JP2006076681A - Paper feeding unit and automatic document feeding device and image forming device provided with it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve stability of document conveyance and convey a document stably even when increasing paper feeding speed without increasing the number of parts and a size of a unit. <P>SOLUTION: This paper feeding unit has a pick-up roller 13 for pulling a document loaded on a paper feeding tray into the inside, a paper feeding roller 14 for conveying the document pulled in by it toward a reading sensor, a pick-up bracket 21 for connecting and holding the pick-up roller and the paper feeding roller mutually and rotatably, a torque limiter 36 for bringing the pick-up roller into pressure-contact with a paper face of the document by rotation force acting on a support shaft of the paper feeding roller, and a gear train 32 for rotating the pick-up roller and the paper feeding roller in the same direction in the interlocking relationship. The pick-up roller and the paper feeding roller are formed to have substantially the same length in the axial direction and are arranged at substantially the same position in the axial direction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a paper feed unit that feeds a document placed on a paper feed tray to a reading position by a line sensor while separating the documents one by one, and an automatic document feeder and an image forming apparatus including the same.

  In a scanner device, a facsimile machine, a copying machine, and a multifunction machine, in order to improve the efficiency of reading a document, the document placed on the paper feed tray is separated one by one and conveyed to a reading position by a line sensor. Automatic document feeders are widely used.

In this type of automatic document feeder, a pickup roller that comes into contact with the paper surface of a document placed on a paper feed tray and draws the document, and conveys the drawn document toward a reading position by a line sensor. There is known one having a paper feeding unit including a paper feeding roller (see, for example, Patent Document 1).
JP 11-35173 A

  However, in the conventional technique, when the paper feed speed is increased for speeding up the processing, the stability of the document transport by the pickup roller and the paper feed roller is lowered, and the document is skewed. In this case, an increase in the number of parts and an increase in the size of the paper feed unit are undesirable because the manufacturing cost increases. .

  The present invention has been devised to solve such problems of the prior art, and its main purpose is to improve the stability of document conveyance without increasing the number of parts and increasing the size of the unit. An object of the present invention is to provide a paper feeding unit configured to improve and stably convey a document even when the paper feeding speed is increased, and an automatic document feeder and an image forming apparatus provided with the paper feeding unit.

  In order to solve such a problem, according to the present invention, as shown in claim 1, a pickup roller that draws an original placed on a paper feed tray into the inside, and an image reading unit that draws the original drawn thereby A paper feed roller that conveys the paper toward the paper, a connection holding member that rotatably connects and holds the pickup roller and the paper feed roller, and a rotational force that acts on a support shaft of the paper feed roller. A pressing means that press-contacts the pickup roller, and an interlocking mechanism that interlocks and rotates the pickup roller and the sheet feeding roller in the same direction, and the pickup roller and the sheet feeding roller are formed to have substantially the same axial length. In addition, they are arranged at substantially the same position in the axial direction.

  According to this, since the conveyance force acting on the document from the pickup roller and the paper feed roller is substantially equal between the pickup roller and the paper feed roller, the document can be stably conveyed even if the paper feed speed is increased. become.

  In particular, as shown in claim 2, a one-way clutch that allows rotation of the pickup roller in the conveying direction with respect to the interlocking mechanism can be accommodated in the pickup roller. According to this, it is possible to ensure a large axial length of the pickup roller without increasing the size of the unit. Further, if a part of the components of the one-way clutch is formed integrally with the components of the pickup roller, the number of components can be reduced.

  As described above, according to the present invention, the stability of document conveyance is improved, and the document can be stably conveyed even when the paper feeding speed is increased. Therefore, the processing speed is increased and the convenience is improved. This has a great effect, and further reduces the number of components and avoids an increase in the size of the paper feed unit, and thus has a great effect in suppressing an increase in manufacturing cost.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is an overall front view showing in cross section the main parts of an image forming apparatus to which the present invention is applied. The image forming apparatus includes a document reading unit (automatic document feeder) 1 that reads an image of a document for each function of facsimile communication, copying, and scanner, at the top of the casing. The document reading unit 1 can also be configured as a scanner device that sends read image data to an information processing device such as a PC.

  The document reading unit 1 is pulled in by a reading sensor (line sensor) 11, a paper feed tray 12 on which the document A is placed, a pickup roller 13 that pulls the document A on the paper feed tray 12 into the inside. A paper feed roller 14 that feeds the document A to the transport path defined by the guide member 17 and a transport roller 15 that transports the document A sent to the transport path along the transport path thereby. The line sensor 11 reads an image of the original while conveying the original along the path. The document that has been read by the line sensor 11 is discharged onto a discharge tray 19 by a discharge roller 18.

  FIG. 2 is a cross-sectional view showing in detail the document feeder in the image forming apparatus shown in FIG. The pickup roller 13 and the paper feed roller 14 are rotatably connected and held by a pickup bracket (connection holding member) 21. The pickup bracket 21 has a metal shaft 22 that serves as a support shaft of the paper supply roller 14. The pickup roller 13 can be moved up and down. A guide member 24 is provided below the pickup roller 13 to guide the leading end portion of the document placed on the paper feed tray. The document A is pressed against the guide member 24 by the lowered pickup roller 13, and the pickup is picked up. As the roller 13 rotates, the uppermost document A is drawn.

  A separation roller 26 for separating the document A into a single sheet is disposed below the sheet feed roller 14, and the separation roller 26 is attached to a lever member 28 provided to be rotatable around a support shaft 27. It is held and urged by a spring 29 in a direction in which it is pressed against the paper feed roller 14. Further, the separation roller 26 is fixed to the lever member 28 via a torque limiter (not shown), and when two originals drawn by the pickup roller 13 are overlapped, the lower original is stopped and the lower original is sent. If one document is pulled in by the pickup roller 13, the document is rotated by following the document fed by the paper feed roller 14.

  A document stopper 31 is disposed between the pickup roller 13 and the paper feed roller 14 so that the leading edge of the document A placed on the paper feed tray is abutted. The tip portion is defined at a position where the pickup roller 13 can be pulled in uniformly. The document stopper 31 is pulled upward when the pickup roller 13 is rotated to pull the document A.

  The pickup roller 13 and the paper feed roller 14 are configured to rotate in the same direction by a gear train (interlocking mechanism) 32 provided inside the pickup bracket 21.

  3 is a perspective view of the paper feeding unit shown in FIG. The pickup roller 13, the sheet feeding roller 14, the pickup bracket 21, and the shaft 22 are assembled together to form the sheet feeding unit 20.

  A gear 33 that transmits the rotational force of a motor (not shown) to the shaft 22 is connected to the end portion of the shaft 22 serving as a support shaft of the paper feed roller 14 so as not to be relatively rotatable. Further, feed levers 34 are provided at both ends of the shaft 22 so as not to move in the axial direction. The feed lever (support member) fixes the shaft 22 to a bearing portion 34a for the shaft 22 and a frame (not shown). And a mounting portion 34b.

  In addition, a torque limiter 36 and a connecting collar 37 are externally mounted on the shaft 22, and the shaft 22 is connected to the inner ring portion of the torque limiter 36 so as not to be relatively rotatable. A connecting collar is provided on the outer ring portion of the torque limiter 36. The pick-up bracket 21 is connected to the non-rotatable portion 37 through 37.

  The pickup bracket 21 is engaged with a torsion coil spring 35 that is externally attached to the connecting collar 37. This is because when the cover body to which the paper feeding unit 20 is attached is opened for maintenance or the like. In addition, the pickup bracket 21 is held in a lifted state with the gear 33 at the end of the shaft 22 disengaged from a gear on the drive motor side (not shown).

  4 is a cross-sectional view of the paper feed unit shown in FIG. The paper feed roller 14 is obtained by inserting a core material 39 made of a synthetic resin into a roller main body 38 made of a cylindrical rubber material capable of securing a large frictional force with a document. The pickup roller 13 is also the same. A core material 46 made of synthetic resin is inserted into a roller body 47 made of a cylindrical rubber material.

  A one-way clutch 41 is provided at one end of the paper feed roller 14 in the axial direction. The one-way clutch 41 prevents the paper feed roller 14 from rotating relative to the shaft 22 in the reverse conveyance direction, and the paper feed roller 14. Relative rotation in the conveying direction with respect to the shaft 22 is allowed. The other end in the axial direction of the paper feed roller 14 is provided with a gear 40 that meshes with the gear at the end of the gear train (interlocking mechanism) 32, and acts on the paper feed roller 14 from the shaft 22 via the one-way clutch 41. The rotational force is transmitted to the gear train (interlocking mechanism) 32.

  At one end in the axial direction of the pickup roller 13, a pickup gear 43 and a one-way ratchet 44 are provided in a state of being covered by a metal support shaft 23. The pickup gear 43 meshes with the gears at the end of the gear train (interlocking mechanism) 32 and rotates in conjunction with these gears. The one-way ratchet 44 has claws arranged in the circumferential direction at the end in the axial direction, and a ratchet portion 45 having claws that mesh with the claws of the one-way ratchet 44 is formed in the core portion 46 of the pickup roller 13. The pickup gear 43, the one-way ratchet 44, and the ratchet part 45 constitute a one-way clutch 48.

  FIG. 5 is an exploded perspective view of the one-way clutch provided on the pickup roller shown in FIG. The one-way ratchet 44 has a hole through which the support shaft 23 is inserted at the center, and a claw 51 that forms a ratchet is formed at the end in the axial direction. A cylindrical recess 57 for accommodating the one-way ratchet 44 is formed in the core portion 46 of the pickup roller 13, and a ratchet portion 45 (having a claw that meshes with the claw 51 of the one-way ratchet 44 is formed at the bottom thereof. 4).

  By accommodating most of the one-way clutch 48 in the pickup roller 13 in this way, the axial length of the pickup roller 13 can be secured large without increasing the size of the paper feed unit 20. Furthermore, since the ratchet portion 45 constituting the one-way clutch 48 is integrally formed with the core portion 46 of the pickup roller 13 with a synthetic resin material, the number of parts can be reduced and the number of assembly steps can be reduced.

  Further, in this one-way ratchet 44, an inclined surface 52 in which the axial distance from the reference surface of the claw 51 gradually changes is formed on the side opposite to the claw 51, and the circumferential end of the inclined surface 52 is formed. Restriction surfaces 53 and 54 are formed in the axial direction.

  The pickup gear 43 includes a protrusion 55 protruding in the axial direction on a surface facing the one-way ratchet 44, and when the protrusion 55 is in contact with one regulating surface 53 of the one-way ratchet 44, the shaft of the one-way ratchet 44 is The displacement in the direction is restrained, and the claw 51 of the one-way ratchet 44 is held in a state of being engaged with the ratchet portion on the pickup roller 13 side. On the other hand, when the projection 55 is in contact with the other regulating surface 54, the one-way ratchet 44 is allowed to be displaced in the axial direction, and the claw 51 of the one-way ratchet 44 is in a free state where it does not mesh with the ratchet portion on the pickup roller 13 side. .

  Here, when the pickup gear 43 rotates forward with respect to the one-way ratchet 44, the protrusion 55 of the pickup gear 43 abuts against one regulating surface 53 of the one-way ratchet 44 to engage the one-way ratchet 44 in the axial direction. On the contrary, when the pickup gear 43 rotates reversely with respect to the one-way ratchet 44, the protrusion 55 of the pickup gear 43 abuts against the other restricting surface 54 to allow the one-way ratchet 44 to be displaced in the axial direction. Thus, it functions as a one-way clutch that allows reverse rotation of the pickup gear 43 with respect to the one-way ratchet 44.

  In the paper feeding unit configured as described above, when a rotational force in the positive direction acts on the shaft 22 as shown in FIG. 3, the rotational force is transmitted to the pickup bracket 21 via the torque limiter 36. As a result, a rotational force is generated in the pickup bracket 21 so as to press the pickup roller 13 against the paper surface of the document A, and the pickup roller 13 presses the document A with a pressing force corresponding to the limit torque of the torque limiter (pressing means) 36. wear.

  The rotational force of the shaft 22 acts on the paper feed roller 14 via the one-way clutch 41 built in the paper feed roller 14, and at this time, the one-way clutch 41 performs relative rotation of the paper feed roller 14 relative to the shaft 22 in the reverse conveyance direction. In order to constrain, the paper feed roller 14 rotates in conjunction with the shaft 22 and feeds the document A.

  Further, the rotational force of the paper feed roller 14 acts on the pickup roller 13 via the gear train 32 and the one-way clutch 48 (see FIG. 4). At this time, the one-way clutch 48 rotates in the reverse conveyance direction of the pickup roller 13 with respect to the gear train 32. Therefore, the pickup roller rotates in conjunction with the paper feed roller 14 and pulls the document.

  On the other hand, when a reverse rotational force acts on the shaft 22, the rotational force is transmitted to the pickup bracket 21 via the torque limiter 36, and a rotational force that lifts the pickup roller 13 upward is generated in the pickup bracket 21. The pick-up bracket 21 is rotated by the rotational force, and the pick-up roller 13 is raised so that the original can be set.

  When the document reaches the transport roller 15 shown in FIG. 1 after the document A is sent to the transport path, the transport roller 15 transports the document at a higher speed than the paper feed roller 14. Since the one-way clutch 41 and the one-way clutch 48 allow relative rotation in the transport direction, the pickup roller 13 follows the document A and rotates with it.

  FIG. 6 is a conceptual diagram showing a state of feeding a document by the pickup roller and the paper feed roller shown in FIG. The pickup roller 13 and the paper feed roller 14 are arranged at the center in the width direction of the document A, are formed to have substantially the same axial length, and are arranged at substantially the same position in the axial direction. For this reason, the areas where the conveying forces of the pickup roller 13 and the paper feeding roller 14 are applied are aligned in the width direction, and the pressure contact state of the pickup roller 13 and the paper feeding roller 14 with respect to the paper surface of the document A due to the shakiness of the support shaft. Even if there is a change, the conveying force acting on the original from the pickup roller 13 and the paper supply roller 14 is substantially equal between the pickup roller 13 and the paper supply roller 14, so that the original A can be stably maintained even if the paper supply speed is increased. Can be conveyed.

  The sheet feeding unit and the automatic document feeding apparatus and image forming apparatus provided with the same improve the stability of document conveyance and increase the feeding speed without increasing the number of parts and the size of the unit. The sheet feeding unit has an effect of stably conveying the document even if it is raised, and includes a sheet feeding unit that feeds the document placed on the sheet feeding tray to the reading position by the line sensor while separating the documents one by one. It is useful as an automatic document feeder and an image forming apparatus.

1 is an overall front view showing in cross section the main part of an image forming apparatus to which the present invention is applied. FIG. 2 is a cross-sectional view showing in detail a document feeder in the image forming apparatus shown in FIG. FIG. 2 is a perspective view of the paper feeding unit shown in FIG. Sectional view of the paper feeding unit shown in FIG. 4 is an exploded perspective view of a one-way clutch provided on the pickup roller shown in FIG. FIG. 4 is a conceptual diagram showing a state of feeding a document by a pickup roller and a paper feed roller shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Document reading part 11 Line sensor 12 Paper feed tray 13 Pickup roller 14 Paper feed roller 15 Carrying roller 20 Paper feed unit 21 Pickup bracket (connection holding member)
22 Shaft (support shaft)
26 Rolling roller 32 Gear train (interlocking mechanism)
36 Torque limiter (pressing means)
41 One-way clutch 48 One-way clutch A Document

Claims (4)

A pickup roller that draws an original placed on the paper feed tray into the inside, a paper feed roller that conveys the drawn original toward the image reading means, and the pickup roller and the paper feed roller are rotatable. A connecting and holding member for connecting and holding, a pressing means that presses the pickup roller against the paper surface of the document by a rotational force acting on a support shaft of the paper feeding roller, and the pickup roller and the paper feeding roller are rotated in the same direction. An interlocking mechanism,
The paper feed unit, wherein the pickup roller and the paper feed roller are formed to have substantially the same axial length and are arranged at substantially the same position in the axial direction.   The sheet feeding unit according to claim 1, wherein a one-way clutch that allows rotation of the pickup roller in the conveyance direction with respect to the interlocking mechanism is housed inside the pickup roller.   An automatic document feeder comprising the paper feed unit according to claim 1.   An image forming apparatus comprising the paper feeding unit according to claim 1.

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