JP2016108079A - Sheet conveying device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet conveying device which can securely separate a sheet one by one without damaging the sheet.SOLUTION: A sheet conveying device includes a feed roller 53 (a rotation body) for conveying a sheet, and a separation roller 54 (a separation member) for separating a sheet one by one at a separation nip N (a contact part) with the feed roller 53. The separation roller 54 is held by a separation roller holder 60 (a holding member), and a nip guide 63 (a guide member) is rotatably supported on the separation roller holder 60. The nip guide 63 is structured so as to rotate in a direction separating from the feed roller 53 in a state that the separation roller 54 presses the feed roller 53.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a sheet conveying apparatus that conveys a sheet and an image forming apparatus including the sheet conveying apparatus.

  2. Description of the Related Art Conventionally, some image forming apparatuses such as printers include a sheet feeding apparatus that stacks recording sheets on a tray and separates and feeds the stacked sheets one by one. In this type of sheet feeding apparatus, a nip guide that guides a sheet toward a separation unit that separates and feeds the sheets one by one is provided, and the nip guide can be moved by entering a sheet bundle. (See Patent Document 1).

  Hereinafter, a conventional sheet feeding apparatus will be described with reference to FIGS. 14 and 15. The sheet feeding device 301 includes a pickup roller 310, a feed roller 353, and a retard roller 364, and the separation nip N is formed when the retard roller 364 pressurizes the feed roller 353 with a predetermined pressure. ing. A rotational driving force in the direction of arrow a is transmitted to the feed roller 353 from a driving source (not shown). A rotational driving force in the direction opposite to the paper feeding direction (the direction of arrow c in FIG. 15B) is transmitted to the retard roller 364 via a torque limiter (not shown).

  Further, the sheet feeding apparatus 301 includes a nip guide 363 so that the sheet S is not caught between the sheet cassette 300 and the separation nip N and jammed. The nip guide 363 is rotatably supported by the rotation shaft 363a and is urged by a tension spring 366 in a direction approaching the feed roller 353 (arrow b direction).

  As shown in FIG. 14, the guide surface 363b of the nip guide 363 has a predetermined angle θ (0 <θ) with respect to the feeding direction H of the sheets S stacked on the intermediate plate 351 pushed up by the rotating arm 356. <90 °) is positioned by the stopper 365. When power is transmitted to the pickup roller 310, the feed roller 353, and the retard roller 364 and the sheet S is fed by the pickup roller 310, the sheet S is separated by the nip guide 363 as shown in FIG. Guided to the nip N. That is, when one sheet S is fed, the load is hardly applied from the sheet S to the guide surface 363b of the nip guide 363, so that the nip guide 363 does not rotate and contacts the stopper 365. Will remain.

  On the other hand, when a plurality of sheets S are sent out from the sheet cassette 300 as a bundle, a large load is applied to the nip guide 363 from the bundled sheets S. Thereby, the nip guide 363 rotates in a direction away from the feed roller 353 (arrow d direction) as shown in FIG. Even if the sheet S fed by the pickup roller 310 is only one sheet, a large load is applied to the nip guide 363 in the case of a sheet such as thick paper having high rigidity, and the nip guide 363 is moved in the direction of the arrow d. To turn. When the nip guide 363 rotates in the direction of the arrow d, the predetermined angle θ formed by the guide surface 363b and the bundled sheet S increases, and the sheet S is guided to the separation nip N while being rolled.

  Other sheet feeding devices include a separation roller frame that swingably holds a separation roller (retard roller), a rush guide plate that is rotatably supported by the separation roller frame and guides the sheet to the separation nip, There has been proposed (see Patent Document 2). When a large number of sheets are fed between the separation roller, the feed roller that forms the separation nip, and the rush guide plate, the rush guide plate is configured to rotate downward to prevent a paper jam. ing.

JP 2003-118865 A JP 63-225043 A

  In the sheet feeding device described in Patent Document 1, as described above, the predetermined angle θ between the nip guide 363 and the sheet S varies depending on the magnitude of the load received by the nip guide 363 from the sheet S. When the nip guide 363 is pressed by the sheet S and retracted in the direction of the arrow d, the contact angle at which the leading edge of the sheet S contacts the peripheral surface of the retard roller 364 increases.

  In particular, recent printers have been reduced in size and tend to reduce the outer diameter of the retard roller 364. In such a case, the contact angle between the leading edge of the sheet S and the peripheral surface of the retard roller 364 increases abruptly as the predetermined angle θ formed by the nip guide 363 and the sheet S changes. In general, since the circumferential surface of the retard roller 364 is made of a material having a large friction coefficient, if the leading edge of the sheet S collides with the retard roller 364 in a state where the contact angle is large, the leading edge of the sheet may be greatly damaged. , Jams occur.

  Further, in the sheet feeding device described in Patent Document 2, the rotation range of the entry guide plate is regulated by the upper limit stopper and the lower limit stopper provided on the separation roller frame. It can be seen that the gap between the upper limit stopper and the lower limit stopper is small, and the rotation range of the entry guide plate is narrow. When the rush guide plate is pressed by a large number of sheets and rotated downward, the rush guide plate comes into contact with the upper limit stopper. However, when the rush guide plate further pivots downward, it is separated together with the rush guide plate. The roller frame rotates downward. Then, the separation roller held by the separation roller frame is separated from the feed roller, and a large number of sheets cannot be separated one by one, and there is a possibility that the sheets are double-fed.

  Therefore, the present invention is configured such that the guide member is configured to be able to be rotated in a direction away from the rotating body with respect to the holding member while restricting the rotation in the direction approaching the rotating body by the restricting portion. An object of the present invention is to provide a sheet conveying apparatus that solves the above-described problems.

  The present invention relates to a sheet transporting apparatus, a stacking unit on which sheets are stacked, a rotating body that rotates while being in contact with the sheets stacked on the stacking unit, and a rotating body that is directed toward the rotating body. A separation member that is pressed and separates sheets one by one at a contact portion with the rotating body, a holding member that holds the separation member, and a rotation member that is rotatable with respect to the holding member. A guide member that can guide the tip of the guide member, and a restricting portion that contacts the guide member and restricts the guide member from rotating in a direction approaching the rotating body. The member can be rotated in a direction away from the rotating body in a state where the member presses the rotating body.

  Further, the present invention provides a sheet conveying apparatus including a stacking unit on which sheets are stacked, a rotating body that conveys a sheet by rotating in contact with the sheets stacked on the stacking unit, and the rotating body. A separation member that is pressed toward and separates the sheets one by one at the contact portion with the rotating body, a holding member that holds the separation member, and a rotation member that is pivotable with respect to the holding member. A guide member capable of guiding the leading end of the sheet, and a regulating portion that abuts on the guide member and regulates the guide member from rotating in a direction approaching the rotating body, the guide member comprising: The holding member is rotatable in a direction away from the rotating body.

  The present invention restricts the guide member from rotating in a direction approaching the rotating body by contacting the restricting portion. Therefore, when the contact angle between the leading edge of the conveyed sheet and the separating member is large, the leading edge of the sheet does not collide with the separating member, and damage to the leading edge of the sheet can be reduced. Can be prevented from jamming.

  Moreover, even if the guide member rotates in a direction away from the rotating body, the separating member maintains a state where the rotating body is pressed. Therefore, a plurality of sheets are prevented from being jammed between the rotating body and the guide member, and jamming is prevented, and the rotating body and the separating member are not separated from each other, so that it is possible to prevent double feeding of the sheets.

1 is an overall schematic diagram illustrating a printer according to a first embodiment of the present invention. The whole front view which shows a manual feeding part. The whole sectional view showing a manual feed part. The whole perspective view which shows a manual feeding part. FIG. 3 is a front view illustrating a manual feeding unit in a state where one sheet is fed. FIG. 3 is a front view illustrating a manual feeding unit in a state where several sheets are fed. The front view which shows the manual feeding part of the state which the nip guide rotated with many sheets. Explanatory drawing for demonstrating the position of the rotation fulcrum of a nip guide. The manual feed part which is a comparative example is shown, (a) is a figure explaining the case where the rotation fulcrum of a nip guide is arrange | positioned in the side near a feed roller with respect to a 1st straight line, (b) is a figure of a nip guide. The figure explaining the case where a rotation fulcrum is arrange | positioned with respect to the 2nd straight line in the side far from the separation nip. In a comparative example, the front view which shows the manual feed part which has arrange | positioned the rotation fulcrum of a stopper and a nip guide in the paper feed frame. (A) shows the state where the feed roller roller is in contact with the separation roller, and (b) shows the state where the feed roller rubber is in contact with the separation roller. (C) shows a state where a plurality of fed sheets are in contact with a feed roller roller, and (d) shows a state where a plurality of fed sheets are in contact with a feed roller rubber. The manual feed portion according to the first embodiment in which the separation roller holder does not follow even when the nip guide rotates, (a) shows the state where the feed roller roller is in contact with the separation roller, (b ) Shows a state in which the feed roller rubber is in contact with the separation roller. It is explanatory drawing for demonstrating the position of the rotation fulcrum of a separation roller holder, Comprising: (a) is a figure explaining that this rotation fulcrum is arrange | positioned in the side near a feed roller from the 3rd straight line. (B) is a figure explaining that this rotation fulcrum is arrange | positioned in the side far from a feed roller from the 4th straight line. The front view which shows the manual feeding part which concerns on the 2nd Embodiment of this invention. FIG. 6 is an overall schematic diagram illustrating a conventional sheet feeding apparatus. 2A and 2B show a conventional sheet feeding apparatus, in which FIG. 1A shows a state where one sheet is fed, and FIG. 2B shows a state where a plurality of sheets are fed.

(First embodiment)
First, a first embodiment of the present invention will be described. A printer 1 (image forming apparatus) according to an embodiment of the present invention is an electrophotographic laser beam printer that forms toner images of four colors. As shown in FIG. 1, the printer 1 includes a cassette feeding unit 10 and a manual feeding unit 50 that feed a sheet, and an image forming unit 30 that forms an image to be transferred to the sheet.

  When an image formation command is output to the printer 1, the image forming process by the image forming unit 30 is started based on image information input from an external computer or the like connected to the printer 1. The image forming unit 30 includes a scanner unit 31, four process cartridges 32Y, 32M, 32C, and 32Bk that form four color images of yellow (Y), magenta (M), cyan (C), and black (Bk). It is equipped with. The four process cartridges 32Y, 32M, 32C, and 32Bk have the same configuration except that the colors of the images to be formed are different. Only the image forming process of the process cartridge 32Y will be described, and the process cartridges 32M, 32C, and 32Bk will be described. Description is omitted.

  The scanner unit 31 irradiates laser light toward the photosensitive drum 33 of the process cartridge 32Y based on the input image information. At this time, the photosensitive drum 33 is charged in advance by a charging roller (not shown), and an electrostatic latent image is formed on the photosensitive drum 33 by irradiation with laser light. Thereafter, the electrostatic latent image is developed by the developing roller 35, and a yellow (Y) toner image is formed on the photosensitive drum 33.

  Similarly, magenta (M), cyan (C), and black (Bk) toner images are formed on the photosensitive drums of the process cartridges 32M, 32C, and 32Bk. Each color toner image formed on each photosensitive drum is transferred to the intermediate transfer belt 37 by the primary transfer rollers 36Y, 36M, 36C, and 36Bk, and conveyed to the secondary transfer roller 38 by the intermediate transfer belt 37 that rotates in the M direction. Is done. The image forming process for each color is performed at the timing of superimposing on the upstream toner image that is primarily transferred onto the intermediate transfer belt 37.

  In parallel with the image forming operation described above, the sheets stored in the cassette feeding unit 10 or the sheets stacked on the manual feeding unit 50 are fed one by one toward the registration roller 15. Then, the toner image on the intermediate transfer belt 37 is transferred by the secondary transfer roller 38 to the sheet conveyed by the registration roller 15 at a predetermined conveyance timing. The sheet on which the toner image has been transferred is fixed on the toner image by the fixing unit 39 and is discharged onto the discharge tray 41 by the discharge roller pair 40.

  When images are formed on both surfaces of the sheet, the sheet on which the image is formed on the first surface by the secondary transfer roller 38 is guided toward the reversing roller pair 43 by the switching member 42, and by the reversing roller pair 43. After being reversed, it is guided to the duplex conveying path 44. Then, the sheet is conveyed again to the registration roller 15, an image is formed on the second surface by the secondary transfer roller 38, and is discharged onto the discharge tray 41.

  Next, the manual feeding unit 50 as a sheet conveying apparatus will be described with reference to FIGS. 2, 3, and 4. The manual feed unit 50 includes a sheet tray 51 on which sheets S or a bundle of sheets Sa can be stacked, a feed roller 53 (rotary member) rotatably supported by a sheet feeding frame 52 (frame member) that is a fixed member, and a conveyance unit. And a roller pair 55. Further, the manual feed unit 50 includes a separation roller 54 (separation member) incorporating a torque limiter (not shown). An intermediate plate 56 (stacking portion) is rotatably supported on the sheet tray 51 so that the downstream side in the feeding direction can be raised and lowered. The intermediate plate 56 is urged toward the feed roller 53 by the intermediate plate spring 57 so that the uppermost sheet S of the sheet bundle Sa can be fed by coming into contact with the feed roller 53.

  Further, the intermediate plate 56 has a sheet stacking upper limit height with respect to the feed roller 53 every time the feeding of the sheets is finished so that the sheets can be additionally stacked each time one stacked sheet is fed. It is necessary to arrange them apart. Therefore, as shown in FIG. 4, elevating cams 58 and 58 are fixed to the feed roller shaft 53c that rotatably supports the feed roller 53, and the intermediate plate 56 slides on the elevating cams 58 and 58. Possible cam followers 56a, 56a are formed. A feed roller gear 59 is attached to the shaft end of the feed roller shaft 53c, and a clutch (not shown) is attached upstream of the drive transmission path of the feed roller gear 59. The power transmitted from the driving source (not shown) to the feed roller 53 is connected / disconnected by this clutch.

  That is, when the feed roller 53 is in the standby state, the cam followers 56a and 56a of the intermediate plate 56 are pushed down by the lift cams 58 and 58, so that sheets can be stacked on the intermediate plate 56. When the clutch is turned on and the feed roller shaft 53c is rotated, the intermediate plate 56 is raised by the intermediate plate spring 57 while the cam followers 56a and 56a slide on the elevating cams 58 and 58. Then, the uppermost sheet S of the sheet bundle Sa stacked on the intermediate plate 56 contacts the feed roller 53, and the sheet S is fed by the feed roller 53. When the feed roller 53 makes one rotation, the sheet S is conveyed by a pair of conveyance rollers 55 and 55 downstream in the feeding direction, and the intermediate plate 56 is pushed down again by the lift cams 58 and 58.

  Here, when the feed roller 53 rotates once and the sheet S is conveyed by the conveyance roller pair 55, 55, the stopped feed roller 53 and the sheet S slide, and the outer periphery of the feed roller 53 The feed roller rubber 53a covering the surface will be unevenly worn. Therefore, the feed roller 53 includes a feed roller rubber 53a formed in a D-cut shape, and feed roller rollers 53b and 53b that are disposed at both axial ends of the feed roller rubber 53a and are rotatably supported. ing. The feed roller rollers 53b and 53b are formed to have an outer diameter smaller than that of the feed roller rubber 53a, and only the portion where the feed roller rubber 53a is D-cut protrudes in the outer diameter direction from the feed roller rubber 53a.

  In the standby state, the feed roller 53 stands by at a position where the feed roller rollers 53b and 53b come into contact with the sheet S. When the sheet S is conveyed by the conveyance roller pairs 55 and 55, the sheet S The feed roller rubber 53a does not slide. Therefore, the feed roller rubber 53a can be prevented from being unevenly worn, and the life of the feed roller 53 can be extended.

  As shown in FIG. 2, a separation roller holder 60 (holding member) is rotatably supported around the rotation fulcrum 60 a on the paper feed frame 52, and the separation roller holder 60 rotates the separation roller 54. Hold it possible. The separation roller holder 60 is urged upward by a separation spring 61 (first urging member), whereby the separation roller 54 comes into contact with the feed roller 53 with a predetermined contact pressure, and a separation nip N (contact portion). Is forming. The separation spring 61 is contracted between the separation roller holder 60 and the bottom plate 52 b of the paper feed frame 52. The sheets S fed by the feed roller 53 are separated one by one by the separation nip N and conveyed to the conveyance roller pair 55.

  A nip guide 63 (guide member) is disposed between the sheet bundle Sa stacked on the intermediate plate 56 and the separation nip N. The nip guide 63 has a separation roller holder 60 around the rotation fulcrum 63a. Is rotatably supported. A tip guide 63b (pressing surface) capable of smoothly guiding the sheet S to the separation nip N is formed on the upper surface of the nip guide 63, and a guide with which the tip of the sheet S contacts the right side surface of the nip guide 63. A surface 63c (contact surface) is formed.

  The nip guide 63 is urged upward by a nip guide spring 64 (second urging member) and is positioned at a contact position where the nip guide 63 is in contact with a stopper 65 (regulator) provided on the separation roller holder 60. Yes. The nip guide spring 64 is contracted between the nip guide 63 and the separation roller holder 60. When the nip guide 63 is in the contact position, the outer peripheral surface of the tip guide 63b and the feed roller 53 is separated by a predetermined distance h. On the right side surface of the nip guide 63, the guide surface 63c and a sheet non-contact surface 63d formed below the guide surface 63c are formed (see FIG. 5). The sheet feeding frame 52 is bent so as to cover the sheet non-contact surface 63d by the abutting surface 52a so that the sheet does not contact the sheet non-contact surface 63d.

  That is, the sheet non-contact surface 63d is formed such that the nip guide 63 in FIG. 2 rotates clockwise when the sheets stacked on the intermediate plate 56 come into contact with the sheet non-contact surface 63d. When the nip guide 63 rotates clockwise, a sheet bundle thicker than the predetermined distance h is likely to enter the separation nip N. Therefore, in the present embodiment, by forming the abutting surface 52a on the sheet feeding frame 52, the sheet contact with the sheet non-contact surface 63d is restricted, and a sheet bundle thicker than the predetermined distance h is separated from the separation nip. It is configured so that it is difficult to enter N. Thereby, while preventing the edge part of a sheet | seat from being damaged, the separation performance of a sheet | seat can be improved. Further, the abutting surface 52a is formed so as to abut on the sheet bundle Sa stacked on the intermediate plate 56 at a substantially right angle, so that the sheet bundle Sa is not damaged when the intermediate plate 56 moves up and down. ing. When the sheet comes into contact with the guide surface 63c of the nip guide 63, a force acts on the nip guide 63 so that the nip guide 63 in FIG. 2 rotates counterclockwise.

  Next, a series of operations of the manual feed unit 50 will be described with reference to FIGS. When the sheet bundle Sa is stacked on the sheet tray 51 and a feeding signal is sent from the printer 1, a driving source (not shown) is driven, and a clutch (not shown) is turned on according to a predetermined feeding timing. As a result, the intermediate plate 56 rises, the sheet bundle Sa contacts the feed roller 53, and the feed roller 53 rotates clockwise in FIG. 5 so that the uppermost sheet S of the sheet bundle Sa enters the separation nip N. It begins to be conveyed toward.

  Here, a case where one sheet S of the sheet bundle Sa is fed by the feed roller 53 and a case where a plurality of sheets S are fed will be described with reference to FIGS. 5 to 7. First, when the sheets S are fed one by one, as shown in FIG. 5, the sheet S passes between the feed roller 53 and the leading end guide 63b and is conveyed toward the separation nip N. . When the uppermost sheet S receives a conveying force to the separation nip N by the feed roller 53, the sheet bundle Sa other than the uppermost sheet S comes into contact with the guide surface 63c due to friction between the sheets, and a pressing force is generated.

  Therefore, the nip guide 63 receives a pressing force in the direction of the arrow Q on the guide surface 63c and tries to rotate counterclockwise about the rotation fulcrum 63a. Rotation in the direction of approaching (3) is restricted. Thereby, the contact position where the nip guide 63 contacts the stopper 65 is maintained.

  Therefore, even when a wide variety of sheets having different rigidity such as thin paper and thick paper are fed, the posture of the nip guide 63 does not change, the tip guide 63b of the nip guide 63 is separated from the feed roller 53, and the tip of the sheet S And the contact angle between the separation roller 54 and the separation roller 54 do not increase. Accordingly, the leading edge of the sheet S does not collide with the separating roller 54 in a state where the contact angle between the leading edge of the sheet S and the separating roller 54 is large, and damage to the leading edge of the sheet S can be reduced. Further, it is possible to prevent the sheet S from sticking to the separation roller 54 and causing jamming.

  When one sheet S is fed to the separation nip N, a torque limiter (not shown) built in the separation roller 54 idles due to the frictional force between the feed roller 53 and the separation roller 54. Thereby, the separation roller 54 is driven and rotated by the sheet S conveyed in the sheet feeding direction, and the sheet S is conveyed downstream.

  Next, a case where a plurality of sheets S are fed in a bundle by the feed roller 53 will be described, but there are the following two cases.

  In the first case, as shown in FIG. 6, several upper sheets of the sheet bundle Sa get over the guide surface 63 c and are conveyed to the separation nip N. That is, this is a case where the thickness of several sheets S over the guide surface 63c is smaller than the predetermined distance h between the front end guide 63b and the outer peripheral surface of the feed roller 53 (t <h).

  In this case, similarly to the case where one sheet S is fed to the separation nip N, the nip guide 63 receives a pressing force in the direction of the arrow Q (sheet conveyance direction) on the guide surface 63c, and counterclockwise. However, the rotation is restricted by the stopper 65. Then, several sheets S that have passed over the guide surface 63c pass between the feed roller 53 and the leading end guide 63b and are conveyed to the separation nip N. At this time, since the frictional force between the sheets S is small with respect to a load of a torque limiter (not shown), the separation roller 54 does not rotate, and several sheets S can be separated one by one in the separation nip N. . As a result, among the several sheets fed from the intermediate plate 56, only the uppermost sheet S is transported downstream in the transport direction, and the other sheets are stopped by the separation roller 54 that is stopped. Stay in separation nip N.

  Second, as shown in FIG. 7, the thickness t of the plurality of sheets S over the guide surface 63c is equal to or greater than a predetermined distance h (t ≧ h). In this case, the bundle of sheets S is sandwiched between the leading end guide 63 b and the feed roller 53. Then, the reaction force of the clamping force that sandwiches the bundle of sheets S acts on the nip guide 63 in the direction of the arrow R in the leading end guide 63b. The nip guide 63 rotates clockwise (in a direction away from the feed roller 53) about the rotation fulcrum 63a against the urging force of the nip guide spring 64 by the reaction force in the direction of arrow R.

  Thus, when the nip guide 63 rotates clockwise, the clamping force of the sheet S by the nip guide 63 and the feed roller 53 is only the force generated by the urging force of the nip guide spring 64. As a result, the clamping force for the bundle of sheets S is reduced. When the bundle of sheets S reaches the separation nip N in this state, the separation roller 54 does not rotate and the bundle of sheets S is not rotated because the frictional force between the sheets S is small with respect to the load of a torque limiter (not shown). I can whisper. In the bundle of sheets S, only the topmost sheet is conveyed downstream in the sheet conveying direction.

  As described above, when the bundle of sheets S is sandwiched between the leading end guide 63 b of the nip guide 63 and the feed roller 53, the nip guide 63 rotates in order to rotate clockwise. 63a is positioned at a position as shown in FIG. That is, the rotation fulcrum 63a is disposed on the far side from the feed roller 53 with respect to the first straight line A passing through the end 63f closest to the feed roller 53 of the guide surface 63c and perpendicular to the guide surface 63c. Further, the rotation fulcrum 63a is disposed on the side closer to the separation nip N with respect to the second straight line B passing through the downstream end 63e in the sheet conveyance direction of the leading end guide 63b and parallel to the normal line of the separation nip N. In this way, a region (shaded portion in the figure) that is on the side farther from the feed roller 53 with respect to the first straight line A and closer to the separation nip N with respect to the second straight line B is defined as region C.

  Here, as a comparative example, a configuration in which the rotation fulcrum 63a of the nip guide 63 is not disposed in the region C will be described with reference to FIG. In addition, in this comparative example, about the same structure as this Embodiment, the same code | symbol is attached | subjected to drawing and description is abbreviate | omitted. First, as shown in FIG. 9A, the case where the rotation fulcrum 163a of the nip guide 163 is arranged on the feed roller 53 side with respect to the first straight line A will be described.

  In such a case, the nip guide 163 rotates clockwise by the pressing force of the sheet bundle Sa in contact with the guide surface 163b in the arrow U direction. Then, the predetermined distance h between the leading end guide 163c and the feed roller 53 is widened, and the contact angle between the leading end of the sheet S that has come over the guide surface 163b and is in contact with the separation roller 54 and the peripheral surface of the separation roller 54 suddenly increases. growing. Since the peripheral surface of the separation roller 54 has a large friction coefficient, if the leading edge of the sheet S collides with the separation roller 54 in a state where the contact angle is large, the leading edge of the sheet may be significantly damaged or jammed. Will occur.

  Next, as shown in FIG. 9B, a case where the rotation fulcrum 263a of the nip guide 263 is arranged on the separation nip N side with respect to the second straight line B will be described. In such a case, when a bundle of sheets S having a thickness of a predetermined distance h or more is sandwiched between the leading end guide 263b of the nip guide 263 and the feed roller 53, the nip guide 263 tries to rotate counterclockwise. . Then, the holding pressure of the bundle of sheets S increases, and a conveying force is generated between the leading end guide 263b and the feed roller 53. If this transport force is excessive, a plurality of sheets S are transported beyond the separation nip N, and the sheets are double-fed, causing jamming.

  Therefore, in the present embodiment, by arranging the rotation fulcrum 63a of the nip guide 63 in the region C, the pressing force from the sheet bundle Sa acts on the guide surface 63c of the nip guide 63, and the nip guide 63 Tries to rotate counterclockwise. However, since the nip guide 63 is positioned at the contact position by the stopper 65, the front end of the sheet collides with the separation member with a large contact angle between the front end of the conveyed sheet S and the peripheral surface of the separation roller 54. There is nothing. Thereby, the damage to the front-end | tip of a sheet | seat can be reduced, and it can prevent that a sheet | seat pierces a separation member and jamming generate | occur | produces.

  Further, when a bundle of sheets S having a thickness of a predetermined distance h or more is sandwiched between the tip guide 63b of the nip guide 63 and the feed roller 53, the nip guide 63 resists the urging force of the nip guide spring 64, Rotate clockwise. At this time, the urging force of the separation spring 61 that is contracted between the separation roller holder 60 and the bottom plate 52 b (see FIG. 2) of the paper feed frame 52 is contracted between the separation roller holder 60 and the nip guide 63. The biasing force of the nip guide spring 64 is set sufficiently larger. Therefore, even if the nip guide 63 rotates clockwise, the separation roller holder 60 does not rotate together with the nip guide 63. As a result, since the state where the separation roller 54 presses the feed roller 53 is maintained, the sheets can be reliably separated one by one. In addition, it is possible to prevent the sheet S from being jammed between the leading end guide 63b of the nip guide 63 and the feed roller 53, thereby causing a jam.

  In the present embodiment, the rotation fulcrum 63 a of the nip guide 63 and the stopper 65 are provided in the separation roller holder 60. This is because the feed roller 53 is composed of a feed roller rubber 53a and a feed roller roller 53b having different outer diameters, and the diameter of the portion in contact with the separation roller 54 changes when the feed roller 53 makes one rotation. It is.

  Here, as a comparative example, a case where a rotation fulcrum of the nip guide and a stopper are provided in the paper feed frame 52 and these are used as the rotation fulcrum 463a and the stopper 465 will be described with reference to FIG. In addition, in this comparative example, about the same structure as this Embodiment, the same code | symbol is attached | subjected to drawing and description is abbreviate | omitted.

  When the feed roller roller 53b and the tip guide 63b face each other, as shown in FIG. 10A, the feed roller 53 and the tip guide 63b are separated by a predetermined distance h1. When the feed roller rubber 53a and the tip guide 63b face each other, as shown in FIG. 10B, the feed roller 53 and the tip guide 63b are separated by a predetermined distance h2. Therefore, when the feed roller 53 makes one rotation to feed the sheets S stacked on the intermediate plate 56, the distance between the feed roller 53 and the leading end guide 63b is a predetermined distance h1 during standby, but is predetermined during feeding. The distance changes to h2.

  When the feed roller rotates once, the diameter of the feed roller 53 changes in the separation nip N, so that the separation roller 54 and the separation roller holder 60 rotate according to the diameter of the feed roller 53. The rotation of the separation roller 54 and the separation roller holder 60 is performed before the sheet S reaches the separation nip N. However, in this comparative example, since the rotation fulcrum 463a and the stopper 465 are provided in the paper feed frame 52, the nip guide 63 does not follow the separation roller holder 60 even if the separation roller holder 60 rotates.

  As shown in FIGS. 10C and 10D, when the thickness t of the sheet S over the guide surface 63c is the same as the predetermined distance h1 (t = h1), when the feed roller 53 makes one rotation, the predetermined distance The nip guide 63 rotates by the amount changed from h1 to the predetermined distance h2. Then, the contact angle α between the leading edge of the sheet S and the peripheral surface of the separation roller 54 increases rapidly. Since the peripheral surface of the separation roller 54 has a large friction coefficient, if the leading edge of the sheet S collides with the separation roller 54 in a state where the contact angle α is large, the leading edge of the sheet may be greatly damaged, A jam will occur.

  Therefore, in the present embodiment, as shown in FIG. 11, the rotation fulcrum 63a of the nip guide 63 and the stopper 65 are provided in the separation roller holder 60, and when the separation roller holder 60 rotates, the nip guide 63 is It is configured to follow the separation roller holder 60. That is, even when the diameter of the feed roller 53 changes in the separation nip N and the separation roller 54 and the separation roller holder 60 rotate, the distance between the feed roller 53 and the front end guide 63b is always the predetermined distance h1. This is because the separation roller 54 and the separation roller holder 60 are pushed down by the feed roller rubber 53a before the nip guide 63 is rotated by the bundle of sheets S sandwiched between the feed roller rubber 53a and the leading end guide 63b. It is. As a result, the contact angle β between the leading edge of the sheet S and the peripheral surface of the separation roller 54 does not increase, and damage to the leading edge of the sheet can be reduced and jamming can be prevented.

  In this embodiment, the separation roller 54 is pushed down by the feed roller rubber 53a. However, a tapered surface having a low friction coefficient is formed upstream of the feed roller rubber 53a in the rotation direction, and the separation roller is formed by the taper surface. 54 may be depressed. Thereby, before the sheet S reaches the separation nip N, the separation roller 54 and the separation roller holder 60 can be surely pushed down, and the leading edge of the sheet S can be prevented from being damaged.

  Further, the guide surface 63 c is formed so as to contact the sheet bundle Sa stacked on the intermediate plate 56 substantially at a right angle in a state where the nip guide 63 is in contact with the stopper 65. In other words, the guide surface 63c is formed along a direction substantially orthogonal to the sheet conveying direction. This prevents the leading end of the sheet bundle Sa from being damaged due to the guide surface 63c sliding with the sheet bundle Sa when the separation roller holder 60 rotates and the nip guide 63 follows. be able to. Note that “substantially perpendicular” or “substantially orthogonal” does not necessarily have to be 90 °, and may be, for example, 80 ° to 100 °.

  The leading end guide 63b is formed to be substantially parallel to the sheet bundle Sa stacked on the intermediate plate 56 in a state where the nip guide 63 is in contact with the stopper 65. In other words, the leading end guide 63b is formed substantially parallel to the sheet conveying direction. Therefore, the reaction force of the clamping force that acts on the tip guide 63b from the bundle of sheets S sandwiched between the tip guide 63b and the feed roller 53 acts in a well-balanced manner over the entire surface of the tip guide 63b. Accordingly, the nip guide 63 can be smoothly rotated, and it is possible to prevent the force from being concentrated on a part of the surface of the sheet S and damaging the surface of the sheet S.

  Note that the term “substantially parallel” does not necessarily mean that the angle formed by the leading end guide 63b and the sheet bundle Sa is 0 °. For example, a slight inclination is provided so as to approach the separation nip N toward the downstream side in the sheet conveying direction. Thus, the sheet S may be smoothly guided to the separation nip N.

  Next, the position of the rotation fulcrum 60a of the separation roller holder 60 will be described with reference to FIG. As shown in FIG. 12A, the rotation fulcrum 60a passes through the end P of the guide surface 63c farthest from the feed roller 53, and the upper surface of the sheet bundle Sa1 having an upper limit height that can be stacked on the intermediate plate 56. The third straight line D is arranged on the side closer to the feed roller 53 with respect to the third straight line D. Further, the rotation fulcrum 60a is disposed on the far side from the feed roller 53 with respect to the fourth straight line E. The fourth straight line E refers to the sheet bundle Sa2 having a predetermined thickness or less in a state where the guide surface 63c passes through the end portion 63f closest to the feed roller 53 and is stacked on the intermediate plate 56 and in contact with the feed roller 53. A straight line parallel to the surface. The sheet bundle Sa2 having a predetermined thickness or less may be, for example, two or three sheet bundles.

  Further, the rotation fulcrum 60a is disposed downstream of the normal line G of the separation nip N, that is, the line perpendicular to the tangent line of the feed roller 53 and the separation roller 54 in the separation nip N in the sheet conveying direction. As described above, the region closer to the feed roller 53 with respect to the third straight line D, the side farther from the feed roller 53 with respect to the fourth straight line E, and the downstream side with respect to the normal G in the sheet conveying direction (the hatched line in the figure). (Part) is defined as region F.

  In the present embodiment, since the rotation fulcrum 60a of the separation roller holder 60 is disposed in the region F, the pressing force in the arrow Q direction acting on the guide surface 63c from the sheet bundle Sa1 or the sheet bundle Sa2 during sheet feeding is It acts toward the rotation fulcrum 60a. Therefore, this pressing force acting on the separation roller holder 60 via the nip guide 63 whose movement is restricted by the stopper 65 does not act as a rotational moment of the separation roller holder 60. As a result, even if the thickness of the sheet bundle Sa stacked on the intermediate plate 56 varies, the contact pressure (separation pressure) of the separation nip N during sheet feeding does not change, and one sheet S is stably provided. Can be separated one by one.

  As described above, in the present embodiment, when a variety of sheets S having different stiffnesses enter the guide surface 63c of the nip guide 63, the nip guide 63 is used regardless of whether the sheet S is a bundle or a single sheet. The sheet can be guided to the separation nip N without rotating and without damaging the leading edge of the sheet.

  When the bundle of sheets S is sandwiched between the leading end guide 63 b of the nip guide 63 and the feed roller 53, the nip guide 63 rotates in a direction away from the feed roller 53. At this time, the separation roller holder 60 does not rotate together with the nip guide 63, and the state where the separation roller 54 presses the feed roller 53 is maintained. As a result, the sheet S can be prevented from being double fed, and the occurrence of jam can be prevented.

  Therefore, the image forming unit 30 can reliably separate the sheets S one by one without damaging the sheets S in response to speeding up, downsizing, and diversification of media used in an image forming apparatus such as a printer. Can be conveyed.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. The same components as those in the first embodiment described above are denoted by the same reference numerals in the drawings, and description thereof will be omitted. The nip guide 63 of the sheet feeding device 650 is urged toward the feed roller 53 by a nip guide spring 664 as shown in FIG. The nip guide spring 664 is contracted between the nip guide 63 and the bottom plate 52 b of the paper feed frame 52.

  Thus, when the nip guide 63 rotates clockwise against the urging force of the nip guide spring 664, almost no force acts on the separation roller holder 60. Therefore, the design freedom of the nip guide spring 664 and the separation spring 61 can be improved.

  In the two embodiments described above, the stopper 65 may be configured integrally with the separation roller holder 60, or another member may be fixed to the separation roller holder 60. Further, the stopper 65 may be fixed to a member other than the separation roller holder 60.

  In the above-described two embodiments, the manual feeding unit 50 including the feed roller 53 and the separation roller 54 has been described as an example. However, the same effect can be obtained by the following feeding method. It is done. For example, the sheet may be fed by a pickup roller, and the sheets may be separated one by one by a feed roller and a separation roller. For example, instead of the separation roller, a sheet using a retard roller (separation member) that rotates in a rotation direction opposite to the feeding direction or a non-rotating body such as a separation pad (separation member) It may be separated.

  Further, the present invention may be applied not only to a manual feeding unit but also to a cassette type cassette feeding unit. Further, the present invention may be applied to a sheet feeding apparatus that directly stacks sheets on a sheet tray without providing an intermediate plate that can be moved up and down.

  1: image forming apparatus (printer), 30: image forming section, 50: sheet conveying apparatus (manual feeding section), 52: frame member (paper feeding frame), 52b: frame member (bottom plate), 53: rotating body ( Feed roller), 54: separation member (separation roller), 56: stacking portion (medium plate), 60: separation roller holder (holding member), 60a: rotation fulcrum, 61: first biasing member (separation spring), 63: Guide member (nip guide), 63a: Rotation fulcrum, 63b: Pressing surface (tip guide), 63c: Abutting surface (guide surface), 63e: Downstream end, 63f: End, 64: Second urging force Member (nip guide spring), 65: restriction part (stopper), A: first straight line, B: second straight line, D: third straight line, E: fourth straight line, G: normal line, N: contact part (separation) Nip), S: sheet, Sa: sheet bundle, Sa1: upper limit height Over sheet bundle, Sa2: predetermined thickness less the sheet bundle, Q: the sheet conveying direction

Claims (13)

A stacking unit on which sheets are stacked;
A rotating body that conveys the sheet by rotating in contact with the sheet stacked on the stacking unit;
A separating member that is pressed toward the rotating body and separates the sheets one by one at a contact portion with the rotating body;
A holding member for holding the separating member;
A guide member provided rotatably with respect to the holding member, and capable of guiding a leading end of a sheet to the contact portion;
A regulating portion that abuts on the guide member and regulates the guide member from rotating in a direction approaching the rotating body,
The guide member is rotatable in a direction away from the rotating body in a state where the separating member presses the rotating body.
A sheet conveying apparatus. A stacking unit on which sheets are stacked;
A rotating body that conveys the sheet by rotating in contact with the sheet stacked on the stacking unit;
A separating member that is pressed toward the rotating body and separates the sheets one by one at a contact portion with the rotating body;
A holding member for holding the separating member;
A guide member provided rotatably with respect to the holding member, and capable of guiding a leading end of a sheet to the contact portion;
A regulating portion that abuts on the guide member and regulates the guide member from rotating in a direction approaching the rotating body,
The guide member is rotatable with respect to the holding member in a direction away from the rotating body.
A sheet conveying apparatus. The guide member has a contact surface that comes into contact with the sheets stacked on the stacking unit, and is pressed against the regulation unit when a force in the sheet conveyance direction acts on the contact surface.
The sheet conveying apparatus according to claim 1 or 2. The guide member has a pressing surface with which a sheet bundle conveyed between the rotating body and the guide member abuts, and a direction away from the rotating body when the pressing surface is pressed by the sheet bundle. To rotate,
The sheet conveying apparatus according to claim 3. A rotation fulcrum about which the guide member rotates with respect to the holding member passes through an end portion of the contact surface closest to the rotating body, and is in the first straight line perpendicular to the contact surface. Disposed on the side farther from the rotating body and closer to the contact portion with respect to a second straight line passing through the downstream end of the pressing surface in the sheet conveyance direction and parallel to the normal line of the contact portion;
The sheet conveying apparatus according to claim 4. The restricting portion is provided on the holding member.
The sheet conveying apparatus according to claim 4 or 5. A rotation fulcrum around which the holding member rotates is a third parallel to the surface of the sheet bundle having an upper limit height that can be stacked on the stacking portion through the end of the contact surface that is farthest from the rotating body. A predetermined thickness in a state of being close to the rotating body with respect to a straight line and passing through the end of the contact surface closest to the rotating body, being loaded on the stacking portion and in contact with the rotating body The fourth straight line parallel to the surface of the sheet bundle below is disposed on the far side from the rotating body and on the downstream side in the sheet conveying direction from the normal line of the contact portion.
The sheet conveying apparatus according to claim 6. The contact surface is formed along a direction substantially orthogonal to the sheet conveying direction in a state where the guide member is in contact with the restricting portion.
The sheet conveying apparatus according to any one of claims 3 to 7. The pressing surface is formed substantially parallel to the sheet conveying direction in a state where the guide member is in contact with the restricting portion.
The sheet conveying apparatus according to any one of claims 4 to 7. The holding member is rotatably supported by the frame member,
A first biasing member that biases the holding member so as to press the separating member against the rotating body;
A second urging member that urges the guide member toward the rotating body,
When the guide member rotates in a direction away from the rotating body against the biasing force of the second biasing member, the separation member presses the rotating body by the second biasing member. Maintained,
The sheet conveying apparatus according to any one of claims 1 to 9. The second urging member is contracted between the holding member and the guide member,
The biasing force of the first biasing member is greater than the biasing force of the second biasing member.
The sheet conveying apparatus according to claim 10. The second urging member is contracted between the guide member and the frame member.
The sheet conveying apparatus according to claim 10. A sheet conveying device according to any one of claims 1 to 12,
An image forming unit that forms an image on a sheet conveyed from the sheet conveying apparatus,
An image forming apparatus.

Images