JP3473163B2 - Paper feeder of image forming device - Google Patents

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 of an image forming apparatus, and more particularly, to a sheet feeding device of an image forming apparatus for surely returning a double-fed sheet to a sheet storage section.

[0002]

2. Description of the Related Art As a paper feeding device of a conventional image forming apparatus,
For example, there is one shown in FIG. This sheet feeding device is disclosed in Japanese Utility Model Laid-Open No. 62-132048, and includes a pickup roller 15 for picking up the uppermost sheet P of the sheets 3 stored in the sheet storage section 32, and a pickup roller 15. Feed roller 11 for feeding paper
And a reverse roller 13 that reversely feeds the multi-fed paper.
And a driven roller 35 and a driven roller 36 that convey the fed paper P to the image recording unit.

The feed roller 11 receives a torque from a motor (not shown) which can rotate forward and backward together with a drive gear 17, and a one-way clutch (not shown) on the feed roller shaft 7.
The drive gear 17 is gear-coupled to the gear 15 for rotating the pickup roller 10 via the idle gear 16. The reverse roller 8 is in contact with the feed roller 11 at a predetermined nip pressure by receiving the elastic force of the coil spring 33, one end of which is fixed to the frame 34, via the arm 39. A drive roller 35 and a driven roller 36 are provided downstream of the nip portion between the feed roller 11 and the reverse roller 13.

In the above structure, the feed roller shaft 7
When the paper is rotated in the clockwise (CW) direction, the pickup roller 10 receives torque via the gears 17, 16 and 15 to rotate in the CW direction, and the uppermost sheet 3 of the sheet storage unit 32 is rotated.
Pick up 1. The paper P picked up is
If there is a sheet that has been fed to the nip portion between the feed roller 11 and the reverse roller 13 and has been double fed, the double feed is prevented by the reverse roller 13 rotating in the CW direction.

As a result, only one sheet of paper P is fed by the feed roller 11 and is conveyed to the image recording section by the driving roller 35 and the driven roller 36, and the image is recorded on the conveyed sheet. When the image recording is completed, the feed roller shaft 7 is rotated in the counterclockwise (CCW) direction, and the feed roller 11 is rotated in the CCW direction. Thus, the sheets that are prevented from being double-fed are fed back to the sheet storage unit 32 by the feed roller 11 that rotates in the CCW direction and the reverse roller 13 that rotates in the CW direction.

FIG. 4 shows a sheet feeding device of another conventional image forming apparatus. This sheet feeding device is described in Japanese Patent Application Laid-Open No. 2-144334, and portions having the same functions as those in FIG. 3 are indicated by the same reference numerals, and a duplicated description will be omitted. In this paper feeding device, the feed roller 11
Has a collar member 111 having a concave portion 111A that engages with a convex portion 112 of the one-way clutch provided on the feed roller shaft 7 with play, and the pickup roller 10 has a collar member 111 of the one-way clutch provided on the pickup roller shaft 15a. The collar member 101 has a concave portion 101A that engages with the convex portion 102 with play.

The feed roller 11 and the pickup roller 10 have a relay roller 42 between them, and the feed roller shaft 7 and the pickup roller 10 shaft 15a are
As in the case of FIG. 3, an idle gear (not shown) is interposed between the gears. On the other hand, the reverse roller 13 is supported by the frame 34 so as to receive torque from the torque limiter 14 via the idle gear 43. The drive roll 38 and the driven roll 3 are provided downstream of the conveyance path for conveying the paper P.
7 is provided with a registration roll 40 and a paper sensor 41, and the paper storage unit 32 is provided with a bottom plate push-up lever 44.

In the above structure, the upper surface of the sheet is raised to the set position by the swing of the bottom plate push-up lever 44, and the feed roller 11 and the pickup roller 10 start forward rotation (CW direction) in response to the sheet feed signal. At least one sheet of paper P that is pressed and nipped by the pickup roller 10 rotating in the normal direction and the pushing force of the bottom plate pushing lever 44 pushes the pickup roller 10 from the sheet storage section 32 to the feed roller 11 and the reverse roller 13 by the frictional force of the pickup roller 10. Sent to the nip. Reverse roller 13 is torque limiter 1
The sheet P is driven in the direction opposite to the traveling direction of the sheet P and is pressed against the feed roller 11 by the initial pressure by the coil spring 33 and the operating pressure generated by the torque of the torque limiter 14.

The reverse roller 13 is a feed roller 1.
Direct contact with 1 (when there is no paper P between the nip)
Alternatively, when the sheet P is fed into the nip of one sheet, it slips over the limit torque and is driven by the feed roller 11. However, when two or more sheets P are fed into the nip, the limit torque overcomes the frictional force between the sheets, the reverse roller 13 is reversed, and the downstream sheet P is pushed back to prevent double feeding. . The feed roller 11 is driven and rotated integrally with the feed roller shaft 7, and at the same time, the pickup roller 10 is also driven and rotated by torque transmission by a gear train (not shown).

That is, the right end surface of the convex portion 112 of the one-way clutch that rotates integrally with the feed roller shaft 7 is
The feed roller 11 is brought into contact with the right end of the recess 111A of the collar member 111 of the feed roller 11 which is loosely fitted to the feed roller shaft 7 to drive and rotate the feed roller 111 integrally with the one-way clutch. The pickup roller 10 is also integrated with the one-way clutch by bringing the convex portion 102 of the one-way clutch that is driven and rotated integrally with the pickup roller shaft 15a into contact with the concave portion 101A of the collar member 101 of the pickup roller 10 that is loosely fitted to the shaft 15a. Is driven to rotate.

Feed roller 11 and reverse roller 13
The paper P that has been fed by the
And the driven roller 37 are fed to the registration roller 40 in a stopped state. At this time, the sensor 33 detects the leading edge of the paper P, and the drive source such as the feed roller 11 is stopped based on the detection signal. At this time, the paper P is abutted against the nip portion of the registration roller 40, but a loop is formed from a time lag after the drive source such as the feed roller 11 is stopped, and the tip of the paper P is difficult to nip due to the restoring force of this loop. At the same time, the leading edge of the paper is aligned and the skew is corrected.

In this way, the paper P whose leading end is aligned by the registration roller 40 is the registration roller 40.
It is pressed and clamped by and conveyed. When the registration roller 40 conveys the paper, the feed roller 11 rotates idly while being pressed against the reverse roller 13 by the conveyance force of the paper P by the registration roller 40.

By the idling of the feed roller 11, the recess 1 of the collar member 111 forming the feed roller 11 is formed.
The end surface of 11A abuts on the end surface of the convex portion 112 of the one-way clutch to idle the one-way clutch in the same direction. Further, the one-way clutch (convex portion 102) also idles in the same direction due to the idle rotation of the pickup roller 10. During this time, the reverse roller 13 rotates in the normal direction when one sheet is in the nip portion, and the reverse roller 2
If more than one sheet is loaded, reverse to reverse and return the second and subsequent sheets.

Next, when the sheet P has finished passing through the nip portion between the feed roller 11 and the reverse roller 13, the peripheral surface of the reverse roller 13 comes into direct pressure contact with the peripheral surface of the feed roller 11, and the feed roller 11 is reversed. Let As a result, the concave portion 1 of the color member 111 of the feed roller 11
11A is rotated counterclockwise to form the concave portion 111A and the convex portion 1
It rotates by the amount of backlash with 12 and comes into contact with the convex portion 112 of the one-way clutch that is stopped because it cannot rotate in the reverse direction and stops.
In this way, the multi-fed sheets are fed back.

[0015]

However, according to the conventional sheet feeding device, in the apparatus shown in FIG. 3, the feed roller is reversely rotated for a predetermined time after the completion of the copying operation so that the double fed sheets are fed. However, when the torque limiter is used, if the feed roller rotates in the reverse direction, the nip pressure between the feed roller and the reverse roller becomes small and the operation of returning the sheet becomes unstable. Further, since both the feed roller and the reverse roller are driven, slipping may occur between them and gear jumping may occur. Further, in the apparatus shown in FIG. 4, the reverse rotation of the feed roller is limited to the angle corresponding to the play formed between the concave portion of the collar member and the convex portion of the one-way clutch, so that the amount of paper returning is insufficient. Is. These problems can be idealized to some extent by ignoring the cost increase, the size increase of the apparatus, and the friction of the rollers.

[0016]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to prevent slipping of a roller forming a nip and tooth jump of a gear, and to sufficiently return a sheet while suppressing cost increase, size increase of apparatus, roller friction and the like. It is another object of the present invention to provide a sheet feeding device of an image forming apparatus that can be reliably performed.

[0017]

In order to achieve the above-mentioned object, the present invention picks up a sheet from a sheet storage section by a pickup roller, and picks up the sheet by a nip between a feed roller and a reverse roller. When two or more sheets of paper are picked up by the pickup roller by feeding in the direction, the feed roller is rotated in the forward direction in the sheet feeding device of the image forming apparatus that prevents double feeding of the sheet by stopping or reversing the reverse roller. When the sheet is fed in the direction of the image recording section by the feed roller shaft that supports the feed roller, normal rotation is transmitted to the feed roller, and the reverse roller reversely rotates so that the sheet is double-fed. When returning to the storage part, the feed driven by the reverse rotation of the reverse roller Comprising a torque transmitting means does not transmit the reverse rotation of the over La to the feed roller shaft, the feed rollers
Is reversely driven by the reverse roller
Rotation speed lower than the rotation speed of the feed roller shaft.
Provided is a sheet feeding device of an image forming apparatus, which is configured to have .

[0018]

The torque transmitting means is provided between the feed roller shaft and the feed roller. This torque transmission means
When the feed roller rotates forward to feed the paper toward the image recording unit, when the feed roller shaft transmits the normal rotation to the feed roller, and the reverse roller reverses to return the double-fed paper to the paper storage unit. , The reverse rotation of the feed roller, which is driven by the reverse rotation of the reverse roller, is prevented from being transmitted to the feed roller shaft. This action is realized, for example, by providing a one-way clutch between the feed roller shaft and the feed roller so that the rotation speed of the feed roller at the time of reverse rotation is not larger than that of the feed roller shaft. If this action is not realized, the feed roller shaft and the reverse roller shaft cannot be connected to the common input portion. If the feed roller shaft and the reverse roller shaft are connected to the common input portion in the state where this action is not realized, slips between the feed roller and the reverse roller and tooth skipping etc. occur in the gear inserted in the torque transmission path.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a paper feeding device according to a first embodiment of the present invention. This paper feeding device has a pickup roller 10, a feed roller 11, and a reverse roller 13, and a feed roller shaft 7 and a reverse roller shaft are respectively provided between the input gear 1 capable of forward and reverse rotation, and the feed roller 11 and the reverse roller 13. 8 are provided.

The input gear 1 and the feed roller shaft 7 are connected via the first gear 2 (path a), and the input gear 1 and the reverse roller shaft 8 are provided with the first one-way clutch when the input gear 1 is normally rotated. Connected via gear 5 (path b),
When the input gear 1 is rotated in the reverse direction, it is connected through the second gear 3, the third gear 4, and the second gear with a one-way clutch 6 (path c). A one-way clutch 12 is provided between the feed roller shaft and the feed roller 11, and the feed roller shaft 7 includes a fourth gear 17, an idle gear 16 and a fifth gear 15 supported by the frame body 20. It is connected to the pickup roller 10 via the. The reverse roller shaft 8 is connected to the reverse roller 13 via a torque limiter 14.

In the above paper feeder, the number of teeth of each gear is set as shown in Table 1, for example. The rotation speeds in Table 1 will be described in the operation of the input gear 1 at the time of reverse rotation.

[Table 1]

The operation of the above configuration will be described. When the input gear 1 rotates in the forward direction, its rotation is transmitted to the feed roller shaft 7 via the first gear 2 (path a), and the rotation of the feed roller shaft 7 is transmitted to the feed roller 11 via the one-way clutch 12. The rotation of the feed roller shaft 7 is also transmitted to the fifth gear 15 via the idle gear 16, and the rotation thereof causes the pickup roller 10 to rotate.
On the other hand, the forward rotation of the input gear 1 is transmitted to the reverse roller shaft 8 via the first one-way clutch gear 5 (path b), and the reverse roller 13 via the torque limiter 14.
Be transmitted to. The transmission of the rotations of the paths a and b causes the pickup roller 10 and the feed roller 11 to rotate normally,
The reverse roller 13 rotates in the reverse direction. Pickup roller 1
0 picks up a sheet from a sheet storage portion (not shown) and sends it to the nip portion between the feed roller 11 and the reverse roller 13. When the sheets are double-fed here, the reverse roller 13 continues the reverse rotation to prevent the double-feed. On the other hand, when only one sheet is fed, the reverse roller 1
3 is driven by the feed roller 11 by the torque limiting action of the torque limiter 14 to feed one sheet in the conveying direction.

When a sheet of paper is fed in the conveying direction,
A transport roller provided on the downstream side transports the sheet toward the image recording unit. At this time, the torque input to the input gear 1 stops and the feed roller 11 and the reverse roller 1
Although the driving of No. 3 is stopped, the feed roller 11 idles due to the trailing edge of the sheet being conveyed by the conveying roller,
The reverse roller 13 follows it.

Then, when a predetermined time period has elapsed, the input gear 1 rotates in the reverse direction. This reverse rotation is transmitted to the feed roller shaft 7 (path a), but is not transmitted to the feed roller 11 by the one-way clutch 12. Further, the reverse rotation of the input gear 1 is not transmitted through the path b by the first gear 5 with the one-way clutch, and the second and third gears 3,
It is transmitted to the reverse roller shaft 8 via the fourth and the second one-way clutch gear 6 (path c). Here, as shown in Table 1, the rotation speed of the input gear 1 at the time of reverse rotation is 10
At 0 RPM, the rotation speed of the feed roller shaft 7 is 75
Become RPM. The number of rotations of the reverse roller 13 which is reversed by the reverse roller shaft 8 is 66.7 RPM.

As described above, the feed roller 11 is not driven by the feed roller shaft 7 because of the one-way clutch 12, but is driven by the reverse roller 13 which is rotated in the reverse direction to rotate in the reverse direction. At this time, if the diameters of the feed roller 11 and the reverse roller 13 are the same, the feed roller 11
Reverses at 66.7 RPM, which is less than 75 RPM of the feed roller shaft 7. As a result, the sheet that has been prevented from being double-fed is returned to the upstream side from the nip portion of the reverse roller 13 and the feed roller 11 that is driven by the reverse roller 13, and is reliably returned to the sheet storage section by the reversing pickup roller 10.

In the first embodiment described above, when the feed roller 11 rotates in the reverse direction, the rotation speed of the feed roller 11 (66.7).
RPM) is the rotation speed of the feed roller shaft 7 (75 RPM)
Made smaller. This is because when the rotation speed of the feed roller 11 is made higher than the rotation speed of the feed roller shaft 7, the one-way clutch 12 is turned on, the feed roller 11 rotates the feed roller shaft 7, and the path a and the path c are connected. This is to prevent slippage between the feed roller 11 and the reverse roller 13 and to prevent tooth skipping or the like from occurring in the gear in the torque transmission path.

In the first embodiment, the feed roller shaft and the feed roller are connected via a one-way clutch. However, the feed roller shaft and the feed roller are integrally fixed with a pin or the like, and a gear or a gear that rotates together with the feed roller is used. The pulley and the feed roller shaft may be connected via a one-way clutch. Further, although the feed roller shaft is one, it may be divided and connected to each other via a one-way clutch. Further, although the reverse roller shaft and the reverse roller are connected via the torque limiter, the torque limiter may be omitted and the both may be integrally connected by a pin or the like. Further, although the reverse roller shaft is one, it may be divided and the torque reaction may be applied by the torque limiter.

FIG. 2 shows a sheet feeding device according to the second embodiment of the present invention. The parts common to those of the first embodiment are indicated by common reference numerals, and the duplicated description will be omitted. In the second embodiment, the input gear 1 and the reverse roller shaft 8 are connected via the gear 3 and the gear 6 with the one-way clutch, and the reverse roller shaft 8 is connected to the frame (fixed system) 21 via the one-way clutch 18. It is connected.

In the above structure, when the input gear 1 rotates in the normal direction, the feed roller 11 rotates in the normal direction via the first gear 2, the feed roller shaft 7 and the one-way clutch 12, and the pickup roller 10 feeds. The roller shaft 7 is rotated through the fourth gear 17, the idle gear 16, and the fifth gear 15 of the roller shaft 7 to rotate normally. At this time, the rotation of the input gear 1 is not transmitted to the reverse roller shaft 8 by the one-way clutch gear 6.

A sheet is fed from a sheet storage section (not shown) by the normal rotation of the pickup roller 10 described above, and the feed roller 11 feeds it to the downstream side. At this time,
When the number of sheets fed is one, the reverse roller 13 follows the movement of the sheet fed by the feed roller 11,
When the number of fed sheets is two or more due to the double feeding, the torque limiter 14 prevents the driven sheets. Even if the reverse roller 13 is driven, the reverse roller shaft 8 is prevented from rotating by the one-way clutch 18. When the fed sheet reaches the downstream transport roller and is transported toward the image recording unit, the torque input to the input gear 1 is stopped. At this time, the feed roller 11 nipping the rear end of the paper
Spins idle. The reverse roller 13 is stopped when there is a double-fed sheet, but idles when driven with one sheet.

Next, when the input gear 1 rotates in the reverse direction, the one-way clutch gear 5 transmits the reverse rotation to the reverse roller shaft 8, and the reverse roller 13 rotates in reverse. At the same time, the feed roller shaft 7 is also rotated in the reverse direction by being driven, but the feed roller 11 is not driven because it has the one-way clutch 12. Due to the reverse rotation of the reverse roller 13, the multi-fed sheets are fed back to the pickup roller 10. At this time, the fourth gear 17, the idle gear 1
The sixth and fifth gears 15 also reverse the pickup roller 10. The rotation speed of the feed roller 11 at this time is set to be smaller than the rotation speed of the feed roller shaft 13 as described in the first embodiment. Therefore,
The feed roller 11 is driven by the reverse roller 13 while the reverse roller 13 is rotating in the reverse direction, and can reliably return the double-fed sheets to the sheet storage section.

In the second embodiment, the modification described in the first embodiment can be applied as it is. Also, the first
In the second embodiment, the input gear 1 receives torque from a motor capable of rotating in the forward and reverse directions, but may receive torque from a common drive source that drives the other through a plurality of gears and a clutch.

[0033]

As described above, according to the sheet feeding device of the image forming apparatus of the present invention, when the reverse roller is reversed to return the double-fed sheets to the sheet storage section, the feed roller is changed to the reverse roller. Since it is driven to rotate in reverse and the reverse rotation of the feed roller is not transmitted to the feed roller shaft, slipping of the feed roller and reverse roller and gear tooth skipping are prevented, while suppressing cost increase and size increase of the device. The double-fed sheets can be reliably returned to the sheet storage section.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a second embodiment of the present invention.

FIG. 3 is an explanatory view showing a conventional paper feeding device.

FIG. 4 is an explanatory view showing another conventional sheet feeding device.

[Explanation of symbols]

1 input gear 2,3,4,15,16,17 gear 5,6 One-way clutch gear 7 Feed roller shaft 8 Reverse roller shaft 10 Pickup roller 11 Feed roller 12,18 One-way clutch 13 Reverse roller 14 Torque limiter 19 Input axis 20 frame 21 Fixed system

Continuation of the front page (56) References JP-A-2-144334 (JP, A) JP-A-4-358641 (JP, A) JP-A-2-132027 (JP, A) Actual development 63-65540 (JP , U) (58) Fields investigated (Int.Cl. ⁷ , DB name) B65H 3/52 330

Claims (3)

(57) [Claims] 1. A pickup roller picks up a sheet from a sheet storage section, feeds the picked-up sheet toward an image recording section by a nip between a feed roller and a reverse roller, and two or more sheets are picked up by the pickup roller. When the feed roller of the image forming apparatus prevents double feeding of paper by stopping or reversing the reverse roller, when the feed roller rotates forward to feed the paper toward the image recording unit, When the feed roller shaft that supports the feed roller transmits normal rotation to the feed roller, and the reverse roller reversely rotates to return the double-fed paper to the paper storage unit, the feed driven by the reverse rotation of the reverse roller. Torque transmission that does not transmit the reverse rotation of the roller to the feed roller shaft. Comprising a reach means, the feed roller, the reverse roller to reverse
When driven to rotate in reverse, the number of rotations of the feed roller shaft
A sheet feeding device of an image forming apparatus, which is configured to have a smaller rotation speed . 2. A first torque transmission, wherein the reverse roller has a first one-way clutch that reverses a rotation direction of an output torque of an input gear that normally rotates and transmits the output torque to a reverse roller shaft that supports the reverse roller. And a second torque transmission path having a gear train and a second one-way clutch for transmitting the output torque of the reversely input gear to the reverse roller shaft, and the feed roller is the second torque transmission path. sheet feeding device of an image forming apparatus according to claim 1 wherein said is by Uni configuration you reversed following the reverse roller to reverse based on the torque input from the path. 3. A third one-way clutch, wherein the reverse roller transmits an output torque of an input gear for reverse rotation to the reverse roller shaft by inputting the output torque through the gear,
And a torque transmission path having a fourth one-way clutch fixed to a fixed system to prevent forward rotation of the reverse roller shaft, wherein the feed roller reversely rotates based on a torque input from the torque transmission path. sheet feeding device of an image forming apparatus according to claim 1, wherein is by Uni configuration you reversed following the roller.