JPH03227839A - Paper sheet feeder - Google Patents

Abstract

PURPOSE:To prevent a succeeding paper sheet from being caught with the paper sheet currently being fed and to arrange so that no paper sheets are left when a paper sheet cassette is removed by reversing the rotation of a feed roller when the rear end of the paper sheet fed out with the feed roller passes the contact point between the feed roller and a reverse roller. CONSTITUTION:A reverse roller 8 is pressed with a spring 11 against a feed roller 1. Paper sheets 4 are pressed with an arm 7 against the feed roller 1 and fed to a point of contact between the feed roller 1 and the reverse roller 8. The reverse roller 8 is provided with a torque limiter mechanism so that only a topmost paper sheet is fed if more than one sheets are sent to be fed. The feed roller 1 is made to be capable of rotating in both normal and reverse directions. The reverse roller 8 is provided with a one way clutch. When the rear end of a paper sheet passes the contact point, the rotation of the feed roller 1 is reversed, the reverse roller 8 is made to rotate in the same direction with the feed roller 1, and a next paper sheet, even if it is caught with the previous paper sheet, is returned to the original position.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a paper feeding device that includes a feed roller and a reverse roller that is in pressure contact with the foot roller and separates paper into sheets one by one using the torque of a torque limiter. Regarding.

C. Prior Art] The above-mentioned paper feeding device, which uses a feed roller and a reverse roller to feed sheets one by one into the main body of an image forming apparatus, is known as the so-called friction separation paper feeding system, and is known from, for example, Japanese Patent Laid-Open No. 5
Many proposals have already been made, such as in Publication No. 6-7847 and Japanese Utility Model Application Publication No. 132048/1983.

C Problems to be Solved by the Invention In the above-mentioned paper feeding device, generally, while the first paper is being fed by the feed roller, the second and subsequent papers reach the contact point between the feed roller and the reverse roller (the lug portion). However, in the conventional paper feeding device, after a predetermined number of copies have been made, the next sheet following the last sheet reaches the contact point and is left to be held by the pair of rollers.

As a result, the leading edge of the paper is creased, which causes jams.

Furthermore, if the cassette is removed from the machine body with paper held in the pair of rollers, the paper remains inside the machine body, resulting in poor work efficiency.

SUMMARY OF THE INVENTION An object of the present invention is to provide a paper feeding device that eliminates the drawbacks of the prior art described above, does not cause paper jams, and is highly efficient.

[Means for Solving the Problem] The above object is to use a feed roller that is rotationally driven at a predetermined timing, and a plurality of sheets of paper that are in pressure contact with this feed roller and are fed out by the feed roller, one by one with a predetermined torque. In a paper feeding device equipped with a separating reverse roller, after the trailing edge of the first paper sent out by the feed roller passes a contact point between the feed roller and the reverse roller, the second paper is transferred to the upstream side of the contact point. This is achieved by providing a feed roller that can be rotated in forward and reverse directions.

[Effect]

The feed roller rotates in reverse after the trailing edge of the first sheet passes through the contact point between the feed roller and the reverse roller, and returns the second sheet in the upstream direction from the contact point.

Further, at this time, the reverse roller also rotates along with the reverse rotation of the feed roller.

〔Example〕

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

FIG. 1 is a block diagram of a paper feeding device according to an embodiment of the present invention, and FIG. 2 is a mechanical diagram of a reverse throw section.

In FIG. 1, 1 is a feed roller, 2 is a feed shaft, 3 is a bottom plate pressure spring, 4 is paper, 5 is a bottom plate, 6 is a cassette, 7 is a pressure arm, 8 is a reverse roller, 9 is a reverse shaft, 10 is a bearing, 11 is a reverse pressure spring, 12 is a reverse bracket, and 13 is a guide plate.

The feed roller ■ and the reverse roller 8 are in pressure contact with each other by a reverse pressure spring 11, and on the other hand, the paper 4, which is in pressure contact with the feed roller L with a predetermined feed pressure by the pressure arm 7, is pressed against the feed roller 1 and the reverse roller from its upper surface. It is fed to the nip portion of the roller 8.

The reverse roller 8 is equipped with a well-known torque limiter mechanism, which will be described later. When the sheets sent out by the feed roller 1 are fed in duplicate, the reverse roller 8 functions to return the sheets other than the topmost sheet, and eventually the sheets are transferred between both rollers. Separate them one by one,
One sheet of paper is fed into the main body of the image forming apparatus through the guide plate 13.

In Fig. 2, I3 is a bearing, I4 is a feed motor,
15 is a torque limiter unit, 16 is a stop gear with a one-way latch, 17 is a free hub, and 18 is a coil spring (
limiter spring), 19 is a fixed hub.

Here, the feed motor 14 is a stepping motor capable of forward and reverse rotation, and rotates the feed roller 1 forward and backward. Further, no rotational driving force is applied to the reverse roller 8,
The configuration is such that only the separation torque force is applied. Therefore, a stop gear 16 with a one-way clutch was connected to the free hub 17 of the limiter unit 15 without using a reverse smoke or the like.

As a result, when the feed roller 1 rotates in the forward direction (the direction in which the paper is sent out), the reverse roller 8 rotates while applying separation torque to the paper, and when the feed roller 1 rotates in reverse, it rotates in the reverse direction without applying separation torque. .

FIG. 3 fat, (bl, (C1 is an explanatory diagram of the paper feeding operation of the present invention, and the operation will be explained based on this diagram.

First, from the standby state shown in the same figure (al), the feed motor 1
4 to rotate the feed roller 1 clockwise. Then, as shown in FIG. 4B, the paper 4 is separated one by one by the feed roller 1 and the reverse roller 8, and the first paper 4a is sent to the registration roller 21 and is on standby. At this time, the pre-registration sensor 20 remains on, and the feed roller 1 stops rotating. Thereafter, the registration rollers 21 rotate in synchronization with the image on the photoreceptor (not shown) and pull the first paper 4a.

At this time, as the first paper 4a moves, the feed roller 1
will take you around. This co-rotation means that the trailing edge of the first sheet 4a is B.
This is done until the point is passed. Therefore, the leading edge of the second sheet 4b and subsequent sheets reaches point A.

On the other hand, the reverse roller 8 maintains a stopped state since the leading edge of the second sheet 4b and subsequent sheets has reached point A.

Then, as shown in FIG.
After passing through, the feed roller l is rotated counterclockwise. As a result, the leading edge of the second sheet 4b and subsequent sheets is separated from point A and returned to point B.

At this time, since the reverse roller 8 is rotated along with the feed roller 1, the sheet can be returned easily.

FIG. 4 is a timing chart of the operation shown in FIG. 3, (11 indicates the timing of the feed motor 14, and (2) indicates the timing of the pre-registration sensor 20.

5, 6, and 7 are sectional views of essential parts showing each type of torque limiter, and FIG. 8 is a side view of the device shown in FIG. 7.

In Fig. 5, 10a is a D-shaped bearing hole.
17 is a freehub with a one-way latch.

Here, the end face of the reverse shaft 9 and the D-shaped bearing 10a are fitted, and the D-shaped bearing 10a is connected to the reverse bracket 12.
However, the reverse shaft 9 cannot rotate. Also, freehub I7 has reverse roller 8
is locked in the direction of rotation as the feed roller 1 rotates.

In the example shown in FIG. 6, a one-way clutch is mounted on the bearing IOb, while the fixed hub 19 is fixed to the reverse shaft 9.

Both of the torque limiter mechanisms shown in FIGS. 5 and 6 have a built-in one-way clutch, and apply a predetermined torque to the reverse roller 8.

In the example shown in FIGS. 7 and 8, a limiter shaft 22 is provided outside the reverse shaft 9, and the reverse roller 8 and limiter unit are separated and connected by a reverse roller gear 23 and a limiter gear 24. 25 is a limiter bracket, 2
6 is a positioning pin.

〔Effect of the invention〕

As explained above, according to the present invention, the feed roller is used to return the paper stuck at the contact point between the feed roller and the reverse roller at the end of the copying operation. It is possible to prevent this from happening, and it is also possible to eliminate paper residue when the cassette is removed.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is a block diagram of a paper feeding device according to an embodiment of the present invention, Fig. 2 is a block diagram of a reverse roller section, and Fig. 3 is an explanatory diagram of the paper feeding operation of the present invention. , Fig. 4 is a timing chart of the operation shown in Fig. 3, Figs. 5, 6, and 7 are sectional views of main parts showing each type of torque limiter, and Fig. 8 is a diagram of the device shown in Fig. 7. FIG. ■...Feed roller, 8...Reverse roller. Figure Figure Figure 3 (σ) Gub) Figure Figure Figure 3!

Claims (2)

[Claims] (1) A paper feeder equipped with a feed roller that is driven to rotate at a predetermined timing, and a reverse roller that is in pressure contact with the feed roller and separates multiple sheets of paper sent out by the feed roller into one sheet at a time with a predetermined torque. In the apparatus, after the trailing edge of the first sheet sent out by the feed roller passes a contact between the feed roller and the reverse roller, the second sheet is returned to the upstream side of the contact. A paper feeding device characterized by being provided with a roller. (2) A paper feeding device according to claim 1, characterized in that the reverse roller is provided so as to be able to rotate along with the reverse rotation of the feed roller.