JP2017057083A - Sheet feeding device, and image formation device equipped with sheet feeding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothly feed a sheet member without causing feeding failure and abnormal sound on each of sheet members having a different friction factor to a separation member.SOLUTION: A manual sheet feeding device 60 includes a separation mechanism 80. The separation mechanism 80 includes a support plate 81, a separation member 82, and a slide moving mechanism 83. The separation member 82 includes a first separation pad 82A and a second separation pad 82B. The slide moving mechanism 83, in a case where a frictional force between a first separation pad and a sheet member P is equal to a sheet transportation force or larger, moves the separation member 82 to a lower stream side along feeding direction D1, to be arranged at a second position where the second separation pad and a peripheral surface of a rubber roller 87 can contact each other.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a sheet feeding device that feeds a sheet member by rotating in contact with the sheet member, and an image forming apparatus including the sheet feeding device.

  A conventional image forming apparatus such as a copying machine or a printer includes a sheet feeding device that takes out and conveys a sheet member accommodated in a sheet feeding cassette. The sheet feeding device includes a rotating roller that rotates in contact with the sheet member, and the sheet member is fed in a predetermined direction by transmitting a rotational driving force to the rotating roller from a motor or the like. .

  This type of sheet feeding apparatus has a separating member (see Patent Document 1). The separation member is provided at a position facing the rotating roller. The separating member is urged toward the rotating roller by an elastic member or the like, and is in contact with the surface of the rotating roller by a predetermined urging force. When a plurality of sheet members enter the nip portion between the rotating roller and the separating member, only the uppermost sheet member is separated by the friction between the separating member and the lower sheet member, and the feeding direction It is fed downstream.

  By the way, the image forming apparatus is used not only for the purpose of forming an image on printing paper formed of paper but also for the purpose of forming an image on a resin sheet such as an OHP sheet. In this case, the resin sheet is accommodated in the sheet feeding cassette, and the resin sheet is fed by the rotating roller of the sheet feeding device.

JP 2003-201032 A

  However, the resin sheet has a larger frictional force with the separating member than the printing paper. Also, the frictional force between the resin sheets is larger than the frictional force between the printing sheets. Therefore, the frictional force between the separation member and the resin sheet and the frictional force between the resin sheets are larger than the sheet conveying force in the feeding direction that occurs when the rotating roller rotates in contact with the resin sheet. Therefore, there is a possibility that the feeding failure of the resin sheet may occur, or a stick-slip phenomenon may occur at the contact portion of each member to generate abnormal noise.

  The present invention has been made in view of the above circumstances, and an object thereof is to smoothly feed a sheet member without causing poor feeding or abnormal noise to each of the sheet members having different friction coefficients with respect to the separation member. An object of the present invention is to provide a sheet feeding apparatus capable of performing the above and an image forming apparatus including the sheet feeding apparatus.

  A sheet feeding device according to one aspect of the present invention includes a sheet tray, a rotating roller, a support member, a separation member, and a moving mechanism. The sheet tray mounts a sheet member. The rotating roller feeds the sheet member in the feeding direction by a first frictional force in a predetermined feeding direction generated between the rotating roller and the sheet member by rotating in contact with the sheet member on the sheet tray. To send. The support member is provided at a position facing the peripheral surface of the rotating roller, and is supported so as to be movable toward the rotating roller. The first biasing member biases the support member toward the rotating roller. The separation member is provided in a region of the support member that can contact the rotating roller, and is disposed on the downstream side in the feeding direction and has a first friction coefficient that is predetermined with respect to the sheet member. And a second separation portion that is disposed upstream of the first separation portion in the feeding direction and has a second friction coefficient smaller than the first friction coefficient with respect to the sheet member. The moving mechanism is provided on a surface of the support member facing the rotating roller, and a first position where the first separating portion and the peripheral surface of the rotating roller can contact, the second separating portion, and the rotation. The separation member is supported so as to be movable along the feeding direction between a second position where the circumferential surface of the roller can come into contact. The second urging member applies an urging force in a direction opposite to the feeding direction to the separating member to hold the separating member in the first position. In the moving mechanism, when the sheet member is fed by the rotating roller, a second frictional force generated between the first separation portion and the sheet member is generated by the urging force of the second urging member. The separation member is maintained at the first position when the second friction force is smaller, and the separation member is moved downstream in the feeding direction when the second frictional force is greater than or equal to the urging force of the second urging member. Then, the separation member is arranged at the second position.

  An image forming apparatus according to another aspect of the present invention includes the sheet feeding device and an image transfer unit provided on the downstream side in the feeding direction with respect to the rotating roller.

  According to the present invention, it is possible to smoothly feed the sheet member to each of the sheet members having different friction coefficients with respect to the separating member without causing poor feeding or abnormal noise during feeding.

FIG. 1 is a perspective view showing a configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a front view showing the configuration of the image forming apparatus of FIG. FIG. 3 is a perspective view showing a configuration of a manual sheet feeder provided in the image forming apparatus of FIG. FIG. 4 is a schematic diagram illustrating the configuration of the manual sheet feeder. FIG. 5 is a diagram illustrating a separation pad moving mechanism of the manual sheet feeder and an operation state thereof. FIG. 6 is a diagram illustrating a separation pad moving mechanism of the manual sheet feeder and an operation state thereof.

  Hereinafter, a manual sheet feeding device 60 (an example of a sheet feeding device according to the present invention) and an image forming apparatus 10 including the manual sheet feeding device 60 according to an embodiment of the present disclosure will be described with reference to the drawings. For convenience of explanation, the vertical direction of the state where the image forming apparatus 10 is installed on a flat surface (the state shown in FIG. 1) is defined as the up-down direction 6. Further, the front-rear direction 7 is defined with the surface on which the operation display panel 17 is provided as the front surface (front surface). Further, a left-right direction 8 is defined with reference to the front of the image forming apparatus 10. In addition, embodiment described below is only an example which actualized this invention, and does not limit the technical scope of this invention.

  First, the configuration of the image forming apparatus 10 will be described with reference to FIGS. 1 and 2. As shown in FIG. 1, the image forming apparatus 10 is a so-called in-body discharge type multifunction peripheral, and includes various functions such as a printer, a copier, a FAX apparatus, and a scanner. The image forming apparatus 10 forms an image on the sheet member P using an input image using a developer such as toner. Note that the image forming apparatus 10 is not limited to a multifunction machine, and the present invention can be applied to a dedicated machine such as a printer, a copying machine, a FAX apparatus, or a scanner.

  The image forming apparatus 10 includes an image reading unit 12 and an image forming unit 14. The image reading unit 12 performs processing for reading an image of a document, and is provided on the upper part of the image forming apparatus 10. The image forming unit 14 performs processing for forming an image based on the electrophotographic method, and is provided below the image reading unit 12. The image forming unit 14 includes two paper feeding devices 27 and 28 arranged in two upper and lower stages. The upper sheet feeder 27 is provided integrally with the housing 29 at the lowermost part of the image forming unit 14. The lower sheet feeding device 28 is of an extension type connected as an optional device to the bottom surface of the casing 29 of the image forming unit 14. The paper feeding device 28 is configured to be detachable from the bottom surface of the image forming unit 14. A paper discharge unit 30 is provided on the right side of the image forming unit 14. The image forming unit 14 is not limited to an electrophotographic type, and may be an inkjet recording type, or may be a recording method or printing method other than that.

  A paper discharge space 21 from which the sheet member P is discharged is provided above the image forming unit 14. The paper discharge unit 30 is provided so as to connect the image forming unit 14 and the image reading unit 12 while forming a paper discharge space 21 between the image forming unit 14 and the image reading unit 12. In the present embodiment, as shown in FIG. 1, the front side and the left side of the paper discharge space 21 are open. Further, the rear side and the right side of the paper discharge space 21 are not opened, the rear side is closed, and a paper discharge unit 30 is provided on the right side.

  As shown in FIG. 1, the image reading unit 12 includes a document table 23. When the image forming apparatus 10 functions as a copying machine, a copy is instructed from the operation display panel 17 after a document is set on the document table 23 and the document cover 24 is closed. Thereby, the reading operation by the image reading unit 12 is started, and the image data of the document is read. Then, the read image data is sent to the image forming unit 14. In FIG. 1, illustration of the document cover 24 of the image reading unit 12 is omitted.

  As shown in FIG. 2, the image reading unit 12 includes an ADF 13. The ADF 13 is provided on the document cover 24. The ADF 13 is an automatic document feeder including a document tray 45, a feeding mechanism 46, a plurality of transport rollers 47, a sheet press 48, a paper discharge unit 49, and the like. The ADF 13 drives each of the feeding mechanism 46 and the conveying roller 47 with a motor (not shown), thereby allowing the document set on the document tray 45 to pass through the reading position 43 on the document placing table 23 and discharging the sheet 49. Transport to. The feeding mechanism 46 includes a feeding roller 46A that takes out a document and a transport roller 46B that transports the document taken out by the feeding roller 46A, and is fed from the document tray 45 by the feeding roller 46A. The original is conveyed downstream in the feeding direction by the conveying roller 46B. And it is further conveyed by the conveyance roller 47 provided in the downstream of the feeding direction. In the process of transporting the document by the ADF 13, the image of the document that passes through the reading position 43 is read by the image reading unit 12.

  The image forming unit 14 forms an image on a sheet member P having a predetermined size such as an A size or a B size based on image data read by the image reading unit 12 or image data input from the outside. In the present embodiment, the image forming unit 14 discharges the sheet member P on which an image has been formed on one side to the discharge space 21 or switches back the sheet member P and sends it to the reverse conveyance path 39. It is possible to form an image.

  As shown in FIG. 2, the image forming unit 14 mainly includes paper feeding devices 27 and 28, an electrophotographic image transfer unit 18, a fixing unit 19, a manual paper feeding device 60, a paper sensor 20, and the image forming unit 14. And a control unit (not shown) that controls the entire system. The image forming unit 14 includes a transport motor and a discharge motor (both not shown). These are provided inside a casing 29 that forms an outer frame cover, an inner frame, and the like of the image forming unit 14.

  The paper feeding devices 27 and 28 include a paper feeding mechanism 15. The paper feed mechanism 15 takes out and conveys the sheet members P accommodated in the paper feeders 27 and 28 one by one. The paper feed mechanism 15 includes a pickup roller 51, a feed roller 52, and a retard roller 53. The feed roller 52 is positioned above the retard roller 53, and these constitute a pair of transport rollers in a state of being pressed against each other. The sheet feeding devices 27 and 28 include a tray-shaped sheet storage unit 22, and a sheet member P on which an image is formed by the image transfer unit 18 is stacked on the sheet storage unit 22. The pickup roller 51 and the feeding roller 52 are provided on the upper side of the right end portion of the paper storage unit 22. When an instruction for feeding the sheet member P to the image forming apparatus 10 is input, the transport motor is rotationally driven. Thereby, the pickup roller 51 and the feeding roller 52 are rotated, and the retard roller 53 is driven and rotated by this rotation. Then, the sheet member P is fed from the sheet storage unit 22 by the pickup roller 51, and conveyed to the downstream side in the feeding direction D <b> 1 (see FIG. 4) of the sheet member P by the feeding roller 52. A vertical conveyance path 26 is formed upward from the feeding roller 52. As shown in FIG. 2, the vertical conveying path 26 extends upward on the right side surface of the housing 29, and the end thereof reaches the paper discharge space 21.

  The image transfer unit 18 is provided above the paper feed mechanism 15. The image transfer unit 18 performs an image transfer process on the sheet member P conveyed from the paper feeding devices 27 and 28 and the manual paper feeding device 60. Specifically, the image transfer unit 18 transfers the toner image to the sheet member P using a printing material such as toner based on the input image data. As shown in FIG. 2, the image transfer unit 18 includes a photosensitive drum 31, a charging unit 32, a developing unit 33, an LSU (Laser Scanning Unit) 34, a transfer roller 35, and a cleaning unit 36. ing. When the sheet member P passing through the vertical conveyance path 26 passes through the nip portion between the transfer roller 35 and the photosensitive drum 31, the toner image is transferred to the sheet member P by the transfer roller 35. The sheet member P to which the toner image has been transferred passes through the vertical conveyance path 26 and is conveyed to the fixing unit 19 disposed on the downstream side (that is, the upper side) in the conveyance direction of the sheet member P with respect to the image transfer unit 18. .

  In the vertical conveyance path 26, a registration roller 55 (an example of the conveyance roller of the present invention) is provided. The registration roller 55 includes a driving roller 55A (see FIG. 4) that is rotationally driven by the transport motor and a driven roller 55B (see FIG. 4) that is pressed against the driving roller 55A. The registration roller 55 is on the downstream side in the feeding direction D1 (see FIG. 4) of the sheet member P from the feeding roller 52 and a rubber roller 87 (see FIG. 3) described later, and from the transfer position by the image transfer unit 18. Is also arranged upstream. The registration roller 55 conveys the sheet member P fed from the feeding roller 52 and the rubber roller 87 toward the transfer position. In the image transfer unit 18, a registration operation (also referred to as registration) is performed on the sheet member P. In the registration operation, the sheet member P is conveyed by a feeding roller 52 or a rubber roller 87 described later, and the sheet member P is in a state in which the leading end of the sheet member P is in contact with the nip portion of the resist roller 55 that is stopped. This is an operation for applying a conveying force in the conveying direction to the member P. By performing this registration operation, the skew of the sheet member P being conveyed is corrected. Further, it is possible to align the image transfer region on the sheet member P and the image transferred to the sheet member P.

  The registration roller 55 is provided at a position spaced from the feeding roller 52 and the rubber roller 87 downstream in the feeding direction D1 by a distance shorter than the length of the sheet member P in the feeding direction D1. For this reason, when the registration operation is completed and the leading edge of the sheet member P is clamped by the registration roller 55, the trailing edge of the sheet member P is clamped in the nip portions of the feeding roller 52 and the rubber roller 87. It becomes a state. That is, the sheet member P is conveyed by the registration roller 55 and the feeding roller 52 or the rubber roller 87 until the rear end thereof passes through the nip portion of the feeding roller 52 or the nip portion of the rubber roller 87. In the present embodiment, the registration roller 55 is rotated at a linear velocity relatively higher than the linear velocity of the feeding roller 52 and the rubber roller 87. Further, when the sheet member P starts to be conveyed by the registration roller 55, the transmission path for transmitting the driving force to the feeding roller 52 is blocked by an electromagnetic clutch or the like, and the feeding roller 52 is in an idling state. Similarly, the transmission path for transmitting the driving force to the rubber roller 87 is blocked by an electromagnetic clutch or the like, so that the rubber roller 87 is in an idling state. Thereby, the sheet member P conveyed by the registration roller 55 is not bent in the conveyance direction. When the sheet member P is fed again, the transmission path for transmitting the driving force to the feeding roller 52 or the rubber roller 87 is connected by the electromagnetic clutch. The linear velocity is a peripheral velocity on the roller surface and is synonymous with the conveying speed of the object to be conveyed.

  The fixing unit 19 fixes the toner image transferred to the sheet member P to the sheet member P by heat. The fixing unit 19 includes a heating roller 41 and a pressure roller 42. When the sheet member P passes through the fixing unit 19, the toner is fixed to the sheet member P by the heating roller 41 and the pressure roller 42. Thereby, an image is formed on the sheet member P.

  A sheet discharge port 37 through which the sheet member P is discharged is provided at the end of the vertical conveyance path 26. That is, the vertical conveyance path 26 is provided between the feeding roller 52 and the paper discharge port 37. Near the end of the vertical conveyance path 26, specifically, a portion 26A (hereinafter referred to as “curved path 26A”) from the branch point T1 on the downstream side of the fixing unit 19 to the paper discharge port 37 in the vertical conveyance path 26. Curved from the vertical direction to the horizontal direction. In the vicinity of the paper discharge port 37, a discharge roller pair 25 that is rotated in both directions by the discharge motor (not shown) is provided. The sheet member P that has passed through the fixing unit 19 and is transported to the curved path 26A is transported from the paper discharge port 37 toward the discharge space 21 by the discharge roller pair 25 that is rotated in the normal rotation direction by the discharge motor. The

  When single-sided printing is performed in the image forming unit 14, the sheet member P on which the toner image is transferred on one side by the image transfer unit 18 passes through the fixing unit 19 and then passes through the vertical conveyance path 26 from the paper discharge port 37. It is discharged outside.

  When double-sided printing is performed in the image forming unit 14, the sheet member P on which an image is first formed on one side passes through the fixing unit 19, and then the front and back are reversed and the sheet member P is again upstream in the conveying direction. Is conveyed in the reverse direction and fed into the reverse conveyance path 39. The sheet member P sent to the reverse conveyance path 39 is guided downward along the reverse conveyance path 39 and is sent to the vertical conveyance path 26 from the junction T2 by the conveyance roller 40. Then, it is conveyed again to the image transfer unit 18 through the vertical conveyance path 26. The sheet member P that has reached the image transfer portion 18 is formed with an image on the surface on which no image is formed. Thereafter, the sheet member P on which images are formed on both sides is discharged from the paper discharge port 37 to the discharge space 21 by the discharge roller pair 25.

  A manual feed tray 44 (an example of the sheet tray of the present invention) is provided on the right side surface of the housing 29 so as to be rotatably supported by the housing 29. The manual sheet feeder 60 feeds the sheet member P placed on the manual tray 44 to the vertical conveyance path 26.

  By the way, the manual sheet feeder 60 is provided with a separation mechanism 80 to be described later in order to feed the uppermost sheet member P from the plurality of sheet members P placed thereon. Conventional typical paper feeders are provided with typical separation pads. Therefore, when a resin sheet such as an OHP sheet is fed to a conventional sheet feeding device, the resin sheet has a larger frictional force with the separation pad than the printing paper, and the frictional force between the resin sheets is also large. Since the frictional force between the printing papers is large, the following problems may occur. That is, rather than the frictional force in the feeding direction D1 (see FIG. 4) generated between the rubber roller 87 and the resin sheet when a rubber roller 87 of the roller unit 62 described later rotates in contact with the resin sheet, The frictional force generated between the separation pad and the resin sheet and the frictional force generated between the resin sheets become larger, resulting in poor feeding of the resin sheet. Further, even if there is no poor feeding of the resin sheet, there is a possibility that a stick-slip phenomenon occurs between the separation pad and the resin sheet, or between the resin sheets, and noise is generated. Therefore, as will be described below, the manual sheet feeder 60 of the present embodiment includes a separation mechanism 80 having a configuration different from that of the conventional one. It is possible to prevent abnormal noise and smoothly feed the sheet member P.

  As shown in FIG. 3, the manual sheet feeder 60 is attached to the support frame 54. The support frame 54 is an internal frame of the housing 29, and is provided below the junction T <b> 2 of the vertical conveyance path 26 and the reverse conveyance path 39. The support frame 54 is formed in a shape that is long in the front-rear direction 7. The support frame 54 rotatably supports the manual feed tray 44.

  The manual paper feeder 60 includes a manual tray 44, a paper feed unit 64, and a separation mechanism 80.

  A plurality of sheet members P are placed on the manual feed tray 44. The manual feed tray 44 constitutes the right side surface of the housing 29 in a state of being closed with respect to the housing 29. When the manual feed tray 44 is opened with respect to the housing 29, the manual feed tray 44 is supported in a posture slightly inclined upward as shown in FIG. That is, the manual feed tray 44 is gently opened downward toward the downstream side in the feeding direction D1 (see FIG. 4) toward the inside of the housing 29 in the opened state. In this state, the manual feed tray 44 can place a plurality of sheet members P on the upper surface thereof. Further, when the manual feed tray 44 is opened with respect to the housing 29, the paper feed opening 38 that is a feed path of the sheet member P from the manual feed tray 44 to the vertical conveyance path 26 is opened. The manual sheet feeder 60 conveys the sheet member P placed on the manual tray 44 to the vertical conveyance path 26 through the sheet feeding opening 38.

  The paper feeding unit 64 is provided on the leading end side in the feeding direction D1 of the opened manual feed tray 44. The paper feed unit 64 includes a base frame 61, a roller unit 62, and a drive shaft 63. The base frame 61 is formed by injection molding a synthetic resin or the like. The base frame 61 is formed in a shape that is long in the front-rear direction 7 like the support frame 54. The base frame 61 is fixed to the support frame 54 or the like. More specifically, the rear end of the base frame 61 is fixed to the frame of the housing 29, and the front end is fixed to the support frame 54 with a fastener such as a screw (not shown). A roller unit 62 and a drive shaft 63 are attached to the base frame 61.

  The base frame 61 is formed in a narrow rectangular parallelepiped shape. The base frame 61 has an internal space that is open at the top and is surrounded by a bottom wall and four side walls. In addition, a rectangular roller accommodating portion 67 in which the right side wall 71 protrudes to the right side is formed in the central portion of the base frame 61 in the longitudinal direction (front-rear direction 7). The roller unit 62 is rotatably accommodated in the roller accommodating portion 67. The bottom side of the roller accommodating portion 67 penetrates. That is, the roller accommodating portion 67 does not have a bottom surface, and the bottom side penetrates. In a state where the roller unit 62 is accommodated in the roller accommodating portion 67, the roller surface of the roller unit 62 is exposed from the bottom side opening to the sheet feeding opening 38 (see FIG. 2), and can contact the sheet member P.

  The drive shaft 63 has a drive gear 78, and rotates in a predetermined forward rotation direction (see the arrow in FIG. 3) when a rotational driving force is transmitted to the drive gear 78 from a motor (not shown).

  The roller unit 62 feeds the sheet member P placed on the manual feed tray 44 in a feeding direction D1 (see FIG. 4) toward the inside of the image forming unit 14 by a rotational driving force and contact friction. The roller unit 62 includes a rubber roller 87 (an example of the rotating roller of the present invention). The rubber roller 87 is provided so as to contact both a sheet member P on the manual feed tray 44 and a separation member 82 (see FIG. 4) described later. Therefore, when the rubber roller 87 is rotationally driven, the circumferential surface thereof contacts the sheet member P on the manual feed tray 44, and the sheet member P is sent out in the feeding direction D1. That is, the rubber roller 87 feeds the sheet member P in the feeding direction D1 by rotating in contact with the sheet member P. The rubber roller 87 is a cylindrical roller member made of an elastic material such as NBR or silicon. The rubber roller 87 is connected to the drive shaft 63. Accordingly, when the rotational driving force is transmitted from the driving gear 78 to the driving shaft 63, the rubber roller 87 is rotated in the normal rotational direction.

  As shown in FIG. 4, a separation mechanism 80 is provided at a position facing the rubber roller 87. The separation mechanism 80 separates the lower sheet member P from the uppermost sheet member P when a plurality of sheet members P enter the nip portion with the rubber roller 87, and only the uppermost sheet member P is separated. Is conveyed in the feeding direction D1. The separation mechanism 80 includes a support plate 81 (an example of a support member of the present invention), a separation member 82, and a slide movement mechanism 83 (an example of a movement mechanism of the present invention).

  As shown in FIG. 5A, the support plate 81 supports the separation member 82 and the slide movement mechanism 83. The separation member 82 is most affected by the frictional force generated between the separation member 82 and the lower sheet member P when a plurality of sheet members P enter the nip portion between the rubber roller 87 and the separation member 82. Only the upper sheet member P is separated from the plurality of sheet members P and fed to the downstream side in the feeding direction D1.

  The support plate 81 is provided at the center in the front-rear direction 7 in the manual sheet feeder 60 and is provided at a position facing the peripheral surface of the rubber roller 87. The support plate 81 is a plate-like member extending along the feeding direction D1. An end 81 </ b> A on the upstream side in the feeding direction D <b> 1 of the support plate 81 is rotatably supported by a support shaft 54 </ b> A provided on the support frame 54. The support plate 81 is urged toward the rubber roller 87 side around the support shaft 54A. Specifically, the rubber roller 87 is biased with a predetermined biasing force by a torsion coil spring 85 (an example of a first biasing member of the present invention) provided on the support shaft 54A. Thereby, a predetermined nip pressure (pressure contact force) is generated between the rubber roller 87 and the separating member 82. The urging mechanism of the support plate 81 is not limited to that using the torsion coil spring 85.

  A slide moving mechanism 83 is provided on the opposing surface of the support plate 81 on the rubber roller 87 side. The slide moving mechanism 83 includes a support groove 91 that supports the separation member 82 so as to be slidable in the feeding direction D1, and a coil spring 92 (an example of the second urging member of the present invention) provided in the support groove 91. . The support groove 91 extends in the feeding direction D1 and is longer than the separating member 82 in the feeding direction D1. A separation member 82 is accommodated in the support groove 91.

  One end of the coil spring 92 is fixed to the end 93 of the support groove 91 on the downstream side in the feeding direction D <b> 1, and the other end is fixed to the separation member 82. The coil spring 92 urges the separating member 82 upstream in the feeding direction D1 in the support groove 91 in a state where no external force is applied. That is, the coil spring 92 applies a biasing force in the direction opposite to the feeding direction D1 to the separating member 82. As a result, the separation member 82 is positioned at the first position (position shown in FIG. 5A) in contact with the upstream end portion 94 in the feeding direction D1 in the support groove 91. Here, the first position is a position at which a later-described first separation pad 82 </ b> A of the separation member 82 can contact the circumferential surface of the rubber roller 87. When the biasing force of the coil spring 92 when the separation member 82 is in the first position is F1, the coil spring 92 biases the separation member 82 toward the first position by the biasing force F1 and separates it to the first position. The member 82 is held. In this embodiment, the coil spring 92 is illustrated as an example of the second urging member. However, the coil spring 92 is not limited to the coil spring 92 as long as the separation member 82 can be held in the first position, and any configuration is possible. There may be.

  The separation member 82 is provided in a region where the rubber roller 87 can contact on the facing surface of the support plate 81. Specifically, the support groove 91 is formed at a position facing the rubber roller 87, and as described above, the separation member 82 is supported by the support groove 91 so as to be movable in the feeding direction D1. The separation member 82 is formed in a flat plate shape. The separation member 82 includes a first separation pad 82A (an example of the first separation part of the present invention) and a second separation pad 82B (an example of the second separation part of the present invention). The first separation pad 82A and the second separation pad 82B are provided side by side in the feeding direction D1, and their adjacent ends are joined together. In the separation member 82, the first separation pad 82A is located downstream of the second separation pad 82B in the feeding direction D1.

  The first separation pad 82A is made of a material having a large friction coefficient with respect to the sheet member P. For example, the first separation pad 82A is made of a rubber material having a friction coefficient μ1 (an example of the first friction coefficient of the present invention) with respect to the sheet member P. It is configured. The second separation pad 82B is made of a material having a smaller friction coefficient than the first separation pad 82A with respect to the sheet member P. For example, the second separation pad 82B has a larger surface roughness (rough surface) than the first separation pad 82A. It is made of a cork material or a non-woven material having a friction coefficient μ2 (an example of the second friction coefficient of the present invention) with respect to the sheet member P. The friction coefficient μ1 of the first separation pad 82A and the friction coefficient μ2 of the second separation pad 82B are elements that vary depending on the material of the sheet member P and the like. There is no change in the relationship of smaller than μ1 (μ1> μ2).

  In the separation member 82, the first separation pad 82A is located downstream of the second separation pad 82B in the feeding direction D1. That is, the second separation pad 82B is disposed on the upstream side in the feeding direction D1 with respect to the first separation pad 82A. In other words, when the sheet member P is fed, the tip of the second separation pad 82B is abutted first. It is arranged at the position. Cork and non-woven fabrics have a rougher surface than rubber. Therefore, the separability of the sheet member P can be improved by using such a rough material as the second separation pad 82B.

  In the present embodiment, the slide movement mechanism 83 urges the separation member 82 toward the first position by the urging force F1 of the coil spring 92 when no external force is applied to the separation member 82. The separation member 82 is held at the first position. With the separating member 82 in the first position, the outer peripheral surface of the rubber roller 87 is in contact with the first separating pad 82A (see FIG. 5A).

  On the other hand, when the rubber roller 87 is rotated in contact with the first separation pad 82A for feeding the sheet member P, the sheet member P is picked up by the rubber roller 87, and the rubber roller 87 and the first separation pad. Enter the nip with 82A. That is, the sheet member P is sandwiched between the rubber roller 87 and the first separation pad 82A (see FIG. 5B). When the rubber roller 87 is continuously rotated in this state, a sheet conveying force F2 for feeding the sheet member P in the feeding direction D1 is generated between the rubber roller 87 and the upper surface of the sheet member P. The sheet conveying force F2 is a frictional force generated between the rubber roller 87 and the upper surface of the sheet member P. Further, a frictional force F3 in the direction opposite to the feeding direction D1 is generated between the lower surface of the sheet member P and the first separation pad 82A. The frictional force F3 acts as a force that prevents the sheet member P from being fed in the feeding direction D1, or acts as a force that moves the separation member 82 from a first position described later to a second position described later. There is a case. Here, the above-described sheet conveyance force F2 and the later-described sheet conveyance forces F21 and F22 are examples of the first friction force of the present invention. Moreover, the above-mentioned friction force F3 and the below-mentioned friction forces F31 and F32 are examples of the 2nd friction force of this invention.

  In this embodiment, as shown in FIG. 5C, when the sheet member P is the printing paper P1, the sheet conveyance force generated between the rubber roller 87 and the printing paper P1 is F21, and the printing paper P1 When the frictional force generated between the first separation pad 82A and the first separation pad 82A is F31, the slide moving mechanism 83 is configured to maintain the relationship of F1> F31. In other words, in the slide moving mechanism 83, the friction coefficient μ1 of the first separation pad 82A, the spring coefficient and natural length of the coil spring 92, the biasing force by the torsion coil spring 85, etc. are determined so as to maintain the relationship of F1> F31. Yes. For this reason, the slide movement mechanism 83 maintains the separation member 82 in the first position when the frictional force F31 generated between the printing paper P1 and the first separation pad 82A is smaller than the biasing force F1. In this case, the sheet conveying force F21 is larger than the frictional force F31. For this reason, the sheet member P receives the sheet conveying force F21 and is smoothly fed in the feeding direction D1.

  Further, when an external force of a predetermined value or more is applied to the separating member 82 in the feeding direction D1, the slide moving mechanism 83 moves the separating member 82 in the feeding direction D1 against the urging force of the coil spring 92. Specifically, as shown in FIG. 6B, the separation member 82 is moved to the downstream side in the feeding direction D1. Then, as will be described later, the separation member 82 is disposed at a second position (see FIG. 6B) where the second separation pad 82B and the peripheral surface of the rubber roller 87 can contact each other.

  In this embodiment, as shown in FIG. 6A, when the sheet member P is a film-shaped resin sheet P2 such as an OHP sheet, a sheet generated between the rubber roller 87 and the resin sheet P2. When the conveyance force is F22 and the friction force generated between the resin sheet P2 and the first separation pad 82A is F32, the sheet conveyance force F22 is larger than the sheet conveyance force F21 (see FIG. 5C), The frictional force F32 is larger than the frictional force F31 (see FIG. 5C). This is because the friction coefficient of the resin sheet P2 is larger than the friction coefficient of the printing paper P1 when compared with the same contact object. In this case, the relationship among the sheet conveying force F22, the friction force F32, and the biasing force F1 is F22> F32, and F32> F1. In other words, in the slide moving mechanism 83, the friction coefficient μ1 of the first separation pad 82A, the spring coefficient and natural length of the coil spring 92, the urging force by the torsion coil spring 85, and the like are determined so as to satisfy the relationship of F1 <F32. . For this reason, since the frictional force F32 larger than the urging force F1 acts on the separating member 82, the slide moving mechanism 83 moves the separating member 82 together with the resin sheet P2 in the feeding direction D1. Then, the separating member 82 is disposed at the second position.

  Further, as shown in FIG. 6B, when the separating member 82 is moved to the second position, the resin is moved in a direction opposite to the feeding direction D1 between the resin sheet P2 and the second separating pad 82B. A frictional force F33 that feeds the sheet P2 is generated. As described above, since the friction coefficient μ2 of the second separation pad 82B is smaller than the friction coefficient μ1 of the first separation pad 82A, the friction force F33 is smaller than the friction force F32. Further, since the coil spring 92 is compressed, the coil spring 92 exerts an urging force F11 larger than the urging force F1 on the separating member 82. Further, since the resin sheet P2 receives the sheet conveying force F22 while being in contact with the first separation pad 82A and is fed in the feeding direction D1, the friction in the direction opposite to the feeding direction D1 from the first separation pad 82A. The force F4 is received from the first separation pad 82A. In this embodiment, when the resin sheet P2 and the separation member 82 are in such a state, the friction coefficient μ1 of the first separation pad 82A is set so that F22> F4 + F32 and F33> F1. The friction coefficient μ2 of the second separation pad 82B, the spring coefficient and natural length of the coil spring 92, the biasing force by the torsion coil spring 85, and the like are determined.

  As described above, when the separation member 82 is moved to the second position in response to the frictional force F33, the coil spring 92 becomes a biasing force F11 larger than the biasing force F1, but when the coil spring 92 moves to the second position. Further, the separating member 82 receives a frictional force F32 that is smaller than the frictional force F33. Therefore, the biasing force of the coil spring 92 is reduced by the amount of decrease in the frictional force at this time. In this case, the separating member 82 is slightly returned to the first position side as much as the urging force is reduced. However, in this embodiment, the second separating pad 82B of the separating member 82 and the rubber are also in the slightly returned position. The friction coefficient μ1, the friction coefficient μ2, the spring coefficient and natural length of the coil spring 92, the urging force by the torsion coil spring 85, and the like are determined so that the peripheral surface of the roller 87 can come into contact. In the present embodiment, the second position includes the returned position.

  When the resin sheet P2 is further fed and the leading end of the resin sheet P2 is nipped and conveyed by the registration roller 55, the transmission path of the driving force to the rubber roller 87 is caused by an electromagnetic clutch (not shown) or the like as described above. As a result, the rubber roller 87 is idled. Therefore, the rubber roller 87 is driven by receiving a frictional force between the resin sheet P2 until the rear end of the resin sheet P2 passes through the nip portion between the separation member 82 and the rubber roller 87. On the other hand, when the rear end of the resin sheet P2 passes through the nip portion between the separation member 82 and the rubber roller 87, the frictional force F33 and the frictional force F4 that the separation member 82 has acted on the resin sheet P2 do not act, The sheet conveying force F22 that the rubber roller 87 has acted on the resin sheet P2 does not act. In this case, since the rubber roller 87 is idling, as shown in FIG. 6 (C), immediately after the resin sheet P2 passes through the nip portion, the urging force F11 acts on the separation member 82 to separate it. The member 82 is returned from the second position to the first position. At this time, the rubber roller 87 is driven by the amount of movement of the separation member 82 in the reverse direction (clockwise rotation in FIG. 6C) under the frictional force generated between the rubber roller 87 and the separation member 82. When the separating member 82 is returned to the first position, the urging force by the coil spring 92 returns from F11 to F1.

  Thus, since the manual sheet feeder 60 is configured, when the resin sheet P2 having a larger friction coefficient than the printing paper P1 is fed to the first separation pad 82A, the feeding direction D1 is defined as The separating member 82 is moved from the first position to the second position so that the frictional force in the opposite direction (frictional force generated between the separating member 82 and the sheet member P) becomes small. Thereby, at the time of feeding of the resin sheet P2, the feeding failure of the resin sheet P2 does not occur and the resin sheet P2 is fed smoothly. Further, since tick slip does not occur between the rubber roller 87 and the resin sheet P2 or between the resin sheet P2 and the separation member 82, abnormal noise such as chatter noise is prevented. Further, when the printing paper P1 is fed, the printing paper P1 is nipped and fed by the first separation pad 82A and the rubber roller 87, so that the printing paper P1 is fed by a sufficient sheet conveying force. It is possible to feed to D1.

  Further, the resin sheet P <b> 2 fed to the vertical conveyance path 26 by the manual sheet feeding device 60 is thereafter nipped and conveyed by the registration roller 55. Also when the resin sheet P2 is conveyed by the registration roller 55, the rear end of the resin sheet P2 is sandwiched between the second separation pad 82B and the rubber roller 87. Therefore, a large force is not acting in the direction opposite to the feeding direction D1. Therefore, even when the rear end of the resin sheet P2 passes through the nip portion between the rubber roller 87 and the separating member 82, over-conveying by the registration roller 55 is prevented. As a result, it is possible to prevent deterioration in image quality formed on the resin sheet P2. Specifically, horizontal streaks appear in the image on the resin sheet P2 and the image is prevented from extending in the transport direction.

  In the above-described embodiment, the manual sheet feeding device 60 has been described as an example. However, the sheet feeding device of the present invention can also be applied to the sheet feeding devices 27 and 28 included in the image forming apparatus 10.

  In the above-described embodiment, specific examples using the printing paper P1 and the resin sheet P2 have been described. However, the invention is not limited to these types of sheet members, and any sheet member having a different friction coefficient with respect to the same contact object may be used. The present invention is applicable.

  In the above-described embodiment, the configuration in which the slide moving mechanism 83 is mounted on the support plate 81 is illustrated, but the slide moving mechanism 83 is not limited to that mounted on the support plate 81. For example, the support plate 81 itself is supported by the support frame 54 so as to be movable in the feeding direction D1, and the slide movement mechanism slides the support plate 81 to move the separation member 82 to the first position and the second position. The structure moved between positions may be sufficient.

10: image forming apparatus 14: image forming unit 44: manual feed tray 54: support frame 60: sheet conveying device 63: drive shaft 77: joint 80: separation mechanism 81: support plate 82: separation member 82A: first separation pad 82B: Second separation pad 83: slide moving mechanism

Claims (5)

A sheet tray on which a sheet member is placed;
A rotating roller for feeding the sheet member in the feeding direction by a first frictional force in a predetermined feeding direction generated between the sheet member and the sheet member by rotating in contact with the sheet member on the sheet tray; ,
A support member provided at a position facing the peripheral surface of the rotating roller and supported to be movable toward the rotating roller;
A first biasing member that biases the support member toward the rotating roller;
A first separation portion that is provided in a region of the support member that can contact the rotating roller, is disposed on the downstream side in the feeding direction and has a first friction coefficient that is predetermined with respect to the sheet member; A separation member including a second separation part that is disposed upstream of the one separation part in the feeding direction and has a second friction coefficient smaller than the first friction coefficient with respect to the sheet member;
A first position provided on a surface of the support member facing the rotating roller, the first separating portion and a peripheral surface of the rotating roller being in contact with each other; a second separating portion; and a peripheral surface of the rotating roller; A moving mechanism that movably supports the separation member along the feeding direction between the second position and the second position that can be contacted;
A second biasing member that applies a biasing force in a direction opposite to the feeding direction to the separation member to hold the separation member in the first position;
The moving mechanism is
When the second frictional force generated between the first separation part and the sheet member is smaller than the urging force of the second urging member when the sheet member is fed by the rotating roller, The separation member is maintained at the first position, and the separation member is moved downstream in the feeding direction when the second frictional force is greater than or equal to the urging force of the second urging member. A sheet feeding apparatus that arranges the sheet at the second position. The moving mechanism is
A support groove provided on the surface of the support member for supporting the separation member so as to be slidable along the feeding direction between the first position and the second position;
The second urging member is provided between an end portion of the support groove on the downstream side in the feeding direction and the separation member, and the separation member is moved to the first position in a state where no external force is applied. The sheet feeding device according to claim 1, wherein the sheet feeding device is held.   The first separation portion is made of a rubber material having the first friction coefficient with respect to the sheet member, and the second separation portion is a cork material or non-woven fabric having the second friction coefficient with respect to the sheet member. The sheet feeding device according to claim 1, wherein the sheet feeding device is made of a material. A sheet feeding apparatus according to any one of claims 1 to 3,
And an image transfer unit provided on the downstream side in the feeding direction with respect to the rotating roller.   5. The apparatus according to claim 4, further comprising a conveyance roller that is provided at a position shorter than the rotation roller by a distance shorter than a length in the feeding direction of the sheet and conveys the sheet member to an image transfer position by the image transfer unit. The image forming apparatus described.

Images