Sheet separation device

Abstract

To provide a sheet separation device capable of suppressing nonfeeding of a sheet, tip-bending, and double-feeding, regardless of a posture change of a separation pad.SOLUTION: A sheet separation device 1 comprises: a separation roller 42; a holder 60 contactable / separable to / from the separation roller 42; an energization member 69 for energizing the holder 60 toward the separation roller 42; a separation pad 49 pressed toward the separation roller 42, that is held by the holder 60; and a conveyance guide 100 comprising a conveyance face 101 onto which a sheet SH is guided toward a nip position N1 of the separation roller 42 and the separation pad 49. The conveyance guide 100 has a first rib 110 located upstream of the nip position N1 in a conveyance direction DT1 and passing through the holder 60 by protruding toward the separation roller 42 from an opposite side of the separation roller 42 with respect to the holder 60 so as to guide the sheet SH toward the nip position N1 by a tip edge 111.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a sheet separation device.

Background Art

[0002] Patent Document 1 discloses an example of a conventional sheet separation device. This sheet separation device includes a feed roller, a receiving base, a separation spring, and a separation pad.

[0003] The feed roller conveys the sheet in the conveyance direction. The receiving base is separable from and attachable to the feed roller. The separation spring exerts a biasing force that biases the receiving base toward the feed roller. The separation pad is held by the receiving base and pressed toward the feed roller. If there are a plurality of sheets conveyed by the feed roller, the separation pad separates the sheets one by one and suppresses double feeding of the sheets.

[0004] In this sheet separation device, when the sheet heading toward the nip position between the feed roller and the separation pad contacts the separation pad upstream of the nip position in the conveyance direction, there is a risk of non-feeding or tip breakage of the sheet due to the load received by the sheet.

[0005] Therefore, this sheet separation device is provided with a front guide portion located at the upstream end in the conveyance direction on the receiving base and a pair of protrusions located on both sides in the axial direction of the feed roller on the receiving base, so that the sheet is less likely to be caught at the upstream end in the conveyance direction of the separation pad, thereby suppressing non-feeding or tip breakage of the sheet.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, in the conventional sheet separation device described above, the posture of the separation pad changes as the separation pad wears and becomes thinner, and the separation pad approaches the separation roller together with the receiving base due to the biasing force of the separation spring. In this case, the actions of the leading portion and the pair of protrusions are likely to vary, so there is a risk that it becomes difficult to suppress non-feeding of the sheet and tip breakage.

[0008] Also, the posture of the separation pad changes as the separation spring elastically deforms according to the state of the sheet approaching the nip position, for example, the thickness, rigidity, etc. of the sheet, and the separation pad moves away from the separation roller together with the receiving base. Also in this case, the actions of the leading portion and the pair of protrusions are likely to vary, so there is a risk that it becomes difficult to suppress non-feeding of the sheet and tip breakage.

[0009] Furthermore, the posture of the separation pad changes as the bundled sheets inserted by the user ride onto the receiving base and the separation spring yields to the weight of the bundled sheets and elastically deforms, and the separation pad moves away from the separation roller together with the receiving base. In this case, since it becomes difficult for the frictional force of the separation pad to act on the sheet that adheres to the sheet conveyed to the separation roller, there is a risk that it becomes difficult to suppress double feeding of the sheet.

[0010] The present invention has been made in view of the above-described conventional situation, and an object thereof is to provide a sheet separation device that can suppress non-feeding, tip breakage, and double feeding of the sheet regardless of changes in the posture of the separation pad.

Means for Solving the Problems

[0011] The sheet separation device of the present invention includes a separation roller that rotates around a rotation axis and conveys a sheet in a conveyance direction orthogonal to the rotation axis, a holder that can be brought into contact with and separated from the separation roller, a biasing member that exerts a biasing force for biasing the holder toward the separation roller, a separation pad that is held by the holder, pressed toward the separation roller, and separates a plurality of sheets conveyed by the separation roller one by one if there are a plurality of sheets, A conveyance guide having a conveyance surface for guiding a sheet toward a nip position between the separation roller and the separation pad, is provided, wherein the conveyance guide has a first rib located upstream of the nip position in the conveyance direction, the first rib protruding from a side opposite to the separation roller with respect to the holder toward the separation roller, penetrating the holder, and guiding the sheet toward the nip position by a leading edge thereof.

[0012] In the sheet separation device of the present invention, since the first rib configured as described above is separate from the separation pad, its posture does not change regardless of the change in the posture of the separation pad.

[0013] Thus, even if the separation pad wears and becomes thinner, and the posture of the separation pad changes due to the separation pad approaching the separation roller together with the holder by the biasing force of the biasing member, the first rib can stably guide the sheet toward the nip position by its leading edge. In particular, even if the sheet toward the nip position is bent, the first rib can correct the intrusion angle of the sheet, so that the frictional force of the separation pad acting on the sheet upstream of the nip position in the conveyance direction is less likely to become excessive. As a result, this sheet separation device can suppress non-feeding of the sheet and tip breakage.

[0014] Also, even if the biasing member elastically deforms according to the state of the sheet approaching the nip position, for example, the thickness, rigidity, etc. of the sheet, and the posture of the separation pad changes due to the separation pad moving away from the separation roller together with the holder, the first rib can stably guide the sheet toward the nip position by its leading edge, and can correct the intrusion angle of the sheet even if the sheet toward the nip position is bent, so that non-feeding of the sheet and tip breakage can be suppressed.

[0015] Furthermore, since the bundled sheet inserted by the user only rides on the tip edge of the first rib penetrating the holder and does not ride on the holder, the biasing member does not yield to the weight of the bundled sheet. Therefore, since the frictional force of the separation pad acts favorably on the sheet that adheres to the sheet conveyed to the separation roller, double feeding of the sheet can be suppressed.

[0016] Therefore, the sheet separation device of the present invention can suppress non-feeding, tip breakage, and double feeding of the sheet regardless of the change in the posture of the separation pad.

Brief Description of the Drawings

[0017]

Figure 1

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Figure 20

BEST MODE FOR CARRYING OUT THE INVENTION

[0018] Hereinafter, Examples 1 and 2 embodying the present invention will be described with reference to the drawings.

[0019] (Example 1) As shown in FIG. 1, an image reading device 1 of the first embodiment is an example of a specific embodiment of the sheet separating device of the present invention.

[0020] In Fig. 1, the side of the operation panel 8P of the image reading device 1 is the front. The side to the left when facing the operation panel 8P is the left side. The front-rear, left-right, and up-down directions shown in Fig. 2 and subsequent figures are all shown corresponding to the directions shown in Fig. 1.

[0021] As shown in FIG. 1, the image reading device 1 includes a main body 8 and a document cover 9. The main body 8 and document cover 9 are made of a plastic material.

[0022] <Main body> The main body 8 is a flat, generally box-shaped body. An operation panel 8P, such as a touch panel, is located on the front of the main body 8. The main body 8 houses the image forming unit 2 in its lower portion. The image forming unit 2 forms an image on a sheet by an inkjet method, a laser method, or the like.

[0023] <Image reading section> 2, the main body 8 accommodates in its upper portion the image reading unit 3. The image reading unit 3 has a document support surface 3A, a reading surface 3B, a reading sensor 3S, and a scanning mechanism (not shown).

[0024] The document support surface 3A is the upper surface of a large-area platen glass located on the upper surface of the main body 8. The reading surface 3B is the upper surface of a platen glass located to the left of the document support surface 3A on the upper surface of the main body 8 and extending in an elongated shape in the front-to-rear direction.

[0025] The document support surface 3A supports a document to be read. The document to be read may be a sheet such as paper or an OHP sheet, or a book. The reading surface 3B is used when the conveying unit 4, which will be described later, is in operation, and the sheet SH shown in FIG. 2 passes over the reading surface 3B.

[0026] The reading sensor 3S is a well-known image reading sensor such as a CIS (Contact Image Sensor) or a CCD (Charge Coupled Device), and extends longitudinally in the front-rear direction. The reading sensor 3S is located below the document support surface 3A and the reading surface 3B.

[0027] When the image reading unit 3 reads the image of the document supported on the document support surface 3A, the reading sensor 3S moves from below the left edge of the document support surface 3A to the right, that is, in the sub-scanning direction, while moving in the front-rear direction, that is, the main scanning direction, and reads the image of the document in a line. When the reading sensor 3S moves to below the right edge of the document support surface 3A, it finishes reading the image and returns to the standby position by the operation of a scanning mechanism (not shown).

[0028] When the conveying unit 4 operates, the reading sensor 3S moves to and stops at a stationary reading position below the reading surface 3B by the operation of a scanning mechanism (not shown).

[0029] <Document cover> As shown in FIG. 1, the document cover 9 is located above the main body 8. The rear end of the document cover 9 is connected to the rear end of the main body 8 via a hinge (not shown). The document cover 9 is swingable around a swing axis X9 extending in the left-right direction.

[0030] As shown in FIG. 2, the document cover 9 has a base member 39. The lower surface of the base member 39 forms the bottom surface of the document cover 9 and has a size capable of covering the entire upper surface of the main body 8. The document cover 9 covers the document placed on the document support surface 3A by the lower surface of the base member 39.

[0031] Although not shown, when the user swings the document cover 9 upward and rearward around the swing axis X9, the document cover 9 opens the document support surface 3A. In this state, the user can place and remove the document on the document support surface 3A.

[0032] <Supply Tray and Discharge Tray> As shown in FIGS. 1 and 2, the document cover 9 has a supply tray 95 and a discharge tray 96. The supply tray 95 and the discharge tray 96 are located in the right portion of the document cover 9.

[0033] The upper surface of the right portion of the base member 39 forms the discharge tray 96. The supply tray 95 is located above the discharge tray 96. The supply tray 95 supports the sheet SH to be image-read in a stacked state. The discharge tray 96 supports the sheet SH that has been image-read in a stacked state.

[0034] In this embodiment, the document on which the image is read using the document support surface 3A and the sheet SH on which the image is read while being conveyed by the conveyance unit 4 may be substantially the same.

[0035] As shown in FIG. 2, the document cover 9 has a lower chute member 37, a conveyance guide 100, and an upper cover 20. The lower chute member 37 is located above a portion of the base member 39 that is to the left of the discharge tray. The conveyance guide 100 is located above the lower chute member 37. The upper cover 20 covers the conveyance guide 100 and a part of the left end side of the supply tray 95 from above.

[0036] <Conveyance Guide> As shown in FIGS. 3 and 4, the conveyance guide 100 integrally has a conveyance guide main body 100M and connecting portions 109A, 109B. In this embodiment, the conveyance guide 100 is a resin molded product manufactured by injection molding of a thermoplastic resin or the like.

[0037] The conveyance guide main body 100M extends in a substantially flat plate shape in the front-rear direction and the left-right direction. The connecting portion 109A is connected to the front end of the conveyance guide main body 100M. The connecting portion 109B is connected to the rear end of the conveyance guide main body 100M.

[0038] The connecting parts 109A and 109B are spaced apart from each other in the front-rear direction by a distance slightly larger than the width of the sheet SH supported by the supply tray 95. Although not shown, the connecting part 109A is connected from above to the front end of the left part of the base member 39. Also, the connecting part 109B is connected from above to the rear end of the left part of the base member 39.

[0039] The transport guide body 100M has a sheet placement surface 105 and a transport surface 101.

[0040] The sheet placement surface 105 is the upper surface of the right part of the transport guide body 100M, and extends so as to gently slope downward to the left. As shown in FIG. 2, the right end of the sheet placement surface 105 is at a position covered from above by the upper surface cover 20 and is adjacent to the left end of the supply tray 95.

[0041] When the user places the sheet SH on the supply tray 95, the user inserts the sheet SH between the upper surface cover 20 and the sheet placement surface 105. As a result, a portion of the sheet SH supported by the supply tray 95 that protrudes to the left of the left end of the supply tray 95 is placed on the sheet placement surface 105.

[0042] As shown in FIGS. 4 and 5, the transport surface 101 is the upper surface of the left part of the transport guide body 100M. The right end 101E of the transport surface 101 is connected to the left end of the sheet placement surface 105. The transport surface 101 extends so as to gently slope upward to the left from the right end 101E, and then curves so as to change the extending direction from leftward to downward.

[0043] As shown in FIG. 2, the transport surface 101 is located below the separation roller 42 described later. The transport surface 101 guides the sheet SH transported in the transport direction DT1 from the supply tray 95 toward the nip position N1 between the separation roller 42 and the separation pad 49 described later. The transport direction DT1 of the sheet SH guided by the transport surface 101 is a leftward direction.

[0044] <Holder accommodation part of the transport guide> As shown in FIGS. 6 and 7, the transport guide body 100M integrally has a holder housing portion 102. The holder housing portion 102 is a portion on the transport surface 101 that slopes upward to the left and is a recess that is substantially rectangular in top view and recesses downward from a portion located at the center in the front-rear direction on the transport surface 101. The A-A cross section in FIG. 6 passes through the center in the front-rear direction on the transport surface 101.

[0045] As shown in FIG. 7, a shaft hole 103A is formed at the right-front corner portion in the holder housing portion 102. A shaft hole 103B is formed at the right-rear corner portion in the holder housing portion 102. The shaft holes 103A and 103B are circular holes centered on a swing axis X60 extending in the front-rear direction, and the upper ends thereof are open by notches.

[0046] As shown in FIG. 6, a rectangular hole 103C is formed at the left-front corner portion on the bottom wall of the holder housing portion 102. As shown in FIGS. 6 and 7, a rectangular hole 103D is formed at the left-rear corner portion on the bottom wall of the holder housing portion 102. The rectangular holes 103C and 103D penetrate the bottom wall of the holder housing portion 102 in the vertical direction.

[0047] As shown in FIGS. 7 and 8, a spring pedestal 103S is formed at the left portion on the bottom wall of the holder housing portion 102. The spring pedestal 103S is a recess that is substantially circular in top view and recesses downward from the bottom wall of the holder housing portion 102.

[0048] <The first rib and a pair of second ribs of the transport guide> As shown in FIG. 7, the transport guide body 100M integrally has one first rib 110 and a pair of second ribs 120.

[0049] The first rib 110 is located to the left of the shaft holes 103A and 103B and to the right of the spring pedestal 103S on the bottom wall of the holder housing portion 102, and protrudes upward from a position below the transport surface 101.

[0050] As shown in FIG. 6, the first rib 110 is located at the center in the front-rear direction on the conveyance surface 101.

[0051] As shown in FIG. 8, the leading edge 111 of the first rib 110 is located above the conveyance surface 101 and extends in the conveyance direction DT1. The distance by which the leading edge 111 is separated from the conveyance surface 101 toward the separation roller 42 side, that is, upward, is defined as distance L1.

[0052] The end portion located most upstream in the conveyance direction DT1 at the leading edge 111 is defined as the first end 111U. The end portion located most downstream in the conveyance direction DT1 at the leading edge 111 is defined as the second end 111D. The respective corners of the first end 111U and the second end 111D are rounded with a small rounding radius.

[0053] The leading edge 111 is formed such that the distance L1 increases as it proceeds from the first end 111U to the second end 111D. The second end 111D of the leading edge 111 is the vertex that is most separated from the conveyance surface 101 of the first rib 110 toward the separation roller 42 side, that is, upward.

[0054] The angle at which the first end 111U side of the leading edge 111 is inclined with respect to the conveyance surface 101 is defined as the first angle α1. The angle at which the second end 111D side of the leading edge 111 is inclined with respect to the conveyance surface 101 is defined as the second angle α2. The first angle α1 is larger than the second angle α2. In this embodiment, as an example, the first angle α1 is about 30°, and the second angle α2 is about 0° to 1°.

[0055] The first rib 110 has a temporary holding portion 119. The temporary holding portion 119 is a recess that is recessed toward the upstream in the conveyance direction DT1 at a position below the separation roller 42 and away from the leading edge 111 of the first rib 110 and at a downstream position in the conveyance direction DT1 of the first rib 110. The first rib 110 has a substantially reverse "L" shape in side view due to the temporary holding portion 119.

[0056] As shown in FIGS. 6 and 7, each second rib 120 has the same other configurations such as shape except for the position. The front second rib 120 is located slightly forward from the front edge of the holder housing portion 102. The rear second rib 120 is located slightly rearward from the rear edge of the holder housing portion 102.

[0057] As shown in FIGS. 7 and 8, each second rib 120 protrudes upward, that is, toward the separation roller 42 side from the conveyance surface 101, and extends in the conveyance direction DT1. Each second rib 120 has a substantially triangular shape in side view having a vertex 120T, a first slope 121, and a second slope 122.

[0058] The vertex 120T is the tip that is farthest upward, that is, toward the separation roller 42 side from the conveyance surface 101 in each second rib 120.

[0059] The first slope 121 is connected to the vertex 120T and extends linearly upstream in the conveyance direction DT1. The first slope 121 extends so as to slope downward to the left. The second slope 122 is connected to the vertex 120T and extends linearly downstream in the conveyance direction DT1. The second slope 122 extends so as to slope downward to the right.

[0060] As shown in FIG. 8, the vertex that is farthest from the conveyance surface 101 toward the separation roller 42 side in the first rib 110, that is, the second end 111D of the leading edge 111, is located downstream of the vertex 120T of each second rib 120 in the conveyance direction DT1, and is also closer to the conveyance surface 101 than the vertex 120T of each second rib 120.

[0061] <First to Third Guides and Conveyance Unit> As shown in FIG. 2, the document cover 9 has a first guide 31, a second guide 32, a third guide 33, and a conveyance unit 4.

[0062] The first guide 31 is composed of a conveyance surface 101 of the conveyance guide 100 and a plurality of ribs protruding downward from the back surface of the upper cover 20. The second guide 32 and the third guide 33 are composed of a guide surface formed on the left portion of the base member 39 and the lower chute member 37 and the like.

[0063] As shown by the solid line in FIG. 2, the upper cover 20 is movable between a closed position that defines the first guide 31 from above and an open position that is separated upward from the conveyance surface 101 as shown by the two-dot chain line in FIG. 2.

[0064] The conveyance unit 4 has a feed roller 41, a separation roller 42, a drive shaft 42S, and a holder arm 50. As shown in FIG. 3, the conveyance unit 4 has a drive source M1, a drive force transmission mechanism (not shown), a gear 4G, a transmission shaft 42T, and a torque limiter 42L.

[0065] As shown in FIG. 2, the conveyance unit 4 has a holder 60, a compression coil spring 69, a separation pad 49, a conveyance roller 43, a conveyance pinch roller 43P, an original pressing member 44, a discharge roller 45, a discharge pinch roller 45P, an auxiliary discharge roller 47, and an elastic piece 48. The compression coil spring 69 is an example of the "biasing member" of the present invention.

[0066] <Feed roller, separation roller, drive shaft, and holder arm> The feed roller 41 faces the sheet placement surface 105 from above. The separation roller 42 is assembled to the drive shaft 42S centered on the rotation axis X42 and faces the conveyance surface 101 from above. The rotation axis X42 extends in the front-rear direction at a position separated to the left from the feed roller 41 and the sheet placement surface 105. The conveyance direction DT1 is orthogonal to the rotation axis X42.

[0067] As shown in FIG. 3, the holder arm 50 has the drive shaft 42S inserted therethrough. The front end 42S1 of the drive shaft 42S protrudes forward of the holder arm 50. The rear end 42S2 of the drive shaft 42S protrudes rearward of the holder arm 50.

[0068] The holder arm 50 extends to the right of the rotation axis X42, and rotatably supports the feed roller 41 at its right end side.

[0069] Although illustration is omitted, the front end 42S1 and the rear end 42S2 of the drive shaft 42 are supported by two bearings held by a plurality of ribs protruding downward from the back surface of the upper cover 20. Thereby, the drive shaft 42 is rotatable around the rotation axis X42. Further, the holder arm 50 is swingable around the rotation axis X42.

[0070] That is, the feed roller 41, the separation roller 42, the drive shaft 42S, and the holder arm 50 are supported on the back surface side of the upper cover 20. When the upper cover 20 moves to the open position shown by the two-dot chain line in FIG. 2, the feed roller 41, the separation roller 42, the drive shaft 42S, and the holder arm 50 also move together with the upper cover 20.

[0071] As shown in FIG. 3, the holder arm 50 supports a gear train 41G that transmits the driving force from the drive shaft 42S to the feed roller 41.

[0072] <Drive source, driving force transmission mechanism, gear, transmission shaft, and torque limiter> The drive source M1 is a motor disposed on the rear surface side of the document cover 9. The drive source M1 is controlled by a control unit (not shown) to generate a driving force by rotating forward and backward.

[0073] A driving force transmission mechanism (not shown) transmits the driving force of the drive source M1 to the gear 4G and the conveying roller 43, the discharge roller 45, and the auxiliary discharge roller 47 shown in FIG. 2.

[0074] As shown in FIG. 3, the gear 4G is disposed on the rear surface side of the document cover 9 and is located below and to the right of the rotation axis X42.

[0075] The transmission shaft 42T is supported by an upper cover 20 (not shown in FIG. 3) and is rotatable about the rotation axis X42 with the upper cover 20 in the closed position. The transmission shaft 42T has a transmission gear 42G at its rear end.

[0076] The transmission gear 42G meshes with the gear 4G with the upper cover 20 in the closed position. Although not shown, when the upper cover 20 moves to the open position, the transmission shaft 42T also moves with the upper cover 20, and the transmission gear 42G separates from the gear 4G.

[0077] The front end of the transmission shaft 42T is connected to the rear end 42S2 of the drive shaft 42S in a state where the driving force of the drive source M1 can be transmitted to the drive shaft 60.

[0078] The torque limiter 42L is interposed between the front end side of the transmission shaft 42T and the holder arm 50. When a torque below the set value acts, the torque limiter 42L transmits the torque from the front end side of the transmission shaft 42T to the holder arm 50. However, when a torque exceeding the set value acts, slip occurs inside, and the torque is no longer transmitted from the front end side of the transmission shaft 42T to the holder arm 50.

[0079] With the upper cover 20 in the closed position, the transmission shaft 42T rotates about the rotation axis X42 when the driving force of the drive source M1 is input from the gear 4G to the transmission gear 42G.

[0080] When the drive source M1 rotates forward, the torque limiter 42L causes the holder arm 50 to rotate with the rotation of the transmission shaft 42T. As a result, the holder arm 50 swings so as to lower the feed roller 41. Then, when the feed roller 41 contacts the sheet placement surface 105 or the uppermost sheet SH placed on the sheet placement surface 105, the torque limiter 42L slips inside and holds the holder arm 50 in that position.

[0081] Also, in this case, the drive shaft 42S to which the driving force is transmitted from the transmission shaft 42T transmits the driving force to the separation roller 42 to rotate the separation roller 42 around the rotation axis X42, and also transmits the driving force to the feed roller 41 via the gear train 41G to rotate the feed roller 41. The feed roller 41 feeds the sheet SH from the sheet placement surface 105. The separation roller 42 conveys the sheet SH fed by the feed roller 41 in the conveyance direction DT1.

[0082] The position of the feed roller 41(41D) shown in FIG. 2 is the lower limit position where the feed roller 41 abuts on the sheet placement surface 105.

[0083] When the drive source M1 rotates reversely, the torque limiter 42L causes the holder arm 50 to rotate in the reverse direction of the rotation of the transmission shaft 42T. As a result, the holder arm 50 swings so as to raise the feed roller 41. The position of the feed roller 41(41U) shown in FIGS. 2 and 11 is the upper limit position. When the feed roller 41 reaches the upper limit position, the torque limiter 42L slips internally and holds the holder arm 50 at that position.

[0084] At this time, since the rotation of the separation roller 42 and the feed roller 41 is meaningless, a control unit (not shown) stops the drive source M1 immediately when the feed roller 41 reaches the upper limit position. The torque limiter 42L holds the holder arm 50 at that position even after the drive source M1 stops.

[0085] <Holder, Compression Coil Spring, and Separation Pad> As shown in FIGS. 9 and 10, the holder 60 integrally has a first plate-like portion 61, a second plate-like portion 62, swing shafts 63A, 63B, through holes 60H, stoppers 63C, 63D, and spring receiving portions 68. In this embodiment, the holder 60 is a resin molded product manufactured by injection molding of a thermoplastic resin or the like.

[0086] The first plate-like portion 61 has a substantially flat plate shape. The separation pad 49 is held by the holder 60 by being attached to the upper surface of the first plate-like portion 61. The separation pad 49 is a plate-like member made of a material having a friction coefficient smaller than the friction coefficient of the material forming the surface of the separation roller 42, for example, natural rubber, synthetic rubber, cork material, urethane material, or the like.

[0087] At the downstream end of the first plate-like portion 61 in the conveyance direction DT1, a rib 61R is formed so as to project upward and extend in the front-rear direction. The rib 61R restricts the separation pad 49 so that the separation pad 49 does not shift downstream in the conveyance direction DT1.

[0088] The upper surface of the portion of the first plate-like portion 61 located upstream of the separation pad 49 in the conveyance direction DT1 is an inclined surface 61S. The inclined surface 61S extends so as to slope upward toward the downstream in the conveyance direction DT1.

[0089] The downstream end of the inclined surface 61S in the conveyance direction DT1 is located above the upper surface 49A of the separation pad 49. The upper surface 49A of the separation pad 49 is the surface of the separation pad 49 on the side of the separation roller 42.

[0090] The second plate-like portion 62 has a substantially flat plate shape with a length in the front-rear direction smaller than the length in the front-rear direction of the first plate-like portion 61. The swing shaft 63A projects forward from a portion of the front surface of the second plate-like portion 62 located upstream in the conveyance direction DT1. The swing shaft 63B projects rearward from a portion of the rear surface of the second plate-like portion 62 located upstream in the conveyance direction DT1. The swing shafts 63A and 63B are shafts having a substantially oval cross-section centered on the swing axis X60.

[0091] As shown in FIGS. 6 and 9, the through-hole 60H penetrates vertically through a part of the first plate-like portion 61 located upstream in the conveyance direction DT1 and a part of the second plate-like portion 62 located downstream in the conveyance direction DT1.

[0092] The through hole 60H is a hole that is substantially rectangular in top view, located at the center in the front-rear direction of the first plate-like portion 61 and the second plate-like portion 62, and extending long in the conveyance direction DT1. The upstream end of the through hole 60H in the conveyance direction DT1 is located downstream of the swing shafts 63A and 63B in the conveyance direction DT1. The downstream end of the through hole 60H in the conveyance direction DT1 is located downstream of the inclined surface 61S in the conveyance direction DT1.

[0093] The separation pad 49 has a relief portion 49C that aligns with the through hole 60H. The relief portion 49C is recessed from the upstream end 49U of the separation pad 49 in the conveyance direction DT1 toward the downstream in the conveyance direction DT1. As shown in FIG. 6, the downstream end of the relief portion 49C in the conveyance direction DT1 substantially coincides with the downstream end of the through hole 60H in top view.

[0094] The stopper 63C is a protrusion that protrudes downward and slenderly from the front end of the first plate-like portion 61, and a key claw is formed at its lower end. The key claw of the stopper 63C protrudes forward and short. The stopper 63D is a protrusion that protrudes downward and slenderly from the rear end of the first plate-like portion 61, and a key claw is formed at its lower end. The key claw of the stopper 63D protrudes backward and short.

[0095] As shown in FIG. 8, the spring receiving portion 68 is provided on the lower surface of the first plate-like portion 61. The spring receiving portion 68 has a fitting convex portion 67. As shown in FIG. 10, the fitting convex portion 67 is a protrusion having a substantially "+" shaped cross section that protrudes downward from the lower surface of the first plate-like portion 61.

[0096] As shown in FIG. 6, the swing shaft 63A is inserted into the shaft hole 103A. The swing shaft 63B is inserted into the shaft hole 103B. Thereby, the conveyance guide main body 100M supports the holder 60 so as to be swingable around the swing axis X60. The holder 60 can be brought into contact with and separated from the separation roller 42 by swinging around the swing axis X60. The swing axis X60 extends parallel to the rotation axis X42 upstream of the separation pad 49 in the conveyance direction DT1.

[0097] In this state, the stopper 63C passes through the rectangular hole 103C and the key claw of the stopper 63C can engage with the front edge of the rectangular hole 103C. The stopper 63D passes through the rectangular hole 103D and the key claw of the stopper 63D can engage with the rear edge of the rectangular hole 103D. Thereby, the stoppers 63C and 63D define the upper limit position when the holder 60 swings upward.

[0098] As shown in FIG. 8, the lower end of the compression coil spring 69 abuts against the bottom surface of the spring pedestal 103S from above and is surrounded by the inner peripheral surface of the spring pedestal 103S. A fitting convex portion 67 is fitted into the upper end 69E of the compression coil spring 69. The upper end 69E of the compression coil spring 69 is an example of "one end of the biasing member" of the present invention.

[0099] The compression coil spring 69 exerts a biasing force F1 that biases the holder 60 toward the separation roller 42. The spring receiving portion 68 engages with the upper end 69E of the compression coil spring 69 at a position overlapping the separation pad 49 in the conveyance direction DT1 and receives the biasing force F1.

[0100] The separation pad 49 is pressed toward the separation roller 42 by the biasing force F1. The nip position N1 between the separation roller 42 and the separation pad 49 is a position where the lower end of the separation roller 42 abuts against the upper surface 49A of the separation pad 49.

[0101] The through hole 60H is located between the nip position N1 in the conveyance direction DT1 and the swing axis X60.

[0102] The first rib 110 protrudes from the side of the holder 60 opposite to the separation roller 42 toward the separation roller 42 and passes through the holder 60 through the through hole 60H. The first rib 110 is located upstream of the nip position N1 in the conveyance direction DT1. As shown in FIG. 6, the first rib 110 is at the same position as the center of the separation pad 49 in the direction of the rotation axis X42, that is, in the front-rear direction.

[0103] As shown in FIG. 8, in the first rib 110, the first end 111U of the leading edge 111 is located upstream in the conveyance direction DT1 from the upstream end 49U in the conveyance direction DT1 of the separation pad 49. The second end 111D of the leading edge 111 is located downstream in the conveyance direction DT1 from the upstream end 49U of the separation pad 49.

[0104] The relief portion 49C of the separation pad 49 runs downstream in the conveyance direction DT1 from the second end 111D of the leading edge 111.

[0105] The apex 120T of each second rib 120 is located upstream in the conveyance direction DT1 from the separation roller 42. The apex 120T of each second rib 120 is separated from the conveyance surface 101 toward the separation roller 42 side more than the upper surface 49A of the separation pad 49. When viewed along the front-rear direction, the second slope 122 intersects the upper surface 49A of the separation pad 49 upstream in the conveyance direction DT1 from the nip position N1.

[0106] As shown in FIG. 6, each second rib 120 is located on one side and the other side in the direction of the rotation axis X42 with respect to the holder 60, that is, in front of and behind the holder 60.

[0107] The width W42 in the direction of the rotation axis X42 of the separation roller 42 is larger than the width W49 in the direction of the rotation axis X42 of the separation pad 49, and is smaller than the distance L2 by which each second rib 120 is separated in the direction of the rotation axis X42.

[0108] <Conveyance roller, conveyance pinch roller, document presser, discharge roller, discharge pinch roller, auxiliary discharge roller, and elastic piece> As shown in FIG. 2, the conveyance roller 43 is located on the left side wall side of the document cover 9 and close to the upper surface of the main body 8. The conveyance pinch roller 43P is located to the left and below the conveyance roller 43 and is pressed toward the conveyance roller 43. The document presser 44 is located directly above the reading surface 3B.

[0109] The discharge roller 45 is located at a position above and to the left of the left end of the discharge tray 96. The discharge pinch roller 45P is located below the discharge roller 45 and is pressed toward the discharge roller 45.

[0110] The auxiliary discharge roller 47 is located at a position above and to the left of the left end of the discharge tray 96 and is shifted to the left from the left end of the discharge tray 96. The upper end of the auxiliary discharge roller 47 is located above the nip position of the discharge roller 45 and the discharge pinch roller 45P.

[0111] The elastic piece 48 is made of a highly rigid film. The elastic piece 48 is cantilevered between the discharge roller 45 and the auxiliary discharge roller 47 and protrudes to the right, bends at a position to the right of the auxiliary discharge roller 47, and slopes downward to the right. The elastic piece 48 is arranged so as to be displaced in the front-rear direction with respect to the auxiliary discharge roller 47.

[0112] The first guide 31 guides the sheet SH fed from the supply tray 95 and the sheet placement surface 105 by the feed roller 41 to the left through the nip position N1 of the separation roller 42 and the separation pad 49, further U-turns downward, and guides it to the conveyance roller 43 and the conveyance pinch roller 43P.

[0113] The second guide 32 guides the sheet SH so as to slope downward from the conveyance roller 43 and the conveyance pinch roller 43P to the reading surface 3B, and then guides it to pass between the document presser 44 and the reading surface 3B, that is, above the reading sensor 3S at the stationary reading position.

[0114] The third guide 33 guides the sheet SH to slope upward to the right at a position to the right of the reading surface 3B, and guides the sheet SH to the auxiliary discharge roller 47 and the elastic piece 48.

[0115] <Shutter and Lock Arm> As shown in FIG. 3, the conveyance unit 4 has two sets of shutters 59 and lock arms 58.

[0116] The front shutter 59 is located in front of the feed roller 41 and the holder arm 50. The rear shutter 59 is located behind the feed roller 41 and the holder arm 50.

[0117] As shown in FIGS. 11 and 12, each shutter 59 is supported by a part of a plurality of ribs formed on the back side of the upper cover 20 and is swingable around a swing axis X59. The swing axis X59 is located almost directly above the left end of the sheet placement surface 105. Although not shown, the swing axis X59 is located above the uppermost sheet SH when the maximum number of sheets SH is placed on the sheet placement surface 105.

[0118] Each shutter 59 has a shutter body 59A and a lock receiving portion 59B. The shutter body 59A projects downward from the swing axis X59. The lock receiving portion 59B projects upward shorter than the swing axis X59.

[0119] As shown in FIG. 3, two shutter recesses 106 are recessed downward in portions located on the left end side of the sheet placement surface 105 and the right end 101E side of the conveyance surface 101 in the conveyance guide 100.

[0120] As shown by the solid line in FIG. 12, the shutter body 59A of each shutter 59 enters its lower end into each shutter recess 106 in a state of protruding vertically downward.

[0121] As shown by the two-dot chain line in FIG. 12, the shutter body 59A of each shutter 59 swings so that its lower end moves rearward, thereby separating its lower end upward from each shutter recess 106.

[0122] As shown in FIG. 3, the front lock arm 58 is swingably supported at the front and right corner of the holder arm 50. The rear lock arm 58 is swingably supported at the rear and right corner of the holder arm 50.

[0123] As shown in FIG. 11, on the back side of the upper cover 20, two unlocking ribs 29 are formed which extend in the front-rear direction and are connected to the ribs supporting the shutters 59 respectively.

[0124] With the holder arm 50 raising the feed roller 41 to the upper limit position, each locking arm 58 projects leftward above the unlocking rib 29, and its tip abuts against the locking receiving portion 59B to lock the swinging of each shutter 59.

[0125] In this state, when a user inserts the sheet SH between the upper cover 20 and the sheet placement surface 105, the shutter body 59A of each shutter 59 abuts against the tip of the sheet SH. At this time, the feed roller 41 at the upper limit position is located above the inserted sheet SH.

[0126] As shown in FIG. 12, when the holder arm 50 swings to lower the feed roller 41 from the upper limit position, each locking arm 58 abuts against the unlocking rib 29 and swings in the clockwise direction in FIG. 12, separating its tip from the locking receiving portion 59B to allow the swinging of each shutter 59.

[0127] In this state, when the feed roller 41 feeds the sheet SH from the sheet placement surface 105, as shown by the two-dot chain line in FIG. 12, each shutter 59 is pushed by the sheet SH and swings to allow the passage of the sheet SH.

[0128] <Follow pressing portion> As shown in FIG. 3, on the upper surface of the portion of the holder arm 50 located to the right of the feed roller 41, a portion to be pressed 57 is recessed downward. The portion to be pressed 57 is located at the center in the front-rear direction of the holder arm 50.

[0129] As shown in FIG. 2, on the back side of the upper cover 20, a follow pressing portion 27 is provided. The follow pressing portion 27 has a pressing portion main body 27A and a compression coil spring 27S.

[0130] The pressing part main body 27A is held by a guide part (not shown) formed on the back side of the upper surface cover 20 so as to be linearly movable in the vertical direction with a short stroke.

[0131] The upper end of the compression coil spring 27S abuts against the back surface of the upper surface cover 20. The lower end of the compression coil spring 27S abuts against the upper surface of the pressing part main body 27A. The compression coil spring 27S biases the pressing part main body 27A downward.

[0132] As shown in FIG. 11, the pressing part main body 27A is at a position corresponding to the pressed part 57 of the holder arm 50. When the holder arm 50 raises the feed roller 41 to the upper limit position, the pressing part main body 27A abuts against the pressed part 57 and is pushed up, and the compression coil spring 27S is compressed and deformed to store a restoring force.

[0133] <Image reading operation of the document supported by the supply tray> When the image reading unit 3 reads an image of the sheet SH placed on the supply tray 95 and the sheet placement surface 105, a control unit (not shown) rotates the drive source M1 forward to operate the conveyance unit 4.

[0134] The conveyance unit 4 rotationally drives the feed roller 41 and the separation roller 42 in the clockwise direction in FIG. 2, rotationally drives the conveyance roller 43 and the discharge roller 45 in the counterclockwise direction in FIG. 2, and rotationally drives the auxiliary discharge roller 47 in the clockwise direction in FIG. 2.

[0135] Thereby, as shown in FIG. 12, the holder arm 50 swings so as to lower the feed roller 41, the feed roller 41 is pressed against the uppermost sheet SH placed on the sheet placement surface 105, and the swing of each shutter 59 is permitted.

[0136] When the number of sheets SH placed on the supply tray 95 and the sheet placement surface 105 is the maximum number or a number close thereto, the follow-up pressing portion 27 transmits the restoring force stored in the compression coil spring 27S to the holder arm 50, and biases the feed roller 41 downward by a short distance from the upper limit position. As a result, it is possible to suppress the problem that the contact pressure at which the feed roller 41 contacts the uppermost sheet SH is insufficient and a feeding failure occurs.

[0137] As shown in FIG. 2, the feed roller 41 feeds the sheet SH from the supply tray 95 and the sheet placement surface 105 to the first guide 31. The conveyance surface 101 guides the sheet SH toward the nip position N1.

[0138] Each second rib 120 scoops up the leading end of the sheet SH by the first slope 121, and when the leading end of the sheet SH passes through the apex 120T, guides the sheet SH toward the nip position N1 by the second slope 122.

[0139] The first rib 110 scoops up the center in the front-rear direction at the leading end of the sheet SH by the leading edge 111, and guides the sheet SH toward the nip position N1.

[0140] When the sheet SH fed by the feed roller 41 reaches the nip position N1, the separation roller 42 conveys the sheet SH in the conveyance direction DT1 toward the conveyance roller 43 and the conveyance pinch roller 43P. The separation pad 49 separates the sheets SH conveyed by the separation roller 42 one by one if there are a plurality of sheets.

[0141] Next, the conveyance roller 43 and the conveyance pinch roller 43P take over the sheet SH conveyed by the separation roller 42, convey the sheet SH guided by the first guide 31 and the second guide 32 to the right, pass it through the reading surface 3B, and send it to the third guide 33. Thereby, the reading sensor 3S reads the image on the surface of the sheet SH passing over the reading surface 3B.

[0142] Thereafter, the discharge roller 45 and the discharge pinch roller 45P take over the sheet SH conveyed by the conveyance roller 43 and the conveyance pinch roller 43P and guided by the third guide 33, and discharge it to the discharge tray 96.

[0143] At this time, the auxiliary discharge roller 47 and the elastic piece 48 assist the discharge roller 45 and the discharge pinch roller 45P, and discharge the sheet SH to the discharge tray 96 from a position higher than the nip position of the discharge roller 45 and the discharge pinch roller 45P.

[0144] When the image reading operation of the sheet SH is completed, a control unit (not shown) rotates the drive source M1 in the reverse direction for a short time. As a result, as shown in FIG. 11, the holder arm 50 swings so as to raise the feed roller 41 to the upper limit position. Also, the swinging of each shutter 59 is locked.

[0145] In the case where the image reading operation of the sheet SH is completed with the sheet SH remaining on the supply tray 95 and the sheet placement surface 105, when the leading end of the remaining sheet SH has moved from the sheet placement portion 105 to the conveyance surface 101 side, each shutter 59 is pushed by the remaining sheet SH and remains in a swung state. In this state, when the user inserts an additional sheet SH between the upper surface cover 20 and the sheet placement surface 105, each shutter 59 cannot regulate the leading end of the sheet SH. For this reason, if the user inserts the additional sheet SH deeply, the leading end of the sheet SH may reach near the nip position N1.

[0146] <Assembly Procedure of Compression Coil Spring, Holder and Separation Pad to Conveyance Guide> As shown in FIG. 13, the operator of the assembly work brings the lower end of the compression coil spring 69 into contact with the bottom surface of the spring pedestal 103S from above.

[0147] Next, the operator pushes down the upper end 69E of the compression coil spring 69. As a result, the compression coil spring 69 is elastically deformed so as to store a restoring force.

[0148] Next, the operator hooks a portion of the upper end 69E of the compression coil spring 69 that is located upstream in the conveying direction DT1 onto the temporary holding portion 119. As a result, the temporary holding portion 119 holds the upper end 69E in a state where the spring receiving portion 68 of the holder 60 is separated from the upper end 69E of the compression coil spring 69.

[0149] Next, with respect to the holder 60, as shown by the two-dot chain line in FIG. 13, the operator raises the holder 60 to a standing posture such that the separation pad 49 is positioned substantially directly above the swing shafts 63A and 63B, and then lowers it. Then, after the operator inserts the swing shafts 63A and 63B into the shaft holes 103A and 103B, as shown by the solid line in FIG. 13, the operator swings the holder 60 to move the separation pad 49 downward and rearward. At this time, the fitting convex portion 67 of the spring receiving portion 68 approaches the upper end 69E of the compression coil spring 69.

[0150] The operator further swings the holder 60 to engage the spring receiving portion 68 with the upper end 69E of the compression coil spring 69. At this time, as shown by the two-dot chain line in FIG. 13, the fitting convex portion 67 moves the upper end 69E downstream in the conveying direction DT1 while fitting into the upper end 69E of the compression coil spring 69. As a result, the upper end 69E comes off the temporary holding portion 119.

[0151] Finally, the operator positions the key claws of the stoppers 63C and 63D so that they can engage with the edges of the rectangular holes 103C and 103D from below. As a result, the operation of assembling the compression coil spring 69, the holder 60, and the separation pad 49 to the conveying guide 100 is completed.

[0152] <Operational Effect> In the image reading apparatus 1 of the first embodiment, as shown in FIG. 8, since the first rib 110 is separate from the separation pad 49 and is integrally formed on the conveying guide 100, its posture does not change regardless of the change in the posture of the separation pad 49.

[0153] As a result, the separation pad 49 wears and becomes thinner. Even if the posture of the separation pad 49 changes due to the separation pad 49 approaching the separation roller 42 together with the holder 60 by the biasing force F1 of the compression coil spring 69, the first rib 110 can stably guide the sheet SH toward the nip position N1 by the tip edge 111. In particular, even if the sheet SH deflects toward the nip position N1, the first rib 110 can correct the insertion angle of the sheet SH, so that the frictional force of the separation pad 49 acting on the sheet SH upstream of the nip position N1 in the conveyance direction DT1 is less likely to become excessive. As a result, the image reading apparatus 1 can suppress non-feeding and tip folding of the sheet SH.

[0154] Further, even if the compression coil spring 69 elastically deforms according to the state of the sheet SH approaching the nip position N1, for example, the thickness, rigidity, etc. of the sheet SH, and the posture of the separation pad 49 changes due to the separation pad 49 moving away from the separation roller 42 together with the holder 60, the first rib 110 can stably guide the sheet SH toward the nip position N1 by the tip edge 111, and can correct the insertion angle of the sheet SH even if the sheet SH deflects toward the nip position N1, so that non-feeding and tip folding of the sheet SH can be suppressed.

[0155] Furthermore, when the user inserts the bundled sheet SH toward the nip position N1 in a state where the sheet SH remains on the supply tray 95 and the sheet placement surface 105 and the swinging of each shutter 59 is not locked, the bundled sheet SH only rides on the tip edge 111 of the first rib 110 passing through the holder 60 and does not ride on the holder 60. As a result, the compression coil spring 69 does not yield to the weight of the bundled sheet SH. Therefore, since the frictional force of the separation pad 49 acts favorably on the sheet SH that is in close contact with the sheet SH conveyed to the separation roller 42, double feeding of the sheet SH can be suppressed.

[0156] Therefore, the image reading apparatus 1 of the first embodiment can suppress non-feeding, tip folding, and double feeding of the sheet SH regardless of the change in the posture of the separation pad 49.

[0157] Also, in this image reading apparatus 1, as shown in FIG. 6, the conveyance guide 100 has one first rib 110, and the first rib 110 is located at the same position as the center of the separation pad 49 in the direction of the rotation axis X42. When the sheet SH deflects toward the nip position N1, the amount of deformation of the sheet SH tends to be large at the center of the separation pad 49 in the direction of the rotation axis X42. In this regard, the first rib 110 having the above-described configuration can reliably correct the intrusion angle of the sheet SH even when the sheet SH deflects toward the nip position N1, so that non-feed and tip breakage of the sheet SH can be further suppressed.

[0158] Furthermore, in this image reading apparatus 1, as shown in FIG. 8, the holder 60 has a through hole 60H located between the nip position N1 and the swing axis X60 in the conveyance direction DT1, and the first rib 110 passes through the holder 60 via the through hole 60H. With this configuration, the first rib 110 can reliably correct the intrusion angle of the sheet SH even when the sheet SH deflects toward the nip position N1, so that non-feed and tip breakage of the sheet SH can be further suppressed. Also, with this configuration, it is possible to suppress the holder 60 and the first rib 110 from bulging in the conveyance direction DT1, and it is not necessary to bifurcate the upstream end of the holder 60 in the conveyance direction DT1, so that a decrease in the rigidity of the holder 60 can be suppressed.

[0159] Also, in this image reading apparatus 1, the leading edge 111 is formed such that the distance L1 from the conveyance surface 101 to the separation roller 42 side increases as it advances from the first end 111U to the second end 111D. With this configuration, the first rib 110 gradually changes the posture of the sheet SH from the first end 111U to the second end 111D at the leading edge 111. As a result, the first rib 110 can reliably correct the intrusion angle of the sheet SH even when the sheet SH deflects toward the nip position N1, so that non-feed and tip breakage of the sheet SH can be further suppressed.

[0160] Furthermore, in this image reading apparatus 1, a first angle α1 at which the first end 111U side of the leading edge 111 is inclined with respect to the conveyance surface 101 is larger than a second angle α2 at which the second end 111D side of the leading edge 111 is inclined with respect to the conveyance surface 101. With this configuration, at the first end 111U side of the leading edge 111, the large first angle α1 can preferably lift the sheet SH, and at the second end 111D side of the leading edge 111, the small second angle α2 can correct the entry angle of the sheet SH so as not to become excessive.

[0161] Also, in this image reading apparatus 1, as shown in FIG. 6, the first end 111U of the leading edge 111 is located upstream in the conveyance direction DT1 from the upstream end 49U of the separation pad 49. The second end 111D of the leading edge 111 is located downstream in the conveyance direction DT1 from the upstream end 49U of the separation pad 49. And the separation pad 49 has a relief portion 49C that escapes from the second end 111D. With this configuration, since the leading edge 111 of the first rib 110 straddles the upstream end 49U in the conveyance direction DT1 of the separation pad 49, there is no risk that the sheet SH will be caught by the upstream end 49U of the separation pad 49.

[0162] Furthermore, in this image reading apparatus 1, as shown in FIG. 8, the apex 120T that is farthest from the separation roller 42 side from the conveyance surface 101 in the pair of front and rear second ribs 120 is located upstream in the conveyance direction DT1 from the separation roller 42. With this configuration, since the leading end of the sheet SH can be lifted by each second rib 120 at a position away from the separation pad 49 in the direction of the rotation axis X42 and the leading end of the sheet SH can be directed toward the separation roller 42, double feeding of the sheet SH can be suppressed with high certainty.

[0163] Also, in this image reading apparatus 1, as shown in FIG. 6, the width W42 of the separation roller 42 is larger than the width W49 of the separation pad 49 and smaller than the distance L2 at which the pair of front and rear second ribs 120 are separated. With this configuration, it is possible to suppress the occurrence of wrinkles in the sheet SH.

[0164] Furthermore, in this image reading apparatus 1, as shown in FIG. 8, the apex 120T of each second rib 120 is farther from the conveyance surface 101 toward the separation roller 42 side than the separation pad 49. Each second rib 120 has a first slope 121 and a second slope 122. And, when viewed along the direction of the rotation axis X42, the second slope 122 intersects the upper surface 49A of the separation pad 49 upstream of the nip position N1 in the conveyance direction DT1. With this configuration, it is possible to suppress the second slope 122 of each second rib 120 from becoming a resistance to the sheet SH heading toward the nip position N1.

[0165] Also, in this image reading apparatus 1, the apex of the first rib 110 that is farthest from the conveyance surface 101 toward the separation roller 42 side, that is, the second end 111D of the leading edge 111, is located downstream of the apex 120T of each second rib 120 in the conveyance direction DT1. With this configuration, the first rib 110 can reliably correct the intrusion angle of the sheet SH that tends to decline toward the nip position N1 after being scooped up by each second rib 120, so that non-feed and tip folding of the sheet SH can be further suppressed.

[0166] Furthermore, in this image reading apparatus 1, the apex of the first rib 110, that is, the second end 111D of the leading edge 111, is closer to the conveyance surface 101 than the apex 120T of each second rib 120. With this configuration, it is possible to suppress wrinkles from forming in the sheet SH.

[0167] Also, in this image reading apparatus 1, as shown in FIG. 13, the first rib 110 has a temporary holding portion 119. In a state where the spring receiving portion 68 is separated from the upper end 69E of the compression coil spring 69, the temporary holding portion 119 catches and holds the upper end 69E of the compression coil spring 69 that has been elastically deformed to store a restoring force. Then, by swinging the holder 60 to engage the spring receiving portion 68 with the upper end 69E of the compression coil spring 69, the upper end 69E is disengaged from the temporary holding portion 119. With such a temporary holding portion 119, the compression coil spring 69 storing the restoring force can be temporarily held in a state where it is easy to assemble, and the temporary holding can be released only by swinging the holder 60, so that the assembly work of the compression coil spring 69 and the holder 60 can be simplified.

[0168] Further, in this image reading apparatus 1, the temporary holding portion 119 is a recess that is recessed toward the upstream in the conveyance direction DT1 at a position separated from the separation roller 42 and downstream in the conveyance direction DT1 of the leading edge 111 in the first rib 110. With this configuration, the temporary holding portion 119 can be integrally formed with the first rib 110.

[0169] Also, in this image reading apparatus 1, when the holder 60 is swung to engage the spring receiving portion 68 with the upper end 69E of the compression coil spring 69, the fitting convex portion 67 moves the upper end 69E downstream in the conveyance direction DT1 while fitting into the upper end 69E of the compression coil spring 69, so that the upper end 69E is disengaged from the temporary holding portion 119. With this configuration, a configuration for releasing the temporary holding can be easily realized only by swinging the holder 60.

[0170] (Modification) As shown in FIG. 14, instead of the first rib 110 according to the first embodiment, a first rib 210 that is separate from the conveyance guide 100 may be adopted, and the first rib 210 may be detachably supported by the conveyance guide 100.

[0171] In this modification, a fitting recess 102Q that is recessed downward in a substantially “+” shape in a top view is formed in the bottom wall of the holder housing portion 102, and a fitting convex portion 210Q having a substantially “+” cross-sectional shape is formed at the lower end of the first rib 210. The first rib 210 is attached to and detached from the conveyance guide 100 by the fitting and separation of the fitting recess 102Q and the fitting convex portion 210Q.

[0172] Other configurations of the modification are the same as those of the first embodiment. Therefore, the same reference numerals are given to the same configurations and the description thereof is omitted.

[0173] Similar to the image reading apparatus 1 of the first embodiment, the image reading apparatus of the modification can also suppress non-feed, tip breakage, and double feed of the sheet SH regardless of the change in the posture of the separation pad 49.

[0174] In addition, in this modification example, since the first rib 210 can be replaced when it is worn due to contact with the sheet SH, improvement in durability can be achieved.

[0175] <Example 2> As shown in FIGS. 15 to 19, in the image reading apparatus of Example 2, regarding the through-hole 60H of the holder 60 according to the image reading apparatus 1 of Example 1, the opening length is changed so as to increase toward the upstream in the conveyance direction DT1.

[0176] As a result, as shown in FIGS. 16 and 18, the upstream edge 60H1 located upstream in the conveyance direction DT1 in the through-hole 60H extends in the direction of the rotation axis X42 at a position closer to the swing axis X60 than in Example 1.

[0177] Further, as shown in FIGS. 17 and 19, in this image reading apparatus, regarding the holder 60 according to Example 1, it is changed to have a pair of third ribs 330 and a pair of holder recesses 339.

[0178] Furthermore, as shown in FIGS. 15 to 18, in this image reading apparatus, a first rib 310 is adopted instead of the first rib 110 according to Example 1.

[0179] Other configurations of Example 2 are the same as those of Example 1. For this reason, the same components as those of Example 1 are denoted by the same reference numerals, and the description thereof is omitted or simplified.

[0180] As shown in FIGS. 17 and 19, each third rib 330 and each holder recess 339 are formed in the second plate-like portion 62 of the holder 60.

[0181] One of the third ribs 330 is located on one side, that is, the front side in the direction of the rotation axis X42 with respect to the through-hole 60H, adjacent to the through-hole 60H, and extends in the conveyance direction DT1. The other third rib 330 is located on the other side, that is, the rear side in the direction of the rotation axis X42 with respect to the through-hole 60H, adjacent to the through-hole 60H, and extends in the conveyance direction DT1.

[0182] The upper surface of each third rib 330 is a flat surface that is flush and continuous with the upper surface located near the swing axes 63A and 63B in the second plate-like portion 62. The downstream end in the conveyance direction DT1 on the upper surface of each third rib 330 is connected to the inclined surface 61S of the first plate-like portion 61.

[0183] One holder recess 339 is adjacent to the third rib 330 located on one side in the direction of the rotation axis X42 on the same side in the direction of the rotation axis X42. One holder recess 339 is recessed downward so as to be one step lower than the upper surface of each third rib 330, and has an inverted trapezoidal groove shape and extends in the direction of the rotation axis X42. One holder recess 339 extends to the outer edge 62E1 located on one side in the direction of the rotation axis X42 in the second plate-like portion 62 of the holder 60.

[0184] The other holder recess 339 is adjacent to the third rib 330 located on the other side in the direction of the rotation axis X42 on the other side in the direction of the rotation axis X42. The other holder recess 339 is recessed downward so as to be one step lower than the upper surface of each third rib 330, and has an inverted trapezoidal groove shape and extends in the direction of the rotation axis X42. The other holder recess 339 extends to the outer edge 62E2 located on the other side in the direction of the rotation axis X42 in the second plate-like portion 62 of the holder 60.

[0185] That is, each holder recess 339 is recessed adjacent to the outside of each third rib 330 in the direction of the rotation axis X42, and extends to the outer edges 62E1 and 62E2 located on the outside in the direction of the rotation axis X42 in the second plate-like portion 62 of the holder 60.

[0186] As shown in FIGS. 17 and 18, the conveyance guide body 100M integrally has one first rib 310.

[0187] The first rib 310 is located to the left of the shaft holes 103A and 103B in the bottom wall of the holder housing portion 102 and to the right of the spring pedestal 103S, and protrudes upward from a position below the conveyance surface 101.

[0188] As shown in FIG. 16, the first rib 310 is located at the center in the front-rear direction on the conveyance surface 101.

[0189] As shown in FIG. 18, the leading edge 311 of the first rib 310 extends in the conveyance direction DT1. The leading edge 311 of the first rib 310 is changed so as to extend upstream and downward in the conveyance direction DT1 than the leading edge 111 of the first rib 110 according to the first embodiment. For this reason, the leading edge 311 of the first rib 310 has a portion located below the conveyance surface 101 upstream in the conveyance direction DT1. Let the distance at which the leading edge 311 separates from the conveyance surface 101 toward the separation roller 42 side, that is, upward be the distance L1A.

[0190] Let the end portion located most upstream in the conveyance direction DT1 of the leading edge 311 be the first end 311U. Let the end portion located most downstream in the conveyance direction DT1 of the leading edge 311 be the second end 311D. The respective corners of the first end 311U and the second end 311D are rounded with a small rounding radius. The first end 311U is located upstream and downward in the conveyance direction DT1 than the first end 111U according to the first embodiment. The second end 311D is at the same position as the first end 111D according to the first embodiment.

[0191] The leading edge 311 is formed such that the distance L1A changes from a negative value to pass through zero and become a positive value and further increases as it progresses from the first end 311U to the second end 311D. The second end 311D of the leading edge 311 is the vertex that is most separated from the conveyance surface 101 of the first rib 310 toward the separation roller 42 side, that is, upward.

[0192] The angle at which the first end 311U side of the leading edge 311 inclines with respect to the conveyance surface 101 is the first angle α1, similar to the first rib 110 according to the first embodiment. The angle at which the second end 311D side of the leading edge 311 inclines with respect to the conveyance surface 101 is the second angle α2, similar to the first rib 110 according to the first embodiment.

[0193] Each third rib 330 is located on the separation roller 42 side, that is, above the first end 311U of the leading edge 311.

[0194] The upstream edge 60H1 of the through hole 60H is located upstream in the conveyance direction DT1 from the first end 311U of the tip edge 311. The upstream edge 60H1 of the through hole 60H is located closer to the separation roller 42 side, that is, above, than the first end 311U of the tip edge 311.

[0195] The vertex farthest from the separation roller 42 side from the conveyance surface 101 in the first rib 310, that is, the second end 311D of the tip edge 311, is located downstream in the conveyance direction DT1 from the vertex 120T of each second rib 120. The second end 311D of the tip edge 311 is located closer to the conveyance surface 101 than the vertex 120T of each second rib 120.

[0196] The first rib 310 has a temporary holding portion 319. Since the configuration and operation of the temporary holding portion 319 are the same as those of the temporary holding portion 119 according to the first embodiment, the description thereof is omitted.

[0197] In the second embodiment, there are changes in the procedure for assembling the compression coil spring 69, the holder 60, and the separation pad 49 to the conveyance guide 100, which was described with reference to FIG. 13 in the first embodiment.

[0198] That is, as shown by the solid line in FIG. 13, when the holder 60 is swung around the swing axis X60 to move the separation pad 49 downward and rearward, the separation pad 49 moves from the position shown by the two-dot chain line in FIG. 20 to the position shown by the solid line in FIG. 20.

[0199] Here, the downstream end 49D in the conveyance direction DT1 of the relief portion 49C of the separation pad 49 is a substantially flat surface facing the radially inner direction of the swing axis X60. When the separation pad 49 moves from the position shown by the two-dot chain line in FIG. 20 to the position shown by the solid line in FIG. 20, the locus depicted by the upper end 49D1 of the downstream end 49D of the relief portion 49C is defined as locus K1, and the locus depicted by the lower end 49D2 of the downstream end 49D of the relief portion 49C is defined as locus K2.

[0200] The second end 311D of the leading edge 311 is located between the locus K1 and the locus K2. Therefore, when the separation pad 49 moves from the position shown by the two-dot chain line in FIG. 20 to the position shown by the solid line in FIG. 20, the lower end 49D2 side of the downstream end 49D of the relief portion 49C abuts against and is pushed by the second end 311D of the leading edge 311, and the relief portion 49C elastically deforms, so that the lower end 49D2 side of the downstream end 49D passes through the second end 311D of the leading edge 311.

[0201] That is, in the process of swinging the holder 60 and assembling it to the conveyance guide 100, the downstream end 49D of the relief portion 49C in the conveyance direction DT1 is in a position where it interferes with the second end 311D of the leading edge 311, and the separation pad 49 passes through the second end 311D of the leading edge 311 by the elastic deformation of the relief portion 49C.

[0202] <Function and effect> Similar to the image reading apparatus 1 of the first embodiment, the image reading apparatus of the second embodiment can suppress non-feed, tip breakage, and double-feed of the sheet SH regardless of the change in the posture of the separation pad 49.

[0203] In addition, this image reading apparatus can also exhibit the same other functions and effects as those described for the image reading apparatus 1 of the first embodiment with respect to the image reading apparatus 1 of the first embodiment.

[0204] Furthermore, in this image reading apparatus, as shown in FIG. 15, the holder 60 has a pair of third ribs 330. The leading edge 311 of the first rib 310 extends in the conveyance direction DT1. As shown in FIG. 18, each third rib 330 is located on the separation roller 42 side, that is, above, rather than the first end 311U of the leading edge 311. With this configuration, when the curled sheet SH is conveyed toward the first rib 310, each third rib 330 abuts against and lifts the sheet SH on one side and the other side in the direction of the rotation axis X42 with respect to the first rib 310, so that the sheet SH can be prevented from being caught by the first end 311U of the leading edge 311.

[0205] Also, in this image reading apparatus, as shown in FIG. 15, it has a pair of holder recesses 339. Each holder recess 339 is recessed adjacent to each third rib 330 on the outer side in the direction of the rotation axis X42, and extends to the outer edges 62E1 and 62E2 in the direction of the rotation axis X42 of the second plate-like portion 62 of the holder 60. With this configuration, when each third rib 330 abuts against and lifts the sheet SH on one side and the other side in the direction of the rotation axis X42 with respect to the first rib 310, the range in which the holder 60 slidably contacts the sheet SH can be reduced by each holder recess 339, so that the sliding resistance acting on the sheet SH from the holder 60 can be reduced.

[0206] Furthermore, in this image reading apparatus, as shown in FIG. 18, the through hole 60H has an upstream edge 60H1 that is located upstream of the first end 311U of the leading edge 311 of the first rib 310 in the conveyance direction DT1 and extends in the direction of the rotation axis X42. The upstream edge 60H1 is located on the side of the separation roller 42, that is, above, with respect to the first end 311U. With this configuration, since the step between the upstream edge 60H1 and the first end 311U does not become a reverse step with respect to the sheet SH being conveyed, the sheet SH that has passed through the upstream edge 60H1 is less likely to be caught by the first end 311U.

[0207] Also, in this image reading apparatus, as shown in FIG. 20, in the process of swinging the holder 60 and assembling it to the conveyance guide 100, the downstream end 49D in the conveyance direction DT1 of the relief portion 49C is at a position where it interferes with the second end 311D of the leading edge 311 of the first rib 310, and the separation pad 49 passes through the second end 311D of the leading edge 311 by the elastic deformation of the relief portion 49C. With this configuration, the distance between the separation pad 49 and the second end 311D of the leading edge 311 can be reduced, so that even if the holder 60 swings closer to the separation roller 42 due to wear of the separation pad 49, the step between the separation pad 49 and the second end 311D of the leading edge 311 is less likely to become a reverse step with respect to the sheet SH being conveyed. As a result, the sheet SH that has passed through the second end 311D of the leading edge 311 is less likely to be caught by the separation pad 49.

[0208] In the above description, the present invention has been described with reference to Example 1, Example 2, and the modified example. However, the present invention is not limited to the above Example 1, Example 2, and the modified example, and it goes without saying that the present invention can be appropriately modified and applied without departing from the spirit thereof.

[0209] In Example 1 and the like, the sheet separation device of the present invention has been embodied as the image reading device 1, but the present invention is not limited to this configuration. For example, the configuration of the present invention may be applied to an image forming device, or the configuration of the present invention may be applied to a multifunction device provided with an image reading device above the image forming device.

[0210] In Example 1 and the like, the conveyance guide 100 has one first rib 110, but the present invention is not limited to this configuration, and a configuration in which the conveyance guide has a plurality of first ribs is also included in the present invention.

[0211] The through hole 60H according to Example 1 and the like penetrates the holder 60 in the vertical direction inside the outer peripheral edge of the holder 60, but the present invention is not limited to this configuration. For example, a configuration in which the upstream side in the conveyance direction of the through hole extends to the upstream end in the conveyance direction of the holder and is open, and the upstream end in the conveyance direction of the holder is bifurcated is also included in the present invention. In this case, a configuration in which a part of the first rib protrudes upstream in the conveyance direction from the through hole and the first rib penetrates the holder through the through hole is also included in the present invention.

[0212] In Example 1 and the like, the conveyance guide 100 has a pair of front and rear second ribs 120, but the present invention is not limited to this configuration, and a configuration in which the conveyance guide has a number of second ribs more than a pair is also included in the present invention.

[0213] In Example 1 and the like, the vertices of the first ribs 110 and 310 are the second ends 111D and 311D, but the present invention is not limited to this configuration. For example, a configuration in which the vertex of the first rib is located between the first end and the second end is also included in the present invention.

[0214] In Example 1 and the like, the first inclined surface 121 and the second inclined surface 122 extend linearly, but the present invention is not limited to this configuration. For example, at least one of the first inclined surface and the second inclined surface may be curved.

Explanation of Signs

[0215] 1... Sheet separation device (image reading device), X42... Axis of rotation SH... Sheet, DT1... Conveying direction, 42... Separation roller 60... Holder, F1... Biasing force, 69... Biasing member (compression coil spring) 49... Separation pad, N1... Nip position, 101... Conveying surface 100... Conveying guide, 110, 210, 310... First rib 111, 311... Leading edge of the first rib, X60... Axis of oscillation 60H... Through hole, 111U, 311U... First end of the leading edge 111D, 311D... Second end of the leading edge L1... Distance at which the leading edge of the first rib is separated from the conveying surface toward the separation roller side α1... First angle, α2... Second angle 49U... Upstream end in the conveying direction of the separation pad 49C... Relief portion, 120... Second rib, 120T... Apex of the second rib W42... Width in the axis of rotation direction of the separation roller W49... Width in the axis of rotation direction of the separation pad L2... Distance at which a pair of second ribs are separated in the axis of rotation direction 121... First inclined surface, 122... Second inclined surface 49A... Surface on the separation roller side of the separation pad (upper surface of the separation pad) 69E... One end of the biasing member (upper end of the compression coil spring) 68... Spring receiving portion, 119, 319... Temporary holding portion, 67... Fitting convex portion 330... Third rib, 339... Holder recess 62E1, 62E2... Outer edge on the X direction of the axis of rotation in the holder 60H1... Upstream edge of the through hole 49D... Downstream end in the conveying direction of the relief portion

Claims

1. a separation roller that rotates about a rotation axis and conveys the sheet in a conveying direction perpendicular to the rotation axis; a holder that can be brought into contact with and separated from the separation roller; a biasing member that exerts a biasing force to bias the holder toward the separation roller; a separation pad that is held by the holder and pressed against the separation roller, and separates the sheets one by one if there are multiple sheets being conveyed by the separation roller; a conveying guide having a conveying surface that guides a sheet toward a nip position between the separation roller and the separation pad; Equipped with The sheet separating device is characterized in that the conveying guide has a first rib located upstream of the nip position in the conveying direction, the first rib protruding toward the separation roller from the opposite side of the holder to the separation roller, penetrating the holder, and guiding the sheet toward the nip position with its leading edge.

2. The transport guide has one first rib, The sheet separating device according to claim 1 , wherein the first rib is located at the same position as a center of the separating pad in the direction of the rotation axis.

3. the conveying guide supports the holder to be swingable about a swing axis extending parallel to the rotation axis upstream of the separation pad in the conveying direction, the holder has a through hole located between the nip position and the pivot axis in the transport direction, The sheet separating device according to claim 1 , wherein the first rib penetrates the holder via the through hole.

4. The tip edge of the first rib extends in the conveying direction, 2. The sheet separating device according to claim 1, wherein the leading edge is formed so that the distance from the conveying surface toward the separation roller increases as the leading edge progresses from a first end located at the most upstream position in the conveying direction to a second end located at the most downstream position in the conveying direction.

5. 5. The sheet separating device according to claim 4, wherein a first angle at which the first end side of the leading edge is inclined relative to the conveying surface is larger than a second angle at which the second end side of the leading edge is inclined relative to the conveying surface.

6. The tip edge of the first rib extends in the conveying direction, a first end of the leading edge located at the most upstream side in the transport direction is located at the upstream side in the transport direction of an upstream end of the separation pad in the transport direction, a second end of the leading edge located at the most downstream side in the transport direction is located downstream of the upstream end of the separation pad in the transport direction; The sheet separating device according to claim 1 , wherein the separation pad has a recessed portion recessed from the upstream end toward the downstream in the conveying direction and receding from the second end of the leading edge.

7. the conveying guide has a plurality of second ribs located on one side and the other side of the rotation axis direction with respect to the holder, protruding from the conveying surface toward the separation roller, and extending in the conveying direction; 7. The sheet separating device according to claim 1, wherein an apex of each of the second ribs that is farthest from the conveying surface toward the separation roller is located upstream of the separation roller in the conveying direction.

8. the transport guide has a pair of the second ribs, 8. The sheet separating device according to claim 7, wherein the width of the separation roller in the direction of the rotation axis is greater than the width of the separation pad in the direction of the rotation axis and is smaller than the distance between the second ribs in the direction of the rotation axis.

9. the apex of each of the second ribs is located farther from the conveying surface toward the separation roller than the separation pad is, each of the second ribs has a first inclined surface connected to the apex and extending toward the upstream in the conveying direction, and a second inclined surface connected to the apex and extending toward the downstream in the conveying direction; The sheet separating device according to claim 7 , wherein, as viewed along the rotation axis direction, the second inclined surface intersects with a surface of the separation pad facing the separation roller, upstream of the nip position in the transport direction.

10. 8. The sheet separating device according to claim 7, wherein an apex of the first rib that is farthest from the conveying surface toward the separation roller is located downstream in the conveying direction from the apex of each of the second ribs.

11. The sheet separating device according to claim 10 , wherein the apex of the first rib is located closer to the conveying surface than the apex of each of the second ribs.

12. 7. The sheet separating device according to claim 1, wherein the first rib is detachably supported by the conveying guide.

13. the conveying guide supports the holder to be swingable about a swing axis extending parallel to the rotation axis upstream of the separation pad in the conveying direction, the holder has a spring receiving portion that engages with one end of the biasing member at a position overlapping with the separation pad in the transport direction to receive the biasing force, the first rib has a temporary holding portion that hooks and holds the one end of the urging member that is elastically deformed to store a restoring force in a state in which the spring receiving portion is separated from the one end of the urging member, 7. The sheet separating device according to claim 1, wherein the holder is swung to engage the spring receiving portion with the one end of the biasing member, thereby disengaging the one end from the temporary holding portion.

14. The sheet separating device according to claim 13 , wherein the temporary holding portion is a recess that is recessed toward the upstream side in the conveying direction at a position farther from the separation roller than the leading edge of the first rib and at a downstream position in the conveying direction of the first rib.

15. The biasing member is a compression coil spring. the spring receiving portion has a fitting protrusion that fits into the one end of the biasing member, The sheet separating device according to claim 13, wherein when the holder is swung to engage the spring receiving portion with the one end of the urging member, the fitting protrusion fits into the one end while moving the one end downstream in the conveying direction, thereby disengaging the one end from the temporary holding portion.

16. the holder has a pair of third ribs that are adjacent to the through hole and located on one side and the other side in the rotation axis direction with respect to the through hole and extend in the conveying direction, The tip edge of the first rib extends in the conveying direction, 4. The sheet separating device according to claim 3, wherein each of the third ribs is located closer to the separation roller than a first end that is located most upstream in the conveying direction of the leading edge.

17. 17. The sheet separating device according to claim 16, wherein the holder has a pair of holder recesses that are recessed adjacent to each of the third ribs on the outer side in the direction of the rotation axis and extend to an outer end edge of the holder in the direction of the rotation axis.

18. the through hole has an upstream edge located upstream in the conveying direction of the first end of the leading edge, the first end being located furthest upstream in the conveying direction, and extending in the direction of the rotation axis; The sheet separating device according to claim 3 , wherein the upstream edge is located closer to the separating roller than the first end.

19. the conveying guide supports the holder to be swingable about a swing axis extending parallel to the rotation axis upstream of the separation pad in the conveying direction, The sheet separating device according to claim 6, wherein in the process of swinging the holder to assemble it to the conveying guide, the downstream end of the relief portion in the conveying direction is in a position where it interferes with the second end, and the separation pad passes through the second end due to elastic deformation of the relief portion.

Images