JPH0717286B2 - Sheet feeding device - Google Patents

Description

The present invention relates to a sheet feeding device in an image forming apparatus such as a copying machine or a laser beam printer, and more specifically, it includes a feeding roller and a separation roller, and a sheet feeding device. The present invention relates to a sheet feeding device that separates and feeds sheets stacked on a mounting table one by one.

(B) Conventional Technology As shown in FIG. 5, the conventional sheet feeding apparatus 1 has a sheet mounting table 2 on which a large number of sheets S are stacked, and above the mounting table 2, sheets are stacked. A pressing member 3 is provided, and further, a half-moon shaped sheet feeding roller 5 is provided below. A separation roller 6 and a feed roller 7 are provided correspondingly to the sheet mounting table 2, and the outer circumferences of these rollers 6 and 7 are formed by alternately forming uneven portions in a comb shape. The concave-convex portion corresponds to the convex portion of the feeding roller 7 with respect to the concave portion of the separation roller 6, and the concave portion of the feeding roller 7 corresponds to the convex portion of the separation roller 6. Further, the separation roller 6 and the feed roller 7 are arranged such that the outer circumferences of the respective convex portions slightly enter the corresponding concave portions and bite in a non-contact state. The sheet S is sandwiched by the biting portion (nip portion) 9 so that the sheet S is subjected to lateral corrugation. The separating roller 6 is driven in the direction of arrow B, and the feed roller 7 is driven in the direction of arrow A, so that when two or more sheets S are fed (double feed), the weight is increased. The feeding sheets S _{1 to} Sn are separated and cooperate with the sheet feeding roller 5 to feed only the lowest sheet S ₁ . And these rollers 6,7
A substantially horizontal lower guide 10 is provided in front of and behind the nip portion 9 to guide the sheet S to the nip portion 9 and the separated sheet S toward the image forming portion. There is.

In the sheet feeding device 1 having the above-described configuration, a large number of sheets S stacked on the sheet mounting table 2 are pressed against the sheet pressing member 3 with an appropriate pressure, and if necessary, the half-moon-shaped sheet feeding roller 5 is provided. When the sheet S is rotated in the direction of the arrow A, the sheet S is moved to the lower guide 10
And is fed toward the nip portion 9 between the separation roller 6 and the feed roller 7. At that time, when the sheet S is double-fed, the multi-fed sheets S _{1 to} Sn are pushed by the convex portion of the feed roller 7 to the lowest sheet S ₁ at the nip portion 9, and the lowest sheet S _{1 to} Sn is pushed. A frictional force is generated between S ₁ and the convex portion of the feed roller 7, and similarly, a frictional force is also generated between the uppermost sheet Sn and the convex portion of the separation roller 6. Since the coefficient of friction between the rollers 6 and 7 and the sheets Sn and S ₁ is larger than the coefficient of friction between the sheets S and S, the lowest sheet S ₁ is the sheet feed roller 5 and the feeding roller 5. The feeding force of the roller 7 feeds the image toward the image forming unit, and the other double-fed sheets S _{2 to} Sn are
By the separation roller 6 rotating in the direction of arrow B, the uppermost sheet Sn is sequentially pushed back toward the sheet mounting table 2,
As a result, only the lowest sheet S ₁ is the other double-fed sheets S _{2 to} Sn.
It is separated from and sent.

Further, when a large number of sheets are fed into the nip portion 9, separation by the separation roller 6 cannot deal with it, and the separation roller 6 comes into contact with the leading end portion of the sheet to curl.
In order to prevent these, a guide plate is provided adjacent to the separation roller 6.
11 is provided, the guide plate 11 regulates the number of sheets sent to the nip portion 9, and further, the contact angle between the leading end of the sheet S and the separation roller 6 is set as tangential as possible, so that the sheet S is It is configured to guide to the nip portion 9.

(C) Problems to be Solved by the Invention By the way, as shown in FIG. 6 (a), the leading end of the guide plate 11 is inserted into the separation roller 6 and the number of sheets passed becomes 2 to 3. When the gap between the lower guide 10 and the lower guide 10 is set small as described above, the leading edge of the sheet S directly abuts on the outer circumference of the separation roller 6 and the sheet S ₂ causes a leading edge curling phenomenon, or the guide 11 feeds the sheet. The sheet S ₂ that tries to enter the nip portion 9 subsequently to the lowermost sheet S ₁ in the middle is pressed against the feed roller 7, and a conveyance force more than necessary is given to these sheets S, which causes a double feed trouble. It is easy to occur. Further, as shown in FIG. 6 (b), if the leading end portion of the guide plate 11 is moved too far from the nip portion 9, the leading end of the sheet S will enter the gap between the leading end portion of the guide plate 11 and the separation roller 6. When the sheet S is caught, the sheet S causes a phenomenon that the tip is rolled.

Therefore, the applicant has arranged the leading end portion of the guide member at a position close to the upstream end portion of the nip portion region where the separation roller and the feed roller bite each other, and sets the double feed sheet at the leading end. It was discovered that the guide member can be separated without curling by regulating and guiding it to a position where it does not curl, but adjusting the guide member to the proper position is extremely delicate, and the thickness and material of the sheet differ. It has been extremely difficult to adjust the guide member to an appropriate position every time the nip portion is adjusted by the above method.

(D) Means for Solving the Problem The present invention is intended to solve the above-mentioned problems, and a plurality of convex outer peripheries are arranged at predetermined intervals in the axial direction, and are arranged in the sheet feeding direction. A rotating comb-teeth-shaped feed roller and a comb-teeth-shaped separating roller, which is arranged in the axial direction with a plurality of convex outer peripheries at predetermined intervals and rotates in the direction opposite to the sheet feeding direction, are provided. In a sheet feeding device for arranging the sheets so as to bite in an alternate manner and feeding the sheets by separating the sheets one by one between the feed roller and the separation roller, the separation roller is rotatably supported and is movable. A supported separating roller supporting means, a biting amount adjusting means for adjusting the moving position of the separating roller supporting means to change the biting amount of the separating roller and the feed roller, and the separating roller supporting means. Shi A guide member fixed to a guide support portion provided on the upstream side in the feeding direction so as to be movable and adjustable, and extending toward the nip portion between the separation roller and the feed roller so as to guide the leading edge of the sheet. The guide member is provided with a plurality of cutout portions at its tip end to form a comb-teeth-shaped tip end portion, the cutout portion includes the convex outer peripheral portion of the separation roller, and the guide member The leading end of the double feed sheet is adjusted and arranged at a position close to the upstream end of the nip area where both rollers bite into each other, and the double feed sheet is regulated and guided to a position where the leading edge does not curl. Even if the bite amount adjusting means moves the separating roller supporting means to adjust the bite amount of the separating roller with respect to the feed roller, the guide member is Pair with the separation roller That Te is maintained at the same position, and is characterized in.

(E) Action Based on the above configuration, most of the multi-feed sheets are regulated by the guide member and stay without contacting the outer periphery of the separation roller. In addition, a small number of double-fed sheets are guided to the leading end of a guide member arranged close to the nip portion and reach the nip portion. Then, these sheets are pressed and pinched on the uneven outer circumferences of the feed roller and the separation roller and are given a corrugated deformation in the lateral direction, and the sheets of these sheets that come into contact with the feed roller or the separation roller are respectively the rollers. With the convex outer periphery of the sheet, a frictional force superior to the frictional force between the sheets is obtained. Then, the sheet contacting the feed roller is separated from the adjacent sheet and fed by the feeding force from the paper feed roller and the feed roller. On the other hand, the sheets contacting the separation rollers are sequentially pushed back toward the sheet mounting table by the conveyance force of the separation rollers that rotate in the direction opposite to the sheet conveyance direction. At this time, since the leading ends of the respective sheets are guided to the optimum positions close to the nip portion, these sheets are pushed back without the leading ends thereof being curled.

Further, by changing the thickness and material of the sheet to be used, the separation roller supporting means is moved by the biting amount adjusting means, and the separation roller is adjusted so that the feeding roller has an appropriate biting amount. . At this time, since the guide member is integrally supported by the separating roller and the supporting means,
Even if the moving position of the support means changes, the separation roller is always kept in the same state (for example, the state described in claim 3).

(F) Embodiments Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the sheet feeding device 20 according to the present embodiment includes a sheet mounting table 2, a sheet pressing member 3 and a half-moon shaped sheet feeding roller 5, and further faces the sheet mounting table 2. The separation roller 6, the feed roller 7, and the lower guide 10 are provided, but these are similar to those of the above-described conventional sheet feeding apparatus 1, and therefore, the same reference numerals are given and the description thereof is omitted. On the other hand, a separation roller support body 21 is provided facing the separation roller 6, and the support body 21 is provided with front and rear side plates 21a and 21b, respectively.
And has a guide support plate 21c on the upstream side. The roller support 21 has a shaft 22 on both side plates 21.
It is provided over a and 21b, and the roller support body 21 is swingably supported about the shaft 22. Further, a separation roller support shaft 23 is arranged across both side plates 21a and 21b, and the separation roller 6 is rotatably supported by the separation roller support body 21 via the shaft 23. Further, a spring is provided between the spring mounting piece 26 of the fixed wall 25 provided above the separation roller support 21 and the spring mounting piece 27 of the separation roller support 21.
29, 29 are stretched so that the separation roller 6 is integrated with the separation roller support 21 and is urged upward with the shaft 22 as a fulcrum. In addition, the fixed wall 25 has a nip adjustment bolt.
30 is provided, and the tip of the bolt 30 has a separation roller support 21.
The nip amount between the separation roller 6 and the feed roller 7 is adjusted by contacting the upper surface of the. On the other hand, a comb tooth guide 31 forming a guide member is fixedly installed on the guide support plate 21c of the separation roller support 21 via screws 32, 32, and the guide 31 has screw mounting holes 33, 33. It is formed to be slightly larger than the outer diameter of the screws 32, 32 so that the attachment of the comb tooth guide 31 can be adjusted. A large number of notches 31a ... Are formed in a comb-like shape at the tip of the guide (see FIG. 2), and the notches 31a .. Thus, the tip end of the comb tooth guide 31 is arranged at a position close to the upstream end 9a in the region C of the nip portion 9 of the separation roller 6 and the feed roller 7 formed by biting each other. ing. Incidentally, FIG. 3 shows the separation roller 6, the feed roller 7 and the comb tooth guide 31.
FIG. 4 is a view showing the arrangement of the respective concave and convex portions, in which the convex tip end portion of the comb tooth roller 31 bites into the convex outer peripheral portion of the separation roller 6 in an alternating manner.

Specifically, as shown in FIG. 1, the guide 31 has a comb-teeth-shaped tip portion, and the tip surface 31d of the comb-teeth-shaped tip portion.
And a guide surface 31b for guiding the sheet are located on the outer side of the outer periphery of the convex portion of the separation roller 6 in a side view, and the intersection Y between the leading end surface 31d and the surface 31c opposite to the guide surface.
Are adjusted and positioned by the screws 32, 32 so that they are located inside the outer periphery of the convex portion of the separation roller 6 in a side view.

Since the sheet feeding device 20 of this embodiment has the above-described configuration, the lowest sheet S ₁ stacked on the sheet mounting table 2 is
By the rotation of the paper feed roller 5, the paper is fed toward the nip portion 9 of the feed roller 7 and the separation roller 6. At this time, the sheet pressing member 3 are a number of sheet S ... are pressed toward the feed roller 5, between the paper feed roller 5 and the sheet S ₁ of the least significant, to convey the sheet S ₁ At the same time, a sufficient frictional force is obtained, and at the same time, a frictional force is generated between the sheets S and S, which causes the sheets S to be double-fed. And most of the multi-feed sheets Sm ~
Although Sn comes in contact with the tip of the comb tooth guide 31 and its progress is restricted, a small number of double-feed sheets S _{1 to} Sl are guided by the lower guide 10 and pass through the tip of the comb tooth guide 31. The nip 9
Reach Then, the small number of the multi-feed sheets S _{1 to} Sl are pressed and sandwiched by the uneven outer circumferences of the separation roller 6 and the feed roller 7 to impart the corrugated deformation in the lateral direction, and at the same time, these sheets S _{1 to} Sl are The sheets Sl and S ₁ contacting the separation roller 6 or the feed roller 7 in the inside each obtain a frictional force exceeding the frictional force between the sheets with the roller by the pressing force from the convex outer periphery of the roller. . Then, only the sheet S ₁ contacting the feed roller 7 is separated from the adjacent sheet by the conveying force from the paper feed roller 5 and the feed roller 7 and is fed toward the image forming unit (not shown). On the other hand, the sheet Sl that contacts the separation roller 6 is pushed back toward the sheet mounting table 2 by the conveyance force of the separation roller 6 that rotates in the direction opposite to the sheet feeding direction. Then, when the sheet Sl is separated from the outer periphery of the separation roller 6, the sheet Sl _-1 adjacent to the sheet Sl is similarly pushed back, so that all the sheets S _{2 to} Sl except the lowest sheet S ₁ are pushed. When pushed back, the sheets S are separated and fed one by one. At this time, the tip of the comb tooth guide 31 is
At the position close to the upstream end of the nip portion area, most of the double-fed sheet is regulated by the leading end of the guide 31 to prevent the sheet from entering the nip portion 9 and reach the nip portion 9. The small number of double-fed sheets S _{1 to} Sl are also regulated to the number of about 5 to 7 sheets in which the leading edge does not actually occur. That is, as shown in FIG. 4, of the sheets contacting the outer periphery of the separation roller 6, the lower sheet Sa has a smaller horizontal component Fr of the separation force F by the separation roller 6 than the upper sheet Sb (reverse The vertical component Fg increases with the increase of the vertical component Fg), and accordingly, the upper end of the lower sheet Sa is less likely to be rolled up, but at the leading end position of the comb tooth guide 31 corresponding to the sheet thickness of about 5 to 7 sheets. The position where there is no curling of the leading edge of the sheet and there is practically no problem.

Further, in this embodiment, the comb tooth guide 31 is provided as a separation roller supporting member.
Since it is fixed to 21 so as to be movable integrally with the separation roller 6, the nip between the separation roller 6 and the feed roller 7 is set after the comb tooth guide 31 and the outer periphery of the separation roller 6 are positioned at the optimum positions. The amount can be adjusted with the nip adjusting bolt 30 without changing the optimum position.

In this embodiment, the sheet feeding roller 5 is disposed below the sheet mounting table 2, the separation roller 6 is disposed above and the feed roller 7 is disposed below, and the sheet mounting roller 5 is stacked on the sheet mounting table 2. Although the sheets are separated and fed one by one in order from the lowest sheet, the present invention is not limited to this, and the paper feed roller is provided above the sheet mounting table, the feed roller is arranged above, and the separation roller is arranged below. It is needless to say that the separation roller may be provided with a comb-teeth guide so that the uppermost sheets stacked on the sheet mounting table 2 are sequentially separated and fed one by one.

(G) Effect of the Invention As described above, according to the present invention, the guide member is
With respect to the separation roller supporting means, the leading end of the separation roller can be adjusted to an optimum position close to the upstream end of the nip region of the feed roller and the separation roller, whereby the multifeed sheet rotates in the reverse direction. Thus, the leading end portion is wound and separated without buckling, and the sheets can be reliably fed one by one.

Even if the bite amount adjusting means is operated to adjust the separating roller so as to obtain an appropriate biting amount due to the difference in sheet thickness and material, the guide member is properly adjusted with respect to the separating roller. In spite of the above adjustments which are maintained in the position and are performed relatively frequently, the guide member is automatically held in an extremely delicate optimum position to always perform reliable sheet separation and feeding. it can.

[Brief description of drawings]

FIG. 1 is a side view of a sheet feeding device according to an embodiment of the present invention, FIG. 2 is a perspective view of a comb tooth guide of the device, and FIG. 3 is a view showing an arrangement of uneven portions of the comb tooth guide. FIG. 5 is a diagram showing the relationship of the force applied to the sheet front end by the separating roller, FIG. 5 is a schematic diagram of a conventional sheet feeding device, FIG. 6 is a diagram showing the mechanism of the sheet front end rolling, and FIG. FIG. 13B is a diagram showing a case where the plate is too close to the nip portion, and FIG. S ...... sheet, S ₁ to SL ...... fraction of the heavy feed sheets, 6 ...... feed roller, 7 ...... separation roller, 9 ...... nip, 9a ......
Upstream end, 20 ... Sheet feeding device, 21 ... Separation roller support means (support), 21c ... Guide support part, 22 ... Support shaft, 23 ... Separation roller support shaft, 31 ... Guide Member, 31
a …… notch, 31b …… guide surface, 31c …… opposite surface, 3
1d ... Tip surface, X, Y ... Intersection, C ... Nip area.

Claims (3)

[Claims] 1. A comb-teeth-shaped feed roller that rotates in the sheet feeding direction by arranging a plurality of convex outer peripheries at predetermined intervals in the axial direction, and a plurality of convex outer peripheries arranged at a predetermined interval in the axial direction. Comb-teeth-shaped separating rollers that rotate in the direction opposite to the sheet feeding direction are arranged so as to bite the outer peripheries of the convex portions alternately, and one sheet is provided between the feeding roller and the separating roller. In a sheet feeding apparatus that separates and feeds, a separation roller supporting unit that rotatably supports the separation roller and is movably supported, and a moving position of the separation roller supporting unit are adjusted to separate the separation roller. A biting amount adjusting means for changing the biting amount between the sheet feeding roller and the feed roller; and a guide supporting portion provided upstream of the separating roller supporting means in the sheet feeding direction so as to be movable and adjustable, and the separating portion. A guide member extending toward the nip portion to guide the leading edge of the sheet to the nip portion between the roller and the feed roller, and the guide member is provided with a large number of cutout portions at the leading end portion of the comb teeth. -Shaped leading end portion, the convex outer peripheral portion of the separating roller is included in these cutout portions, and the leading end portion of the guide member is located at the upstream end portion of the nip portion region in which the both rollers bite into each other. It is configured so that it can be adjusted and arranged at a position close to each other so that the multi-feed sheet can be regulated and guided to a position where the leading edge of the sheet does not curl, and further the separation roller support means is moved by the biting amount adjustment means. Thus, the guide member is maintained at the same position with respect to the separation roller even if the biting amount of the separation roller is adjusted with respect to the feed roller. 2. The sheet feeding according to claim 1, wherein the position of the leading end of the guide member is a position separated from the other guide for guiding the feeding sheet by a thickness of 5 to 7 sheets. apparatus. 3. The side surface of the guide member, the intersection of the guide surface for guiding the sheet and the front end surface of the front end portion is located outside the outer periphery of the convex portion of the separation roller, and does not guide the sheet. The sheet feeding device according to claim 1 or 2, wherein the crossing portion between the surface on the opposite side and the leading end surface is positioned so as to be located inside the outer periphery of the convex portion of the separation roller.