JPH069090A - Paper feeding device - Google Patents

Abstract

PURPOSE:To prevent paper feeding trouble, and to reduce the toner contamination of the surface of a separate roller or the fouling of an image when a paper sheet on the one side of which an image has been formed is fed by providing a driving/pressing means by which the separate roller is energized so as to be pressedly brought into contact with a feed roller when the roller is drawn with a prescribed pressure larger than that at the time the separate roller is not driven. CONSTITUTION:A separate roller 131 is supported on a shaft 225, and is oscillatable in the direction of a feed roller 130 making a bearing 227, as a center and is energized by a spring 230 so as to be pressedly brought into contact with the feed roller 130. When a driving means 251 is turned on, the driving force is successively transmitted to gears 253, 254, 255, and 256, and the separate roller 131 is turned at low speed in the counter feeding direction. In this case, when the separate roller is driven, a dynamic pressure is added, and the paper sheet having entered a separation nip N is slightly returned. After a paper sheet bundle 200 has reached a blip roller pair 132, a feed roller clutch 211 (not shown) and a separate roller clutch are turned off to stop driving, and the separation pressure is reduced.

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 or the like of a copying machine, a down-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 bottommost 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 that the lower side of the sheet bundle on the feeding side is formed into a wedge shape which precedes 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. Are known.

However, this technique has the following drawbacks.

That is, since the separation roller continues to rotate in the returning direction even after the paper is separated, the paper is stained and the image quality is deteriorated.
Paper dust is easily generated. Further, as the load increases and changes, image expansion / contraction, wrinkles, folds, abnormal noises, and the like are likely to become problems.

On the other hand, Japanese Unexamined Utility Model Publication No. 2-142744 proposes a technique for separating the separate roller from the feed roller after the leading edge of the sheet passes through the sheet feeding section.

[0008]

In the above-mentioned prior art, since the separate roller is separated from the feed roller, the problem in the technology disclosed in Japanese Patent Laid-Open No. 63-41332 is solved, but the separation roller is separated. However, if this is applied to the lower-feeding paper feeding device, there is a fatal defect that the next paper is fed together with the separation. That is, it is applicable only to the upper feed method.

Further, in the system in which the feed roller and the separate roller are in pressure contact with each other, if for some reason there is no paper inside the nip while both rollers are rotating in the same direction, a large load occurs. It is likely to cause abrasion of the rollers.

The present invention can prevent troubles during the paper feeding operation, and can prevent the contamination of the surface of the separate roller when feeding the paper on which the one-sided image is formed and the accompanying contamination of the image. The purpose is to provide.

[0011]

SUMMARY OF THE INVENTION The above-described object is to provide a sheet feeding device for separating sheets one by one from the bottom sheet side of stacked and accommodated sheets by a frictional force and feeding the sheets, the bottom sheet being fed in the feeding direction. Formed by a feed roller for feeding paper to a sheet, a separate roller made of a material having a lower coefficient of friction than the feed roller, pressed against the feed roller, and rotating in the counter feeding direction to prevent double feeding of paper, and a feed roller and a separate roller. It is achieved by the first means including a sheet conveying means provided downstream of the separation nip, and a driving and pressing means for pressing the separate roller with a predetermined pressure larger than that when the roller is not driven to press the feed roller. It

Further, the above-mentioned object is to provide a sheet feeding device for separating and feeding one by one from the lowermost sheet side of the stacked and accommodated sheets by a frictional force and feeding the lowermost sheet. To the separation nip, a feed roller for feeding the bottom sheet in the feeding direction, a separate roller arranged in pressure contact with or facing the feed roller and rotating in the opposite feeding direction to prevent double feeding, At the time of paper, the paper conveying means is driven prior to the rotation of the separate roller,
This is achieved by the second means including drive control means for controlling the driving of the separate roller so that the separation roller is rotationally driven after the leading edge of the paper is transferred to the separation nip.

[0013]

In the first means, the first sheet is separated by the feed roller and the separate roller, and the separation pressure is reduced after the sheet is nipped by the grip roller on the downstream side. On the other hand, unnecessary load does not occur.

In the second means, the calling roller is driven prior to the rotation of the separate roller, and the feed roller and the separate roller are controlled to rotate after the leading edge of the paper is surely fed into 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, the 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 length of the sheet 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 is collided with the stopper (stopper gate means) 103 to align the sheet advancing edges.

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 makes one rotation, 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 only one sheet of the bottom sheet and feeds it.
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 during separated 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 sheet 2 is conveyed by the conveying roller 102 to the stopper abutting surface 103 of the stopper 103.
Since the sheet is conveyed to a and the conveying roller 102 slips on the sheet 2 after the sheet abuts, 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 around the shaft 108.

The stopper 103 comprises a feed roller 130 and a separate roller 13 which constitute a separation roller pair 105.
The abutting surface 103a is arranged upstream of the separation nipple (nip portion) N formed by 1, and the abutting surface 103a of the solenoid 106 advances and retreats from the transport path. 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 paper 2 easily enters along the abutting surface 103a, so that a member having a proper friction coefficient, a raised 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,
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 lifted and transferred to the separation roller pair 105. Sending roller 1
20 is driven by a clutch 113 which 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. Pressure plate 1
15 is an upper guide plate 110 as shown in FIG.
Although it is retracted inside, when it is retransmitted, the sheet bundle 200 is sent out from the opening 110a of the upper guide plate 110 onto the uppermost sheet in accordance with the rotation of the delivery roller 120, and the sheet bundle 200 is sent out.
It is pressed and urged to the 20 side.

The paper separating section is fed by a feed roller 130 driven in the feeding direction, a separate roller 131 pressed by the feed roller 130 and rotated in the counter feeding direction by a driving means, a feed roller 130, and a separate roller. A pair of grip rollers 132 provided downstream of 131, an upper guide plate 110, and a lower guide plate 111.
Etc. Further, a conveying roller pair 133 is provided further downstream of the grip roller pair 132.

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

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 on a support portion 110b extending from the upper guide plate 110. (For example, urethane rubber, thermoplastic elastomer, rubber cork, etc.) 150a, and as shown in FIG. 5, the lower end is a deformable free end protruding by L ₁ from the supporting portion 110b. 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 L ₂ from the lower end. In this way, the gap 151 and the pressure reducing space 151 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, the leading edge of the paper and the surface of the feed amount regulating member 150 are prevented from being caught and the paper 2 is smoothly moved 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 sheet guide 134 made of polyester film or the like, and a thin elastic sheet 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 extends its free end 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 the tip as close to the separation nipple N as possible.

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 supported on the shaft 210 and is rotated in the feeding direction under the control of the electromagnetic clutch 211. Reference numeral 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 against the feed roller 130 by a spring 230. Then, when the driving means 251 is turned on, the driving force is transmitted to the gears 253, 254, 255, 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, when l ₁ = 45 mm is set, it can be seen that 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 supporting 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 > μ ₂ > μ _P So that both rollers 130, 131
Select the material of. For example, a soft rubber material may be used for the feed roller 130, and a polyurethane foam rubber may be used for the separate roller 131.

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 be applied to a case in which both rollers are arranged so as to face each other in a staggered manner.

Further, in order to improve the separability, the peripheral speed of the separating 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 an obstacle (timing delay) at the time of the next sheet feeding.

FIG. 10 is a timing chart of the operation in each part after a predetermined number of sheets of paper is stored in the intermediate tray and is 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 portion is 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, the separate roller clutch 252 is turned on, the separate roller 131 is rotated at a low speed in the counter feeding direction, and the separation nip N
The paper that has entered the paper is returned a little (at this time, the feed roller 1
30 is 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.

After that, the above steps are repeated.

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

In the above embodiment, the separate roller 1
Since 31 is rotated in the counter-feed 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 contacting 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, especially when the separate roller 131 is arranged on the image side of the one-sided 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 by 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
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, so that the surface of the stationary roller 130 does not prevent the sheet from advancing, and the leading edge of the sheet bundle 200 is smoothly separated. Can lead to.

[0050]

According to the first aspect of the present invention, the first sheet is separated by the feed roller and the separate roller, and the separation pressure is reduced after the first sheet is nipped by the grip roller on the downstream side. There is no unnecessary load on the first sheet. Therefore, it is possible to prevent paper feeding troubles such as slipping, non-feeding, and skewing during sheet conveyance, and it is possible to reduce toner contamination and image stains on the surface of the separate roller when feeding a sheet on which one-sided image is formed.

According to the second aspect of the invention, the calling roller is driven prior to the rotation of the separate roller,
Since the feed roller and the separate roller are controlled to rotate after the leading edge of the paper is reliably fed into the separation nip, the time during which the feed roller and the separate roller are in direct pressure contact is significantly shortened, and the load on the device increases and the roller wears. Abnormal vibration can be prevented or reduced.

[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 configuration diagram of a main part showing a state at the time of separated sheet feeding in 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 a diagram showing mathematical expressions.

[Explanation of symbols]

 130 Feed Roller 131 Separate Roller 132 Grip Roller Pair (Paper Conveying Means) 134,135 Thin Elastic Paper Guide 230 Spring (Drive Pressurizing Means Component) 251 Drive Means (Drive Pressurizing Means) 253 to 256 Gear (Drive Pressurizing) Means Component) N Separation Nip

Claims (2)

[Claims] 1. A feeding roller for feeding the lowermost paper in a feeding direction in a paper feeding device for separating and feeding one by one from the lowermost paper side of the stacked and accommodated papers by frictional force, and a feed roller. It is made of a material with a coefficient of friction lower than that of the feed roller. A sheet feeding device comprising: a sheet conveying unit; and a driving pressure unit that biases the separate roller when the roller is driven with a predetermined pressure larger than that when the roller is not driven. 2. A paper feeding device for separating and feeding the stacked sheets of paper one by one from the bottom sheet side by frictional force, and is provided below the stacked sheets and separates the bottom sheet. A sheet feeding means for feeding the sheet to the feeding roller, a feeding roller for feeding the bottom sheet in the feeding direction, a separate roller arranged in pressure contact with or facing the feeding roller and rotating in the counter feeding direction to prevent double feeding, and at the time of feeding, A sheet feeding means is driven prior to the rotation of the separate roller, and the sheet feeding means is provided with drive control means for controlling the driving of the separate roller after the leading edge of the sheet is transferred to the separation nip. apparatus.