JPH10218403A - Paper feeding device and image forming device using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an occurrence of a jam by preventing the transfer paper from stopping while the paper is caught by a nipped part between a feed roller and a reverse roller of a paper sheet feeding device. SOLUTION: In this device the rotation of a feed clutch and a reverse clutch is turned on according to a paper feed starting signal, so that a transfer paper 2 is called by a pick-up roller 3 in order to be drawn out from a paper sheet feeding tray 1. As soon as the tail end of the transfer paper 2 passes the nipping part between a feed roller 4 and a reverse roller 5, the rotation of the feed roller 4 and the reverse roller 5 is reversed by the drive of a reverse shaft 8, so that the transfer paper 2, whose tail end still remains in the nipping part between the feed roller 4 and the reverse roller 5, is returned to the paper feeding tray (1) side. After this, when a paper feeding sensor indicates OFF, the reverse clutch is turned OFF.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feeder used for an image forming apparatus such as a copying machine, a printer, and a facsimile. It is related to those that have long life.

[0002]

2. Description of the Related Art FIG.
FIG. 2 shows an example of this kind of general paper feeder. The apparatus according to the present embodiment employs a separation method called an FRR method, in which a transfer paper stacking unit, that is, the highest transfer paper 2 loaded on a paper feed tray 1 is fed with transfer paper. Roller 3 that rotates in the forward direction with respect to the direction and that can move up and down
As a result, a feed roller 4 that also rotates in the forward direction and a torque limiter are built-in, and are fed between the reverse roller 5 that rotates in the reverse direction, and the conveying force due to the forward rotation of the feed roller 4 and the wiping action due to the reverse rotation of the reverse roller 5. The uppermost transfer paper 2 is fed between the pair of grip rollers 6 and fed to the next process via a feeding path.

When two or more sheets of transfer paper 2 are held between the feed roller 4 and the reverse roller 5 during such a paper feeding operation, the transfer of the second and subsequent sheets is performed by the reverse roller 5 rotating in the reverse direction. The paper 2 is returned to the paper feed tray 1, but the final transfer paper 2 is stopped in a state where it is held in the nip between the feed roller 4 and the reverse roller 5 as shown in FIG.

In this state, if the paper feed tray 1 is removed from the image forming apparatus or the side cassette tray is removed,
The final transfer paper 2 is composed of a feed roller 4 and a reverse roller 5
The nip portion may cause a problem such as a jam when the paper feed tray 1 is mounted on the image forming apparatus again. When the image forming apparatus has a plurality of paper feed stages,
The driving force is also applied to the reverse roller 5 of the sheet feeding device located at the unused sheet feeding port, and the load of the torque limiter built therein increases the load on the driving system of the entire image forming apparatus, and also increases the torque limiter. Your life will be shorter.

The present invention has been made in view of such a conventional problem. In the paper feeder according to the first and second aspects, the transfer paper is held in a nip portion between a feed roller and a reverse roller. It is an object of the present invention to provide a sheet feeding device that does not stop in a state and prevents a trouble such as a jam.

In the image forming apparatus according to a third aspect,
It is an object of the present invention to provide a sheet feeder that not only reduces the load on the entire drive system but also extends the life of a torque limiter built in the sheet feeder.

[0007]

According to a first aspect of the present invention, in order to achieve the above object, a sheet feeding apparatus according to the first aspect of the present invention feeds one sheet at a time from the uppermost sheet of a stacked transfer sheet to a second sheet. In a paper feeder using the FRR paper feed system,
The feed roller and the reverse roller each have their own transmission means for rotational driving force, and a sensor that detects the presence or absence of a transfer sheet downstream of the feed roller in the direction of feeding the transfer sheet and near the fed transfer sheet. When the driving force is applied to the reverse roller in a state where the driving force is not applied to the feed roller by the transmission means, both the feed roller and the reverse roller are moved in the transfer paper feeding direction. And reverse
A driving force can be applied to the reverse roller until the rear end of the transfer sheet passes through the position of the sensor and is fed.

According to a second aspect of the present invention, the transmission means applies a driving force to the reverse roller until a predetermined time has elapsed after the trailing edge of the transfer sheet has passed the position of the sensor.

According to a third aspect of the present invention, there is provided an image forming apparatus using the sheet feeding device according to the first or second aspect,
A driving force is not applied to the feed roller and the reverse roller of the sheet feeding device disposed in the unused sheet feeding port.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. In the following description, portions common to those of the related art will be denoted by common reference numerals. FIG. 3 is a diagram showing the configuration of an embodiment of the sheet feeding device according to the present invention.
The rotation of the feed roller 4 is transmitted by a clutch (not shown) (not shown), and the feed roller 4 is turned on / off.
F. The feed roller 4 has a feed shaft 7.
A one-way clutch is incorporated (not shown) so as to be fixed or rotate only in the forward direction.

On the other hand, the rotation of the reverse roller 5 is transmitted and turned on / off by a clutch different from the clutch of the feed roller 4 (hereinafter referred to as a reverse clutch), and the reverse shaft 8 has a built-in torque limiter. (Not shown).

In FIG. 1, reference numeral 9 denotes a paper feed sensor,
It is provided downstream of the transfer sheet 2 in the feeding direction of the transfer sheet 2 and in the vicinity of the lower surface of the transferred transfer sheet 2 so as to detect the presence or absence of the transfer sheet 2 in this portion.

Next, the operation of the present embodiment will be described with reference to the timing chart of FIG. As shown in the figure, the rotation of the feed clutch and the reverse clutch is turned on by a paper feed start signal a, and the transfer paper 2 is called out by the pickup roller 3 and fed out of the paper feed tray 1, and the transfer paper 2 is detected by the paper feed sensor 9. (B), the rotation of the feed roller 4 and the reverse roller 5 is turned off, and the transfer paper 2
Is temporarily stopped. When the feed clutch and the reverse clutch are turned on again in accordance with the timing of image formation in the image forming apparatus (c), the transfer paper 2 is conveyed again, and when conveyed by the grip roller pair 6, the feed clutch is turned off. The feed roller 4 is caused to rotate along with the transfer paper 2 being conveyed.

At this time, the reverse roller 5 reverses when there are two or more transfer papers 2 (e), and returns the second and subsequent transfer papers 2 to the paper feed tray 1, and when the return is completed, the torque limiter slips, Like the feed roller 4, the transfer paper 2 is caused to rotate along with the transfer paper 2.

When the rear end of the transfer paper 2 passes through the nip between the feed roller 4 and the reverse roller 5, the transfer paper 2
And the reverse roller 5 and the feed roller 4 are rotated in reverse by the drive of the reverse shaft 8, and the transfer paper 2 remaining in the nip portion between the feed roller 4 and the reverse roller 5 is returned to the paper feed tray 1 side and fed. Paper sensor 9 is OF
The reverse clutch is turned off at the time point (g) when the state becomes F.

In order to sufficiently return the transfer paper 2 at the nip between the feed roller 4 and the reverse roller 5 to the paper feed tray 1 side, as shown by a dotted line h in FIG.
The reverse clutch may be turned off after a certain time (t seconds) from the time (g) when the FF is set.

In the case where the image forming apparatus has a plurality of paper feed stages, the paper feed device according to the above-described embodiment, which is provided in an unused paper feed port, has a feed clutch and a reverse clutch which remain OFF. No driving force is applied to the roller 4 and the reverse roller 5, and the required power is reduced accordingly.

[0018]

According to the first aspect of the present invention, as described above, the feed roller is provided between the trailing end of the fed transfer paper and the sensor on the downstream side in the feeding direction after passing through the feed roller. And the reverse roller are rotated in the reverse direction, so that the next transfer paper in the nip between the feed roller and the reverse roller can be returned to the original direction in which it was stacked, and the transfer paper is transferred to the nip between the feed roller and the reverse roller. There is an effect that a jam caused by being left sandwiched can be prevented.

As described above, in the paper feeder according to the present invention, the trailing end of the fed transfer paper passes through the feed roller, passes through the sensor on the downstream side in the feeding direction, and continues until a predetermined time elapses. Since the feed roller and the reverse roller are configured to rotate in reverse, in addition to the same effects as those of the first aspect,
There is an effect that the next transfer paper in the nip portion between the feed roller and the reverse roller can be more reliably returned to the original direction in which the paper was stacked.

According to a third aspect of the present invention, as described above, a driving force is not applied to an unused feed roller and a reverse roller by using any one of the above-described paper feeders. Thus, in addition to the same effects as those of the first and second aspects, the load on the drive system of the entire apparatus can be reduced, and the life of the built-in torque limiter can be extended.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a general FRR type sheet feeding apparatus.

FIG. 2 is an enlarged view of a main part of the example of the apparatus in FIG.

FIG. 3 is a diagram illustrating a configuration of an embodiment of a sheet feeding device according to the present invention.

FIG. 4 is a timing chart showing an operation of the embodiment device of FIG. 3;

[Explanation of symbols]

 Reference Signs List 1 paper feed tray 2 transfer paper 3 pickup roller 4 feed roller 5 reverse roller 6 grip roller pair 7 feed shaft 8 reverse shaft 9 paper feed sensor

Claims (3)

[Claims] In a sheet feeding apparatus using a FRR sheet feeding method, in which a sheet is fed one by one from the uppermost sheet of stacked transfer sheets and returns the second and subsequent sheets, a feed roller and a reverse roller each independently transmit a rotational driving force. Having means,
A sensor for detecting the presence or absence of a transfer sheet is disposed downstream of the feed roller in the direction of feeding the transfer sheet and in the vicinity of the transfer sheet to be fed, and no driving force is applied to the feed roller by the transmission means. When a driving force is applied to the reverse roller in this state, both the feed roller and the reverse roller are rotated in the reverse direction with respect to the transfer paper feeding direction, and the rear end of the transfer paper passes through the position of the sensor. A sheet feeding device wherein a driving force can be applied to the reverse roller until the sheet is fed. 2. The sheet feeding device according to claim 1, wherein the transmission means applies a driving force to the reverse roller until a predetermined time has elapsed after the rear end of the transfer sheet has passed the position of the sensor. 3. An image forming apparatus using the sheet feeding device according to claim 1 or 2, wherein a driving force is not applied to the feed roller and the reverse roller of the sheet feeding device disposed in an unused sheet feeding port. An image forming apparatus characterized in that: