Abstract
A document conveying device includes a feed roller, a separation pad, a pad holder, a tension spring, and a separation pad support mechanism. The feed roller and the separation pad form a separation nip at which a sheet is separated and conveyed. The pad holder holds the separation pad and can be turned upward and downward around a turning shaft. The tension spring biases the pad holder upward to press the separation pad against the feed roller. The separation pad support mechanism turns the pad holder in a direction to separate the separation pad from the feed roller against a biasing force of the tension spring.
Claims
1. A document conveying device comprising: a feed roller and a separation pad which forms a separation nip at which a sheet is separated and conveyed; a pad holder which holds the separation pad and can be turned upward and downward around a turning shaft; a tension spring which biases the pad holder upward to press the separation pad against the feed roller; and a separation pad support mechanism which turns the pad holder in a direction to separate the separation pad from the feed roller against a biasing force of the tension spring.
2. The document conveying device according to claim 1, wherein the separation pad support mechanism includes: a rotating member which is rotatably supported around an axis parallel to the turning shaft of the pad holder and to which one end of the tension spring is connected; a link bar which couples the rotating member to the turning shaft of the pad holder; and a driving member which rotates the rotating member, wherein during normal sheet feeding, the rotating member is pulled by the tension spring and rotates in one direction to rotate the pad holder upward via the link bar to press the separation pad against the sheet feed roller, and when a sheet jam occurs at the separation nip, the driving member rotates the rotating member in an opposite direction against the biasing force of the tension spring and turns the pad holder downward via the link bar to separate the separation pad from the feed roller.
3. The document conveying device according to claim 2, comprising: a conveying roller which is disposed downstream of the separation nip in the sheet conveyance direction, and a conveying gear which can rotate integrally with the conveying roller and can rotate with respect to the conveying roller within a certain angle, wherein the driving member is provided with a driving gear which is engaged with the conveying gear.
4. The document conveying device according to claim 3, wherein the separation pad support mechanism includes a ratchet mechanism which transmits a rotation of the driving gear to the rotating member when the driving gear rotates in one direction and does not transmit the rotation of the driving gear to the rotating member when the driving gear rotates in the other direction, wherein when the conveying gear rotates so that the conveying roller rotates in the direction in which the conveying roller conveys the document, the driving gear rotates in the other direction and the rotation of the driving gear is not transmitted to the rotating member by the ratchet mechanism, and when the conveying gear rotates in the opposite direction, the driving gear rotates in one direction and the rotation of the driving gear is transmitted to the rotating member by the ratchet mechanism and the rotating member rotates in the opposite direction.
5. The document conveying device according to claim 4, wherein the conveying gear rotates within the angle in the opposite direction with respect to the conveying roller.
6. The document conveying device according to claim 1, wherein the tension spring and the separation pad holding mechanism are disposed outside a document conveying region.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a perspective view showing a document conveying device to one embodiment of the present disclosure.
[0009] FIG. 2 is a cross-sectional view showing a sheet feeding part of the document conveying device according to the embodiment of the present disclosure.
[0010] FIG. 3 is a plan view showing an inner frame of the document conveying device according to the embodiment of the present disclosure.
[0011] FIG. 4 is a view of a separation pad support mechanism (holder turning shaft, rotating member, and driving member) viewed from the rear side, in the document conveying device according to the embodiment of the present disclosure.
[0012] FIG. 5 is a cross-sectional view showing the separation pad support mechanism (pad holder and holder turning shaft) in the document conveying device according to the embodiment of the present disclosure.
[0013] FIG. 6 is a perspective view showing the separation pad support mechanism (holder turning shaft, rotating member, and driving member) in the document conveying device according to the embodiment of the present disclosure.
[0014] FIG. 7 is a cross-sectional view showing the separation pad support mechanism (rotating member and driving member) in the document conveying device according to the embodiment of the present disclosure.
[0015] FIG. 8 is a cross-sectional view showing the separation pad support mechanism (driving member) in the document conveying device according to an embodiment of the present disclosure.
[0016] FIG. 9 is a perspective view showing the separation pad support mechanism (in a state in which a ratchet cylinder is separated from the rotating member) in a document conveying device according to an embodiment of the present disclosure.
[0017] FIG. 10 is a perspective view showing the separation pad support mechanism (in a state in which the ratchet cylinder is engaged with the rotating member) in the document conveying device according to the embodiment of the present disclosure.
[0018] FIG. 11 is a view showing the separating pad support mechanism (when a separating nip is formed) viewed from the rear side, in the document conveying device according to the embodiment of the present disclosure.
[0019] FIG. 12 is a view showing the separation pad support mechanism (when the separation nip is released) viewed from the rear side, in the document conveying device according to the embodiment of the present disclosure.
[0020] FIG. 13 is a side view showing a conveying roller in the document conveyance apparatus according to the embodiment of the present disclosure.
[0021] FIG. 14 is a cross-sectional view showing the conveying roller in the document conveyance apparatus according to the embodiment of the present disclosure.
[0022] FIG. 15 is a view showing the separation pad support mechanism and s conveying gear (when the separation nip is released) viewed from the rear side, in the document conveying device according to the embodiment of the present disclosure.
[0023] FIG. 16 is a view showing the separation pad support mechanism and the conveying gear (when the separation nip is formed) viewed from the rear side, in the document conveying device according to the embodiment of the present disclosure.
DETAILED DESCRIPTION
[0024] Hereinafter, with reference to the drawings, a document conveying device according to one embodiment of the present disclosure will be described.
[0025] First, the entire configuration of the document conveying device 1 will be described with reference to FIG. 1. FIG. 1 is a perspective view showing the document conveying device 1. Fr, Rr, L, and R in each figure indicate the front, rear, left, and right of the document conveying device, respectively.
[0026] The document conveying device 1 includes a conveying part in which a document (sheet) is conveyed and an image on one side of the document is read, a sheet feed tray 5 on which the document is placed, and a discharge tray 7 on which the document with the image read is loaded. The document conveying device 1 is disposed above an image reading device (not shown) for reading an image of the other side of the document by a reading sensor.
[0027] First, the conveying part 3 will be described with reference to FIG. 2. FIG. 2 is a cross-sectional view showing the conveying part 3. A sheet feed port 11 and a discharge port 13 are formed on the right side surface of the conveying part 3. The discharge port 13 is disposed below the sheet feed port 11.
[0028] The conveying part 3 includes an inner frame 15 and an outer frame 17, and a transverse U-shaped conveyance path 19 is formed between both the frames 15, 17, passing through a document reading position P from the sheet feed port 11 to the discharge port 13. A direction in which the document is conveyed along the conveyance path 19 is a conveyance direction X. An opening 21 along the width direction of the document is formed at the left end portion of the lower surface of the inner frame 15. A transparent glass plate 23 is disposed in the opening 21. A reading sensor 25 is disposed above the glass plate 23. The reading sensor of the image reading device is disposed below the glass plate 23. When the document is conveyed under the glass plate 23, images on both sides of the document are read by the reading sensor 25 and the reading sensor of the image reading device. A predetermined position below the glass plate 23 is set as a reading position P.
[0029] On the conveyance path 19, in order from the upstream side in the conveyance direction X, a pickup roller 31, a sheet feed roller 33, a separation pad 35, a first pair of conveying rollers 37, a second pair of conveying rollers 39, and a pair of discharge rollers 41.
[0030] The pickup roller 31 is rotatably supported by the outer frame 17 inside the sheet feed port 11. The sheet feed roller 33 is rotatably supported by the outer frame 17. The separation pad 35 is supported by the inner frame 15 and pressed against the sheet feed roller 33 as described later. Thus, a separation nip N is formed between the sheet feed roller 33 and the separation pad 35. The first pair of conveying rollers 37 includes a conveying roller 101 and a driven roller. The conveying roller 101 is rotatably supported by the inner frame 15, and the driven roller is rotatably supported by the outer frame 17. The second pair of conveying rollers 39 is disposed between the first pair of conveying rollers 37 and the reading position P, and includes a driving roller and a driven roller. The driving roller is rotatably supported by the inner frame 15, and the driven roller is rotatably supported by the outer frame 17. The pair of discharge rollers 41 includes the conveying roller 101 and a driven roller disposed inside the discharge port 13, and is rotatably supported by the inner frame 15. The conveying roller pair of 101 also serves as the conveying roller 101 of conveying rollers 37.
[0031] Next, the sheet feed tray 5 and the discharge tray 7 will be described. As shown in FIG. 1, the sheet feed tray 5 is supported below the sheet feed port 11 in a posture inclined downward toward the sheet feed port 11 of the conveying part 3. As shown in FIG. 1, the discharge tray 7 is provided below the sheet feed tray 5 below the discharge port 13 of the conveying part 3.
[0032] Next, an image reading operation will be briefly described. The document placed on the sheet feed tray 5 is fed from the sheet feed tray 5 to the conveyance path 19 by the pickup roller 31. When only a single document is fed, the document is conveyed through the separation nip N. When several documents are fed, only the uppermost document is separated at the separation nip N from the other documents and conveyed from the separation nip N. The document is conveyed to the reading position P by the first pair of conveying rollers 37 and the second pair of conveying rollers 39. At the reading position P, images of both sides or one side of the document are read by the reading sensors 25. Thereafter, the document is conveyed by the pair of discharge rollers 41 and discharged to the discharge tray 7 through the discharge port 14.
[0033] As described above, the separation pad 35 is pressed against the sheet feed roller 33, and the separation nip N is formed between the separation pad 35 and the sheet feed roller 33. Hereinafter, a separation pad support mechanism 45 for pressing the separation pad 35 against the sheet feed roller 33 and separating the separation pad 35 from the sheet feed roller 33 will be described with reference to FIG. 3 and FIG. 4. FIG. 3 is a plan view showing the inner frame 15 by which the separation pad support mechanism 45 is supported, and FIG. 4 is a view showing the separation pad support mechanism 45 viewed from the rear side.
[0034] The separation pad support mechanism 45 is provided with a pad holder 51 which holds the separation pad 35, a holder turning shaft 53 connected to the pad holder 51, a tension spring 55 which biases the holder turning shaft 53, a rotating member 57 arranged between the holder turning shaft 53 and the tension spring 55, and a driving member 59 which rotates the rotating member 57 only in one direction.
[0035] First, the inner frame 15 on which these are supported will be described with reference to FIG. 3 and FIG. 5. FIG. 5 is a side view showing the pad holder 51. The inner frame 15 guides the lower surface of the document conveyed along the conveyance path 19 along the conveyance direction X. As shown in FIG. 3, a horizontal wall 15a and a vertical wall 15b are formed in the inner frame 15 below the sheet feed roller 33 (see FIG. 3). The horizontal wall 15a is formed between two grooves parallel to the conveyance direction X. On both side surfaces of the horizontal wall 15a, rotational shafts 15c are stood along the width direction crossing the conveyance direction X (see FIG. 5). The vertical wall 15b is disposed on the downstream side of the horizontal wall 15a in the conveyance direction X with a gap therebetween from the horizontal wall 15a.
[0036] Further, as shown in FIG. 3, an outer cover plate 16 is fixed to the outside of the rear side plate of the inner frame 15 with a predetermined distance from the rear side plate.
[0037] Next, the pad holder 51 will be described with reference to FIG. 3 and FIG. 5. As shown in FIG. 5, the pad holder 51 has a rectangular plate-like holding portion 61 on which the separation pad 35 is supported, two leg portions 63 formed on one short side of the holding portion 61, and a hook portion 65 bent downward from the other short side of the holding portion 61.
[0038] As shown in FIG. 5, the two leg portions 63 are rotatably supported by the rotational shafts 15c stood on both side surfaces of the horizontal wall 15a of the inner frame 15. The hook portion 65 enters the gap between the horizontal wall 15a and the vertical wall 15b. The pad holder 51 is turnable upward and downward around the rotational shaft 15sc between an upper position where the hook portion 65 is locked to the vertical wall 15b (see the solid line in FIG. 5) and a lower position where the holding portion 61 is locked to the horizontal wall 15a (see the two-dotted chain line in FIG. 5).
[0039] Next, the holder turning shaft 53 will be described. As shown in FIG. 3, one end (front end) of the holder turning shaft 53 is integrally rotatably coupled to one leg portion 63 of the pad holder 51 by a coupling (see also FIG. 5). The other end (rear end) of the holder turning shaft 53 penetrates the rear side plate of the inner frame 15, and protrudes between the rear side plate and the outer cover plate 16. An arm portion 71 extending in the radial direction of the holder turning shaft 53 is formed at the protruding end portion (see FIG. 3 and FIG. 4). By rotating the holder turning shaft 53, the pad holder 51 is turned upward and downward between the upper position and the lower position. The movement of the holder turning shaft 53 in the width direction is restricted by the outer cover plate 16.
[0040] Next, the tension spring 55 will be described. As shown in FIG. 4, the fixed end of the tension spring 55 is fixed on the outer surface of the rear side plate of the inner frame 15 above the holder turning shaft 53.
[0041] Next, the rotating member 57 will be described with reference to FIG. 4, FIG. 6, FIG. 7, and FIG. 8. FIG. 6 is a perspective view showing the separation pad support mechanism 45 (holder turning shaft 53, rotating member 57, and driving member 59), FIG. 7 is a cross-sectional view showing the separation pad support mechanism 45 (rotating member 57 and driving member 59), and FIG. 8 is a cross-sectional view showing the separation pad support mechanism 45 (driving member 59).
[0042] As shown in FIG. 4, the rotating member 57 has a cylindrical portion 81, and a long arm portion 83 and a short arm portion 85 extending from the side surface of the cylindrical portion 81 in the radial direction of the cylindrical portion 81. The long arm portion 83 and the short arm portion 85 are arranged at a predetermined interval in the circumferential direction of the cylindrical portion 81. As shown in FIG. 6, ratchet teeth 81a are formed on one end surface of the cylindrical portion 81. The ratchet teeth 81a are inclined in a counterclockwise direction when viewed from the rear side. As shown in FIG. 7, a protruded portion 81b is formed on the inner peripheral surface of the cylindrical portion 81 along the circumferential direction. The rotating member 57 is supported by the driving member 59 as described later.
[0043] Next, the driving member 59 will be described with reference to FIG. 4, and FIG. 6 to FIG. 8. The driving member 59 has a drive shaft 91, a driving gear 93 provided coaxially with the drive shaft 91, and a ratchet cylinder 95 rotatably supported by the drive shaft 91.
[0044] First, the drive shaft 91 will be described. As shown in FIG. 7, a stepped portion 91a is formed along the circumferential direction on the outer peripheral surface of one end portion of the drive shaft 91. As shown in FIG. 4, the drive shaft 91 is disposed on the downstream side (left side in FIG. 4) of the holder turning shaft 53 in the conveyance direction X. Both ends of the drive shaft 91 are rotatably supported by the rear side plate of the inner frame 15 and the outer cover plate 16. More specifically, as shown in FIG. 7, one end (rear end) of the drive shaft 91 is rotatably inserted into an opening formed in the outer cover plate 16, and the other end (front end) of the drive shaft 91 is rotatably supported by a recess formed in the rear side plate.
[0045] Next, the driving gear 93 will be described. The driving gear 93 is fixed substantially at the center of the drive shaft 91. As shown in FIG. 8, a protruding piece 93a is formed on a part of the outer surface (a surface facing the outer cover plate 16) of the driving gear 93 along the circumferential direction around the drive shaft 91.
[0046] Next, the ratchet cylinder 95 will be described. As shown in FIG. 6, on one end surface (rear end surface) of the ratchet cylinder 95, ratchet teeth 95a capable of engaging with the ratchet teeth 81a formed on the cylindrical portion 81 of the rotating member 57 is formed. The ratchet teeth 95a are inclined in the clockwise direction when viewed from the rear side. On the other end surface (front end surface) of the ratchet cylinder 95, two protruding pieces 95b extending in the axial direction of the ratchet cylinder 95 are formed apart in the circumferential direction. Further, as shown in FIG. 6, on the other end surface (front end surface) of the ratchet cylinder 95, an inclined surface 95c inclined in the axial direction of the ratchet cylinder 95 is formed between the two protruding pieces 95b. The inclined surface 95c is inclined away from the ratchet teeth 95a in the clockwise direction when viewed from the rear side.
[0047] As shown in FIG. 7, the ratchet cylinder 95 is fitted around the drive shaft 91 between the driving gear 93 and the outer cover plate 16. The ratchet teeth 95a is opposite to the driving gear 93, and the two protruding pieces 95b face the driving gear 93. The ratchet cylinder 95 is movable along the drive shaft 91, and rotatable around the drive shaft 91. Further, when the driving gear 93 rotates in either direction and the protruding pieces 93a (see FIG. 8) of the driving gear 93 abuts against the protruding piece 95b of the ratchet cylinder 95 and pushes the protruding piece 95b, the ratchet cylinder 95 rotates in the same direction as the driving gear 93.
[0048] As described above, the rotating member 57 is supported by the driving member 59. More specifically, as shown in FIG. 6 and FIG. 7, the cylindrical portion 81 of the rotating member 57 is fitted around the drive shaft 91 of the driving member 59. The ratchet teeth 81a of the cylindrical portion 81 face the ratchet teeth 95a of the ratchet cylinder 95. As shown in FIG. 7, the distal end surface of the cylindrical portion 81 abuts on the outer cover plate 16, and the protruded portion 81b formed on the inner peripheral surface abuts on the stepped portion 91a of the drive shaft 91. Thus, the rotating member 57 can rotate around the drive shaft 91 and cannot move in the axial direction of the drive shaft 91.
[0049] Next, an operation in which the driving member 59 rotates the rotating member 57 only in one direction will be described with reference to FIG. 9 and FIG. 10. FIG. 9 and FIG. 10 are perspective views showing the separation pad support mechanism 45 (rotating member 57 and driving member 59).
[0050] When the drive shaft 91 is driven in a state where the ratchet teeth 81a of the cylindrical portion 81 of the rotating member 57 is engaged with the ratchet teeth 95a of the ratchet cylinder 95 (see FIG. 6), and the driving gear 93 is rotated in the counterclockwise direction (as viewed from the rear side) (see the arrow A1 in FIG. 6), the protruding piece 93a of the driving gear 93 abuts against the protruding piece 95b of the ratchet cylinder 95 (see FIG. 8), and the protruding piece 95b is pushed in the counterclockwise direction. Then, the ratchet cylinder 95 rotates in the counterclockwise direction (see the arrow A2 in FIG. 6).
[0051] Since the rotating member 57 cannot move in the axial direction as described above, when the ratchet cylinder 95 rotates in the counterclockwise direction (see the arrow A2 in FIG. 6), the ratchet teeth 95a of the ratchet cylinder 95 are guided in the counterclockwise direction by the ratchet teeth 81a of the cylindrical portion 81 of the rotating member 57. Then, the ratchet cylinder 95 moves in a direction (forward) away from the rotating member 57 while rotating in the counterclockwise direction around the drive shaft 91 (see the arrow A3 in FIG. 6). As a result, as shown in FIG. 9, the ratchet cylinder 95 is separated from the cylindrical portion 81 of the rotating member 57, and the rotation of the ratchet cylinder 95, that is, the rotation of the drive shaft 91 is not transmitted to the cylindrical portion 81, that is, the rotating member 57.
[0052] On the other hand, when the drive shaft 91 is driven and the driving gear 93 rotates in the clockwise direction (viewed from the rear side) in a state where the ratchet cylinder 95 is separated from the cylindrical portion 81 of the rotating member 57 (see FIG. 9) (see the arrow B1 in FIG. 9), as shown in FIG. 10, the edge of the protruding piece 93a of the driving gear 93 presses the inclined surface 95c of the ratchet cylinder 95, and the ratchet cylinder 95 moves away from the driving gear 93 while rotating in the same direction as the driving gear 93 (see the arrow B2 in FIG. 10) (see the arrow B3 in FIG. 10). Then, the ratchet teeth 95a of the ratchet cylinder 95 are engaged with the ratchet teeth 81a of the cylindrical portion 81 of the rotating member 57. As a result, the rotating member 57 rotates in the same direction as the driving gear 93, that is, the drive shaft 91 through the ratchet cylinder 95. As described above, the ratchet teeth 81a of the cylindrical portion 81 of the rotating member 57 and the ratchet teeth 95a of the ratchet cylinder 95 of the driving member are an example of the ratchet mechanism according to the present disclosure, which transmits a rotation of the driving gear 93 to the rotating member 57 when the driving gear 93 rotates in one direction and does not transmit the rotation of the driving gear 93 to the rotating member 57 when the driving gear 93 rotates in the other direction.
[0053] Accordingly, when the drive shaft 91 rotates in the clockwise direction (viewed from the rear side) (see the arrow B1 in FIG. 9 and FIG. 10), the rotating member 57 rotates in the clockwise direction via the ratchet cylinder 95. On the other hand, when the drive shaft 91 rotates in the counterclockwise direction (see the arrow A1 in FIG. 6), the rotation in the counterclockwise direction is not transmitted to the rotating member 57 by the ratchet cylinder 95. That is, the rotating member 57 is rotated only in the clockwise direction by the driving member 59.
[0054] In the rotating member 57 thus supported by the driving member 59, as shown in FIG. 4, the arm portion 71 of the holder turning shaft 53 is connected to the short arm portion 85 via a link bar 89, and the free end of the tension spring 55 is connected to the long arm portion 83. More specifically, the long arm portion 83 is connected to the free end of the tension spring 55 on the right side (opposite to the holder turning shaft 53) and above the center of the drive shaft 91 of the driving member 59.
[0055] An operation of forming and releasing the separation nip by the above-described separation pad support mechanism 45 will be described with reference to FIG. 11 and FIG. 12. FIG. 11 and FIG. 12 are views showing the separation pad support mechanism 45 viewed from the rear side.
[0056] First, the operation of forming the separation nip N will be described with reference to FIG. 11. When the separation nip is formed, the driving gear 93 of the driving member 59 stops the rotating. As described above, since the rotating member 57 can rotate around the drive shaft 91 of the driving member 59, when the long arm portion 83 is pulled by the tension spring 55 (see the arrow F1), the rotating member 57 rotates in the counterclockwise direction of FIG. 11 (see the arrow A1). The rotation of the rotating member 57 is restricted by the contact of the long arm portion 83 with the engaging piece 15d formed on the rear side plate of the inner frame 15. When the rotating member 57 rotates in this manner, the arm portion 71 of the holder turning shaft 53 is pulled leftward via the link bar 89 (see the arrow A2), and the holder turning shaft 53 rotates in the counterclockwise direction (see the arrow A3).
[0057] Then, as shown in FIG. 5, the pad holder 51 is turned upward, and the separation pad 35 is pressed against the sheet feed roller 33 (see FIG. 2). Note that the pad holder 51 is not necessarily turned to the upper position. Thus, the separation pad 35 is pressed against the sheet feed roller 33 to form the separation nip N.
[0058] To release the separation nip N, as shown in FIG. 12, the drive shaft 91 of the driving member 59 is rotated in the clockwise direction by a predetermined angle (see the arrow B1). The driving gear 93 rotates in the clockwise direction together with the drive shaft 91. As described above, the rotating member 57 is rotated only in the clockwise direction by the driving member 59. Accordingly, when the driving gear 93 rotates in the clockwise direction, the rotating member 57 rotates in the clockwise direction via the ratchet cylinder 95 (see the arrow B2). Then, the tension spring 55 is pulled by the long arm portion 83 (see the arrow F2). Further, the short arm portion 85 pushes the arm portion 71 of the holder turning shaft 53 leftward via the link bar 89 (see the arrow B3). Then, the holder turning shaft 53 rotates in the clockwise direction (see the arrow B4).
[0059] As a result, as shown in FIG. 5, the pad holder 51 is turned downward, and the separation pad 35 is separated downward from the sheet feed roller 33. At this time, it is not necessary for the separation pad 35 to be completely separated from the sheet feed roller 33, but it is sufficient if the nip pressure of the separation nip N is low enough to allow the document to be pulled out with a light force.
[0060] As is clear from the above description, according to the present disclosure, the separation nip N can be released (the nip pressure can be reduced) by the separation pad support mechanism 45, so that the sheet jammed at the separation nip can be removed with a light force. Further, the separation pad 35 is pressed against the sheet feed roller 33 by the tension spring 55. The tension spring 55 is disposed outside the rear side plate of the inner frame 15, that is, outside the sheet passing region. That is, it is not necessary to arrange the tension spring 55 below the separation pad 35 as in the case where the compression coil spring is used as the biasing member for pressing the separation pad 35 against the sheet feed roller 33. Therefore, the height of the document conveying device 1 can be reduced as compared with the case where the compression coil spring is used as the biasing member. As an example, the height can be reduced by about 8% compared with the case where the compression coil spring is used.
[0061] Next, an example of a mechanism for rotating the drive shaft 91 of the driving member 59 will be described with reference to FIG. 3 and FIG. 4, and FIG. 13 and FIG. 14. FIG. 13 is a perspective view showing the conveying roller 101, and FIG. 14 is a cross-sectional view showing the conveying roller 101.
[0062] In this example, the drive shaft 91 of the driving member 59 is rotated by the conveying roller 101 of the first pair of conveying rollers 37 (the pair of discharge rollers 41) (see FIG. 2). As shown in FIG. 3, the conveying roller 101 is disposed downstream of the separation pad 35 in the conveyance direction X. The conveying roller 101 protrudes on the conveyance path 19 through an opening formed in the inner frame 15.
[0063] As shown in FIG. 3, the rear end of the drive shaft of the conveying roller 101 is rotatably supported by the outer cover plate 16 through the rear side plate of the inner frame 15. Between the rear side plate of the inner frame 15 and the outer cover plate 16, a conveying gear 103 is supported on the conveying roller 101 so as to be rotatable with respect to the conveying roller 101 and not movable in the axial direction of the conveying roller 101. As shown in FIG. 4, the conveying gear 103 is engaged with the driving gear 93 of the driving member 59 of the separation pad support mechanism 45.
[0064] As shown in FIG. 13 and FIG. 14, two protruding portions 103a are formed on the inner surface (rear surface) of the conveying gear 103 at predetermined intervals in the circumferential direction of the conveying roller 101. The conveying gear 103 is engaged with an output gear (not shown) connected to a motor (not shown). When the motor is driven, the conveying gear 103 is rotated through the output gear.
[0065] Further, a connecting member 105 is fixed to the conveying roller 101 on the inner side (front side) of the conveying gear 103. The connecting member 105 is a disk-shaped member, and as shown in FIG. 14, two protruding portions 105a are formed on the outer surface (rear surface) at predetermined intervals in the circumferential direction of the conveying roller 101. The two protruding portions 103a of the conveying gear 103 and the two protruding portions 105a of the connecting member 105 overlap each other in the axial direction of the conveying roller 101. Therefore, when the conveying gear 103 is rotated, the protruding portions 103a of the conveying gear 103 pushes the protruding portions 105a of the connecting member 105, and the conveying roller 101 rotates in the same direction as the conveying gear 103.
[0066] On the other hand, until the protruding portions 103a of the conveying gear 103 separates from one protruding portion 105a of the connecting member 105 and abuts against the other protruding portion 105a (see the arrow R in FIG. 14), the conveying gear 103 can be rotated relative to the conveying roller 101.
[0067] An operation of forming and releasing the separation nip N in this example will be described with reference to FIG. 11 and FIG. 12, and FIG. 15 and FIG. 16. FIG. 15 and FIG. 16 are views showing the separation pad support mechanism 45 viewed from the rear side.
[0068] When the document conveying operation is not executed, the first pair of conveying rollers 37 and the pair of discharge rollers 41 are not driven, so that the conveying roller 101 is not rotated and the conveying gear 103 is not rotated. That is, the driving gear 93 engaged with the conveying gear 103 is also not rotated. In this case, as described with reference to FIG. 11, the long arm portion 83 of the rotating member 57 is pulled by the tension spring 55, and the rotating member 57 rotates in the counterclockwise direction of FIG. 11. Then, the arm portion 71 of the holder turning shaft 53 is pulled rightward through the link bar 89, and the holder turning shaft 53 is rotated in the counterclockwise direction. As a result, the pad holder 51 is turned upward, and the separation pad 35 is pressed against the sheet feed roller 33 to form the separation nip N.
[0069] Next, a case in which the document conveying operation is executed will be described with reference to FIG. 15. In this case, the first pair of conveying rollers 37 and the pair of discharge rollers 41 are rotated in the direction of conveying the document. That is, the motor is driven and the conveying gear 103 is rotated via the output gear in the clockwise direction as viewed from the rear side (see the arrow C1). When the conveying gear 103 is rotated, the protruding portion 103a of the conveying gear 103 pushes the protruding portion 105a of the connecting member 105, and the connecting member 105 is rotated in the same direction as the conveying gear 103. As the connecting member 105 is rotated in this manner, the conveying roller 101 is rotated in the clockwise direction when viewed from the rear side (see the arrow C2 in FIG. 15), and the document is conveyed in the conveyance direction X.
[0070] As described above, when the conveying gear 103 is rotated in the clockwise direction, the driving gear 93 engaged with the conveying gear 103 is rotated in the counterclockwise direction when viewed from the rear side (see the arrow C3). As described above, when the driving gear 93 is rotated in the counterclockwise direction, the rotation of the driving gear 93 is not transmitted to the rotating member 57 by the ratchet cylinder 95. In other words, the separation nip N remains formed as in the case where the document conveying operation is not executed. Therefore, when the document fed by the pickup roller 31 reaches the separation nip N, only the uppermost document at the separation nip N is fed by the feed roller 33. Thereafter, the document is conveyed along the conveyance path 19 by the first pair of conveying rollers 37.
[0071] Next, the case where the document is jammed at the separation nip N will be described with reference to FIG. 16. In this case, the motor is driven to rotate the conveying gear 103 through the output gear by a predetermined angle in the counterclockwise direction (see the arrow D1). The predetermined angle is the angle until the protruding portion 103a of the conveying gear 103 leaves one protruding portion 105a of the connecting member 105 and is in contact with the other protruding portion 105a (see the arrow R in FIG. 14). As described above, in this case, the conveying gear 103 is rotated with respect to the conveying roller 101 and the conveying roller 101 does not rotate.
[0072] When the conveying gear 103 rotates in this manner, the driving gear 93, which is engaged with the conveying gear 103, rotates by a predetermined angle in the clockwise direction (see the arrow D2). Then, as described above, the clockwise rotation is transmitted to the rotating member 97 via the ratchet cylinder 95 (see the arrow D3). As the rotating member 97 rotates in this manner, the tension spring 55 is pulled by the long arm portion 83 (see the arrow F2). Furthermore, the short arm portion 85 pushes the arm portion 71 of the holder turning shaft 53 leftward via the link bar 89 (see the arrow D4). The holder turning shaft 53 then rotates in the clockwise direction (see the arrow D5). As a result, the pad holder 51 is turned downward and the separation pad 35 separates downward from the sheet feed roller 33. Since the separation nip N is released in this manner, the jammed document can be easily removed.
[0073] As is clear from the above description, since the driving member 59 of the separation pad support mechanism 45 can be driven by the motor that rotates the conveying roller 101 of the first pair of conveying rollers 37 (the pair of discharge rollers 41), there is no need to provide a separate drive source to form and release the separation nip N. When releasing the separation nip N, the conveying gear 103 rotates in the direction opposite to the direction of rotating the conveying roller 101, but this rotation is not transmitted to the conveying roller 101. Therefore, the document is not conveyed in the direction opposite to the conveyance direction X.
[0074] The driving gear 93 may be driven by a dedicated motor. In this case, during the sheet jam treatment, the driving gear 93 is rotated in the clockwise direction viewed from the rear side by a predetermined angle. Alternatively, the holder turning shaft 53 may be rotated by a dedicated motor without the driving gear 93. In this case, for example, the free end of the tension spring 55 is connected to the arm portion 71 of the holder turning shaft 53. When forming the separation nip N, the holder turning shaft 53 is pulled by the tension spring 55 and rotates in the counterclockwise direction when viewed from the rear side. This causes the pad holder 51 to turn upward, and the separation pad 35 is pressed against the sheet feed roller 33. During the sheet jam treatment, the holder turning shaft 53 is rotated in the clockwise direction by the motor. This causes the pad holder 51 to turn downward to release the separation nip N.
[0075] The above description of the embodiments of the present disclosure describes suitable embodiments in the document transport device and image forming device pertaining to the present disclosure, and therefore, various technically preferred limitations may be attached, but the technical scope of the present disclosure is not limited to these modes unless specifically stated to limit the present disclosure. However, the technical scope of the present disclosure is not limited to these forms unless specifically stated to limit the present disclosure.
