JPH0494383A - Double-sided paper supply device - Google Patents

Abstract

PURPOSE:To eliminate stagnation of paper on a guide plate so as to prevent paper jam by moving a separating roller from the vicinity of lower edge of a guide member for a predetermined range nearly along the guide member. CONSTITUTION:Paper sheets copied on one side and introduced into an double- side unit 10 in a direction B is supplied by a carrying roller 11 onto a paper supply roller 12 which is rotating clockwise. The paper sheets guided by the paper supply roller 12 and carried in a direction C is guided by a separating roller 14 which follows the movement of paper supply roller 12 and rotates counterclockwise, then stacked on an intermediate tray 15. A part of the paper sheets is located on a bottom plate 17 which is in lowering state. At this time, since an electromagnetic solenoid 20 is in demagnetized state and the separating roller 14 is located in the vicinity of the lower edge of a guide plate 16, there is no fear that the paper sheets which have left from the separating roller 14 remains on the guide plate 16.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a duplex paper feeding device in an image forming apparatus such as a copying machine or a printer equipped with a duplex unit.

[Conventional technology]

In image forming devices such as copying machines and printers, paper with an image formed on one side is once stacked in a duplex unit, and then the paper is re-fed and a different image is combined on the image side of the paper, or the image is formed on the other side. Some devices are equipped with a duplex unit that forms a new image on the other side that has not been previously printed.

Conventionally, as a double-sided paper feeder in this type of image forming apparatus, there is one shown in FIG. 4, for example.

To explain this simply, paper (copy paper) is fed from a paper feed cassette (not shown) in the direction of arrow A, and is sent by a registration roller 1 to a photosensitive drum 2 that rotates clockwise at a predetermined timing. After a visible image is transferred to one side, the paper passes through a fixing device 3 and is conveyed to a paper discharge roller 4.

The paper that has passed through the paper ejection roller 4 is normally sent onto a paper ejection tray (not shown), but during double-sided copying, the switching claw 5
In the state shown in the figure, the paper is guided in the direction of arrow B, introduced into the duplex unit 10, and reaches the paper feed roller 12, which is rotated clockwise by the conveyance roller 11. Then, it is guided by the composite two-sided switching claw 13 and moves along the paper feed roller 12 as indicated by the arrow C.
The sheets guided in this direction are stacked on an intermediate tray 15 through a separating roller 14 that rotates counterclockwise along with the sheet feeding roller 12.

After the required number of sheets have been stacked, the sheet feed roller 12 is reversed and rotated counterclockwise, the bottom plate 17 is raised, and the stacked sheets are transferred to the sheet feed roller 12. At this time, the separation roller 14 is also rotating counterclockwise, so the plurality of sheets are separated by the separation roller 14, and one by one the sheets are re-fed on the guide plate 16 in the direction of the arrow, and then the registration rollers 14 The paper is passed to the receiver, passes through the same path as when copying one side, and is ejected after being copied on the other side.

[Problem to be solved by the invention]

However, in such a conventional duplex paper feeder, when stacking sheets copied on one side on the intermediate tray 15 of the duplex unit 10 for duplex copying, after the trailing edge of the paper passes the separation roller 14, Since the conveying force is no longer applied, the paper may remain in that state without removing the guide plate 16. If the next sheet is conveyed in this state, the probability of jam occurrence increases.

The present invention has been made in view of the above points, and an object of the present invention is to provide a double-sided paper feeding device that can eliminate the accumulation of paper on a guide plate and prevent the occurrence of jams.

[Means to solve the problem]

In order to achieve the above object, the present invention includes a paper feed roller that can be rotated in forward and reverse directions for stacking sheets with an image formed on one side and refeeding the sheets, and a stacking direction in contact with the paper feed roller. In a double-sided sheet feeding device having a rotating separation roller and a guide member for guiding the paper in a paper refeeding direction, driving means is provided for moving the separation roller by a predetermined range from near its lower end substantially along the guide member. It is something that

Preferably, the driving means is an electromagnetic solenoid, but it is also possible to use frictional force with the paper feed roller.

[For production]

The duplex paper feeder according to the present invention is configured as described above, and when stacking sheets with an image formed on one side, the paper is moved to the vicinity of the lower end of the guide member by moving the separation roller to the vicinity of the lower end of the guide member. This prevents any residue from remaining and prevents jams from occurring during the next paper feeding.

Moreover, by moving the separation roller to the same position as before when refeeding sheets, it is possible to reliably separate the sheets during refeeding.

If the driving means for the separation roller is made up of an electromagnetic solenoid, the separation roller can be reliably moved to a predetermined position with a simple configuration, and if it is made to be driven by frictional force with the paper feed roller, In particular, it becomes possible to move the separation rollers without providing a drive mechanism.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to FIGS. 1 to 3 of the accompanying drawings. Parts corresponding to those in FIG.

FIGS. 1 and 2 are block diagrams showing an embodiment of the present invention, with FIG. 1 showing the stacking state and FIG. 2 showing the paper re-feeding state, respectively.

In this embodiment, the shaft 12a of the paper feed roller 12 and the separation roller 1
The separation roller 14 is connected to the shaft 14a of the paper feed roller 12 through the connecting link 18, so that the separation roller 14 can revolve around the force 1 in contact with the paper feed roller 12. The actuator 20a is connected to the shaft 14a of the separation roller 14.

When the electromagnetic solenoid 20 is in a de-energized state, the actuator 20a protrudes from its own biasing force.
When the separation roller 14 is located near the lower end of the lever guide plate 16 and is in an excited state as shown in FIG.
The respective relative positions are set so that they are at the same positions as in the conventional case shown in FIG.

Note that the other configurations are the same as the conventional example shown in FIG.

Next, the operation of this embodiment configured as described above will be explained.

In FIG. 1, a single-sided copy sheet introduced into the duplex unit 10 from the direction of arrow B is fed by a conveying roller 11 to a sheet feeding roller 12 rotating clockwise.

The paper guided by the paper feed roller 12 and conveyed in the direction of arrow C passes through the separation roller 14, which rotates counterclockwise along with the paper feed roller 12, and is stacked on the intermediate tray 15. is on the bottom plate 17 in the lowered state.

At this time, the electromagnetic solenoid 20 is in a non-energized state, the separation roller 14 is located near the lower end of the guide plate 16, and there is no possibility that the paper that has left the one-separation roller 14 will remain on the guide plate 16.

To refeed the paper stacked on the intermediate tray 15, the electromagnetic solenoid 20 is energized to pull up the separation roller 14 in the direction of the arrow, and the paper feed roller 12 is reversed and rotated counterclockwise. After that, lift the bottom plate 17 as shown in FIG. At this time, the separation roller 14 continues to rotate counterclockwise.

Therefore, the paper fed to the paper feed roller 12 by the rise of the bottom plate 17 is separated into the uppermost layer paper and the lower layer paper by the separation roller 14, and only the uppermost layer paper is sent to the guide plate 16.
The paper is re-fed in the direction of the arrow along the arrow, passed to the registration rollers 1 shown in FIG. 4, copied again on the other side of the paper, and then discharged.

In the above embodiment, as shown in FIG. 3, an elongated hole 19 is provided to restrict the movement range of the shaft 14a of the separation roller 14, and the electromagnetic solenoid 2o is omitted, and the paper feed roller 12, which rotates in forward and reverse directions, is connected. It is also possible to move the separating roller 14 to the end of the surface movement and hold it in that position by means of frictional force.

According to this embodiment, since there is no need to provide a special drive mechanism, it is possible to further simplify the device and reduce costs.

Furthermore, in these embodiments, if the movement of the separation rollers 14 and the vertical movement of the bottom plate 17 are linked, the mechanism can be further simplified.

〔Effect of the invention〕

As described above, in the duplex paper feeding device according to the present invention, the separation roller, which rotates in the direction of stacking the paper in contact with the paper feed roller that can be rotated in the forward and reverse directions, is attached to the guide member that guides the paper in the direction of refeeding the paper. Since a driving means for moving the paper along the guide member is provided, when stacking, the separating roller is moved near the lower end of the guide member, so there is no risk of the paper remaining on the guide member, and paper jams due to paper remaining can be prevented. It can be prevented.

If the driving means is composed of an electromagnetic solenoid, the separation roller can be reliably moved to a predetermined position with a simple configuration.

In addition, if the drive means is based on frictional force with the paper feed roller, there is no need to provide a special drive mechanism.
It becomes possible to further simplify the configuration and reduce production costs.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the paper stacking state of one embodiment of the present invention, FIG. 2 is a block diagram showing the same paper refeeding state, and FIG. 3 is a main part of another embodiment of the present invention. A configuration diagram showing the. FIG. 4 is a block diagram showing a conventional double-sided paper feeder together with an image forming apparatus.

Claims (1)

[Scope of Claims] 1. A paper feed roller that can rotate in forward and reverse directions for stacking and refeeding sheets with an image formed on one side, and a separation roller that rotates in the stacking direction in contact with the paper feed roller. , a double-sided paper feeding device having a guide member for guiding the paper in the paper refeeding direction, further comprising a drive means for moving the separation roller by a predetermined range from near the lower end thereof substantially along the guide member. Duplex paper feeder. 2. The double-sided sheet feeding device according to claim 1, wherein the driving means comprises an electromagnetic solenoid. 3. The double-sided sheet feeding device according to claim 1, wherein the driving means is driven by frictional force with the sheet feeding roller.