JP5587461B2 - Sheet feeding device, scanner, printer, facsimile, and copying machine - Google Patents

Description

  The present invention relates to a sheet feeding apparatus that is used in, for example, a scanner, a facsimile machine, a copying machine, a printer, and the like and separates and feeds sheets such as originals one by one.

  FIG. 10 shows a scanner provided with a conventional sheet feeding apparatus.

  The sheet feeding apparatus shown in FIG. 10 includes a pickup roller 102 that abuts against the upper surface of a bundle of documents (sheets) stacked on the sheet feed tray 101 and feeds the documents in the transport direction. The document 100a sent out by the pickup roller 102 is separated one by one by the feeding roller 104 and the separation roller 105 and fed to the conveyance path.

  Between the feed roller 104 and separation roller 105 and the registration roller pair 115, a double feed detecting means 107 for detecting double feed of the original is disposed.

  In the conventional sheet feeding apparatus, when the double feed detection unit 107 detects double feed of a document, generally, the document fed by the pickup roller 102 is separated and fed one by one by the feed roller 104 and the separation roller 105. Stop operation and issue a warning of double feed. The operator re-feeds the document that has been double-feeded based on this warning or the like to prevent image loss.

  However, if double feeding of originals occurs in the image reading process, paper feeding stops, and the operator needs to remove the double fed originals or check whether the originals being read remain in the device. There is.

  In addition, since the operation of the scanner is temporarily stopped every time a document double feed occurs, a reduction in operating rate is inevitable. For this reason, work efficiency is greatly reduced when a large amount of documents are processed.

  In order to eliminate such inconvenience, when a double feed of a document is detected, the document feed operation is once stopped, the double fed document 100a is automatically returned to the paper feed tray 101 side, and a separate feed operation is performed again. There has been proposed a scanner that performs a return operation.

  In such a scanner, after detecting the double feed of the document, the feed roller 104 is rotated in a direction opposite to the document feed direction, and the separation roller 105 is rotated in the document separation direction to perform double feed. Documents can be returned to the paper feed tray 101 side.

  Between the feed roller 104 and a driving means (not shown) that drives the feed roller 104, the feed roller 104 is subjected to a transport load when the document reaches the downstream transport roller and is transported. In order to prevent this, a one-way clutch 501 is provided.

  For this reason, even if the driving means is rotated in the reverse direction so as to drive the feeding roller 104 in the reverse direction, the driving torque is not transmitted to the feeding roller 104, and the force for returning the document to the feeding tray 101 side is from the separation roller 105. Only the transfer force that can be transmitted.

  On the other hand, the separation roller 105 includes torque transmission means 502 such as a torque limiter and a spring clutch for applying a constant torque in a direction opposite to the document feeding direction. This is communicated via means 502.

  For this reason, when returning a double-fed document to the paper feed tray 101 side, the conveying force of the separation roller 105 is limited by the sliding force of the torque limiter or the spring clutch, and a sufficient conveying force may not be obtained.

  Therefore, a rotation member having a protrusion on the same axis as the separation roller 105 is provided, and the rotation member is driven to rotate in a direction opposite to the document feeding direction, whereby the document fed by the protrusion is overlapped with the sheet feed tray 101. A technique for returning to the side has been proposed (Patent Document 1).

  However, in this proposal, it is necessary to individually control the driving of the separation roller 105 and the rotating member, and since only the protruding portion of the rotating member is in contact with the document, a sufficient conveying force can be obtained. Absent.

  In addition, as shown in FIG. 11, comb-like uneven portions are formed on the outer peripheral portions of the feeding roller 201 and the separation roller 202, and the concave portion and the convex portion of the feeding roller 201 are formed into the convex portion and the concave portion of the separation roller 202. There has been proposed a non-contact arrangement arranged so as to overlap each other in the axial direction (Patent Document 2).

  In this proposal, as shown in FIG. 12, the feeding roller 201 rotates in the feeding direction, the separation roller 202 rotates in the direction opposite to the feeding direction, and the shaft between the feeding roller 201 and the separation roller 202 is rotated. Move closer or away. Thus, the amount of overlap between the concave portion and the convex portion is changed, and the originals fed in the transport direction by the pickup roller 102 are separated and fed one by one.

  In this case, the separation roller 202 always rotates in the direction reverse to the feeding direction of the document, and a sufficient rotational torque in the direction opposite to the feeding direction can be ensured. Since it is not in contact with the separation roller 202, a sufficient document feeding force cannot be obtained.

  Therefore, in such a configuration, the pickup roller 102 compensates the feeding force of the document that is separated and fed by the feeding roller 201 and the separation roller 202.

  However, since the pickup roller 102 is retracted when the document fed by the feeding roller 201 and the separation roller 202 is transported to the paper feed tray 101 side after the document double feed is detected, a sufficient transport force is obtained. Can't get.

  Further, as shown in FIG. 13, one using a feeding roller 104 and a separating pad member 301 has been proposed.

  In this proposal, even if it is attempted to reverse the feed roller 104 so as to return the document to the paper feed tray 101 side after detecting the double feed of the document, in most cases, the feed roller 104 has a built-in one-way clutch or the like. Therefore, the feed roller 104 cannot be reversed.

  In some cases, the image reading unit 116 may read an original document with an envelope or a sticky note attached thereto.

  For a document having such an overlapped portion, as shown in FIG. 14, the double feed detecting means 107 provided at the center position in the width direction of the transport path is used for double feed even if the normal document is transported. Will be detected. Therefore, when transporting a document or the like with a sticky note attached, it is necessary not to detect double feeding of the document at the position where the sticky note is attached.

  In order to solve this, as shown in FIG. 15, an apparatus has been proposed in which a plurality of double feed detection means 107 are arranged in the width direction of the transport path.

  In this proposal, an area for detecting double feed is set in advance, and a plurality of double feed detection means 107 are arranged in the width direction of the transport path so that a sticky note can be pasted even on a sticky note. It is possible to prevent detection of a double feed of a document at the attached position.

  In addition, since it is possible to detect the double feed of the document at a plurality of positions where the double feed detection unit 107 is arranged, it is possible to detect the double feed of the document even when documents of different sizes are mixedly loaded on the paper feed tray 101. It becomes.

  For example, as shown in FIG. 15, even when a document 100a having a small size is mixed with the document 100a having a small size being mixed and fed together, it is possible to detect double feed, Paper jams can be prevented.

  However, in the case of such a double-fed document, the feeding is performed when the double-fed document is detected by the feeding roller 104 and the separation roller 105 and then returned to the paper feed tray 101 side. In some cases, the roller 104 and the separation roller 105 may not contact a small document that has been double-fed.

  When the original returning operation is performed in such a state, when the large document in contact with the feeding roller 104 and the separation roller 105 is returned to the paper feed tray 101 side, the small document on the size is smaller than the original. The large original is taken back to the paper feed tray 101 side.

  In this case, if a small-size document comes into contact with the transport guide or the like and is prevented from moving to the paper feed tray 101 side, the small-size document may be left in the transport path. This may cause paper jams and document damage.

Japanese Patent Laid-Open No. 2-147533 Japanese Patent No. 3262664

  The present invention has been made to solve the above-described inconveniences, and provides a sheet feeding apparatus capable of sufficiently obtaining a conveying force for returning a plurality of multi-fed sheets to the stacking table side. The purpose is to do.

In order to achieve the above object, a sheet feeding apparatus according to the present invention includes a stacking table on which sheets are stacked, a feeding member that feeds a sheet on the loading table to a conveyance path, and the feeding member. A separation member that separates the sheets fed to the conveyance path one by one, and a overlap that is provided on the downstream side of the feeding member in the sheet feeding direction and detects double feeding of the sheets fed to the conveyance path. A return roller disposed between the feed detection unit, the feeding member and the double feed detection unit, and returning the double fed sheet toward the stacking base in a double fed state; and the return roller A return driven roller that is disposed opposite to and rotates with the rotation of the return roller, a drive unit that rotates the return roller in a direction opposite to the sheet feeding direction, and the double-feed detection unit is a sheet When a double feed is detected, the return The The feeding direction of the sheet and control means for controlling said drive means so as to rotated toward the opposite direction, said the feed member and the return roller, the sheet feeding of the returning roller An end portion corresponding to the upstream side in the direction is arranged so as to overlap the feeding member in the rotation axis direction .
Further, the sheet feeding device of the present invention is fed to the transport path by a stacking table on which sheets are stacked, a feeding member that feeds a sheet on the stacking table to the transport path, and the feeding member. A separating member that separates the sheets to be conveyed one by one, a multi-feed detection unit that is provided downstream of the feeding member in the sheet feeding direction, and detects double feeding of the sheets fed to the conveyance path, A return roller disposed between the feeding member and the double feed detection means, and a return roller for returning the double fed sheet toward the stacking base in a double fed state, and disposed opposite to the return roller, A return driven roller that rotates as the return roller rotates, a drive unit that rotates the return roller in a direction opposite to the sheet feeding direction, and the double feed detection unit detects double feed of the sheet. When the return roller is in the sheet feeding direction Control means for controlling the driving means so as to rotate in the reverse direction, and the return roller is movable between a position contacting the sheet and a position retracting from the sheet It is characterized by.

  ADVANTAGE OF THE INVENTION According to this invention, the sheet | seat supply apparatus which can fully obtain the conveyance force for returning the several sheet | seat which carried double feeding to the loading stand side can be provided.

FIG. 3 is a cross-sectional view for explaining the sheet feeding apparatus according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view for explaining a scanner including the sheet feeding device in FIG. 1. FIG. 10 is a cross-sectional view for explaining a state in which the return roller is in press contact with a fed document with a constant load. FIG. 6 is a cross-sectional view for explaining a state in which a plurality of documents fed in a double feed are returned to the paper feed tray side. FIG. 10 is a plan view for explaining an operation of returning a plurality of double-fed documents to the paper feed tray side. It is sectional drawing for demonstrating the sheet feeding apparatus which is the 2nd Embodiment of this invention. It is sectional drawing for demonstrating the sheet feeding apparatus which is the 3rd Embodiment of this invention. FIG. 10 is a plan view for explaining a sheet feeding apparatus according to a fourth embodiment of the present invention. FIG. 6 is a plan view for explaining a state in which a return roller comes into contact with a document when documents of different sizes are brought close to each other and double-fed. It is sectional drawing for demonstrating the scanner provided with the conventional sheet feeding apparatus. It is a perspective view for demonstrating the conventional feed roller and separation roller in which the comb-shaped uneven | corrugated | grooved part was formed in the outer peripheral part. FIG. 12 is a cross-sectional view for explaining a sheet feeding apparatus including the conventional feeding roller and separation roller shown in FIG. 11. It is sectional drawing for demonstrating the conventional sheet feeding apparatus provided with a feeding roller and the pad member for isolation | separation. FIG. 10 is a plan view for explaining a conventional sheet feeding apparatus in which a multifeed detection unit is arranged at a center position in a width direction of a conveyance path. FIG. 10 is a plan view for explaining a conventional sheet feeding apparatus in which a plurality of double feed detection units are arranged in the width direction of a conveyance path.

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

(First embodiment)
FIG. 1 is a sectional view for explaining a sheet feeding apparatus according to a first embodiment of the present invention, and FIG. 2 is a sectional view for explaining a scanner including the sheet feeding apparatus of FIG.

  As shown in FIGS. 1 and 2, a sheet feeding apparatus according to the present embodiment includes a sheet feeding tray (stacking table) 101, a pickup roller 102, a feeding roller (feeding member) 104, and a separation roller (separating member) 105. , A double feed detecting means 107 and a return roller 108.

  The pickup roller 102 abuts on the upper surface of the original (sheet) bundle 100 stacked on the paper feed tray 101 and sends out the original 100 a in the transport direction. The pickup roller 102 is rotatably supported by a swing arm 103, and the swing arm 103 is swingably supported by a support shaft 103a.

  The document 100a sent out by the pickup roller 102 is separated one by one by the feeding roller 104 and the separation roller 105 and fed to the conveyance path. Above and below the conveyance path, a conveyance guide 113 is provided that guides the document along the conveyance path while regulating the posture of the document conveyed on the conveyance path.

  Between the feed roller 104 and separation roller 105 and the registration roller pair 115, a double feed detecting means 107 for detecting double feed of the original is disposed.

  As the double feed detection means 107, an optical double feed detection sensor such as a transmission type optical sensor for detecting double feed based on a change in the amount of light transmitted between a single document and a plurality of documents is known. In addition, the double feed detecting means 107 is provided with an ultrasonic transmitter and a receiver with the document conveyance path in between, and the attenuation of the ultrasonic wave when the original is being fed is used as a reference. In addition, there is known an ultrasonic double feed detection sensor that determines double feed when an attenuation greater than this is detected.

  A registration sensor 106 is disposed between the feeding roller 104 and the separation roller 105 and the double feed detection unit 107. Based on a document detection signal from the registration sensor 106, a control unit (not shown) detects the next document. The paper feed timing is determined.

  A pair of shafts that are rotationally driven in opposite directions with respect to the document feeding direction on both ends in the axial direction of the feeding roller 104 (both sides in the width direction of the sheet orthogonal to the sheet feeding direction). The return roller 108 is disposed at a substantially symmetrical position.

  As shown in FIG. 5, the pair of return rollers 108 is located near the feeding roller 104 in the sheet feeding direction, that is, substantially at the same position as the axis thereof, as viewed from the axial direction. It is arranged to overlap. Note that the pair of return rollers 108 may be disposed on the upstream side of the conveyance path with respect to the axis of the feed roller 104.

  The pair of return rollers 108 is rotatably supported by the arm 109 via a support shaft 109a, and the arm 109 is a position where the return roller 108 contacts the document according to the state of the fed document. And a retreat position.

  A driving pulley 110a driven by driving means (not shown) is attached to the arm 109, and the rotational driving force of the driving pulley 110a is transmitted to the driven pulley 110c attached to the return roller 108 via the timing belt 110b. The As a result, the return roller 108 is rotationally driven in a direction opposite to the document feeding direction.

  The arm 109 has a position where the return roller 108 comes into contact with the document by the cam action of the rotation lever 111 in a state where the return roller 108 is urged by the tension coil spring 112 in a direction to contact the document with a constant load. It swings to a position where it is retracted from the document.

  That is, the arm 109 is disposed at a position where the return roller 108 is retracted from the fed document by cam-engaging with the rotation lever 111 when the document is normally separated and fed.

  In this state, when the rotation lever 111 rotates and the cam engagement with the arm 109 is released, the arm 109 is fixed to the original fed with the return roller 108 by the urging force of the tension coil spring 112. It swings to a position where it makes a pressing contact with a load (see FIG. 3). Note that the rotation control of the rotation lever 111 and the drive means of the drive pulley 110a are controlled by a control means (not shown).

  A return driven roller 114 is disposed at a position facing the return roller 108 across the conveyance path. The return driven roller 114 is rotatably supported by the conveyance guide 113. On the downstream side of the registration roller pair 115, an image reading unit 116 for reading an image of a document conveyed on the conveyance path by photoelectric conversion and taking it as image data is disposed. The document whose image has been read by the image reading unit 116 is discharged to the paper discharge tray 119 via the conveyance roller pair 117 and the paper discharge roller pair 118.

  Next, a series of operation examples of the scanner configured as described above will be described. A series of operations of the scanner described here is performed by loading a control program stored in a storage unit (not shown) (ROM, hard disk, etc.) into a RAM (not shown), and then by a control unit (CPU, etc.) not shown. Executed.

  First, when an image reading command is input from an external device such as a PC (not shown), the control means controls the drive mechanism (not shown) of the swing arm 103 and the pickup roller 102 to move the pickup roller 102 in FIG. Move in the direction of arrow a and rotate. As a result, the pickup roller 102 comes into contact with the upper surface of the original bundle 100 loaded on the paper feed tray 101, and the operation of feeding out the original is started.

  The documents sent out by the pickup roller 102 are separated one by one by a feeding roller 104 and a separation roller 105 driven by the control of the control means, and fed to the conveyance path.

  Here, the drive shaft of the feed roller 104 and the feed roller 104 are connected via a one-way clutch (not shown). When the conveyance speed of the document conveyed by the registration roller pair 115 becomes faster than the document feeding speed by the feeding roller 104, the feeding roller 104 is rotated with the conveyed document.

  The separation roller 105 is driven in a direction opposite to the document feeding direction via a torque limiter (not shown). When a torque exceeding the torque that can be transmitted by the torque limiter is applied, the separation roller 105 moves in the document feeding direction. Take around.

  In this state, the control means controls the rotation position of the rotation lever 111 so that the rotation lever 111 is cam-engaged with the arm 109, and the outer periphery of the return roller 108 is located on the upper side as shown in FIG. Is retracted to a position substantially on the same plane as the transport guide 113.

  Here, when the return roller 108 is retracted to a position above the conveyance guide 113, the document may be caught in a hole at a position corresponding to the return roller 108 of the conveyance guide 113, so the return roller 108 is retracted. It is necessary to cover the hole later with another member. In this case, the number of parts increases, the structure becomes complicated, and the cost increases.

  On the other hand, the return roller 108 is generally made of a material having a high coefficient of friction such as rubber in order to secure the conveying force of the document. If the document comes into contact with the retracted position, a large load is applied to the document. Or a paper jam.

  For this reason, when a normal document feeding operation is performed, the return roller 108 is retracted to the position of the conveyance guide 113 and rotated in the same direction and at the same peripheral speed as the feeding roller 104 to convey the document. It is preferable to have a guiding function.

  Next, when the original document separated and fed to the conveyance path is conveyed to the registration sensor 106, the control unit controls the drive mechanism based on the original detection signal from the registration sensor 106 to move the pickup roller 102 to the original document. The swing arm 103 is moved so as to be retracted. As a result, the delivery of the next document is stopped.

  Next, the control means determines whether or not the document is being double fed based on the detection signal from the double feed detection means 107. If it is determined that the document is not double-fed, the control unit continues to transport the document, and after the document reaches the registration roller pair 115, the control unit transports the document to the image reading unit 116 at a constant speed. Then, the image reading unit 116 reads the image of the document.

  The document that has passed through the image reading unit 116 is discharged to the discharge tray 119 by the conveyance roller pair 117 and the discharge roller pair 118. By performing the above operation for each original document, all images of the original document loaded on the paper feed tray 101 are read by the image reading unit 116.

  On the other hand, when the control unit determines that the document is being double-fed based on the detection signal from the double-feed detection unit 107, the control unit performs the separation / feed operation of the document by the feed roller 104 and the separation roller 105. The drive system of each roller 104, 105 is controlled so as to stop once.

  At this time, the multiple fed originals are stopped on the conveyance path, and the originals fed to the conveyance path before that are read by the image reading unit 116 in the same manner as described above, and then the conveyance roller pair The paper is discharged to a paper discharge tray 119 via 117 and a paper discharge roller pair 118.

  Next, the control means controls the rotation position of the rotation lever 111 so that the cam engagement between the rotation lever 111 and the arm 109 is released. As a result, the arm 109 is rotated counterclockwise in FIG. 3 by the urging force of the tension coil spring 112, and a plurality of documents fed by the return roller 108 are sandwiched between the return driven roller 114. Thus, the original is pressed against the original with a constant load.

  The control unit then feeds the plurality of documents fed in the double direction to the position shown in FIG. 4 toward the paper feed tray 101 (in the direction indicated by the arrow d in FIG. 5). And control the drive system. Accordingly, the rollers 104, 105, and 108 are rotated in the direction opposite to the document feeding direction. As a result, it is possible to obtain a sufficient conveying force for returning the multiple fed documents to the paper feed tray 101 side.

  At this time, the multiple fed originals pass through the double feed detecting means 107 or the registration sensor 106, and are then conveyed and stopped for a predetermined time or a predetermined rotation amount of the drive motor of the return roller 108, for example.

  Regardless of whether or not the document double feed is detected, the control means rotates the return roller 108 in the direction opposite to the document feeding direction, and the arm 109 rotates the return roller 108. You may make it contact or retract.

  After returning the multiple fed originals to the paper feed tray 101, the control unit controls the rotation position of the rotation lever 111 so that the rotation lever 111 is cam-engaged with the arm 109. As a result, the outer peripheral portion of the return roller 108 is retracted to a position substantially on the same plane as the upper conveyance guide 113.

  Then, the control means drives the drive system such as the pickup roller 102, the feed roller 104, and the separation roller 105 so that the document returned to the paper feed tray 101 is again separated and fed to the conveyance path in the same manner as described above. To control.

  In the present embodiment, the operation of returning a plurality of documents fed to the paper feed tray 101 and the subsequent separation and feeding operation of the documents are repeatedly performed up to a predetermined number of times (for example, a preset number). .

  If the double feed detection means 107 detects the double feed of the originals even if the upper limit number of times is exceeded, the control means conveys the multiple fed originals to the paper discharge roller pair 118 and discharges the pair of paper discharge rollers. Control is performed so as to stop in a state of being sandwiched by 118. As a result, the operator can be surely notified which document has been double fed, and the operator can be urged to manually return the document fed to the paper feed tray 101.

  As described above, in the present embodiment, when double feeding of originals occurs, a plurality of double fed originals are automatically returned to the paper feed tray 101 side and separation feeding is automatically attempted again. As a result, it is possible to prevent image data from being lost due to double feeding of documents. In addition, since the return roller 108 is provided at an appropriate position, it is possible to reliably prevent troubles such as document breakage due to the failure to return a plurality of documents that have been double-fed to the sheet feed tray 101 side, and document processing capability. Can be increased.

  In addition, since the pair of return rollers 108 are arranged symmetrically on both ends in the axial direction of the feed roller 104, it is ensured that the narrow document is shifted to the paper feed tray 101 side even if it is fed one by one. Can be returned.

(Second Embodiment)
Next, a sheet feeding apparatus according to the second embodiment of the present invention will be described with reference to FIG. In addition, about the part which overlaps with the said 1st Embodiment, the same code | symbol is attached | subjected to a figure and the description is abbreviate | omitted. In this embodiment, since the feeding roller 201 and the separation roller 202 already described with reference to FIGS. 11 and 12 are used, the description will be made with reference to FIGS. 11 and 12.

  As shown in FIG. 11, the sheet feeding apparatus according to the present embodiment has comb-like uneven portions formed on the outer peripheral portions of the feeding roller 201 and the separation roller 202, and the concave portion and the convex portion of the feeding roller 201 are separated. It arrange | positions so that the convex part and recessed part of the roller 202 may mutually overlap in an axial direction without contact. The feed roller 201 is driven to rotate in the feed direction, and the separation roller 202 is driven to rotate in the direction opposite to the feed direction, and the shafts of the feed roller 201 and the separation roller 202 are moved closer to and away from each other. This is performed by a mechanism (not shown).

  As shown in FIG. 12, the originals stacked on the paper feed tray 101 are sent out in the transport direction by the pickup roller 102 as in the first embodiment.

  Here, the control means controls a moving mechanism (not shown) so as to adjust the distance between the axes of the feeding roller 201 and the separation roller 202 to move the feeding roller 201. As a result, the distance between the axes of the feeding roller 201 and the separation roller 202 becomes a distance suitable for passing one document.

  When the control unit detects that the document has passed between the rollers 201 and 202 using the registration sensor 106 or the like, the control unit stops the operation of adjusting the inter-axis distance and fixes the inter-axis distance at that time. .

  Next, when the control unit determines that the document is not double-feeded based on the detection signal from the double-feed detection unit 107, the control unit moves to the registration roller pair 115 while supplementing the document feeding force by the pickup roller 102. Be transported.

  By performing the above operation for each original document, all the originals stacked on the paper feed tray 101 can be read by the image reading unit 116. When a document having a constant thickness is stacked on the sheet feeding tray 101 and an image of the document is read by the image reading unit 116, the distance between the axes of the feeding roller 201 and the separation roller 202 is adjusted for each sheet. Instead, the document may be separated and fed at fixed intervals.

  On the other hand, when the control unit determines that the document is being double-fed based on the detection signal from the double-feed detection unit 107, the control unit performs the separation / feed operation of the document by the feed roller 201 and the separation roller 202. The drive system of each roller 201, 202 is controlled so as to stop once.

  At this time, a plurality of documents that have been multi-fed are stopped on the conveyance path, and the document that has been fed to the conveyance path before that is read by the image reading unit 116 in the same manner as described above, and then the conveyance roller. The paper is discharged to the paper discharge tray 119 via the pair 117 and the paper discharge roller pair 118.

  Next, the control means controls the rotation position of the rotation lever 111 so that the cam engagement between the rotation lever 111 and the arm 109 is released. As a result, the arm 109 swings counterclockwise in FIG. 6 by the urging force of the tension coil spring 112, and a plurality of documents fed by the return roller 108 are sandwiched between the driven return roller 114. Thus, the original is pressed against the original with a constant load. At this time, the feeding roller 201 and the separation roller 202 maintain an inter-axis distance when the document is separated and fed.

  Then, the control means controls each drive system of the return roller 108, the feed roller 201, and the separation roller 202 so as to return a plurality of documents fed in the double feed direction to the paper feed tray 101 side. 202 is rotated in the direction opposite to the document feeding direction. Further, the control unit controls the drive system of the pickup roller 102 so that the pickup roller 102 that has stopped the document feeding operation is moved to a position where it does not come into contact with the document stacked on the sheet feed tray 101.

  After the multifeed document is removed from the multifeed detection means 107 or the registration sensor 106, it is transported to the paper feed tray 101 side for a predetermined time or a predetermined rotation amount of the drive motor of the return roller 108 and stopped. .

  As described above, in the present embodiment, a plurality of multi-fed originals are returned to the paper feed tray 101 side only by the conveying force in the direction opposite to the original feeding direction generated by the feeding roller 201 and the separation roller 202. Therefore, the shortage of the conveyance force is compensated by the return roller 108. As a result, when a double feed of originals occurs, a plurality of double fed originals can be reliably returned to the paper feed tray 101 side and re-feeded.

  When returning a plurality of multi-fed originals to the paper feed tray 101 side, the distance between the axes of the feed roller 201 and the separation roller 202 is adjusted to a distance at which an appropriate return conveyance force can be obtained, and the double feed is performed. A returning operation of a plurality of documents may be performed. Other configurations and operational effects are the same as those of the first embodiment.

(Third embodiment)
Next, with reference to FIG. 7, a sheet feeding apparatus according to a third embodiment of the present invention will be described. In addition, about the part which overlaps with the said 1st Embodiment, the same code | symbol is attached | subjected to a figure and the description is abbreviate | omitted.

  As shown in FIG. 7, the sheet feeding apparatus according to the present embodiment is in contact with the feeding roller 104 and uses the frictional force generated by contact with the document, as illustrated in FIG. A separation pad 301 is used as a friction member that separates into two. The separation pad 301 is movably supported by a moving mechanism (not shown) at a position where it comes into contact with the feeding roller 104 and a position where it is separated from the feeding roller 104. The control unit controls the moving mechanism based on the signal from the double feed detection unit 107 to move the separation pad 301 to a position where the separation pad 301 comes into contact with or separates from the feed roller 104.

  In the present embodiment, the return roller 108 is disposed at substantially the same position as the contact position between the feeding roller 104 and the separation pad 301 in the document feeding direction, or between the feeding roller 104 and the separation pad 301. It is desirable to arrange it upstream of the contact position in the document feeding direction.

  In the present embodiment, the originals stacked on the paper feed tray 101 are sent out between the feeding roller 104 serving as the separation feeding unit and the separation pad 301 by the pickup roller 102. When there are a plurality of documents sent to the separation feeding unit, the documents are separated one by one by the frictional force of the separation pad 301 and fed to the conveyance path.

  Here, when the control unit determines that the document fed to the transport path is being fed based on the detection signal of the double feed detection unit 107, the control unit temporarily stops the transport operation of the document to the separation feeding unit. Thus, the drive system of the rollers 102 and 104 is controlled. The multiple fed originals are stopped on the conveyance path, and the previously separated and fed originals are read by the image reading unit 116 and then passed through the conveyance roller pair 117 and the discharge roller pair 118. The paper is discharged to a paper discharge tray 119.

  Next, the control means controls the rotation position of the rotation lever 111 so that the cam engagement between the rotation lever 111 and the arm 109 is released. As a result, the arm 109 swings counterclockwise in FIG. 7 by the urging force of the tension coil spring 112, and a plurality of documents fed by the return roller 108 are sandwiched between the driven return roller 114. Thus, the original is pressed against the original with a constant load.

  At the same time, the control unit controls the drive system of the pickup roller 102 so as to move the pickup roller 102 whose operation has been stopped to a position where it does not come into contact with the documents stacked on the paper feed tray 101. Further, the control means controls the moving mechanism of the separation pad 301 so that the separation pad 301 is also moved downward in the drawing to be retracted to a position separated from the feeding roller 104, and the original is returned to the paper feed tray 101 side. So as not to overload.

  After that, the control unit controls each drive system of the return roller 108 and the feed roller 201 so as to return the multiple fed documents to the paper feed tray 101 side, and feeds each of the rollers 108 and 201 to feed the documents. Rotate in the opposite direction.

  After the multifeed document is removed from the multifeed detection means 107 or the registration sensor 106, it is transported to the paper feed tray 101 side for a predetermined time or a predetermined rotation amount of the drive motor of the return roller 108 and stopped. .

   As described above, in the present embodiment, by using the return roller 108, even in the case of having a separation feeding unit that is not equipped with a separation roller, the conveyance force in the return direction of a plurality of multi-fed documents can be ensured. Can get to. Other configurations and operational effects are the same as those of the first embodiment.

(Fourth embodiment)
Next, a sheet feeding apparatus according to a fourth embodiment of the present invention will be described with reference to FIG. In addition, about the part which overlaps with the said 1st Embodiment, the same code | symbol is attached | subjected to a figure and the description is abbreviate | omitted.

  In the present embodiment, as shown in FIG. 8, a plurality of (three in the figure) double feed detectors 107 are arranged at substantially equal intervals in the width direction of the document orthogonal to the document transport direction. This is an example in which it is possible to select a position for determining the double feed.

  In the present embodiment, as shown in FIG. 7, the return roller 108 is provided with a double feed detecting means for reliably returning the multiple fed originals to the paper feed tray 101 side and restarting the separation and feeding operation of the originals. The document 107 is disposed in the vicinity of the document in the width direction or at the outer position (the outer position in the figure). As a result, as shown in FIG. 9, when documents of different sizes are brought together and fed together, the return roller 108 contacts the document, so that the document can be reliably returned to the paper feed tray 101 side. . Other configurations and operational effects are the same as those of the first embodiment. In the present embodiment, the case where a plurality of double feed detection means 107 are arranged with respect to the first embodiment has been exemplified, but a plurality of multifeed detection means 107 is provided with respect to the second embodiment or the third embodiment. A double feed detection means 107 may be arranged.

  In addition, this invention is not limited to what was illustrated by said each embodiment, In the range which does not deviate from the summary of this invention, it can change suitably.

DESCRIPTION OF SYMBOLS 101 Paper feed tray 102 Pickup roller 104 Feed roller 105 Separation roller 107 Double feed detection means 108 Return roller 109 Arm 111 Rotating lever 112 Tension coil spring 114 Return driven roller 201 Feed roller 202 Separation roller 301 Separation pad

Claims (13)

A loading table for loading sheets;
A feeding member that feeds a sheet on the stack to a conveyance path;
A separation member that separates the sheets fed to the conveyance path one by one by the feeding member;
A double feed detecting means provided on the downstream side in the sheet feeding direction from the feeding member, and detecting a double feed of the sheet fed to the transport path;
A return roller that is disposed between the feeding member and the double feed detection means, and returns the double fed sheet toward the stacking base in a double fed state;
A return driven roller disposed opposite to the return roller and rotating in accordance with the rotational drive of the return roller;
Drive means for rotating the return roller in a direction opposite to the sheet feeding direction;
Control means for controlling the drive means so as to rotationally drive the return roller in a direction opposite to the sheet feeding direction when the double feed detecting means detects double feeding of the sheet ,
The sheet feeding member and the return roller are arranged such that an end portion of the return roller corresponding to the upstream side in the sheet feeding direction overlaps with the feeding member in the rotation axis direction. Feeding device. A loading table for loading sheets;
A feeding member that feeds a sheet on the stack to a conveyance path;
A separation member that separates the sheets fed to the conveyance path one by one by the feeding member;
A double feed detecting means provided on the downstream side in the sheet feeding direction from the feeding member, and detecting a double feed of the sheet fed to the transport path;
A return roller that is disposed between the feeding member and the double feed detection means, and returns the double fed sheet toward the stacking base in a double fed state;
A return driven roller disposed opposite to the return roller and rotating in accordance with the rotational drive of the return roller;
Drive means for rotating the return roller in a direction opposite to the sheet feeding direction;
Control means for controlling the drive means so as to rotationally drive the return roller in a direction opposite to the sheet feeding direction when the double feed detecting means detects double feeding of the sheet,
The return roller has a position abutting on the seat, it characterized and to Resid over preparative feeder that is movable between a position retracted from the sheet. A sheet detection sensor for detecting the presence or absence of a sheet to be fed is disposed between the feeding member and the multifeed detection means, and the return roller is disposed between the sheet detection sensor and the feeding member. Placed in
The sheet feeding apparatus according to claim 1 , wherein the control unit determines a next sheet feeding timing based on a detection signal from the sheet detection sensor . The sheet feeding apparatus according to any one of claims 1 to 3, wherein the double-feed detection unit is an ultrasonic double-feed detection sensor . 5. The sheet feeding apparatus according to claim 1 , wherein the return roller is movable between a position in contact with the sheet and a position retracted from the sheet. The multifeed detecting means is disposed downstream of the feeding member in the sheet feeding direction, and the return roller faces both sides of the feeding member so as to sandwich a gap between the feeding member and the multifeed detecting means. The sheet feeding device according to claim 1, wherein the sheet feeding device is arranged as described above. When the double feed detecting means detects double feeding of sheets, the control means controls the driving means to rotate the return roller in a direction opposite to the sheet feeding direction, and double feed is performed. The sheet feeding device according to any one of claims 1 to 6 , wherein after the sheet is returned to the stacking table, the feeding member and the separation member are re-driven to perform the separation feeding operation again. Feeding device. When the double feed detecting means detects double feeding of the sheet, the sheet separating and feeding operation by the feeding member and the separating member and the return roller are driven to rotate in the direction opposite to the sheet feeding direction. The sheet feeding apparatus according to claim 1 , wherein the returning operation for controlling the driving unit by the control unit is repeated a predetermined number of times . 9. The sheet feeding device according to claim 8, wherein when the double feeding detecting unit detects the double feeding of the sheets even after the predetermined number of repetitions, the double fed sheet is conveyed to a pair of discharge rollers. Feeding device . Scanner comprising the sheet feeding apparatus according to any one of claims 1-9. Printer characterized by comprising a sheet feeding apparatus according to any one of claims 1-9. Facsimile comprising the sheet feeding apparatus according to any one of claims 1-9. A copying machine comprising the sheet feeding device according to claim 1.

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