JP2017171441A - Sheet transport device and image reading device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet transport device capable of preventing occurrence of damage such as folding on a sheet, and an image reading device.SOLUTION: A pick up roller 32 (feeding means) for feeding a sheet which is supported to a document tray (sheet support means) comprises: a roller body 320 (first rotation member) comprising a first outer peripheral face 320a which has a radius R1 (first radius), which is formed into an arc-shape and feeds a sheet, and a second outer peripheral face 320b which has a shorter distance from a center than the radius R1; and a roller 321 (second rotation member) which is arranged coaxially to the roller body 320, and which has a radius R2 (second radius) which is larger than a shortest distance from the second outer peripheral face 320b to the center and shorter than the radius R1.SELECTED DRAWING: Figure 8

Description

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

  2. Description of the Related Art Conventionally, an image reading apparatus that is provided above an image forming apparatus such as a copying machine and reads an image of a document is known (see Patent Document 1). This image reading apparatus feeds a document on a document feed tray by a pickup roller, and separates the documents one by one by a separation nip of the document feed roller and the separation pad. The position of the leading edge of the document on the document feed tray is regulated between the pickup roller and the separation nip by a stopper piece.

  Further, the pickup roller and the document feed roller are driven by a single motor, and a drive transmission path between the motor and the pickup roller and the document feed roller is provided with a slidable transmission gear. .

  Until the leading edge of the document reaches a conveyance roller provided downstream of the document feed roller, the drive between the motor, the pickup roller, and the document feed roller is connected. When the leading edge of the document reaches the transport roller, the pickup roller and the document feed roller receive a rotational force from the document transported by the transport roller rotating at a speed faster than the separation roller, and the transmission gear slides. As a result, the drive between the motor, the pickup roller, and the document feed roller is cut, and the pickup roller and the document feed roller are idled. With such a configuration, the image reading apparatus described in Patent Document 1 continuously feeds a document with a certain interval between a preceding document and a succeeding document.

JP 2013-86902 A

  However, in the image reading apparatus described in Patent Document 1, the succeeding document is fed to the document fed in advance, and the leading end of the succeeding document is conveyed to the separation nip beyond the stopper piece. There is. Since the pickup roller is provided upstream in the sheet feeding direction from the document feeding roller, when the trailing edge of the document passes the pickup roller, the drive transmission from the motor resumes before the document feeding roller. .

  For this reason, when a subsequent document whose leading edge reaches the separation nip is fed by the pickup roller while the document feeding roller is stopped, a loop is formed at the leading edge of the document. At this time, for example, when the original is thin paper or the like, there is a possibility that a loop formed at the front end of the original is buckled and damage such as bending is formed on the original.

  SUMMARY An advantage of some aspects of the invention is that it provides a sheet conveying apparatus and an image reading apparatus that prevent a sheet from being damaged.

  The present invention relates to a sheet conveying apparatus, a sheet supporting unit for supporting a sheet, a feeding unit for feeding a sheet supported by the sheet supporting unit, and a conveyance for conveying a sheet fed by the feeding unit. A rotating unit; a separating unit that separates sheets one by one by a separation nip formed together with the conveying rotating unit; and a driving unit that drives the feeding unit and the conveying rotating unit. A first rotating member having a first outer peripheral surface that is formed in an arc shape having a first radius and feeds a sheet; and a second outer peripheral surface that is shorter from the center than the first radius; A second rotating member disposed coaxially with the first rotating member and having a second radius that is longer than the shortest distance from the second outer peripheral surface to the center and shorter than the first radius. It is characterized by.

  According to the present invention, the loop formed in the sheet is eliminated by the contact of the sheet with the second rotating member protruding in the radial direction from the second outer peripheral surface of the first rotating member. Can be prevented.

1 is a perspective view showing a printer according to a first embodiment. The side view which shows an image reading apparatus. It is a figure which shows a sheet | seat stopper, Comprising: (a) is a front view, (b) is a side view, (c) is a rear view. It is a figure which shows the sheet | seat stopper of the state pushed down, Comprising: (a) is a front view, (b) is a side view. It is a figure which shows the drive system of a pick-up roller, Comprising: (a) is a top view, (b) is DD sectional drawing of (a), (c) is EE sectional drawing of (b). FIG. 3 is a control block diagram of a printer. The flowchart explaining feeding operation | movement. (A) is a top view which shows a pick-up roller, (b) is side surface sectional drawing which shows the dimension of a roller main body and a roller. (A) is a side view showing a state in which the first outer peripheral surface is in contact with the sheet, (b) is a side view showing a state in which the roller and the sheet are in contact. (A) is a side view showing a state immediately after the trailing edge of the preceding sheet has passed through the pickup roller. FIG. 6B is a side view illustrating a state in which the distance between the sheets is maximized. (C) is a side view showing a state in which the trailing edge of the preceding sheet and the leading edge of the succeeding sheet overlap in the separation nip. Side surface sectional drawing which shows the pick-up roller and intermediate plate which concern on 2nd Embodiment. FIG. 6 is a control block diagram of a printer according to a second embodiment. The flowchart explaining feeding operation | movement.

<First Embodiment>
〔overall structure〕
First, a first embodiment of the present invention will be described. The printer 100 according to the first embodiment is an electrophotographic laser beam printer. As shown in FIG. 1, the printer 100 includes a printer main body 2 and an image reading device 104 mounted on the upper portion of the printer main body 2.

  The printer main body 101 includes an image forming unit 102 that forms an image on a sheet, and a sheet feeding unit 105 that feeds the sheet to the image forming unit 102. The image forming unit 102 includes a laser writing unit, an electrophotographic process unit, a fixing unit, and the like (not shown), and forms an image on the sheet fed from the sheet feeding unit 105 by a conventionally known electrophotographic method.

[Image reading device]
Next, the image reading device 104 will be described in detail. As shown in FIGS. 1 and 2, the image reading device 104 feeds documents stacked on the document tray 30 (sheet support means) and discharges them to the discharge tray 40, and the ADF 2. And a reading unit 1 for reading the conveyed document. An ADF 2 (Auto Document Feeder) is rotatably supported by the reading unit 1 by a hinge so that an original platen glass 11 described later can be opened. Note that the document (sheet) may be a blank sheet, or an image may be formed on one side or both sides.

  The ADF 2 includes a pickup roller 32 (feeding means), a sheet stopper 35, a separation roller 33 (conveyance rotating body), a separation pad 34 (separation means) that forms a separation nip N together with the separation roller 33, and a conveyance roller pair. 22 and a discharge roller pair 42. Further, the ADF 2 detects a pickup arm 31 that swingably supports the pickup roller 32, a sheet presence sensor 24 that detects sheets stacked on the document tray 30, and that the leading and trailing edges of the sheets have passed. A sheet edge sensor 23.

  Inside the ADF 2, a substantially U-shaped sheet conveyance path 20A and a reverse conveyance path 20B for reversing the sheet are provided. The sheet conveyance path 20 </ b> A is formed by the conveyance frame 21 and an openable / closable upper cover 60, and the reverse conveyance path 20 </ b> B is formed by the conveyance frame 21 and the upper conveyance guide 50 facing the conveyance frame 21.

  In the case of reading both sides of the document, the document transport is temporarily stopped at the timing when the rear end of the document is positioned upstream of the discharge roller pair 42 after the surface of the document is read. Then, the motor M2 is reversely rotated, and the document is sent to the conveyance roller pair 22 via the conveyance path 20B. After the leading edge of the document reaches the conveyance roller pair 22, the discharge roller pair 42 is separated by the solenoid 25 (see FIG. 6). When the trailing edge of the document passes through the discharge roller pair 42, the solenoid 25 is operated again to bring the discharge roller pair 42 into contact. As described above, the duplex reading is performed, and the document is discharged to the discharge tray 40.

  The reading unit 1 includes a platen glass 10, a document table glass 11, a jump table 15, and a reading unit 12 (image reading means). The reading unit 12 is in the sub-scanning direction (left and right in FIG. 2). Direction). As shown in FIG. 6, the reading unit 12 includes a light source 16, a photoelectric conversion element 17, a mirror and a lens (not shown), and is driven in the sub-scanning direction by a motor M1. The light emitted from the light source 16 is reflected by the document, and the reflected light is incident on the photoelectric conversion element 17 through a mirror and a lens. The photoelectric conversion element 17 photoelectrically converts the reflected light from the document, whereby an image of the document can be obtained as image information.

[Sheet stopper]
Next, the sheet stopper 35 (tip restricting portion) will be described in detail. As shown in FIG. 3A, the sheet stopper 35 connects the swinging shaft 35c attached to the upper conveyance guide 50, the sheet regulating surface 35a that comes into contact with the sheet, and the swinging shaft 35c and the sheet regulating surface 35a. An arm portion 35d. As shown in FIG. 3B, an inclined portion 35e that inclines toward the downstream in the sheet conveying direction extends from the upper end of the sheet regulating surface 35a. A pressed portion 35b that comes into contact with the pressing portion 31a is provided.

  The swing shaft 35c extends in a direction parallel to the sheet conveying direction and perpendicular to the axial direction of the separation roller shaft 65 on which the pickup arm 31 (arm member) is rotatably supported. For this reason, the sheet stopper 35 is configured to be rotatable on a plane having a width direction orthogonal to the sheet conveying direction. As shown in FIG. 3C, the swinging shaft 35c is fitted with a coil portion 36a of a stopper spring 36. One end portion 36b extending from the coil portion 36a is fixed to the upper transport guide 50, and the coil portion 36a The other end 36c that extends is fixed to the back side of the sheet regulating surface 35a. The sheet stopper 35 is biased upward by the biasing force of the stopper spring 36 so that the pressed portion 35b and the pressing portion 31a of the pickup arm 31 are in contact with each other.

  For this reason, when the pickup arm 31 is located at the standby position shown in FIG. 3B, the sheet regulating surface 35a of the sheet stopper 35 protrudes upward to a position where the sheet feeding path R is blocked, The sheet S is prevented from entering the separation nip N. When the pickup arm 31 moves from the standby position to the feeding position shown in FIGS. 4A and 4B, the sheet stopper 35 is pressed downward by the pickup arm 31 against the urging force of the stopper spring 36. When the pickup arm 31 is positioned at the feeding position, the sheet regulating surface 35a of the sheet stopper 35 is positioned below the uppermost sheet S stacked on the document tray 30, and the sheet S is It is allowed to enter the separation nip N.

  When the sheet S is fed by the pickup roller 32 in this state, the sheet S pushes down the sheet stopper 35 against the urging force of the stopper spring 36 while contacting the inclined portion 35e of the sheet stopper 35. As a result, the sheet S enters the separation nip N.

[Pickup roller drive system]
Next, the elevating unit 400 that contacts or separates the pickup roller 32 and the sheets stacked on the document tray 30 will be described in detail. As shown in FIG. 5A, the elevating unit 400 (elevating means) includes a separation roller shaft 65, a pickup roller shaft 61, a pickup arm 31, transmission gears 66, 64, 62, and the like. Yes. The separation roller shaft 65 is rotated by the driving force of the motor M2 (see FIG. 6, driving means) input from the driving input unit 651. The rotation of the separation roller shaft 65 is transmitted to the pickup roller shaft 61 via transmission gears 66, 64 and 62. As shown in FIGS. 5B and 5C, a one-way clutch 67 is interposed between the separation roller shaft 65 and the transmission gear 66, and between the pickup roller shaft 61 and the transmission gear 62, A one-way clutch 63 is interposed.

  As shown in FIG. 5A, the transmission gear 66 is formed with a recess 662, and the recess 662 engages with a protrusion 332 formed on the separation roller 33. Thereby, the rotation of the transmission gear 66 is transmitted to the separation roller 33. Similarly, a concave portion 622 is formed in the transmission gear 62, and the concave portion 622 engages with a convex portion 322 formed on the pickup roller 32. Thereby, the rotation of the transmission gear 62 is transmitted to the pickup roller 32.

  As shown in FIG. 5C, collars 69 and 68 are loosely fitted to the separation roller shaft 65 with the pickup arm 31 interposed therebetween. The collar 69 is fixed to the separation roller shaft 65 by a parallel pin 70. Yes. A spring clutch 71 is provided across the collar 69 and the receiving portion 31a of the pickup arm 31, and the spring clutch 71 is tightened when the separation roller shaft 65 rotates in the direction of arrow C (see FIG. 5B). Transforms into

  That is, when the separation roller shaft 65 rotates in the forward rotation direction (arrow C direction), the one-way clutches 67 and 63 transmit driving, and the separation roller 33 and the pickup roller 32 rotate in the arrow C direction and the arrow B direction, respectively. . At the same time, when the spring clutch 71 is tightened, the rotation of the collar 69 that rotates together with the separation roller shaft 65 is transmitted to the pickup arm 31, and the pickup arm 31 descends from the standby position toward the feeding position (rotates in the direction of arrow F). )

  When the drive to the separation roller shaft 65 is stopped, the pickup arm 31 loses the force to rotate in the direction of arrow F, and the pickup arm 31 is raised from the feeding position toward the standby position by a return spring (not shown).

[Control unit]
FIG. 6 is a control block diagram of the printer 100. As shown in FIG. 6, the printer 100 includes an image forming apparatus control unit 200, an image reading apparatus control unit 201, and a sheet conveying apparatus control unit 202, and the image forming apparatus control unit 200 The reading device control unit 201 and the sheet conveying device control unit 202 are integrated. The image reader control unit 201 is connected to the motor M1, the light source 16, and the photoelectric conversion element 17.

  The sheet conveying device control unit 202 includes a motor control unit 203 to which the motor M2 is connected, a solenoid control unit 204 connected to the solenoid 25, and a sensor control unit 205 connected to the sheet edge sensor 23 and the sheet presence / absence sensor 24. ,have. Note that the image forming apparatus control unit 200, the image reading apparatus control unit 201, and the sheet conveying apparatus control unit 202 may be provided collectively in the printer main body 101, the image reading apparatus 104, or the ADF 2, or may be provided in a distributed manner.

[Feeding operation]
Next, a sheet feeding operation when a sheet reading job is input will be described with reference to FIG. The form of reading the document conveyed by the ADF 2 is called flow reading, and the form of reading the document placed on the platen glass 11 and moving the reading unit 12 in the sub-scanning direction is called fixed reading. In this embodiment, only the flow reading will be described. When a document is stacked on the document tray 30 by the user, the presence of the sheet S is detected by the sheet presence / absence sensor 24 (steps S101 and S102). At this time, the position of the leading edge of the sheet S stacked on the document tray 30 is regulated by the sheet regulating surface 35 a of the sheet stopper 35.

  When the user inputs a reading job from an operation unit (not shown), the motor control unit 203 rotates the motor M2 forward (step S103). Accordingly, the pickup arm 31 is rotated downward from the standby position toward the feeding position (step S104), and the sheet stopper 35 is pushed down by being pressed by the pressing portion 31a of the pickup arm 31 (step S105). Then, the pickup roller 32 comes into contact with the uppermost sheet S1 (see FIG. 2) stacked on the document tray 30, and this sheet is fed by the rotating pickup roller 32.

  The fed sheets S1 are conveyed while pushing down the sheet stopper 35, and are separated one by one by the separation nip N (step S106). The sheet S1 is conveyed to the conveyance roller pair 22 (downstream rotating body pair) along the sheet conveyance path 20A. When the leading edge of the sheet S1 is detected by the sheet edge sensor 23 provided immediately downstream of the conveying roller pair 22 in the sheet conveying direction, reading of the image of the sheet S1 by the reading unit 12 is started after a predetermined time from here. Steps S108 and S109). At this time, the sheet S <b> 1 is pressed against the platen glass 10 by the white background plate 14.

  The sheet S <b> 1 is picked up by the jumping table 15 and conveyed toward the discharge roller pair 42 while an image is read by the reading unit 12. When the sheet edge sensor 23 detects the trailing edge of the sheet S1, reading of an image by the reading unit 12 is finished after a predetermined time from here (step S109). The sheet S1 for which image reading has been completed is discharged to the discharge tray 40 by the discharge roller pair 42, and the image reading apparatus 104 repeats the above-described reading operation until there is no sheet S stacked on the document tray 30 (step S110). , S111).

  When the sheet presence / absence sensor 24 detects that there is no sheet in the document tray 30, the motor control unit 203 stops the motor M2 (steps S111 and S112). Then, the pickup arm 31 is raised by the biasing force of a return spring (not shown) and returns to the standby position (step S113). The pickup arm 31 is stopped at a standby position by a stopper (not shown), for example. When the pickup arm 31 moves to the standby position, the sheet stopper 35 is raised by the biasing force of the stopper spring 36, and the sheet feeding operation is completed (step S114).

  If the sheet edge sensor 23 does not detect the leading edge of the sheet S1 in step S107, the sheet conveying apparatus control unit 202 displays a warning on an operation unit (not shown) and stops the operation of the image reading apparatus 104 (step S107). S115). The user can take out the jammed sheet by opening the upper cover 60 or the upper conveyance guide 50, for example.

[Pickup roller]
Next, the pickup roller 32 will be described in detail. As shown in FIG. 8A, the pickup roller 32 includes a roller body 320 (first rotating member), rollers 321 and 321 (second rotating member) arranged side by side across the roller body 320, have. Since the rollers 321 and 321 have the same configuration, the rollers 321 and 321 are simply referred to as rollers 321 below.

  The roller main body 320 and the roller 321 are arranged on the same axis, and the roller main body 320 is driven together with the separation roller 33. However, the roller 321 rotates following the sheet. That is, as shown in FIG. 5C, the roller body 320 is spline-engaged with the boss portion 61a that can be rotated by the motor M2, and the roller 321 is loosely fitted with the boss portion 61a.

  As shown in FIG. 8B, the roller body 320 has a first outer peripheral surface 320a having a radius R1 (first radius) and formed in an arc shape, and a first distance shorter from the center than the radius R1. 2 outer peripheral surfaces 320b. The second outer peripheral surface 320b is a flat surface, and the shortest distance to the center is the length R3. The difference between the radius R1 and the length R3 is the length H (R1−R3 = H). The first outer peripheral surface 320a is formed at three positions with a phase shift at equal intervals. 320a is formed with equal circumferential length. Similarly to the first outer peripheral surface, the second outer peripheral surface 320b is also formed at three places.

  The roller 321 is a disk member having a radius R2 (second radius), and the radius R2 is longer than the length R3 and shorter than the radius R1 (R3 <R2 <R1). For this reason, when viewed from the axial direction, a part of the outer peripheral surface of the roller 321 protrudes in the radial direction from the second outer peripheral surface 320b. In the present embodiment, the protrusion amount of the roller 321 from the second outer peripheral surface 320b is set to about 0.5 mm at the maximum position. The roller body 320 is made of a material having a relatively large frictional resistance such as rubber, and the roller 321 is made of a material having a relatively small frictional resistance such as polyacetal resin.

  Next, the operation of the pickup roller 32 will be described. When the sheet feeding operation is started, the pickup arm 31 is lowered as described above. At this time, as shown in FIG. 9A, the first outer peripheral surface 320a abuts on the sheet S1, or as shown in FIG. 9B, the second outer peripheral surface 320b faces the sheet S1 and the roller 321 is placed. Is brought into contact with the sheet S1.

  When the pickup roller 32 rotates in this state, the sheet S1 alternately abuts on the first outer peripheral surface 320a of the roller body 320 and the outer peripheral surface of the roller 321. Since the roller 321 has a low frictional resistance and slides on the sheet, the sheet S1 cannot be conveyed. That is, the outer peripheral surface of the roller 321 has a sheet feeding force weaker than that of the first outer peripheral surface 320 a of the roller body 320. Accordingly, the sheet S1 is intermittently conveyed from the reference position A where the leading edge of the sheet S1 is regulated by the sheet stopper 35 to the separation nip N.

  When the sheet is conveyed to the separation nip N, the sheet S1 is conveyed by the separation roller 33 at the conveyance speed V1 (first conveyance speed). When the sheet S1 reaches the conveyance roller pair 22, the sheet S1 is conveyed by the conveyance roller pair 22 at a conveyance speed V2 (second conveyance speed). Note that the sheet edge sensor 23 detects that the sheet S1 has reached the conveyance roller pair 22, for example. When the sheet S1 is conveyed by the conveyance roller pair 22 at the conveyance speed V2, the pickup roller 32 and the separation roller 33 are idled with respect to the drive shaft by the one-way clutches 63 and 67, respectively.

  FIG. 10A shows a state in which the leading edge of the succeeding sheet S2 fed to the sheet S1 reaches the separation nip N immediately after the trailing edge of the preceding sheet S1 passes through the pickup roller 32. is there. When the sheet S2 is conveyed in this state, the leading edge of the sheet S2 abuts at the separation nip N, and thus a loop is formed in the sheet S2 by the amount conveyed by the pickup roller 32.

  However, in the present embodiment, even when the pickup roller 32 rotates, the sheet can be conveyed only by the first outer peripheral surface 320a of the roller body 320, and the roller 321 slides with respect to the sheet. For this reason, when the sheet S2 is conveyed by the length La in the circumferential direction of the first outer peripheral surface 320a and the sheet S2 faces the roller 321, the sheet S2 slides with respect to the roller 321 by the stiffness of the sheet S2, and the sheet S2 The loop formed in is eliminated. That is, the size of the loop formed in the sheet S2 is a maximum of the length La. In the present embodiment, the length La in the circumferential direction of the first outer peripheral surface 320a is set to about one third of the distance L from the reference position A to the separation nip N (La = 1/3 × L).

  Immediately after the trailing edge of the preceding sheet S1 has passed through the pickup roller 32, even if the leading edge of the succeeding sheet S2 has not reached the separation nip N, the above-described case will occur after the leading edge of the sheet S2 has reached the separation nip N. It is the same. As shown in FIG. 10B, when the rear end of the sheet S1 and the upstream end of the first outer peripheral surface 320a face each other, the distance between the sheet S1 and the sheet S2 is maximized.

  As shown in FIG. 10C, when the leading edge of the sheet S2 reaches the separation nip N immediately after the trailing edge of the sheet S1 passes through the separation nip N, the interval between the sheet S1 and the sheet S2 is instantaneously reduced to zero. Become. Thereafter, when the sheet S1 is conveyed by the conveyance roller pair 22 at the conveyance speed V2, the interval between the sheet S1 and the sheet S2 starts to open. When the leading edge of the sheet S2 reaches the separation nip N after the trailing edge of the sheet S1 passes through the separation nip N, a loop is not normally formed in the sheet S2.

  As described above, in the pickup roller 32, the first outer peripheral surface 320a of the roller body 320 and the roller 321 are in contact with the sheet alternately. Even if the loop is formed on the sheet, the loop 321 is in contact with the sheet. Is resolved. Further, since the length in the circumferential direction of the first outer peripheral surface 320a is set to about one third of the length L from the reference position A to the separation nip N, an excessive loop is not formed on the sheet. . For this reason, it can prevent that damage, such as a bend, generate | occur | produces on a sheet | seat.

  Further, since the step between the first outer peripheral surface 320a and the outer peripheral surface of the roller 321 is very small, the distance between the pickup roller shaft 61 of the pickup roller 32 and the uppermost sheet can be maintained substantially constant. For this reason, it is possible to prevent the pickup roller 32 from bouncing against the uppermost sheet, and to keep the contact pressure between the pickup roller 32 and the sheet constant.

  Further, since the separation roller 33, the pickup roller 32, and the conveyance roller pair 22 are driven by one motor M2, and the pickup roller 32 can be continuously fed without moving up and down, the configuration is simplified and the cost is reduced. You can go down.

  In the present embodiment, the first outer peripheral surface 320a and the second outer peripheral surface 320b are provided at three locations, respectively. However, the present invention is not limited to this, and the number may be smaller or more than three. Moreover, although the roller main body 320 was comprised in the shape which notched a part of perfect circle, it is not limited to this. That is, the roller main body 320 may have any shape as long as it has a portion protruding in the radial direction and a recessed portion from the outer peripheral surface of the roller 321. Further, instead of the separation pad 34 used in the present embodiment, a roller may be used.

<Second Embodiment>
Next, a second embodiment of the present invention will be described. In the second embodiment, the pickup arm 31 according to the first embodiment is eliminated and an intermediate plate 301 is provided. For this reason, about the structure similar to 1st Embodiment, illustration is abbreviate | omitted or attaches | subjects the same code | symbol to a figure and demonstrates.

  The pickup roller shaft 61 is rotatably supported by a frame (not shown), and the pickup roller shaft 61 supports a pickup roller 32 having a roller body 320 and a roller 321 as shown in FIG.

  An intermediate plate 301 (sheet support means) is supported on the tray base 300 so as to be swingable about the shaft portion 301P, and a pressure lever 303 is swung around the shaft portion 303P below the intermediate plate 301. It is supported movably. The pressure lever 303 can be raised and lowered by a cam 304 (elevating means, cam member) that rotates about a cam shaft 305. The cam shaft 305 is rotated by an intermediate plate motor M3 (see FIG. 12). A middle plate biasing spring 302 is contracted between the pressure lever 303 and the middle plate 301, and the middle plate 301 is biased toward the pickup roller 32 by the middle plate biasing spring 302. The biasing force with respect to the middle plate 301 of the middle plate biasing spring 302 is changed when the pressure lever 303 is moved up and down by the cam 304. In the cam 304, a position indicated by a broken line in FIG. 11 is a standby position, and a position indicated by a solid line in FIG. 11 is a feeding position.

  The intermediate plate 301 is provided with a sheet presence / absence detection lever 306. When a sheet is stacked on the intermediate plate 301, the sheet presence / absence detection lever 306 rotates. Corresponding to the rotation of the sheet presence / absence detection lever 306, the sheet presence / absence sensor 124 (see FIG. 12), which is a photosensor, can detect the presence / absence of a sheet. Further, a regulating member 307 that regulates the position of the leading edge of the sheets stacked on the middle plate 301 is provided downstream of the middle plate 301 in the sheet feeding direction.

[Feeding operation]
Next, a sheet feeding operation when a sheet reading job is input will be described with reference to FIG. When a document is stacked on the document tray 30 by the user, the presence of the sheet S is detected by the sheet presence / absence detection lever 306 and the sheet presence / absence sensor 124 (steps S201 and S202). At this time, the position of the leading edge of the sheet S stacked on the intermediate plate 301 is regulated by the regulating member 307.

  When the user inputs a reading job from an operation unit (not shown), the motor control unit 203 drives the intermediate plate motor M3 (step S203). As a result, the cam 304 rotates from the standby position to the feeding position, and the intermediate plate 301 rises. Note that the intermediate plate biasing spring 302 is set to a spring pressure such that the force with which the uppermost sheet presses the roller body 320 or the roller 321 is within a certain range regardless of the number of stacked sheets.

  Then, the same reading operation as that in the first embodiment is repeated until the sheets S stacked on the intermediate plate 301 disappear (steps S205 to S212). When the sheet presence / absence sensor 124 detects that there is no sheet on the intermediate plate 301, the motor control unit 203 stops the motor M2 (steps S212 and S213). Further, the motor control unit 203 drives the intermediate plate motor M3 to rotate the cam 304 from the feeding position to the standby position (step S214). As a result, the intermediate plate 301 is lowered, and the sheet feeding operation is finished (step S215).

  2: Sheet conveying device (ADF) / 12: Image reading unit (reading unit) / 22: Downstream rotating member pair (conveying roller pair) / 30: Sheet supporting unit (original tray) / 31: Arm member (pickup arm) / 32: Feeding means (pickup roller) / 33: Conveying rotator (separation roller) / 34: Separation means (separation pad) / 35: Tip regulating portion (sheet stopper) / 104: Image reading device / 301: Sheet support means (Inner plate) / 304: Elevating means, cam member (cam) / 320: first rotating member (roller body) / 320a: first outer peripheral surface / 320b: second outer peripheral surface / 321: second rotating member (roller) / 400: Lifting means (lifting unit) / A: Reference position / La: Length / M2: Driving means (motor) / N: Separation nip / R1: First radius (radius) / R2: Second radius (radius) / R3: Distance (Length) / S: Sheet / V1: first conveying speed (conveying speed) / V2: second conveying speed (conveying speed)

Claims (11)

Sheet support means for supporting the sheet;
A feeding means for feeding a sheet supported by the sheet supporting means;
A transport rotating body for transporting the sheet fed by the feeding means;
Separation means for separating the sheets one by one by a separation nip formed together with the conveying rotator;
Driving means for driving the feeding means and the conveying rotating body,
The feeding means is
A first rotating member having a first outer peripheral surface that has a first radius and is formed in an arc shape and feeds a sheet; and a second outer peripheral surface that is shorter from the center than the first radius;
A second rotating member disposed coaxially with the first rotating member and having a second radius that is longer than the shortest distance from the second outer peripheral surface to the center and shorter than the first radius;
A sheet conveying apparatus. A front end restricting portion that restricts the position of the front end of the sheet supported by the sheet supporting means at a reference position;
The circumferential length of the first outer peripheral surface is shorter than the distance from the reference position to the separation nip.
The sheet conveying apparatus according to claim 1. The length of the first outer peripheral surface in the circumferential direction is about one third of the distance from the reference position to the separation nip.
The sheet conveying apparatus according to claim 2. When the feeding unit is driven by the driving unit, the sheet supported by the sheet supporting unit alternately contacts the first outer peripheral surface of the first rotating member and the outer peripheral surface of the second rotating member. Touching,
The sheet conveying apparatus according to claim 1, wherein the sheet conveying apparatus is a sheet conveying apparatus. The outer peripheral surface of the second rotating member has a sheet feeding force weaker than that of the first outer peripheral surface of the first rotating member.
The sheet conveying apparatus according to claim 4. The second outer peripheral surface is a plane.
The sheet conveying apparatus according to claim 1, wherein the sheet conveying apparatus is a sheet conveying apparatus. Arranged downstream of the conveying rotator in the sheet conveying direction, comprising a pair of downstream rotators for conveying the sheet,
The downstream rotating body pair transports the sheet at a second transport speed that is faster than the first transport speed at which the feeding unit and the transport rotating body transport the sheet.
The sheet conveying apparatus according to claim 1, wherein the sheet conveying apparatus is a sheet conveying apparatus. Elevating means for abutting or separating the sheet supported by the sheet supporting means and the feeding means;
The sheet conveying apparatus according to claim 1, wherein the sheet conveying apparatus is a sheet conveying apparatus. The elevating means has an arm member that supports the feeding means in a swingable manner.
The sheet conveying apparatus according to claim 8. The sheet support means is rotatably supported.
The elevating means has a cam member that rotates the sheet supporting means.
The sheet conveying apparatus according to claim 8. A sheet conveying device according to any one of claims 1 to 10,
Image reading means for reading an image of a sheet conveyed by the sheet conveying device,
An image reading apparatus.

Images