed sheet,
The recessed portion formed by offsetting the guide surface of the moving member to the second roller side relative to the surface of the guide member on the first roller side is a detection region of the sensor.
The sheet conveying apparatus according to any one of claims 2 to 4, wherein the sheet conveying apparatus is provided. The first roller is a driving roller driven by a driving force,
The second roller is a driven roller driven by the first roller;
The transport means includes biasing means for biasing the second roller toward the first roller,
The moving member is driven by the driving means to move the second roller in a direction away from the first roller against the urging force of the urging means.
The sheet conveying apparatus according to claim 1, wherein the sheet conveying apparatus is a sheet conveying apparatus. A downstream guide surface that is disposed immovably downstream of the moving member in the sheet conveyance direction and forms a sheet conveyance path and guides the sheet guided by the guide surface;
A downstream end of the guide surface of the moving member in the sheet conveying direction and an upstream end of the downstream guide surface in the sheet conveying direction are located downstream of the conveying unit in the sheet conveying direction.
The sheet conveying apparatus according to claim 1, wherein the sheet conveying apparatus is a sheet conveying apparatus. The downstream end of the moving member in the sheet conveying direction is closer to the nip line that is the common tangent of the first roller and the second roller than the upstream leading end of the downstream guide surface in the sheet conveying direction. Located in the
The sheet conveying apparatus according to claim 7. A skew correction means for abutting a sheet conveyed to correct the skew of the sheet;
The conveying means conveys the sheet to the skew feeding correcting means;
The sheet conveying apparatus according to claim 1, wherein the sheet conveying apparatus is a sheet conveying apparatus. A sheet conveying device according to any one of claims 1 to 9,
An image forming unit that forms an image on the sheet conveyed by the sheet conveying device,
An image forming apparatus.

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