JP2008133079A - Sheet feeder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet feeder capable of well separating even sheets such as coated paper which are difficult to be separated during the feeding. <P>SOLUTION: A flange-like nip pressure adjusting member 12 integrally rotated with a roller part 15 of a feed roller 11 is disposed at both ends of the roller part 15. The nip pressure adjusting member 12 has large circular arc parts 43a larger in radius than the outer peripheral surface 15a of the roller part 15 at four positioned equally spaced in the circumferential direction, respectively. The uppermost sheet S disposed at the feed position M is fed by the rotation of the feed roller 11 in the direction of an arrow R11. When the outer peripheral surface 15a of the roller part 15 is brought into contact with the sheet S, the nip pressure of a nip N1 is large, and when the large arcuate part 43a is brought into contact therewith, the nip pressure is small. Since the nip pressure is cyclically changed, a conveying force is also cyclically changed. Consequently, the sheet can be easily separated. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sheet feeding device that is mounted on an image forming apparatus such as a copying machine or a printer and feeds an image-formed sheet to an image forming unit.

  In an image forming apparatus such as a copying machine, a printer, or a facsimile, a technique is known in which the uppermost sheet among a plurality of sheets set in a stacked state is fed by friction of a sheet feeding roller (for example, Patent Document 1).

By rotating the paper feed roller arranged so as to contact the leading edge of the uppermost sheet and the separation member, the sheet can be double fed due to the difference in frictional force of the paper feed roller, the sheet, and the separation member. While being prevented, the toner is supplied to the downstream conveying roller. Further, a collar having a rotational axis eccentric with the feed roller is arranged at both ends of the feed roller. After the sheet reaches the transport roller, the collar is brought into contact with the leading edge of the sheet and the separation member. Thus, the sheet feeding roller is prevented from coming into contact with the leading edge of the sheet and the separating member. Thereby, it is possible to prevent a certain portion (the same portion) of the sheet feeding roller from being intensively worn, thereby improving durability and stabilizing sheet feeding performance and separation performance.
JP 2001-88955 A

  However, the above-described technique disclosed in Patent Document 1 prevents the sheet feeding roller from contacting the sheet or the separation member more than necessary after the sheet fed by the sheet feeding roller is conveyed downstream. It is a technology for improving durability and stabilizing paper feeding / separation performance. That is, according to this technique, it is not possible to prevent double feeding of sheets that is started to be fed by the paper feed roller. That is, for example, recently, the use of various types of coated paper is increasing in order to increase the color printing output, but the coated paper has higher surface smoothness than ordinary copy paper. Therefore, particularly in a high-humidity environment, the adhesive strength between the coated papers becomes high, and two or more coated papers bundle into the separation member and exceed the processing capacity of the separation member, There is a problem that jam (paper jam) occurs.

  Accordingly, an object of the present invention is to provide a sheet feeding apparatus that can satisfactorily separate even a sheet that is difficult to separate such as coated paper.

  The invention according to claim 1 relates to a sheet feeding device that feeds a plurality of stacked sheets from the topmost sheet in order toward the downstream side. The sheet feeding device according to the present invention is disposed so as to be capable of driving and rotating, and is elastically deformed by being brought into contact with the vicinity of the end portion on the downstream side in the feeding direction of the uppermost sheet to form a nip and rotate. A sheet feeding roller that feeds a sheet by frictional force in the nip, and a plate-shaped nip pressure adjusting member that is disposed near both ends of the sheet feeding roller and rotates in synchronization with the sheet feeding roller; The nip pressure adjusting member has a convex portion on an outer peripheral edge that makes the nip pressure of the paper feed roller smaller than a normal nip pressure by contacting the uppermost sheet when the paper feed roller rotates. And a recess having a normal nip pressure.

  According to a second aspect of the present invention, in the sheet feeding apparatus according to the first aspect, a plurality of the convex portions are formed at positions that equally divide the nip pressure adjusting member in the circumferential direction, and between the adjacent convex portions. The concave portion is formed.

  According to a third aspect of the present invention, in the sheet feeding apparatus according to the first or second aspect, the convex portion protrudes radially outward from the outer peripheral surface of the paper feed roller and is a great circle that contacts the sheet. It has an arc-shaped portion, and the concave portion has a small arc-shaped portion that is recessed radially inward from the outer peripheral surface of the paper feed roller.

  The invention according to claim 4 is the sheet feeding apparatus according to claim 3, wherein the large arc-shaped portion and the small arc-shaped portion are formed to have substantially the same length, and the end of the large arc-shaped portion; An end portion of the small arc-shaped portion adjacent thereto is connected by an inclined portion inclined with respect to the radial direction.

  According to a fifth aspect of the present invention, in the sheet feeding apparatus according to any one of the second to fourth aspects, at least the large arc-shaped portion is formed by a low friction member having a small friction coefficient with the sheet. Or is covered by a low friction member.

  According to a sixth aspect of the present invention, in the sheet feeding device according to any one of the first to fifth aspects, the sheet feeding roller feeds the downstream side of the sheet feeding roller along the sheet feeding direction. A conveyance roller that conveys the fed sheet to the downstream side and a retard roller that is in contact with the conveyance roller and prevents double feeding of the sheet are provided.

  According to a seventh aspect of the present invention, in the sheet feeding apparatus according to the sixth aspect, at least one sheet is fed while the sheet fed by the paper feeding roller reaches the contact portion between the conveying roller and the retard roller. The circumferential pitch of the adjacent large arc-shaped portions is set so that the convex portion comes into contact with the sheet.

  According to an eighth aspect of the present invention, in the sheet feeding device according to the sixth or seventh aspect, the sheet feeding roller and the conveying roller are rotatably supported, and the sheet feeding device is detachably supported by the sheet feeding device body. A feeding frame, and a lift plate that stacks a plurality of stacked sheets and is biased upward by a biasing member to bring the uppermost sheet into contact with the paper feed roller. It is characterized by that.

  According to the first aspect of the present invention, the nip pressure adjusting member reduces the nip pressure by contacting the uppermost sheet with the convex portion on the outer peripheral edge by the rotation of the paper feed roller. That is, during one rotation of the paper feed roller, the nip pressure decreases at least once, and the nip pressure periodically increases or decreases as the paper feed roller rotates. As described above, when the nip pressure periodically changes, a small conveying force and a large conveying force act alternately on the sheet. For this reason, it becomes easy to generate double feeds, for example, even for coated paper. The low nip pressure includes the case where the nip pressure is zero.

  According to the second aspect of the present invention, since the plurality of convex portions are respectively arranged at positions where the nip pressure adjusting member is equally divided in the circumferential direction, the plurality of convex portions are formed during one rotation of the paper feed roller. The sheet comes in contact with the sheet, and the magnitude of the conveying force is repeated twice or more. For this reason, the sheets are more easily separated.

  According to the invention of claim 3, since the convex portion has the large arc-shaped portion that comes into contact with the sheet, the sheet is not required in the vertical direction while the large arc-shaped portion is in contact. There is no change, so a smooth transition can be made the next time the surface of the paper feed roller is brought into contact. Similarly, when the sheet is brought into contact with the large arcuate portion from the state where the sheet is in contact with the surface of the paper feed roller, the process is smoothly performed. Thereby, the magnitude of the nip pressure (the magnitude of the conveying force) can be repeated stably and periodically.

  According to the invention of claim 4, the normal nip pressure and the small nip pressure are alternately repeated at substantially the same time. That is, since the strength is repeated at the same cycle, this makes it easier to separate the sheets.

  According to the invention of claim 5, since the large arc-shaped portion itself is formed by the low friction member or is covered by the low friction member, when the low friction member abuts on the sheet, Sliding easily occurs between them. That is, even when the large arc-shaped portion is brought into contact with the nip pressure of the paper feeding roller to be reduced or zero, when the large arc-shaped portion is brought into contact, the frictional force between the large arc-shaped portion and the sheet is greatly applied. Then it doesn't make sense. Therefore, in the present claims, the friction between the large arc-shaped portion and the sheet is reduced.

  According to the sixth aspect of the present invention, since the sheet supplied to the contact portion between the feeding roller and the retard roller by the sheet feeding roller is easily separated when fed by the sheet feeding roller, the sheet is fed by the conveying roller and the retard roller. Sheet separation can be further ensured.

  According to the seventh aspect of the present invention, the nip pressure changes at least once after the uppermost sheet reaches the abutting portion between the conveyance roller and the retard roller after feeding is started. Will be done.

  According to the eighth aspect of the present invention, the paper feed roller and the transport roller are rotatably supported by the feed frame, and the feed frame is detachably supported by the feeder main body. When a jam occurs in the vicinity, the paper feed roller and the transport roller can be easily removed together with the feed frame. For this reason, the jam processing is easy.

  Hereinafter, the best embodiment of the present invention will be described in detail with reference to the drawings. In addition, in each drawing, the member etc. which attached | subjected the same code | symbol are the same structures, The duplication description about these shall be abbreviate | omitted suitably. Moreover, in each drawing, members and the like that are not necessary for the description are omitted as appropriate.

<Embodiment 1>
The sheet feeding apparatus 1 according to the present invention will be described with reference to FIGS. Among these, FIG. 1 is a view of the vicinity of the feeding unit 10 in the sheet feeding apparatus 1 as viewed from the front side. FIG. 2 is a perspective view of the feeding unit 10 as viewed obliquely from the lower right front side. FIG. 3 is a perspective view of the paper feed roller 11 as viewed from the front right and diagonally upward. FIG. 4 is a view of the sheet feeding roller 11 as viewed from the front side. 5A and 5B are diagrams for explaining the operation of the paper feed roller 11 and the nip pressure adjusting member 12.

  As shown in these drawings, the sheet feeding apparatus 1 according to the present invention includes a sheet feeding roller 11 and nip pressure adjusting members 12 disposed at both ends in the axial direction. The paper feed roller 11 includes a cylindrical cored bar 13, a shaft 14 (see FIGS. 1 and 2) penetrating the center thereof, and a rubber roller unit 15 surrounding the outer peripheral surface of the cored bar 13 in a cylindrical shape. have. As will be described later, the roller portion 15 is elastically deformed to form the nip N1 when the sheet S comes into contact with the outer peripheral surface (front surface) 15a. A small diameter portion 16 is formed on the front end side of the shaft 14. In the sheet feeding roller 11, the cored bar 13, the shaft 14, and the roller unit 15 are integrally formed, and the cored bar 13 and the roller unit 15 are rotated integrally with the rotation of the shaft 14. The nip pressure adjusting member 12 is formed in a substantially disk shape, is fixed to the cored bar 13, and rotates integrally with the rotation of the paper feed roller 11. The nip pressure adjusting member 12 will be described in detail later.

  As shown in FIGS. 1 and 2, the paper feed roller 11 is incorporated in a feed frame 18 together with a later-described transport roller 17 to constitute a feed unit 10 as a whole. The feeding frame 18 is formed in a box shape without a bottom, and includes a front side plate 20, a rear side plate 21, a right side plate 22, a left side plate 23, and an upper plate 24. A plate-like pedestal 25 projects from the upper end of the front plate 20 slightly to the left of the center in the left-right direction. On this pedestal 25, a projecting semi-annular support portion 26 is provided so as to project outward toward the left side. The rear side plate 21 is formed in the same shape as the front side plate 20 and has the same pedestal 25 and support portion 26. These support portions 26 are for attaching the feeding unit 10 to a sheet feeding apparatus main body (not shown) as will be described later. Here, the sheet feeding apparatus main body refers to a part of the sheet feeding apparatus 1 excluding the feeding unit 10, in particular, a main body frame for attaching each constituent member.

  The sheet feeding roller 11 is arranged on the upstream side in the sheet feeding direction of the feeding frame 18 (the right side in FIGS. 1 and 2: hereinafter simply referred to as “upstream side”) and on the lower side, and the front end of the shaft 14. The small-diameter portion 16 and the rear end side of the side are rotatably supported by the front side plate 20 and the rear side plate 21, respectively. The rear end side of the shaft 14 of the paper feed roller 11 protrudes rearward from the rear plate 21, and a coupling (not shown) is attached to this protruding portion. In this coupling, by attaching the feeding unit 10 to the sheet feeding apparatus main body, a motor (not shown) as a drive source and a transmission mechanism (not shown) arranged on the sheet feeding apparatus main body side are provided. It is connected via.

  As shown in FIGS. 1 and 2, the transport roller 27 is made of a rubber that surrounds a cylindrical cored bar 28, a shaft 30 that passes through the center of the cored bar 28, and an outer peripheral surface of the cored bar 28 in a cylindrical shape. The roller part 31 is provided. In the transport roller 27, the cored bar 28, the shaft 30, and the roller unit 31 are integrally configured, and the cored bar 28 and the roller unit 31 rotate integrally with the rotation of the shaft 30. The conveying roller 27 is disposed on the downstream side in the sheet feeding direction of the feeding frame 18 (left side in FIGS. 1 and 2; hereinafter, simply referred to as “downstream side”) and on the lower side, and the shaft 30 is a front plate. 20 and a rear plate 21 are rotatably supported. The rear end side of the shaft 30 of the transport roller 27 protrudes rearward from the rear plate 21 and is connected to the shaft 14 of the paper feed roller 11 via a power transmission mechanism (not shown) such as a gear train. . The diameters of the roller portions 15 and 31 of the paper feed roller 11 and the transport roller 27 are set to be the same, and are rotated synchronously via the power transmission mechanism described above.

  As shown in FIG. 1, the feeding unit 10 configured as described above engages the support portion 26 obliquely from the upper left with the positioning boss 32 (see the two-dot chain line in FIG. 1) on the sheet feeding apparatus main body side. By combining them, the sheet feeding apparatus main body is arranged at a predetermined position. Here, the predetermined position means that the feeding unit 10 rotates around the positioning boss 32 in the direction of the arrow R10 (counterclockwise) by its own weight acting on the center of gravity G of the feeding unit 10 by the above-described engagement. Thus, a reference surface (not shown) formed on a part of the upper plate 24 of the feeding frame 10 abuts against a stopper 33 (see a two-dot chain line in FIG. 1) on the sheet feeding apparatus main body side. Thus, the entire feeding unit 10 is in a stable state. In this state, the conveyance roller 27 is brought into contact with the retard roller 34 on the sheet feeding apparatus main body side from substantially above, and forms a nip (contact portion) N2 with the retard roller 34. .

  The retard roller 34 is equipped with a one-way clutch (not shown) that allows only rotation in the direction of arrow R34 and a spring (not shown) that biases in the opposite direction. When only one sheet S is supplied to the nip N2, the spring rotates the retard roller 34 in the direction of the arrow r34 by the sheet S, while two or more sheets S are in the nip N2. Is supplied, the retard roller 34 is stopped and the sheet S in contact with the retard roller 34 is adjusted so as not to be conveyed downstream.

  As shown in FIG. 1, the sheet S fed by the paper feed roller 11 is placed in a stacked state on a lift plate 37 disposed on the bottom 36 in the paper feed cassette 35. The lift plate 37 has a swing center (not shown) on the upstream side (right side in FIG. 1), and the tip side 38 can swing substantially vertically. The lift plate 37 is biased upward by a compression spring 40 interposed between the back surface of the front end side 38 and the bottom portion 36 of the paper feed cassette 35. As a result, the uppermost sheet S among the stacked sheets S is brought into contact with the sheet feeding roller 11 and stopped. In this state, a nip N1 (see FIG. 5A) is formed between the sheet feeding roller 11 and the uppermost sheet S. If the position of the sheet S at this time is a sheet feeding position M, the sheet S is urged upward by the compression spring 40 via the lift plate 37, so that the uppermost sheet S is the arrow of the sheet feeding roller 11. When the sheet S is fed by rotation in the R11 direction, the next highest sheet S is sequentially arranged at the sheet feeding position M such that the next sheet S is arranged at the sheet feeding position M. Become.

  Next, the nip pressure adjusting member 12 will be described in detail. As shown in FIGS. 3 and 4, the nip pressure adjusting member 12 is formed in a substantially disk shape and is fixed to the core metal 13 of the paper feed roller 11. The nip pressure adjusting member 12 has a through hole 41 on the center side, and is fixed by engaging a claw portion 42 formed at the peripheral edge of the through hole 41 with the core bar 13. In the present embodiment, the nip pressure adjusting member 12 has a convex portion 43 formed at a position where the peripheral edge portion is equally divided into four in the circumferential direction, and a concave portion 44 is formed between the two convex portions 43 adjacent in the circumferential direction. ing. As shown in FIG. 4, the convex portion 43 has a large arc-shaped portion 43 a that protrudes outward from the outer peripheral surface 15 a of the roller portion 15 of the paper feed roller 11. The large arc-shaped portion 43a is formed with a radius R2 larger than the radius R1 of the outer peripheral surface of the roller portion 15. The circumferential length L1 is the circumferential length of a small arc-shaped portion 44a described later. It is almost the same as L2. On the other hand, the concave portion 44 has a small arc-shaped portion 44 a that is recessed inward from the outer peripheral surface 15 a of the roller portion 15 of the paper feed roller 11. The small arc-shaped portion 44a is formed with a radius R3 smaller than the radius R2 of the outer peripheral surface 15a of the roller portion 15. The circumferential length L2 is the circumferential length of the large arc-shaped portion 43a. It is almost the same as L1. The circumferential end of each large arc-shaped portion 43a described above and the circumferential end of the small arc-shaped portion 44 adjacent to the large arc-shaped portion 43a are connected by an inclined portion 45 that is inclined with respect to the radial direction. In the nip pressure adjusting member 12, at least the large arc-shaped portion 43 a that is in direct contact with the sheet S is formed of a member having a small coefficient of friction with the sheet S, for example, polyacetal. Instead of this, the large arc-shaped portion 43a may be covered with a sheet-like low friction member.

  In the sheet feeding apparatus 1 configured as described above, when the uppermost sheet S is fed by the rotation of the sheet feeding roller 11 in the direction of the arrow R11 shown in FIGS. The nip pressure is periodically changed so that the conveying force for the sheet S is periodically changed. Hereinafter, this point will be described in detail.

  As shown in FIG. 1, when the uppermost sheet S is disposed at the sheet feeding position M, when the sheet feeding roller 11 rotates in the direction of the arrow R <b> 11, the uppermost sheet S is in friction with the sheet feeding roller 11. Is fed downstream. When the outer peripheral surface 15a of the roller portion 15 of the paper feeding roller 11 comes into contact with the uppermost sheet S by the rotation of the paper feeding roller 11 at the time of paper feeding (see FIG. 5A), the nip pressure is adjusted. The case where the large arc-shaped portion 43a of the member 12 abuts (see FIG. 5B) is alternately and periodically repeated. When the outer peripheral surface 15a of the roller unit 15 is brought into contact with the uppermost sheet S, a normal nip N1, that is, nip pressure adjustment is performed between the outer peripheral surface 15a of the roller unit 15 and the uppermost sheet S. A nip similar to the case where the member 12 is not mounted is formed. The nip pressure at this time is a normal nip pressure. Under this normal nip pressure, the paper feed roller 11 can apply a normal conveying force to the uppermost sheet S. On the other hand, when the large arc-shaped portion 43a of the nip pressure adjusting member 12 contacts the uppermost sheet S, the outer peripheral surface 15a of the roller portion 15 does not contact the uppermost sheet S, or Even in the case of contact, the nip pressure is small (small nip pressure, including the case where the nip pressure is zero). In this case, the conveyance force for the uppermost sheet S is a conveyance force (small conveyance force) smaller than the above-described normal conveyance force.

  As described above, when the uppermost sheet S is fed by the paper feed roller 11, the normal nip pressure and a smaller nip pressure smaller than the normal nip pressure are periodically cycled as the paper feed roller 11 rotates. Repeated. As a result, the conveying force for the uppermost sheet S is periodically and alternately repeated between the normal conveying force and the small conveying force. That is, the acceleration in the transport direction and the acceleration in the opposite direction act on the sheet S alternately, and the vibration (shock) is intermittently applied to the sheet S being transported. Further, the fact that the nip pressure periodically changes means that the frictional force acting between the uppermost sheet S and the next sheet S changes periodically. The same is true between the next sheet S and the next next sheet S. That is, it means that the frictional force between the two overlapping sheets S changes periodically. In addition, the change in the nip pressure means that an operation of hitting the sheet S from above is added. For this reason, a plurality of upper sheets S including the uppermost sheet S are easily separated. Accordingly, when the uppermost sheet S is fed, a plurality of sheets S are temporarily fed by the rotation of the paper feed roller 11 in the direction of the arrow R11, and the transport roller 27 and the arrow R34 are rotated in the direction of the arrow R27. Even when entering the nip N2 between the retard roller 34 rotating in the direction, since these sheets S are easily separated, only the uppermost sheet S is conveyed downstream, The following sheets S are stopped when the retard roller 34 is stopped to prevent double feeding.

  The present invention is particularly effective for the above-described coated paper as the sheet S, that is, a sheet having high surface smoothness and being easy to adhere to each other at high humidity. Or, conversely, it is also effective in the case where double feed is likely to occur due to the low smoothness of the surface of the sheet itself. That is, the present invention is effective in the case where double feeding of the sheet S is likely to occur at the time of paper feeding due to the properties of the sheet S itself and environmental conditions such as ambient humidity.

  In the present invention, in principle, the nip pressure adjusting member 12 has the large arc-shaped portion 43a at least at one position on the peripheral edge, and at least once during the rotation of the paper feed roller 11. For example, when the distance from the leading edge of the uppermost sheet S to be fed to the nip N2 between the transport roller 27 and the retard roller 34 is short, the change in the nip pressure is sufficient. There may be a case where the leading edge of the sheet S reaches the nip N2 before the roller 11 makes one rotation. In such a case, for example, the nip pressure adjusting member 12 is provided with a plurality of large arc-shaped portions 43a, and the number of the large arc-shaped portions 43a between the adjacent large arc-shaped portions 43a is from the leading edge of the sheet S to the nip N2. If the distance is shorter than this distance, a change in the nip pressure always occurs before the leading edge of the sheet S reaches the nip N2.

  In the above embodiment, the case where four large arc-shaped portions 43a and four small arc-shaped portions 44a are alternately provided along the peripheral edge of the nip pressure adjusting member 12 has been described as an example. For example, if at least one convex portion 43 is provided, the size of the nip pressure can be realized by the rotation of the paper feed roller 11. That is, the number of convex portions 43 can be arbitrarily set.

  In the above description, the case where the circumferential length L1 of the large arc-shaped portion 43a and the circumferential length L2 of the small arc-shaped portion 44a are approximately the same length has been described as an example. It may be a length. Furthermore, for example, it is possible to form each large arcuate portion 43a so that the lengths thereof are different.

  In the above description, the small arc-shaped portion 44a is provided in the concave portion 44. In this case, the small arc-shaped portion 44a can be used as a regulating member for regulating the upper limit of the nip pressure. That is, when the nip N1 is formed in the portion corresponding to the small arc-shaped portion 44a in the outer peripheral surface 15a of the roller portion 15, the small arc-shaped portion 44a is brought into contact with the sheet S so that the nip pressure is reduced. It can be used to set an upper limit so that it does not become higher. Therefore, in the case where the small arc-shaped portion 44a does not contact the sheet S, it is sufficient to simply form the recess 44 instead of the small arc-shaped portion 44a.

  In the above description, the case where the large arc-shaped portion 43a is formed in an arc shape with the center of the shaft 14 as a reference has been described. However, the present invention is not limited to this, and smooth Any shape may be used as long as the shape is arbitrary.

  In the above description, the case where the present invention is applied to a sheet feeding apparatus has been described as an example. However, the present invention is not limited to a sheet, and can be widely used when feeding a member cut into a thin plate shape. there is a possibility.

FIG. 5 is a view of the vicinity of a feeding unit in the sheet feeding apparatus as viewed from the front side. It is the perspective view which looked at the feeding unit from diagonally downward on the front right side. It is the perspective view which looked at the paper feed roller from the front right diagonally upward. FIG. 6 is a view of a sheet feeding roller as viewed from the front side. (A), (b) is a figure explaining operation | movement of a paper feed roller and a nip pressure adjusting member.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Sheet feeding apparatus, 11 ... Paper feed roller, 12 ... Nip pressure adjusting member, 27 ... Conveyance roller, 34 ... Retard roller, 36 ... Lift plate, 43 ... Projection, 43a ... Large arc-shaped portion, 44 ....... concave portion, 44 a... Small arc-shaped portion, 45 .. inclined portion, N 1 ..nip between sheet feeding roller and uppermost sheet, N 2. Nip (contact part), S ... sheet

Claims (8)

Among a plurality of stacked sheets, in the sheet feeding apparatus that feeds the downstream sheet in order from the top sheet,
It is arranged so that it can be driven and rotated, and is elastically deformed by being brought into contact with the vicinity of the downstream end of the uppermost sheet in the feeding direction to form a nip, and the sheet is made by the frictional force in the nip as it rotates. A feed roller for feeding,
A plate-like nip pressure adjusting member disposed near both ends of the paper feed roller and rotating in synchronization with the paper feed roller;
The nip pressure adjusting member comes into contact with the uppermost sheet at the time of rotation of the paper feed roller at the outer peripheral edge, and a convex part that makes the nip pressure of the paper feed roller smaller than a normal nip pressure, And a recess having a nip pressure of
A sheet feeding apparatus characterized by that. A plurality of the convex portions are formed at positions that equally divide the nip pressure adjusting member in the circumferential direction, and the concave portions are formed between the adjacent convex portions.
The sheet feeding apparatus according to claim 1. The convex portion has a large arc-shaped portion that protrudes radially outward from the outer peripheral surface of the paper feed roller and contacts the sheet,
The concave portion has a small arc-shaped portion that is recessed radially inward from the outer peripheral surface of the paper feed roller.
The sheet feeding apparatus according to claim 1, wherein the sheet feeding apparatus is a sheet feeding apparatus. The large arc-shaped portion and the small arc-shaped portion are formed to have substantially the same length, and an end portion of the large arc-shaped portion and an end portion of the small arc-shaped portion adjacent thereto are in a radial direction. Connected by a slanted inclined part,
The sheet feeding apparatus according to claim 3. At least the large arc-shaped portion is formed by a low friction member having a small coefficient of friction with the sheet, or is covered by a low friction member,
The sheet feeding device according to any one of claims 2 to 4, wherein the sheet feeding device is provided. A sheet conveying roller that conveys the sheet fed by the sheet feeding roller to the downstream side of the sheet feeding roller along the sheet feeding direction, and a sheet roller A retard roller for preventing feeding is disposed,
The sheet feeding apparatus according to claim 1, wherein the sheet feeding apparatus is a sheet feeding apparatus. While the sheet fed by the paper feed roller reaches the contact portion between the transport roller and the retard roller, the adjacent large arc shape so that the convex portion comes into contact with the sheet at least once. The circumferential pitch of the part is set,
The sheet feeding apparatus according to claim 6. A feeding frame that rotatably supports the sheet feeding roller and the conveying roller, and is detachably supported by a sheet feeding apparatus body;
A plurality of stacked sheets are stacked, and are urged upward by an urging member, thereby providing a lift plate that abuts the uppermost sheet against the paper feed roller.
The sheet feeding apparatus according to claim 6, wherein the sheet feeding apparatus is a sheet feeding apparatus.

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