JPH05338837A - Paper feeding device - Google Patents

Abstract

PURPOSE:To smoothly and surely convey paper sheets while separating them from one another. CONSTITUTION:In a paper feeding device which conveys paper sheets while separating them from one another by means of a feed roller 130 and a separate roller 131 which is pressed into contact with the feed roller 130 and can be rotated in the opposite direction to feeding, a thin piece elastic body paper guide 134 having one end extended near a separating nip N from roughly the tangential direction of the outer peripheral surface of the separate roller 131 is provided to surely convey a bundle of paper sheets to the separating nip N.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding device used in an image forming apparatus such as a copying machine, a printer and a facsimile machine.

[0002]

2. Description of the Related Art In a double-sided device of a copying machine, a downward-feeding re-feeding device is used to adjust the page order of copies to be made and to improve the processing speed.

By the way, generally, in the lower feed,
At the time of feeding the bottom sheet, the upper sheet bundle also tries to be fed to the separation nip, so that a paper feeding problem (double feeding, non-feeding, slipping, etc.) is more likely to occur than upper feeding.

As a conventional technique for improving this, as shown in Japanese Patent Laid-Open No. 63-41332, it is known to form a wedge shape in which the lower side of the feeding side of the sheet bundle is made to precede the upper side. ing. If the sheet bundle is shaped like this and the sheets are fed in order from the lower sheet, the bottom sheet is likely to reach the separation nip, and the upper sheet bundle is easily separated, so that the sheet feeding performance may be improved. Are known.

There is also known a paper feed system in which a feed roller and a separate roller are used, and the separate roller is rotated in a counter feeding direction to feed back a double feed.

[0006]

In the above-mentioned prior art, when a large number of sheets are advanced to the nip at a time, the separating means is pushed open by the wedge effect at the leading edge of the sheet bundle. Was pushed up and double feeding was likely to occur.

Further, in the system in which the separate roller is rotated in the counter feeding direction, as shown in FIG. 11, the leading edge of the second and subsequent sheets of paper 10 is curled up by the separate roller 11, and the leading edge is scratched. At the same time, the scratches tend to cause double feeding and non-feeding. Further, since a double-sided device or the like handles a sheet on which one side has been copied, there is a problem in that the toner falling off the image surface contaminates the roller or the edge of the sheet becomes extremely dirty.

It is an object of the present invention to provide a sheet feeding device which can smoothly and reliably separate and convey sheets.

[0009]

SUMMARY OF THE INVENTION The above-described object is to provide a sheet feeding device for feeding sheets of paper stacked and accommodated one by one from the bottom sheet side by frictional force and feeding the bottom sheet. Feeding roller, a separate roller made of a material having a coefficient of friction lower than that of the feeding roller, pressed against or facing the feeding roller and rotating at a low speed in the counter feeding direction, and one end thereof is supported by a fixed portion above the conveying path. ,
Further, the other end is provided with a thin elastic sheet guide extending from a substantially tangential direction of the outer peripheral surface of the separate roller to the vicinity of the separation nip.

Further, the free end of the thin elastic paper guide is elastically contacted with the outer peripheral surface of the separate roller,
2-30% of the peripheral speed of the feed roller
It can also be achieved by a configuration of rotating in the counter feeding direction at a peripheral speed of.

Further, in a paper feeding device for feeding one by one from the bottom paper side of the stacked and accommodated papers by frictional force and feeding the paper, the bottom paper is provided below the stacked papers, and the bottom paper is separated. Sheet feeding means, a feeding roller for feeding the lowermost sheet in the feeding direction, a separate roller arranged in pressure contact with or facing the feeding roller and for preventing double feeding, and one end supported by a fixed portion at the bottom of the feeding path. It is also achieved by a configuration including a thin elastic paper guide whose other end extends along the outer peripheral surface of the feed roller to the vicinity of the separation nip.

[0012]

By elastically contacting the thin elastic paper guide in a direction substantially tangential to the outer peripheral surface of the separation roller, the leading end of the paper can reach the vicinity of the separation nip sufficiently, and when the separation roller rotates in the counter feeding direction, Rolling up and damage to the surface of the separate roller are prevented.

Further, since the separate roller is rotated in the counter feeding direction at a peripheral speed ratio of 2 to 30%, when the leading edge of the sheet bundle enters in a wedge shape, the upper layer of the sheet bundle in contact with the peripheral surface of the separate roller is sent back. The pressure increase due to the wedge effect is alleviated, the sheets are easily separated one by one, and the surface of the sheet and the surface of the separate roller are not significantly contaminated by the falling toner.

Further, by extending the thin elastic paper guide along the outer peripheral surface of the feed roller to the vicinity of the separation nip, the leading edge of the paper is separated from the surface of the feed roller by the thin elastic paper guide, and the feed roller is fed. The surface does not hinder the progress of the paper,
The leading edge of the sheet bundle is smoothly guided to the separation nip.

[0015]

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

FIG. 2 is a block diagram of a double-sided device of a copying machine.
In the figure, a double-sided device 100 is an intermediate tray 101.
A transport roller 102 provided on the downstream side of the intermediate tray 101 in the transport direction, a stopper 103 further provided on the downstream side of the intermediate tray 101, and a delivery roller for delivering the sheet on the intermediate tray 101 provided on the lower surface side of the intermediate tray 101. 12
It is mainly composed of 0 group.

By transferring the image on the photosensitive drum 1, the sheet 2 which has been copied on one side is fixed by the fixing device 3, the branching claw 4,
It is fed into the double-sided device 100 through the switch back device 5. The sheet 2 carried into the double-sided device 100 is discharged and stored on the intermediate tray 101 from the discharge gates A1 to A4 which are predetermined according to the sheet length in the transport direction.
That is, the long letter is emitted from the A1 side and the short letter is emitted from the A4 side. The discharged sheet 2 slides on the already stored sheet 2, is further conveyed by the conveying roller 102, and collides with the stopper (stopper gate means) 103 to align the advancing edges of the sheet.

When a predetermined number of sheets 2 are accommodated, the stopper 103 makes one turn around the support shaft 104, and the conveying path is opened. After that, the delivery roller group 12 having a missing circle portion 12
0 rotates once, and the entire sheet bundle 200 is transferred to the separation roller pair 105 on the downstream side, and at the same time, the separation roller pair 105 separates and feeds the bottom sheet by one sheet, and the double-sided device 10
It is sent from 0.

FIG. 1 is a detailed configuration diagram of a main portion of a re-feeding device according to an embodiment of the present invention, and FIG. 3 is a main-portion configuration diagram showing a state of the re-feeding device at the time of separate sheet feeding.

The transport roller 102 is made of a material having a relatively low coefficient of friction, and is supported by a support arm 107.
The support arm 107 is further suspended from the drive shaft 108. A belt 109 is stretched between the drive shaft 108 and the conveyance roller 102 via a pulley, and rotates the conveyance roller 102 counterclockwise. The discharged paper 2 is conveyed by the conveyance roller 102 to the stopper abutting surface 103 of the stopper 103.
After the sheet is abutted against the sheet a and the sheet abuts against the sheet, the conveying roller 102 slips on the sheet 2, so that the abutted sheet 2 does not buckle. Further, as the number of sheets of paper 2 accommodated increases, the transport roller 102 can move upward about the shaft 108.

The stopper 103 comprises a feed roller 130 and a separate roller 13 which form a separation roller pair 105.
It is arranged upstream of the separation nipple (nip portion) N formed by 1, and the abutting surface 103 a of the solenoid 106 advances and retreats from the conveyance path by the solenoid 106. Further, the abutting surface 103a is provided so as to be inclined toward the upstream side with respect to the stacking surface of the intermediate tray 101. The angle (tilt angle) θ of the stopper 103 shown in FIG. 4A is preferably 30 degrees to 70 degrees. Note that reference numeral 11
Reference numeral 2 denotes a paper pressing guide that presses the curl and floating of the paper 2 from above.

Therefore, the re-sending end shape of the sheet bundle 200 after being accommodated can be stacked and accommodated in a substantially wedge shape in which the lower side is first and the upper side is gradually retracted as shown in FIG. In addition, the shape of the retransmission end can be changed as shown in FIGS. 4B to 4E. Further, when the inclination angle θ is large, the discharged sheet 2 easily enters along the abutting surface 103a, so that a member having a proper friction coefficient, a brushed sheet, or the like is attached to the abutting surface 103a, or the parallel surface is used. It is advisable to engrave grooves or irregularities on the surface to prevent the paper 2 from getting in.

A plurality of delivery rollers 120 are provided below the retransmission side of the intermediate tray 101. The delivery roller 120 is made of a high-friction material (for example, soft rubber or sponge rubber) having a half-moon shape, a triangular shape, a polygonal shape, or the like,
The surface of the sheet is retracted below the conveying surface of the intermediate tray 101 when accommodating the sheets, but at the time of re-sending, the outer periphery jumps out of the opening 101a on the intermediate tray 101 and comes into contact with the lowermost sheet, so that the sheet bundle 200 moves upward. The entire sheet bundle 200 is transferred to the separation roller pair 105 by lifting. Sending roller 1
20 is driven by a clutch 113 that is controlled to rotate once.

A pressure plate 115, which is supported by a support shaft 114 above the re-sending end of the sheet bundle 200 and whose swing is controlled by a solenoid 116 about the support shaft 114, is provided. The pressure plate 115 is provided on the upper guide plate 1 as shown in FIG.
It is retracted inside 10, but when retransmitted
The opening 110a of the upper guide plate 110 according to the rotation of 0
From the above to the uppermost sheet, the sheet bundle 200 is sent out, and is pressed and biased toward the roller 120 side.

The sheet separating section is fed with a feed roller 130 which is driven in the feeding direction, a separate roller 131 which is urged into pressure contact with the feed roller 130 and is rotated in the counter feeding direction by a driving means, the feed roller 130 and the separating roller. The pair of grip rollers 132 provided downstream of the roller 131, the upper guide plate 110, and the lower guide plate 1
11 and the like. Also, the grip roller pair 13
A pair of transport rollers 133 is provided further downstream of 2.

Between the separation nip N and the downstream of the stopper abutment surface 103a, preferably from the separation nip N to 20.
A feed amount regulating member 150 that is inclined in the same direction as the stopper abutment surface 103a is provided at a close position of mm or less.

FIG. 5 is an enlarged configuration diagram of the vicinity of the feed amount regulating member. The feed amount regulating member 150 is a flexible elastic friction member attached to a support portion 110b extending from the upper guide plate 110. (For example, urethane rubber, thermoplastic elastomer, rubber cork, etc.) 150a, the lower end of which is a deformable free end protruding from the supporting portion 110b by L1 as shown in FIG. Further, a sheet (polyester film, Teflon film, etc.) 150b having a friction coefficient smaller than that of the elastic friction member 150a is attached to the portion opposite to the support side except for L2 from the lower end. In this way, the space 151 for reducing pressure and the gap d through which a regulated amount of paper can pass are provided between the lower end of the feed amount regulating member 150 and the lower guide plate 111. The sheet 150b
In the face curl paper, it prevents the leading edge of the paper from being caught by the surface of the feed amount regulating member 150, and smoothly moves the paper 2 downward.
It is provided for paying out.

Further, upstream of the separation nipple N, one end is fixed on a support portion 110b extending from the upper guide plate 110, and the other end is extended along the outer peripheral surface of the separation roller 131 to the vicinity of the separation nipple N. A thin elastic paper guide 134 made of polyester film or the like, and a thin elastic body made of polyester film or the like that is fixed to the lower guide plate 111 at one end and extends to the vicinity of the separation nip N along the outer peripheral surface of the feed roller 130. Paper guide 135
And. The free ends of the paper guides 134 and 135 may be elastically brought into sliding contact with the outer peripheral surfaces of the rollers 130 and 131, respectively. In particular, the paper guide 134 has its free end extended from the substantially tangential direction of the outer peripheral surface of the separate roller 131 so that the thin piece does not roll up even if it comes into contact with the peripheral surface of the separate roller 131 that rotates in the opposite feeding direction. It is effective to extend its tip as close as possible to the separation nipple N.

FIG. 6 is a sectional view of the shaft supporting portion of the feed roller,
FIG. 7 is a sectional view of the shaft supporting portion of the separate roller.
In the above, the feed roller 130 is pivotally supported on the shaft 210 and is rotated in the feeding direction under the control of the electromagnetic clutch 211. In addition, 130a is a one-way clutch for accompanying rotation.

In FIG. 7, a separate roller 131
Is rotatably supported on a shaft 225, is swingable in the direction of the feed roller 130 around the bearing 227, and is urged by the spring 230 against the feed roller 130. Then, when the driving means 251 is turned on, the driving force is transmitted to the gears 253, 254, 255 and 256, and the separate roller 131 is rotated at a low speed in the counter feeding direction. In addition,
257 is a one-way clutch for preventing the reverse rotation of the separate roller.

FIGS. 8A, 8B, and 8C are explanatory views relating to the separation pressure in the separation roller 131 and the feed roller 130, and the separation roller 131 by the above mechanism.
Driven by, a dynamic pressure ΔP _B is added. The separation pressure P _B during driving is represented by the formula shown in FIG.

FIG. 8 (c) shows the measurement result. For example, it can be seen that when l ₁ = 45 mm is set, the separation pressure P _B becomes about twice the pressure at rest.

FIG. 9 is a sectional view showing a modified example of the shaft support portion of the separate roller 131.
Is swingable in the direction of the feed roller 130 around the bearing 227, but since the gears 255 and 256 are arranged outside the auxiliary side plate 258, the separation pressure P _B during driving and the stationary pressure P _B are Can be equal.

The material of the separate roller 131 is
A material having a friction coefficient slightly smaller than that of the feed roller 130 is selected. That is, when the friction coefficients between the feed roller 130 and the paper, between the separate roller 131 and the paper, and between the papers are μ ₁ , μ ₂ , and μ _P , μ ₁
Both rollers 13 so that the order relation of> μ ₂ > μ _P is established.
The material of 0,131 is selected. For example, a soft rubber material is used for the feed roller 130, and a separate roller 131 is used.
It is recommended to use foamed polyurethane rubber.

In this embodiment, the feed roller 130 is used.
Although the separate roller 131 and the separate roller 131 are in pressure contact with each other, the present invention is not limited to this and can also be applied to a case where both rollers are arranged opposite to each other in a staggered manner.

Further, in order to improve the separability, the peripheral speed of the separation roller 131 is set to 2% or more of the peripheral speed of the feed roller 130, and in order to reduce image contamination,
It is preferably 30% or less (the lower the speed, the better). When the separating roller 131 is at a low speed, it is possible to prevent the double-fed sheet from being swiftly ejected to the upstream side, which causes a trouble (timing delay) at the time of the next sheet feeding.

FIG. 10 is a timing chart of the operation in each part until a predetermined number of sheets are stored in the intermediate tray and then re-fed. When the solenoid 106 is turned on, the stopper 103 is retracted upward. Simultaneously speed switching solenoid (not shown)
Turns on.

Then, the feed roller solenoid (not shown) and the pressure plate solenoid 116 are turned on, the feed roller 120 makes one rotation at a low speed by the one rotation clutch 113, and the pressure plate 116 descends onto the paper. So
The sheet bundle 200 is transported in the separation nip N direction. On the way
The upper layer portion of the sheet bundle 200 is regulated by the regulating member 150 so as to stop the movement, only the lower layer portion continues to advance, and the leading end portions are guided by the sheet guides 134 and 135 to reach the separation nip N.

Then, the speed switching solenoid is turned off (which allows the delivery roller 120 to rotate at a normal rotation speed).

Then, the delivery roller solenoid and the pressure plate solenoid 116 are turned on again. At the same time, a separate roller clutch (not shown) is turned on, the separate roller 131 is rotated at a low speed in the counter feeding direction, and the sheet that has entered the separation nip N is slightly returned (at this time, the feed roller 130 is in a rotation free state).

After a short time (time t), the feed roller clutch 211 is turned on, the lowermost sheet is fed by the feed roller 130, and the upper sheet is prevented from advancing by the separate roller 131. (See FIG. 3).

The sheet bundle 200 has a pair of grip rollers 132.
After that, the feed roller clutch 211 and the separate roller clutch are turned off and the driving is stopped.
The feed roller 130 is rotated together with the paper by the one-way clutch.

Thereafter, the above steps are repeated.

In this way, the lower layer paper is fed sheet by sheet. At the time of feeding the last sheet of the lower layer paper, a part or all of the upper layer portion which is blocked by the regulating member 150 moves in the separating nipple N direction together with the final sheet of the lower layer paper, and the sheet bundle 200 is moved to the separating nipple N portion. It will be automatically replenished.

In the above embodiment, the separate roller 1
Since 31 is rotated in the counter feeding direction at a peripheral speed ratio of 2 to 30%, when the leading edge of the sheet bundle 200 enters in a wedge shape, the sheet bundle 20 in contact with the peripheral surface of the separate roller 131.
Since the upper layer of 0 is sent back, the pressure increase due to the wedge effect is alleviated, and the remarkable effect is that the sheets that have entered in the block shape are easily separated one by one.

Further, particularly when the separate roller 131 is arranged on the image side of the one-side copied sheet, the peripheral speed ratio is set to 30% or less, so that the sheet surface and the surface of the separate roller 131 are caused by the falling toner. It is not significantly contaminated.

Further, when the separate roller 131 rotates in the counter feeding direction, the leading edge of the second and subsequent sheets to be sent back tends to be separated from the surface of the separate roller 131 by the thin elastic sheet guide 134. It is possible to prevent the occurrence of curling scratches due to the separate roller 131. Further, even if the separate roller 131 is contaminated due to toner adhesion, the contamination of the sheet from the separate roller 131 is reduced.

The thin elastic paper guide 134 is also used.
Is elastically contacted from the outer peripheral surface of the separate roller 131 in a substantially tangential direction, the tip can sufficiently reach the vicinity of the separation nip N, and the separate roller 131 rolls up when rotating in the anti-feeding direction. It is possible to prevent the surface of the separate roller 131 from being damaged.

Further, when the sheet bundle 200 is transferred, the sheet bundle 2
Since the leading edge of the sheet 00 is about to be separated from the surface of the feed roller 130 by the thin piece elastic body guide 135, the sheet surface 200 which is stationary is not hindered from advancing the sheet, and the leading edge of the sheet bundle 200 is smoothly separated. Can lead to.

[0050]

According to the first aspect of the invention, the thin elastic paper guide is elastically contacted from the outer peripheral surface of the separate roller substantially in the tangential direction, so that the paper can be rotated when the separate roller rotates in the anti-feed direction. It is possible to prevent problems such as roll-up of paper and damage to the surface of the separate roller during separation and feeding.

According to the second aspect of the present invention, since the separate roller is rotated in the counter feeding direction at the peripheral speed ratio of 2 to 30%, the pressure increase due to the wedge effect is alleviated and the separation of the sheet is good. Moreover, it is possible to prevent the paper surface and the surface of the separate roller from being contaminated with the falling toner.

According to the third aspect of the present invention, the thin elastic paper guide is extended to the vicinity of the separation nip along the outer peripheral surface of the feed roller, so that the advance of the paper is not hindered by the surface of the feed roller. The leading edge of the sheet bundle can be smoothly guided to the separation nip.

[Brief description of drawings]

FIG. 1 is a detailed configuration diagram of a main part of an embodiment of a sheet feeding device of the present invention.

FIG. 2 is a configuration diagram of a double-sided device of a copying machine.

FIG. 3 is a main-part configuration diagram showing a state at the time of separated sheet feeding according to the present embodiment.

FIG. 4 is an explanatory diagram showing various wedge shapes of a sheet bundle.

FIG. 5 is an enlarged configuration diagram in the vicinity of a feed amount regulating member.

FIG. 6 is a sectional view of a shaft supporting portion of a feed roller.

FIG. 7 is a cross-sectional view of a shaft support portion of a separate roller.

FIG. 8 is an explanatory diagram related to separation pressure.

FIG. 9 is a cross-sectional view showing a modified example of the shaft supporting portion of the separate roller.

FIG. 10 is a timing chart of the operation in each part of this embodiment.

FIG. 11 is an explanatory diagram of a conventional feeding state.

FIG. 12 is a diagram showing mathematical expressions.

[Explanation of symbols]

 130 Feed roller 131 Separate roller 134,135 Thin elastic paper guide N Separation nip

Claims (3)

[Claims] 1. A feeding roller for feeding the lowermost sheet in a feeding direction in a sheet feeding device for separating and feeding the stacked sheets from the lowermost sheet side by frictional force one by one. A separate roller which is made of a material having a lower friction coefficient than that of the feed roller and which is arranged in pressure contact with or opposite to the feed roller and rotates at a low speed in the counter feeding direction, and one end of which is supported by a fixed portion above the conveying path and the other end of which is a separate roller. A sheet feeding device, comprising: a thin elastic sheet guide extending from a substantially tangential direction of the outer peripheral surface to the vicinity of the separation nip. 2. The free end of the thin elastic paper guide is
The elastic roller is elastically contacted with the outer peripheral surface of the separate roller, and the separate roller is rotated in a counter feeding direction at a peripheral speed of 2 to 30% of the peripheral speed of the feed roller.
Paper feeder. 3. A paper feeding device for separating and feeding the stacked sheets of paper one by one from the bottom paper side by frictional force, and is provided below the stacked paper sheets and separates the bottom paper. Sheet feeding means, a feeding roller for feeding the lowermost sheet in the feeding direction, a separate roller arranged in pressure contact with or facing the feeding roller and for preventing double feeding, and one end supported by a fixed portion at the bottom of the feeding path. A sheet feeding device having a thin elastic sheet guide having the other end extended to the vicinity of the separation nip along the outer peripheral surface of the feed roller.