JPH06329283A - Sheet feeding device and image forming device - Google Patents

Abstract

PURPOSE:To prevent a sheet from being defectively fed by designing the area of the outer circumferential surface of each pick-up roller in contact with the surface of the sheet to be increased even if the sheet is greatly deformed. CONSTITUTION:A plurality of pick-up rollers 3 are rotatably supported in such a way that the outer circumferences of them are moved along the surface of a sheet due to rattle (clearance) between each shaft 4 and 6 and each arm 5 and the like. This constitution thereby allows each pick-up roller 3 to be rocked along the surface of the sheet even if the sheet S is deformed, enables the surface of the sheet in contact with the circumferential surface of each roller to be made large in area, and thereby allows feeding force to be surely transmitted to the sheet S, so that the sheet can thereby be prevented from being defectively fed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding apparatus for feeding sheets such as originals and recording sheets to image forming apparatuses such as electronic copying machines, printers and facsimiles.

[0002]

2. Description of the Related Art A sheet feeding apparatus for feeding a sheet to a conventional image forming apparatus such as an electronic copying machine is a retard roller type sheet feeding apparatus including a pickup roller, a conveyance roller, a separation roller (reverse rotation roller) and the like. There is a sending device. This retard roller type sheet feeding device is generally used because it is possible to stably separate and feed sheets such as recycled paper which are likely to be double fed.

In this retard roller type sheet feeding device, a sheet loaded on an intermediate plate provided in a cassette is usually picked up by a pickup roller by rotating an intermediate plate pressing arm to raise the intermediate plate. It is urged toward and ready for feeding.

In this feedable state, the uppermost sheet of the sheets stacked on the middle plate is in contact with the pickup roller, and the uppermost sheet is sequentially fed out by the rotation of the pickup roller.

The sheets sent by the pickup roller enter the nip portion between the conveying roller and the separating roller, and are separated here one by one.

The conveying roller is rotated by receiving a driving force from a driving source so as to rotate in a sheet advancing direction, and the separation roller is rotated through a torque limiter (not shown) so as to rotate in a direction for preventing the sheet advancing. A driving force is received from the driving source.

1 at the nip portion between the transport roller and the separation roller
When a single sheet enters, the torque limiter cuts off the driving force to the separation roller, and the separation roller rotates together with the conveyance roller. Further, when two or more sheets enter, the separation roller rotates counterclockwise in the figure, and the sheets on the separation roller side are sequentially prevented from being fed, and only the sheet on the conveyance roller side is fed out.

In the image forming apparatus employing the retard roller type sheet feeding device, if the sheet in the cassette is left for a long period of time or is placed in a low humidity environment, the water content of the sheet becomes extremely small. , There may be a large curve or bulge in the cassette. The curving or swelling occurs because the shrinkage rate differs between the front and back sides of the sheet when the sheet has a reduced water content and shrinks.

FIG. 6 shows the state of the pickup roller 3 when the sheet S rises in the cassette. The shaft 6 that supports the pickup roller 3 is not always kept horizontal, but the sheet S It is swingably provided so as to follow the deformation and tries to secure a contact area of the outer peripheral surface with the sheet S so as to be inclined according to the displacement of the sheet S.

[0010]

However, even if the pickup roller 3 is swingably provided so as to follow the deformation of the sheet S, the deformation of the sheet becomes large. Pickup roller 3
The contact area between the outer peripheral surface of the sheet and the sheet S is very small,
In the worst case, the surface contact state is lost, and as shown in FIG. 6, the pickup roller 3 comes into line contact with only the corners 3a, 3a, and the rotation of the pickup roller 3 is not sufficiently transmitted to the sheet S. . Therefore, there is a problem that a sufficient feeding force of the pickup roller 3 is not transmitted to the sheet, the sheet cannot be pushed between the transport roller and the separation roller, and separation failure easily occurs.

This problem is not limited to the retard roller type sheet feeding device, and may occur in the claw separation type sheet feeding device and the friction separation type sheet feeding device. That is, in the separation claw method, if the feeding force applied to the sheet is small, the edge of the sheet cannot get over the separation claw and separation failure occurs.
Similar to the retard roller method, the sheet cannot be pushed between the conveying roller and the separating member, and the separation failure easily occurs.

The present invention has been made in view of the above problems, and an object of the present invention is to prevent sheet feeding failure by surely bringing the outer peripheral surface of the pickup roller into contact with the sheet even if the sheet is largely deformed. And

[0013]

According to the present invention, there are provided a sheet supporting means for stacking and supporting sheets, a plurality of feeding rotating bodies for feeding out the sheets supported by the sheet supporting means, and each of the feeding rotating bodies. Rotating body supporting means for swingably supporting each of the feeding rotating bodies such that the outer peripheral surface is along the surface of the sheet.

As a structure in which the feeding rotary body can be swung, the feeding rotary body is attached to a shaft whose both ends are supported by one end of an arm, and the feeding rotary body is fixed by a clearance between the shaft and the arm. It may be swingable, or the feeding rotating body may be swingable by a clearance between the arm and a drive shaft to which the other end of the arm is attached.

Further, the feeding rotary member is attached to each of a pair of shafts, one end of which is swingably supported by an arm and the other end of which is connected by a universal joint.
The feeding rotary body may be swingable by a universal joint.

[0016]

According to the above construction, since the feeding rotary member is swingable, even when the seat is deformed, the feeding rotary member is also displaced along with the deformation and comes into contact with the surface of the sheet. The area of the outer peripheral surface of the feeding rotating body can be increased. Therefore, the feeding force of the feeding rotating body is reliably transmitted to the sheet.

[0017]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a perspective view showing a main part of a sheet feeding apparatus according to the first embodiment of the present invention. The sheet feeding apparatus according to this embodiment is an image forming apparatus described later as shown in FIG. The sheet is sent out from the front loading type paper feed cassettes 2 and 2 arranged on the lower side of 1.

In the present embodiment, a structure in which a plurality of pickup rollers are conventionally supported by one shaft is configured to support each pickup roller 3, 3 by a single shaft.

The drive shaft 4 is supported by a side plate (not shown) via a bearing so as to rotate in the direction of arrow A in the figure.
It is connected to a drive source such as a motor (not shown) and rotates by the rotational force from the drive source.

Each pick-up roller 3 is attached to a shaft 6 which is hung on one end of each of a pair of arms 5 and 5. A large backlash (clearance) is provided at a fitting portion between the shaft 6 and the arms 5 and 5, so that the shaft 6 can swing with respect to the arms 5 and 5. The other ends of the arms 5 and 5 are attached to the drive shaft 4, and a large play (clearance) is also provided in a fitting portion between the arms 5 and 5 and the drive shaft 4.
Is swingable with respect to the drive shaft 4.

In this way, the shaft 6 and the pickup roller 3
Since the backlash of the fitting portion with and the backlash of the fitting portion between the arm 5 and the drive shaft 4 are set to be large respectively, the pickup roller 3 can largely swing in the D direction in FIG.

A belt pulley 7 is fixed to the drive shaft 4, a belt pulley 8 is also fixed to the shaft 4, and a belt 9 is stretched around these belt pulleys 7, 8. Then, as the drive shaft 4 rotates, the rotation is transmitted to the pickup roller 3 and the sheet S is sent out.

Next, when the pickup roller 3 feeds the sheet S and separates the sheet S by the conveying roller 10 (shown in FIG. 5) and the separating roller 11 (shown in FIG. 5), the sheet S is transferred to the sheet S. A configuration for separating the pickup roller 3 from the sheet S in order to reduce the applied load will be described.

As shown in FIG. 5, the sheets S in the paper feed cassette 2 are stacked on a swingable middle plate 12, and the lifter 13 lifts the middle plate 12 to lift the sheets S.
The lifter 13 is controlled so that the highest position of the lifter is maintained at a constant position.

As shown in FIG. 1, one end of a connecting plate 14 is attached to the arm 5, and the other end of the connecting plate 14 is an arm 15 for moving the pickup roller 3 up and down.
It is attached to one end of. The other end of the arm 15 is fixed to a shaft 16 that rotates in the B and C directions in the figure. Then, by rotating the shaft 16, the pickup roller 3 comes into contact with or separates from the uppermost position of the sheet S which is positioned in the left-right direction by the side regulating plate 17 and maintained at a constant height by the lifter 13. You can do it. As a result, the load on the sheet S can be reduced by raising the pickup roller 3 after feeding the sheet S.

According to the structure of the first embodiment, as shown in FIG. 2, each pickup roller 3 is displaced following the deformed sheet S and the outer peripheral surface comes into contact with the sheet surface to reduce the contact area. Can be secured. Therefore, the feeding force of the pickup roller 3 is properly transmitted to the sheet S,
The sheet S is placed in the nip portion between the transport roller 10 and the separation roller 11.
The sheet can be pushed in properly and sheet feeding defects can be prevented.

FIG. 3 is a perspective view showing a second embodiment of the present invention.

The pickup roller 3 has a shaft 1 respectively.
The shafts 18, 18 are connected to each other by a belt pulley 19 with a universal joint at one end on the center side. The other ends of the shafts 18, 18 are supported by the arms 20, 20, respectively, and play is provided between the shafts 18, 18 and the arms 20, 20.
8, 18 are swingable with respect to the arms 20, 20. The arms 20, 20 are swingably supported by a drive shaft 4 for transmitting rotation to the pickup roller 3. The drive shaft 4 is connected to a drive source such as a motor (not shown).

The drive shaft 4 is provided with a pulley 21, and a belt 22 is stretched between the pulley 21 and the belt pulley 19 with a universal joint.
The drive of the drive shaft 4 is transmitted by the belt 22 to the shafts 18 and 18 via the belt pulley 19 with a universal joint to rotate the pickup roller 3. The belt pulley 19 with a universal joint has a structure in which the drive transmission is transmitted to the shafts 18 and 18 without any trouble even if the respective pickup rollers 3 are inclined along the sheet surface.

Further, in order to prevent the outer diameter of the universal joint portion of the belt pulley 19 with a universal joint from directly contacting the seat S, the connecting plate having the same structure as that of the above-mentioned embodiment is universal by a method not shown which does not hinder the rotation. The vertical position of the jointed belt pulley 19 is regulated.

In the second embodiment described above, as shown in FIG. 4, the pickup roller 3 is displaced following the ups and downs of the sheet S so that the outer peripheral surface comes into contact with the sheet surface to secure a contact area. . Further, even if the shaft 18 is tilted, it does not affect the other pickup roller 3, the rotation of the pickup roller 3 is properly transmitted to the sheet S, and it is possible to prevent feeding failure due to deformation of the sheet S.

In this embodiment, since only one belt for transmitting the rotation to the pickup roller 3 is required,
The apparatus can be simplified and the cost can be reduced.

Next, FIG. 5 shows an example of an image forming apparatus (copier) provided with the sheet feeding apparatus of the present invention.

The apparatus main body 50 is provided with a document placing table 51, a light source 52, a lens system 53, a paper feeding section 54, an image forming section 55 and the like. The sheet feeding unit 54 has sheet feeding cassettes 2 and 2 that accommodate the sheet S and can be attached to and detached from the front of the apparatus main body 50. The present invention is applied to the feeding of the sheet S from the sheet feeding cassette 2. There is. The image forming section 55 is provided with a cylindrical photosensitive member 56, a developing device 57 containing toner, a transfer charger 58, a separation charger 59, a cleaner 60, a primary charger 61, and the like. The conveying device 62, the fixing device 63, and the discharge roller 6 are provided on the downstream side of the image forming unit 55.
4 etc. are arranged.

The operation of the image forming apparatus 1 will be described.

When a paper feed signal is output from a controller (not shown) provided in the apparatus main body 50, the paper feed cassette 2
The sheet S is fed from. On the other hand, the light that is applied from the light source 52 to the original placed on the original placing table 51 and reflected therefrom is applied to the photoconductor 56 via the lens system 53. The photoconductor 56 is charged in advance by the primary charger 61, and an electrostatic latent image is formed by being irradiated with light, and then a toner image is formed by the developing device 57.

The skew of the sheet S fed from the sheet feeding section 54 is corrected by the pair of registration rollers 65, and the sheet S is fed to the image forming section 55 at a timed timing. Image forming unit 5
In 5, the toner image on the photoconductor 56 is transferred onto the sheet S sent by the transfer charger 58, and the transferred sheet S is charged with a polarity opposite to that of the transfer charger 58 by the separation charger 59 to be exposed. Separated from body 56.

Then, the separated sheet S is conveyed to the fixing device 63 by the conveying device 62, and the unfixed transfer image is permanently fixed on the sheet S by the fixing device 63. The sheet S having the image fixed thereon is ejected from the apparatus main body 50 by the ejection roller 64.

In this way, the sheet S fed from the paper feed cassette 2 is formed with an image and is discharged.

Although the sheet feeding apparatus of the present invention is applied to the copying machine in the present embodiment, the present invention is not limited to this, and other image forming apparatuses such as printers and facsimiles. The present invention can also be applied to a document feeding unit in a copying machine, a facsimile, etc., a re-feeding unit for performing double-sided copying in a copying machine, or a re-feeding unit in an intermediate tray.

[0042]

As described in detail above, the present invention is
Since the feeding rotating body is provided so as to be swingable so as to be displaced along with the deformation of the seat, the area of the outer peripheral surface of the feeding rotating body that comes into contact with the seat surface can be made large. The feeding force of the rotating body is reliably transmitted to the sheet, and stable feeding can be performed without causing feeding defects.

[Brief description of drawings]

FIG. 1 is a perspective view of a sheet feeding device according to a first embodiment of the present invention.

FIG. 2 is a front view showing a state in which a deformed sheet is fed in the sheet feeding device shown in FIG.

FIG. 3 is a perspective view of a sheet feeding device according to a second embodiment of the present invention.

FIG. 4 is a front view showing a state in which a deformed sheet is fed in the sheet feeding apparatus shown in FIG.

FIG. 5 is a vertical cross-sectional view showing an example of an image forming apparatus provided with a sheet feeding device of the present invention.

FIG. 6 is a front view showing a state in which a deformed sheet is fed in an example of a conventional sheet feeding apparatus.

[Explanation of symbols]

 3 Pick-up roller (feeding rotating body) 4 Drive shaft 5,20 Arm 6,18 Shaft 7,8,21 Pulley 19 Belt pulley with universal joint S Seat

Claims (8)

[Claims] 1. A sheet supporting means for stacking and supporting sheets, a plurality of feeding rotating bodies for feeding the sheets supported by the sheet supporting means, and outer peripheral surfaces of the respective feeding rotating bodies are along the surface of the sheet. A sheet feeding device, comprising: a rotating body supporting means for swingably supporting each of the feeding rotating bodies. 2. The seat according to claim 1, wherein the feeding rotating body is attached to a shaft whose both ends are supported by an arm, and can be swung by a clearance provided in a supporting portion between the shaft and the arm. Feeding device. 3. The feeding rotary body is attached to a shaft whose both ends are supported by one end of an arm, and the other end of the arm is attached to a drive shaft connected to a rotary drive source. The sheet feeding device according to claim 1, wherein the feeding rotating body can be swung by the clearance between the arm and the supporting portion. 4. The seat according to claim 3, further comprising a rotation transmission means for transmitting the rotation of the drive shaft to the feeding rotary body between the shaft to which the feeding rotary body is attached and the drive shaft. Feeding device. 5. The feeding rotating body is attached to each of a pair of shafts, one end of which is swingably supported by an arm and the other end of which is connected by a universal joint.
The sheet feeding device according to claim 1, wherein the feeding joint is configured to be swingable by the universal joint. 6. The arm is attached to a drive shaft connected to a rotary drive source, and transmits the rotation of the drive shaft to the feeding rotary body between the pair of shafts and the drive shaft. The sheet feeding device according to claim 5, further comprising rotation transmission means. 7. The sheet feeding apparatus according to claim 6, wherein the rotation transmitting means includes a pulley provided on the drive shaft, a pulley provided on the universal joint, and a belt stretched between the pulleys. apparatus. 8. A sheet supporting means for stacking and supporting sheets, a plurality of feeding rotating bodies for feeding the sheets supported by the sheet supporting means, and outer peripheral surfaces of the respective feeding rotating bodies are along the surface of the sheet. As described above, the rotating body supporting means for swingably supporting each of the feeding rotating bodies and the image forming means for forming an image on the sheet fed by the feeding rotating body are provided. Image forming apparatus.