JP4840977B2 - Sheet feeding apparatus, and image reading apparatus and image forming apparatus provided with the same - Google Patents

Description

  The present invention relates to a sheet feeding device which prevents separation of sheets fed from a stacking tray, in particular, a sheet remaining on the stacking tray, by a separation pad, and an image reading apparatus and an image including the sheet feeding device The present invention relates to a forming apparatus.

  In an image forming apparatus (for example, a copying machine or a printer) or an image reading apparatus, a sheet-like recording material or a document (hereinafter referred to as “sheet”) is set at a predetermined position on a stacking tray. Then, the sheet is fed by a feeding roller to perform image formation and image reading.

  By the way, when the sheet placement surface of the stacking tray is formed in a flat shape, the sheet fed from here is not stable in posture, so that conveyance failure such as skew feeding or double feeding occurs. There is.

  Therefore, by curving or projecting a part of the stacking tray, the sheets set on the stacking tray are actively curved to follow them, so that the posture of the sheet at the time of setting or feeding is stabilized. For example, Patent Literature 1 proposes a technique for making the above.

  This is provided with a protrusion on a part of the upstream side of the sheet placement surface of the stacking tray. By this protrusion, the left end and the right end of the sheet set on the sheet placement surface are curved so that the upstream end of the sheet protruding from the upstream end of the sheet placement surface does not hang downward. . Then, the posture of the sheet fed from the paper feed tray by the feeding roller is stabilized to prevent skew and jammed paper based on the skew.

  In such a stacking tray, a sheet-like separation pad is affixed to a position corresponding to the feeding roller on the downstream side of the sheet placing surface to prevent double feeding of sheets fed from the sheet placing surface. In particular, the multi-feed of the sheet with the remaining number of sheets or the lowest sheet is prevented. When this separation pad is stuck in a state of being recessed from the sheet placement surface, the effect of preventing double feed is low, so generally, the separation pad is on the same plane as the sheet placement surface or slightly from the sheet placement surface. For example, it sticks with a double-sided tape so as to protrude.

JP 9-175659 A

  In the stacking tray as described above, when a plurality of sheets are set in a predetermined position in a stacked state, the back surface of the lowermost sheet is slid from the upstream side to the downstream side on the sheet placement surface. The sheet is set by bringing the leading edge of the sheet into contact with the stopper.

  However, as described above, when the separation pad is provided on the same plane as the sheet placement surface or so as to protrude from the sheet placement surface, the sheet is placed on the sheet placement surface as described above. If it is set so as to slide from the upstream side toward the downstream side, the leading edge of the lowermost sheet is caught by the separation pad and bent or does not reach the stopper. These cause sheet feeding defects.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a sheet feeding device, an image forming apparatus, and an image reading device that prevent a sheet feeding failure caused by a part of a sheet being caught by a separation pad when setting a sheet on a stacking tray. To provide an apparatus.

According to the first aspect of the present invention, the uppermost sheet among a plurality of sheets set in a stacked state on the stacking tray is sequentially arranged at the feeding position, and the downstream side is caused by friction based on the rotation of the feeding member. The present invention relates to a sheet feeding apparatus that feeds a sheet. The sheet feeding device according to the present invention is configured so that the end of the sheet on the stacking tray on the downstream side in the transport direction is the front end, and the left and right ends in the transport direction are the side ends. A stopper for positioning the sheet in the feeding direction by restricting the leading edge of the placed sheet; a side regulating member for positioning in the sheet passing width direction by regulating the side edge of the sheet placed on the stacking tray; A lift plate that can be moved up and down having a placement surface that supports the front end side of the sheet positioned on the stacking tray from below, and when the sheet is set, the lift plate is lowered to a lower set position, and when the sheet is fed distribution wherein the lift plate, the so protrude from the mounting surface at a position corresponding to the feed member in the lifting means and, the mounting surface of the uppermost sheet raises so as to be positioned in said feed position A separation pad that has a separation surface placed thereon, and that contacts the back surface of the lowest sheet after setting to prevent double feeding of the sheet, and slides on the placement surface from the upstream side to the downstream side. A guide member that guides a sheet set to be rubbed in the vicinity of the separation pad, and the guide member has an inclined guide portion disposed in the vicinity of each side end of the separation pad, The inclined guide portion is inclined so that the upstream side is higher and the downstream side is lower than the separation pad, and has an intersecting portion that intersects the separation surface when viewed from the sheet passing width direction.

  According to a second aspect of the present invention, in the sheet feeding apparatus according to the first aspect, a contact portion between the separation surface of the separation pad and the feeding member when the lift member is disposed at the feeding position. Is the nip, and the distance between the upstream end and the downstream end of the nip is the nip width, the inclined guide portion is positioned so that the intersecting portion is located within the nip width when viewed from the sheet passing width direction. It is characterized by being arranged.

  According to a third aspect of the present invention, in the sheet feeding apparatus according to the second aspect, in the state where the inclined guide portion is viewed from the sheet passing width direction, the intersecting portion has a center of the nip width and an upstream end of the nip. It arrange | positions so that it may be located between.

  According to a fourth aspect of the present invention, in the sheet feeding device according to the second aspect, the inclined guide portion is positioned so that the intersecting portion is positioned immediately upstream of the upstream end of the nip when viewed from the sheet passing width direction. It is characterized by being arranged in.

  According to a fifth aspect of the present invention, in the sheet feeding device according to any one of the first to fourth aspects, the feeding member is formed so that a width in a paper passing width direction is narrower than a width between the inclined guide portions. It is characterized by being.

  A sixth aspect of the present invention relates to an image reading apparatus including a sheet feeding device that feeds a sheet-like document and an image reading unit that reads an image of the document fed by the sheet feeding device. The image reading apparatus according to the present invention is characterized in that the sheet feeding apparatus is the sheet feeding apparatus according to any one of claims 1 to 5.

  According to a seventh aspect of the present invention, there is provided an image forming apparatus comprising: a sheet feeding device that feeds a sheet on which an image is formed; and an image forming unit that forms an image on the sheet fed by the sheet feeding device. About. The image forming apparatus according to the present invention is characterized in that the sheet feeding device is the sheet feeding device according to any one of claims 1 to 5.

  According to the first aspect of the present invention, the inclined guide portion of the guide member has a portion located upstream from the intersection with the separation surface in the state viewed from the sheet passing width direction, and is higher than the separation surface. The part located further downstream is formed so as to be lower than the separation surface. Therefore, the sheet set so as to rub on the placement surface of the lift plate from the upstream side to the downstream side is lifted from the placement surface by the portion of the inclined guide portion that is located on the upstream side of the intersecting portion. It is done. For this reason, the tip of the lowermost sheet does not come into contact with the upstream portion of the separation pad, so that it is less likely to get caught by the separation pad. Here, when the separation surface and the inclined guide part do not have an intersection, the following problems occur. That is, when the inclined guide portion intersects the placement surface on the upstream side of the separation surface, the leading edge of the lowermost sheet at the time of setting starts to contact the separation surface from the upstream end of the separation surface and the downstream end of the separation surface This is the same as in the prior art that does not have an inclined guide portion. On the other hand, when the inclined guide portion intersects the placement surface on the downstream side of the separation surface, the leading edge of the lowest sheet at the time of setting is lifted from the placement surface by the inclination guide portion and contacts the separation surface. However, since the lowermost sheet after setting does not come into contact with the separation surface, there is a possibility that poor feeding such as double feeding may occur when the sheet is fed.

  In this claim, by arranging the inclined guide part so as to intersect the separation surface, the lowermost sheet contacts with the separation surface at the time of setting, while the lowermost sheet is effective on the separation surface after setting. By making contact with the sheet, sheet feeding defects are reduced.

  According to the second aspect of the present invention, the intersecting portion between the separation surface and the inclined guide portion as viewed from the sheet passing width direction is set within the nip width between the separation surface and the feeding member, and the lift plate is mounted. When the remaining number of sheets on the placement surface is reduced, the portion located downstream of the intersecting portion in the nip effectively acts as the nip when feeding the sheet, so that multiple feeding can be prevented.

  According to the invention of claim 3, the intersection of the separation surface and the inclined guide portion in the state viewed from the sheet passing width direction is disposed between the center of the nip width and the upstream end of the nip, When the remaining number of sheets on the loading surface is reduced, the portion located downstream from the intersection in the nip, that is, the portion more than half of the nip width effectively acts as a nip when feeding the sheet. Thus, it is possible to prevent double feeding more reliably than in the second aspect.

  According to the invention of claim 4, the intersecting portion of the separation surface and the inclined guide portion as viewed from the sheet passing width direction is disposed on the upstream side immediately adjacent to the upstream end of the nip, and is on the mounting surface of the lift plate. When the remaining number of sheets decreases, the entire nip width in the nip effectively acts as a nip during sheet feeding, so that it is possible to prevent double feeding more reliably than in the third aspect.

  According to the invention of claim 5, regardless of the height relationship between the separation pad and the inclined guide portion, the feeding member properly contacts the separation pad to form a nip.

  According to the invention of claim 6, the image forming apparatus can exhibit the same operations and effects as described above.

  According to the seventh aspect of the invention, the image reading apparatus can achieve the same operations and effects as described above.

  Hereinafter, the best embodiment of the present invention will be described in detail with reference to the drawings. In the following drawings, illustrations of members unnecessary for explanation are omitted as appropriate.

<Embodiment 1>
First, an outline of an image reading apparatus provided with a sheet feeding apparatus according to the present invention will be described, and then the sheet feeding apparatus will be described in detail.

  The image reading apparatus 10 will be described with reference to FIGS. Among these, FIG. 1 is a diagram showing an overview of the image reading apparatus 10 as a whole, and is a perspective view of the image reading apparatus 10 as viewed from diagonally right above the front side (front side, front side). FIG. 2 is a schematic view of a longitudinal section in the left-right direction of the image reading apparatus 10 as viewed from the front side. In the following description, the arrow A-B direction in FIGS. 1 and 2 is the left-right direction (sheet feeding direction), the arrow A side is the left side (downstream side of the feeding tray), and the arrow B side is On the right side (upstream side of the feeding tray). Further, the arrow CD direction in FIG. 1 is the front-rear direction (paper passing width direction), the arrow C side is the front side, and the arrow D side is the rear side (back side, back side).

  As shown in FIGS. 1 and 2, the image reading apparatus 10 includes a sheet feeding device 11 that feeds a sheet (original) P with an image attached thereto, and a sheet P fed by the sheet feeding device 11. A sheet conveying device 12 for conveying, an image reading means 13 for reading an image of the sheet P conveyed by the sheet conveying device 12, and a discharge tray 14 for discharging the sheet P after image reading are provided.

  Among these, the sheet feeding apparatus 11 includes a stacking tray 21 on which a plurality of sheets P are stacked in a stacked state. The plurality of sheets P are placed on the stacking tray 21 with their image surfaces facing upward. As will be described later, a plurality of sheets P on the stacking tray 21 are arranged at predetermined feeding positions in order from the uppermost sheet P (the uppermost sheet P), and a feeding roller as a feeding member The sheet is fed downstream from the feeding position by the rotation of the arrow 22 in the direction of arrow E. The sheet feeding apparatus 11 will be described in detail later.

  The sheet conveying device 12 includes a conveying belt 23 and a retard roller 24 disposed immediately downstream of the above-described feeding roller 22. The conveyor belt 23 is stretched between a driving roller 25 and a driven roller 26, and is rotated in the direction of arrow F (sheet feeding direction) by the driving roller 25. On the other hand, the retard roller 24 is rotated in the arrow G direction (sheet return direction). When only one sheet P is fed from the sheet feeding device 11 by the feeding roller 22, the sheet P is further conveyed downstream by the conveying belt 23. On the other hand, when a plurality of sheets P are overlapped and overlapped, only the uppermost sheet P (first sheet P) is conveyed downstream by the conveying belt 23. At the same time, conveyance of the next and subsequent sheets P (second and subsequent sheets P) is stopped by the retard roller 24 and stopped. The first sheet P conveyed downstream has its leading end collide with the nip of the stopped registration roller pair 27 to correct skewing, and the rotation of the registration roller pair 27 thereafter further increases the skew. It is conveyed downstream. The sheet P conveyed downstream is conveyed to the image reading position R by the large-diameter common roller 28 and the small-diameter conveying rollers 30, 31, 32, and further from the image reading position R to the conveying roller 33 and the conveying roller pair. 34, and is discharged onto the discharge tray 14 by the discharge roller pair 35.

  The image reading unit 13 reads an image of the sheet P conveyed from the sheet conveying device 12 described above. The image reading unit 13 irradiates light from a light source (not shown) toward the image reading position R, and reflects light from the sheet P through a mirror and an imaging lens (both not shown) to a CCD (not shown). ) To read the image on the surface side of the sheet P. Note that a contact image sensor 38 is disposed at a position facing the above-described conveyance roller 33, and an image on the back side of the sheet P can also be read by the contact image sensor 38. The read image is sent as image information to an image forming apparatus (not shown) such as a copying machine, a printer, or a facsimile. When the image forming apparatus is a copying machine or a printer, an image is formed on the recording material (recording medium) such as paper on the basis of the image information, and the image forming apparatus is a facsimile machine. If so, the image information is transmitted.

  The discharge tray 14 is disposed below the stacking tray 21 described above. The sheet P after image reading is discharged and stacked on the discharge tray 14 by the above-described discharge roller pair 35 with the image surface facing downward. As shown in FIG. 1, ribs 36 and recesses 37 are provided on the discharge tray 14. Among these, the rib 36 reduces the frictional resistance of the sheet P discharged onto the discharge tray 14 to improve the alignment of the sheet P on the discharge tray 14, and at the downstream side in the discharge direction (the right side in FIG. 1). ) To prevent the sheet P from jumping out of the discharge tray 14 to the downstream side. Further, the concave portion 37 is for facilitating insertion of a hand into the lower surface side of the sheet P on the discharge tray 14 and facilitating removal of the sheet P.

  In the image reading apparatus 10 having the above-described configuration, a plurality of sheets P set at predetermined positions on the stacking tray 21 of the sheet feeding apparatus 11 are sequentially downstream from the feeding position by the feeding roller 22 from the topmost one. The image is read on the sheet P at the image reading position R of the image reading unit 13 while the fed sheet P is conveyed by the sheet conveying device 12, and the sheet P after the image reading is discharged to the discharge tray 14. It will be discharged above. This is the end of the general description of the image reading apparatus 10.

  The sheet feeding apparatus 11 according to the present invention can be used in the above-described image reading apparatus 10 given as an example.

  The sheet feeding apparatus 11 will be described in detail with reference to FIGS. 3, 4, 5, 6, and 7, and appropriately using FIGS. 1 and 2. Among these, FIG. 3 is a perspective view of the vicinity of a separation pad 45 (described later) shown in FIG. FIG. 4 is a front view showing a state in which the lift plate 43 is arranged at the lower set position and the sheet P is set. FIG. 5 is a front view showing a state in which the lift plate 43 is disposed at the upper feeding position and is in contact with the feeding roller 22. FIG. 6 is a diagram schematically showing features of the present invention. FIG. 7 is a diagram illustrating the behavior of the sheet P at the time of setting, as viewed from the downstream side.

  The sheet feeding device 11 includes a stacking tray 21, a feeding roller 22, a stopper 40, side regulation plates (side regulation members) 41 and 42, a lift plate 43, an elevating means 44, a separation pad 45, Guide members 46 and 47 are provided.

  As shown in FIGS. 1 and 2, the stacking tray 21 is formed in a substantially plate shape, and the downstream side (the left side in FIG. 2) is swingably supported by the image reading apparatus main body 48, and the upstream side The side (the right side in FIG. 2) is a free end. The entire stacking tray 21 can move upward on the upstream side with reference to the downstream side. Thereby, it becomes easy to take out the sheet P discharged onto the discharge tray 14.

  As shown in FIG. 1, a part of the stacking tray 21 is an auxiliary tray 51. The auxiliary tray 51 is a rectangular member arranged on the upstream side and the near side of the stacking tray 21, and can swing substantially vertically with respect to a shaft 52 extending in the left-right direction. It is normally biased by a member (not shown) and is disposed at the home position shown in FIG. The auxiliary tray 51 facilitates the removal of the sheets P discharged onto the discharge tray 14 below the stacking tray 21 by lifting the front side upward against the urging force of the urging member. .

  As shown in FIGS. 4 and 5, the stopper 40 is disposed near the downstream end of the stacking tray 21 on the image reading apparatus main body 48 side. As shown in FIG. 4, the stopper 40 is erected so that the upper end 53 side is slightly inclined to the downstream side (left side in FIG. 4), and regulates the leading end of the sheet P placed on the stacking tray 21. Thus, positioning in the sheet feeding direction is performed.

  As shown in FIG. 1, on the downstream side of the stacking tray 21, the front side and the rear side of the sheet P are regulated in the both sides (front end and rear end) in the sheet passing width direction to perform positioning in the sheet passing width direction. The restricting plates 41 and 42 are disposed, and are moved in the front-rear direction by being guided by the two guide grooves 54 and 55. The two side regulating plates 41 and 42 are set in an interlocking relationship by, for example, a rack and pinion mechanism (not shown). When one of the side regulating plates 41 and 42 is moved inward, the other moves inward, and conversely, the other moves outward. If it is made, the other will also move outside. Below the lift plate 43, a width detection sensor (not used) that detects the size in the sheet passing width direction of the sheet P set at a predetermined position on the stacking tray 21 by detecting the positions of the side regulating plates 41 and 42. (Shown) is provided.

As shown in FIGS. 1 to 7, the lift plate 43 is disposed on the downstream side of the stacking tray 21. Lift plate 43 has on its upper surface, and a mounting surface S1, in contact with the back surface of the lowermost sheet P. Also, as shown in FIG. 3, a pad base 43a for sticking a separation pad 45 described later protrudes from the center on the downstream side of the placement surface S1. As shown in FIGS. 3, 5, and 7, the pad base 43 a is inclined so that the pad mounting surface 43 b on the upper surface is higher on the downstream side than the placement surface S <b> 1. The pad base 43a further has an inclined surface 43c having a high downstream side and a leading end support surface 43d following the inclined surface 43c so as to be continuous with the downstream side of the pad mounting surface 43b. The tip support surface 43d is disposed at a position slightly lower than a separation surface S2 of the separation pad 45 described later. In the present embodiment, as shown in FIG. 3, the front end and the rear end on the downstream side of the placement surface S1 of the lift plate 43 include the front end on the front side of the sheet P set on the placement surface S1 and Inclined surfaces 43e and 43f for lifting the rear end from below are formed. These inclined surfaces 43e and 43f are formed slightly lower than the pad mounting surface 43b. Therefore, as will be described later, the sheet P set on the placement surface S1 is lifted by the separation pad 45 at the center on the front end side, and the front and rear ends on the front end side.

  As shown in FIG. 2, the lift plate 43 is swingable substantially vertically in the downstream side with respect to the shaft 43g on the upstream side. The lift plate 43 can move between the lowermost set position shown in FIG. 4 and the uppermost feed position shown in FIG. Here, the set position is a position when the stacked sheets P are set on the stacking tray 21 and the placement surface S1 of the lift plate 43, and the feeding position is the most when the sheet P is fed. This is the position where the upper sheet P is arranged. Therefore, immediately after the last sheet on the placement surface S1 is fed, the placement surface S1 is arranged at the feeding position shown in FIG.

  As schematically shown in FIG. 2, the elevating means 44 includes an elevating mechanism 56 for elevating the lift plate 43, a motor 57 for driving the elevating mechanism 56, and the uppermost sheet P on the lift plate 43. The detection sensor (not shown) to detect and the control apparatus 58 which controls the motor 57 based on the output of a detection sensor are comprised. Here, as the lifting mechanism 56, for example, a mechanism using an eccentric cam can be used. The above-described detection sensor detects the sheet P when the uppermost sheet P among the sheets P set on the lift plate 43 is raised to a predetermined feeding position by the lift plate 43 being lifted by the lifting mechanism 56. The control device 58 stops the motor 57 based on this detection signal. Here, the feeding position is a position suitable for feeding the uppermost sheet P to the downstream side by the feeding roller 22, and the uppermost sheet P is arranged at this feeding position. A nip having an appropriate nip width is formed between the roller 22 and the feeding roller 22 in contact with the feeding roller 22. In the present embodiment, the detection sensor detects the vicinity of the leading end at the center in the sheet passing width direction of the uppermost sheet P, and each time the uppermost sheet P is fed, the next uppermost sheet P is detected. The position of is detected. As the entire lifting / lowering means 44, when the uppermost sheet P fed by the feeding roller 22 is always arranged at the feeding position and the sheet P is no longer on the lift plate 43, the lift plate 43 is disposed as described above. Is pushed down to the set position.

  As shown in FIGS. 1 and 3, the separation pad 45 is disposed at the substantially center in the front-rear direction at the downstream end of the lift plate 43. The separation pad 45 is made of a rectangular cloth-like member that is long in the left-right direction, for example, a felt material, and is attached to the pad mounting surface 43b of the pad base 43a of the lift plate 43 by a double-sided tape. As described above, the pad mounting surface 43b protrudes from the mounting surface S1 while being inclined so that the downstream side becomes higher with respect to the mounting surface S1, and thus is attached to the pad mounting surface 43b. Similarly, the separation surface S2 on the upper surface of the separation pad 45 protrudes from the placement surface S1 while being inclined so that the downstream side is higher than the placement surface S1.

  As shown in FIG. 3, the guide members 46 and 47 are disposed near the front end and the rear end of the separation pad 45. In the present embodiment, the guide members 46 and 47 are formed in a long rib shape along the conveying direction of the sheet P at the time of setting, and project from the placement surface S1. The guide members 46 and 47 have inclined guide portions 46a and 47a at their upper ends. The inclined guide portions 46a and 47a are inclined with respect to the placement surface S1 so that the upstream side is low and the downstream side is high. On the other hand, as shown in FIGS. 5 and 6, the inclined guide portions 46 a and 47 a are formed so that the upstream side is higher and the downstream side is lower than the separation surface S <b> 2 of the separation pad 45. Further, each of the inclined guide portions 46a and 47a has an upstream end located further upstream than the upstream end of the separation surface S2, and each downstream end located further downstream than the downstream end of the separation surface S2. is doing. The distance between the inclined guide portions 46a and 47a of the two guide members 46 and 47 is set to be longer than the length in the front-rear direction (length in the sheet passing width direction) of the feeding roller 22 described above. Yes. That is, when the lift plate 43 is raised to the feeding position and comes into contact with the feeding roller 22, the feeding roller 22 enters between the two inclined guide portions 46a and 47a.

  In FIG. 6, the nip N formed by the lift plate 43 being disposed at the feeding position and the separation surface S2 of the separation pad 45 being in contact with the feeding roller 22, the separation surface S2 of the separation pad 45, and the guide The positional relationship with the inclination guide parts 46a and 47a of the members 46 and 47 is shown typically. However, in order to facilitate understanding of the present invention, for example, the nip width Na of the nip N is made wider than the actual one, or the inclination angle of the inclination guide portions 46a and 47a with respect to the separation surface S2 is increased. ing.

In FIG. 6, the width of the nip N when the nip N is properly formed is the nip width Nw, the downstream end of the nip N is Na, the upstream end is Nb, and the center of the nip N is Nc. In the present invention, the inclined guide portions 46a and 47a of the guide members 46 and 47 are inclined such that the upstream side is high and the downstream side is low with respect to the separation surface S2, and the separation pad 45 is viewed from the sheet passing width direction. The crossing portion intersects with the separation surface S2. Thus, when the stacked sheet P is set against the lift plate 43 arranged at the set position so as to slide on the placement surface S1 from the upstream side to the downstream side, the lowermost sheet P is The tip of the inclined guide portions 46a and 47a is lifted from the mounting surface S1 by the portion located on the upstream side of the intersecting portion. For this reason, the tip of the lowermost sheet P does not come into contact with the upstream portion of the separation pad 45, so that it is less likely to be caught by the separation pad 45.

  FIG. 7 shows a schematic view of the behavior of the sheet P during setting as viewed from the downstream side. The sheet P moves along the placement surface S1 of the lift plate 43 so as to slide from the upstream side to the downstream side. Here, since the upstream ends 46b and 47b of the inclined guide portions 46a and 47a of the guide members 46 and 47 are higher than the separation surface S2 of the separation pad 45, the leading end of the lowermost sheet P is the inclined guide portions 46a and 46a. 47a rises from the mounting surface S1 and is guided with the center curved in a concave shape as indicated by P1 in the figure. This curvature becomes smaller as the leading edge of the sheet P approaches the intersection. When the leading edge of the sheet P reaches the intersection, the height relationship between the inclined guide portions 46a and 47a and the separation surface S2 is reversed, and the inclined guide portions 46a and 47a are located below the separation surface S2. The tip of the sheet P is curved in a convex shape at the center as indicated by P2. Thereafter, as shown in FIG. 6, the leading edge of the sheet P is disengaged from the downstream end of the separation surface S2, deviated from the inclined guide portions 46a and 47a, guided by the inclined surface 43c, and placed on the leading end support surface 43d. (See FIG. 4) and stopped. As a result, the sheet P is positioned in the transport direction on the stacking tray 21. Depending on the position of the above-described intersection, when the sheet P is fed by the rotation of the feeding roller 22, a sufficient nip width may not be ensured. In this case, the sheet separation performance deteriorates.

In the following, as shown in FIG.
(1) When the intersection a1 is on the downstream side of the downstream end Na (a in FIG. 6),
(2) When the intersection b1 is between the downstream end Na and the center Nc (b in FIG. 6),
(3) When the intersection c1 is between the center Nc and the upstream end Nb (c in FIG. 6),
(4) When the intersection d1 is located immediately upstream of the upstream end Nb (d in FIG. 6),
This will be explained separately.
In any of the cases (1) to (4), the sheet P at the time of setting does not come into contact with the part of the separation surface S2 that is located on the upstream side of the respective intersections a1, b1, c1, and d1. , It comes into contact with the portion located on the downstream side. Therefore, the contact length of the lowest sheet P at the time of setting is the shortest in (1) and becomes longer in the order of (2), (3), and (4). On the other hand, the contact length between the sheet P after setting and the separation surface S2 is a portion of the separation surface S2 that is located on the downstream side of each of the intersecting portions a1, b1, c1, and d1. Therefore, (1) is the shortest and becomes longer in the order of (2), (3), and (4). When the sheet P is fed with the remaining number of sheets P on the lift plate 43 being reduced, the nip N cannot be secured in (1). In (2), the width of the nip width Nw positioned between the downstream end Na and the intersecting portion b1, and in (3), the width of the nip width Nw positioned between the downstream end Na and the intersecting portion c1. Each can be secured, and in (4), the entire nip width Nw can be secured. That is, for feeding the sheet P, (4) that can secure the nip width is the most preferable, and the rest is in the order of (3), (2), and (1). Further, when the inclined guide portions 46a and 47a are at a position higher than the separation surface S2, the set sheet P is set in a state of being lifted from the separation surface S2 by this portion. Therefore, when the feeding of the sheet P advances and the remaining number of sheets P on the placement surface S1 decreases, the portion of the sheet P positioned at the inclined guide portions 46a and 47a is separated by the feeding roller 22 into the separation surface S2. Therefore, traces (guide traces) of the inclined guide portions 46a and 47a are made on the sheet P. In (4), this guide trace is not made, but the guide trace increases in the order of (3), (2), and (1).

  The above is summarized as follows.

  In any of (1) to (4), a sheet is set on the placement surface S1 of the lift plate 43 as compared with the case where there are no guide members 46 and 47 having the inclined guide portions 46a and 47a (corresponding to the conventional example). The leading end of the lowermost sheet P at this time is less likely to be caught on the separation surface S2.

  When the sheet is fed after setting, (4) is the best for the sheet separation performance and the number of guide marks, and the rest are in the order of (3), (2), and (1).

  As described above, since it is difficult for the sheet P to be caught at the time of setting and the sheet separation performance at the time of feeding and the like are mutually contradictory, which one of (1) to (4) is selected is, for example, In consideration of various conditions such as the length and properties of the separation surface S2 of the separation pad 43, the nip width Nw, the length of the nip N in the sheet passing width direction, the quality of the sheet P, etc. Good.

  However, in (4), in which the intersection d1 is set immediately upstream of the upstream end Nb of the nip N, it is not affected by these conditions, and the separation performance during sheet feeding is not deteriorated. When the sheet P is set, the sheet P can be hardly caught on the separation surface S2.

  In the above embodiment, the case where the sheet feeding apparatus 11 according to the present invention is used in the image reading apparatus 10 has been described as an example. However, the sheet feeding apparatus 11 according to the present invention is not limited to this. For example, in an image forming apparatus such as a copying machine, a printer, or a facsimile, the sheet P can be used as a sheet feeding apparatus that feeds the sheet P to the image forming unit. In this case, since the conveyance failure of the sheet P due to the leading edge of the sheet P being bent can be prevented, an image defect caused by the conveyance failure, for example, an image is formed on the folded sheet P Further, it is possible to prevent image defects such as image displacement with respect to the sheet P, and to form a high-quality image.

  In the above description, the case where the sheet feeding apparatus of the present invention is applied to an image reading apparatus has been mainly described as an example. However, the present invention is not limited to an image reading apparatus, for example, a copying machine, a printer, a facsimile machine, and the like. Also in an image forming apparatus such as a multifunction machine, the present invention can be widely applied as a sheet feeding apparatus for feeding a sheet to be an image forming target.

FIG. 2 is a diagram showing an overview of the entire image reading apparatus, and is a perspective view of the image reading apparatus as viewed from the upper left side obliquely upward. FIG. 5 is a schematic diagram of a longitudinal section taken along the sheet feeding direction of the image reading apparatus as viewed from the left. It is the perspective view which looked at the vicinity of the separation pad from the diagonally upper left of the front side. It is a front view which shows the state in which the lift plate was arrange | positioned in the downward setting position, and the sheet | seat was set. It is a front view which shows the state which the lift board has been arrange | positioned in the upper feeding position, and contact | abutted to the feeding roller. It is a figure which shows typically the positional relationship of a nip, the separation surface of a separation pad, and the inclination guide part of a guide member. It is the figure seen from the downstream explaining the behavior of the sheet | seat at the time of setting.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Image reading device, 11 ... Sheet feeding device, 13 ... Image reading means, 22 ... Feeding roller (feeding member), 40 ... Stopper, 41, 42 ... Side regulating plate (Side regulating) Member), 43 ... lift plate, 44 ... lifting means, 45 ... separation pad, 46, 47 ... guide member, 46a, 47a ... inclined guide part, a1, b1, c1, d1 ... crossing part, N ... Nip, Na ... downstream end of nip, Nb ... upstream end of nip, Nc ... center of nip, Nw ... nip width, P ... sheet, S1 ... loading surface, S2 ... separation surface,

Claims (7)

The uppermost sheet among a plurality of sheets set in a stacked state on the stacking tray is sequentially arranged at the feeding position, and is fed downstream by friction based on the rotation of the feeding member. In the feeding device,
When the end on the downstream side in the transport direction of the sheet on the stacking tray is the front end, and the left and right ends in the transport direction are the side edges,
A stopper that regulates the leading edge of the sheet placed on the stacking tray and performs positioning in the feeding direction;
A side regulating member that regulates the side edge of the sheet placed on the stacking tray and performs positioning in the sheet passing width direction;
A lift plate capable of moving up and down having a placement surface for supporting the front end side of the sheet positioned on the stacking tray from below;
Elevating means for lowering the lift plate to a lower set position when setting a sheet, and raising the lift plate so that the uppermost sheet is located at the feeding position when feeding a sheet;
Has a separation surface disposed so as to protrude from the mounting surface in a position corresponding to the feed member in the placement surface, the separation surface in contact with the back surface of the lowermost sheet after the set of sheets A separation pad to prevent double feeding,
A guide member for guiding a sheet set so as to be rubbed from the upstream side to the downstream side on the placement surface, in the vicinity of the separation pad, and
The guide member has an inclined guide portion disposed in the vicinity of each side end of the separation pad,
The inclined guide portion is inclined so that the upstream side is high and the downstream side is low with respect to the separation pad, and has an intersecting portion that intersects the separation surface when viewed from the sheet passing width direction.
A sheet feeding apparatus characterized by that. A contact portion between the separation surface of the separation pad and the feeding member when the lift member is disposed at the feeding position is defined as a nip, and a distance between an upstream end and a downstream end in the nip is defined as a nip width. When
The inclined guide portion is disposed such that the intersecting portion is located within the nip width in a state viewed from the sheet passing width direction.
The sheet feeding apparatus according to claim 1. The inclined guide portion is disposed so that the intersecting portion is located between the center of the nip width and the upstream end of the nip in a state viewed from the sheet passing width direction.
The sheet feeding apparatus according to claim 2, wherein the sheet feeding apparatus is a sheet feeding apparatus. The inclined guide portion is disposed so that the intersecting portion is positioned immediately upstream of the upstream end of the nip in a state viewed from the sheet passing width direction.
The sheet feeding apparatus according to claim 2, wherein the sheet feeding apparatus is a sheet feeding apparatus. The feeding member is formed such that the width in the sheet passing width direction is narrower than the width between the inclined guide portions.
The sheet feeding device according to any one of claims 1 to 4, wherein the sheet feeding device is provided. An image reading apparatus comprising: a sheet feeding device that feeds a sheet-like document; and an image reading unit that reads an image of the document fed by the sheet feeding device.
The sheet feeding device is the sheet feeding device according to any one of claims 1 to 5,
An image reading apparatus. In an image forming apparatus comprising: a sheet feeding device that feeds a sheet on which an image is formed; and an image forming unit that forms an image on the sheet fed by the sheet feeding device;
The sheet feeding device is the sheet feeding device according to any one of claims 1 to 5,
An image forming apparatus.

Images