JP2561702B2 - Sheet loading and feeding device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a sheet stacking / feeding apparatus having a sheet storage portion inside a device such as a double-sided image forming apparatus.
The present invention relates to setback stacking in which sheets are sequentially shifted backward and stacked at predetermined intervals.

(B) Conventional Technology Conventionally, in a double-sided image forming apparatus such as a double-sided copying machine,
Generally, an intermediate tray for accommodating the transfer material on which the first side image has been formed is provided, and after completion of the image formation on the first side, the transfer materials stacked in the intermediate tray are separated and fed out one by one, and the image is reproduced again. The image was formed on the second surface by being conveyed to the forming unit. An important point in performing such double-sided image formation is the reliability of the transfer material transportation, that is, whether or not the transfer material can be properly transported. In particular, reliability is a problem in the re-feeding operation in which the transfer material on which the first surface image has been formed is separated one by one from the intermediate tray and sent out.

FIG. 7 shows an example of a conventional double-sided image forming apparatus 100. In the figure, a sheet S such as plain paper, which is fed from inside a cassette 101 and copied on the first side by an image forming unit 102.
After the copy image is fixed via the fixing device 103, the image is stored in the intermediate tray 104. Next, at the time of copying on the second side, the sheets on which the first side is copied are re-fed one by one from the intermediate tray 104, conveyed to the image forming section, and copied on the second side by the transfer section 102. Is done. Here, the sheets stacked on the intermediate tray 104 after the copying on the first side passes through the fixing device 103 for fixing the copied toner image, and thus the copied surface (first In some cases, silicon oil may be attached to one surface), or a reaction force (curl) may be generated at the end or the like due to heat or pressure applied during fixing. For this reason, when re-feeding from the inside of the intermediate tray 104, there is a possibility that double feeding or jamming may occur.

FIG. 8 shows an example of a double-sided image forming apparatus configured to increase the reliability of the transfer material conveyance (Japanese Patent Laid-Open No. 55-63).
(See Japanese Patent Publication No. 90). In this example, the sheet S is stored in the intermediate tray 110.
Are configured to be loaded one by one in a setback state. That is, as soon as the copied sheet on the first side is discharged onto the intermediate tray 110, the sheet is immediately sent out by a predetermined amount by the roller pair 111 rotating at a speed lower than the conveying speed at the time of copying. This operation is performed every time a sheet is discharged onto the intermediate tray 110. As a result, as shown in the figure, the sheets are stacked on the belt 112 in the state of being set back from the lowermost portion in order. When the lowermost sheet located at the top reaches the roller pair 113, the roller pair 113 rotates at a peripheral speed that is substantially the same as the conveying speed at the time of copying, and the one lowermost sheet is again transferred to the transfer unit 102. And is copied to the second surface.

The above-mentioned conventional example has a sufficiently large intermediate tray 104, 110.
Since it is necessary to increase the size of the entire device, a method of setting back sheets, stacking them, and feeding them in a small space as described below (hereinafter referred to as an improved example)
Is being considered.

This modified example will be described with reference to FIG. 9. Guide plates 120 and 121 are provided to guide the sheet on which the first image has been formed, and a pair of conveying rollers that rotate only in the forward direction are provided downstream thereof.
122 is installed, and further forward and reverse rotation is possible
A forward / reverse rotation roller pair 123 that can intermittently convey sheets with a freely adjustable timing is provided. Below these roller pairs 122 and 123, a sheet storage guide that stores a group of sheets to be stacked by being set back. A section 124 is provided. Here, the transport roller pair 122 and the forward / reverse rotation roller pair 123
The distance P between the shortest sheet is such that the shortest sheet among these sheets to be used can be conveyed to the forward / reverse roller pair 123 with respect to the sheets of various sizes conveyed to the sheet storage guide section 124. The distance is set to be slightly shorter than the length.

As described above, since the distance between the roller pair 122 and 123 is restricted by the shortest sheet, in order to cope with a sheet longer than this, as shown in FIG. It is necessary to convey the sheet S further forward by the distance R, and to pull out the trailing edge Q of the sheet S from the pair of conveying rollers 122. Then, in order to form a set back amount with the sheet S to be conveyed next, It is fed back from the pair 123 to the distance l and waits for the next sheet to be conveyed.
At this time, since the trailing edge Q of the sheet has been pulled out from the pair of transport rollers 122, the sheet S is dropped (arrow T) onto the upper surface of the sheet storage guide portion 124 due to the weight of the sheet S, and is transported when the sheet S is fed backward. After a predetermined amount of sheets are stacked without colliding with the roller pair 122, the sheet is again fed to the image forming unit by the forward / reverse rotation roller pair 123 and the feeding roller pair 125 from the bottom. The actual value in this improved example is that if the shortest sheet is set to B5 size, the length of B5 size is 182 mm.
And P = 170 mm, and the setback amount l = 10 m
Considering m and the radius U of the conveyance roller 122 = 10 mm, the length of the A4 size is 210 mm in order to correspond to the A4 size, so the pullout amount R is at least 210− (P−U) = 50 mm.
The above is required, and the reverse feed amount is 50-10 = 40 mm.

(C) Problems to be Solved by the Invention By the way, the above-described improved setback stacking method is very effective in terms of space, but in order to handle a plurality of sheet sizes, the sheet is temporarily pulled out, It is necessary to drop the rear end of the sheet into the sheet storage guide portion by its own weight and store the sheet.

However, if the trailing edge of the sheet is deformed due to curl or the like, the trailing edge Q of the sheet S may be curled or the like as shown in FIG. It rises due to deformation and contacts the transport roller pair 122.
There is a risk that the sheets may collide with each other and the sheets cannot be normally stacked on the sheet storage guide portion 124.

In addition, in general, the sheet conveyed to the intermediate tray portion is
When an image is formed on the first screen, heat and pressure are applied between the rollers to the fixing device, so deformation is likely to occur due to so-called curl. Ideally, this curl should be removed. Considering various paper types and various environmental conditions, it is difficult to completely remove the curl only by using the conventional curl removing means.

(D) Means for Solving the Problems The present invention is intended to solve the above problems, and includes a forward / reverse rotation roller pair, a conveyance roller pair for conveying a sheet to the roller pair, A sheet storage guide portion disposed below the conveying roller pair, and the trailing end of the sheet conveyed in the downstream direction by the forward rotation of the conveying roller pair and the forward / reverse rotation roller pair forms the conveying roller pair. In the removed state, the forward / reverse rotation roller pair reversely rotates and conveys the sheet in the upstream direction by a predetermined amount, and a plurality of sheets are sequentially shifted upstream with respect to the lower sheet at a predetermined interval. In the sheet stacking and feeding apparatus that stacks the sheets on the sheet storage guide unit in this manner, the sheet is allowed to be conveyed to the downstream side of the conveying roller pair when the sheet is conveyed in the downstream direction, and the sheet is conveyed. Transport in the upstream direction When, characterized in that a trailing edge of the sheet provided with a guide member for guiding toward the sheet storage guide portion.

(E) Operation Based on the above configuration, the sheet conveyed by the conveying roller pair is further conveyed downstream by the forward / reverse rotation roller pair. When the trailing edge of the sheet comes out of the pair of transport rollers, the sheet is fed back by the forward / reverse rotation roller pair that started reverse rotation, and the trailing edge is guided by the guide member toward the sheet storage guide portion, and the sheet storage guide. The sheets are sequentially stacked on the set at predetermined intervals.

(F) Example Hereinafter, examples embodying the present invention will be described with reference to the drawings.

First, a first embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a side view showing a sheet stacking / feeding apparatus 1 arranged inside a double-sided copying machine. The configuration of the feeding device 1 is the device of the above-mentioned improving agent (Fig. 9, Fig. 10, Fig.
(See FIG. 11), guide plates 120 and 121 are provided on one side to guide the sheet S on which the image formation is completed to form a conveyance path, and a conveyance roller pair 122 is provided at the end of the conveyance path, and further downstream. , The forward / reverse rotation roller pair 12 at a distance slightly shorter than the length of the shortest sheet used from the conveyance roller pair 122.
The sheet storage guide portion 124 corresponding to a so-called intermediate tray is provided below the pair of rollers 122 and 123.

A swing guide member 11 that appears in the transport path and drops the sheet S downward is provided in the vicinity of the downstream side of the transport roller pair 122. The guide member 11 rotates about an axis 12. Is attached to the other end, and a link member 13 is provided at the other end.
15 is provided, and when a current is applied to the solenoid 14, the shaft of the solenoid 14 moves in the direction of arrow C, and the link member 13
Also, the swing guide member 11 moves downward from the home position shown by the solid line that is retracted upward from the transport path,
When the current is cut off, the spring 15 returns to the home position.

Further, the swing guide member 11 is, as shown in FIG.
A plurality of sheets are provided in parallel in the direction perpendicular to the sheet conveying direction, and are projected and retracted from a plurality of holes 16 corresponding to these swing guide members 11 provided in the guide plate 120. The guide surface of the sheet S is formed over the entire width direction of S, and normally the guide plate 12 is formed by the spring 15.
Waiting at home position above 0.

Since the present embodiment is configured as described above, the sheet S that has been conveyed to perform image formation on the second side after the image formation on the first side is completed is conveyed by the conveyance rollers of the sheet stacking and feeding apparatus 1. The sheet is nipped by the pair 122 and is conveyed to the pair of forward / reverse rotation rollers 123 further downstream, and the setback stacking operation is started.

First, similarly to the above-described improved example, the sheet S is conveyed downstream of the forward / reverse rotation roller pair 123 so as to pass by a predetermined amount R (see FIG. 10), and then the sheet S is conveyed to the rear end Q of the sheet S. When the sheet exits, the forward / reverse rotation roller pair 123 starts reverse rotation in the direction opposite to the arrow A, and feeds the sheet S in the direction indicated by arrow B. On the other hand, the solenoid 14 is excited in synchronization with the timing,
Pulling the link member 13 in the direction of arrow C, the swing guide member
11 moves to the broken line position. Therefore, the rear edge Q of the sheet S
(The front end in the reverse feeding direction) is forcibly pushed down in the direction of arrow D and guided to the sheet storage guide portion 124 arranged below the conveying roller pair 122. Here, the guide member 11
The shape, arrangement, and movement amount of are set so that the trailing edge Q of the sheet does not collide with or contact the conveying roller pair 122 when the sheet is fed backward, and the operation timing is set so as not to cause any inconvenience. ing. Then, the sheet S is guided by the sheet storage guide portion 124 without coming into contact with the pair of transport rollers 122, stands by until the next sheet S is transported, and the same operation is repeated to sequentially shift the sheet S rearward. After stacking and stacking a predetermined amount, the sheet S is conveyed again to the image forming unit to form an image on the second surface of the sheet S.

Next, the sheet stacking and feeding apparatus 2 of the second embodiment will be described with reference to FIG.

The rocking guide member 21 is the same as the above-mentioned first embodiment except that the rocking guide member is different. The rocking guide member 21 is rotatably supported about a central shaft 22, and the rocking guide member is supported with respect to the central shaft 22. The center of gravity of the member 21 is arranged on the left side in the drawing, and a light rotational moment is always applied in the arrow E direction, and the member 21 has an upper guide surface 23 and a lower guide surface 24.

Therefore, when the sheet S is conveyed by the conveying roller pair 122 in the forward arrow G direction, the sheet S slightly pushes the swing guide member 21 by the conveying force and passes by the forward / reverse roller pair 123. When fed backward, the lower guide 24 of the swing guide member 21 guides the leading edge and the trailing edge (leading edge in the backward feeding direction) Q of the sheet S downward, so that the sheet S is brought into contact with the transport roller pair 122. It is prevented and easily stacked on the sheet storage guide portion 124. In this embodiment,
Unlike the first embodiment, a driving means such as a solenoid is unnecessary.

Further, the sheet stacking / feeding apparatus 3 of the third embodiment will be described with reference to FIGS. 4 and 5.

A sheet-like elastic guide member 31 having elasticity such as a polyester sheet is used in place of the swinging guide member 21 in the second embodiment described above.
Is the lower guide member 121 immediately downstream of the pair of transport rollers 122.
5 is obliquely attached to the downstream end 121a of the sheet S. As shown in FIG. 5, a plurality of sheets are provided in parallel in the lateral width direction of the sheet S, and a guide surface is formed over the entire lateral width of the sheet S. . The elastic guide member 31 is the upper guide member.
The tip is slightly overlapped so that there is no gap to the guide surface of 120, and as a result,
It is in a state of hitting the guide surface of the upper guide member 120 and being sunk.

Therefore, the sheet S conveyed in the forward direction by the pair of conveying rollers 122 pushes away the elastic guide member 31 and passes therethrough, but after the passage, the elastic guide member 31 is elastically urged by the elastic guide member 31 to guide the original upper guide member 120. It will return to the state of hitting the surface. The timing of the backward feeding of the sheet S for stacking the setback is determined by the trailing edge Q of the sheet S.
Is set when the contact point J between the elastic guide member 31 and the guide surface of the upper guide member 120 is completely passed through as shown by the dotted line in the figure, and at this timing, the sheet S is paired with the forward / reverse roller pair. When the sheet S is fed back in the direction of the arrow K by 123, the sheet S is guided to the sheet storage guide portion 124 along the elastic guide member 31 as shown by a chain line.

The sheet stacking / feeding device 4 of the fourth embodiment will be described with reference to FIG.

Except for the operation of the conveying roller pair 122 described above, the configuration is the same as that of the third embodiment described above, and even when the sheet S is fed back in the direction of arrow L by the forward / reverse roller pair 123,
The upper and lower roller pairs 122a and 122b are rotated in the forward direction of the arrow M, and the trailing edge Q of the sheet S is fed backward (the leading edge when feeding backward).
However, when it comes into contact with the surface of the lower roller 122b of the roller pair 122, the sheet S operates as a part of the guide member without causing an inconvenient deformation of the sheet S due to the rotation operation in the same direction as the sheet conveying direction. It is not necessary to separately provide a guide member for the lower roller 122b.

(G) Effect of the Invention As described above, according to the present invention, in a device such as a double-sided image forming apparatus that has an intermediate storage portion and performs so-called set-back stacking, the sheets are forward and reverse rollers. Even when the sheets are conveyed backward by a pair, the guide member is provided to guide the sheet toward the sheet storage guide portion, so that even if the sheet deformed by curling or the like is mixed and conveyed, the sheet is accurately conveyed. The sheets can be stacked on the sheet storage guide portion, and it is possible to prevent occurrence of a jam during conveyance and subsequent image shift.

[Brief description of drawings]

1 is a side view of a first embodiment of a sheet stacking and feeding apparatus according to the present invention, FIG. 2 is a perspective view of FIG. 1, and FIG. 3 is a side view of a second embodiment according to the present invention. 4 is a side view of the third embodiment according to the present invention, FIG. 5 is a perspective view of FIG.
FIG. 6 is a side view of the fourth embodiment according to the present invention. Seventh
FIG. 8 is a diagram showing a conventional example, FIG. 8 is a diagram showing another conventional example, and FIGS. 9, 10, and 11 are improved sheet stacking / feeding devices on which the present invention is based. It is a side view explaining the state of. 1 ... Sheet stacking / feeding device, 11 ... Guide member (swing guide member), 122 ... Conveying roller pair, 123 ... Forward / reverse roller pair, 124 ... Sheet storage guide section, Q ... Sheet Rear end, S ... Sheet.

Claims (1)

(57) [Claims] 1. A forward / reverse rotation roller pair, a conveyance roller pair that conveys a sheet to the roller pair, and a sheet storage guide portion disposed below the conveyance roller pair. The forward / reverse rotation roller pair reversely rotates while the trailing edge of the sheet conveyed in the downstream direction by the forward rotation of the reverse rotation roller pair has passed through the conveyance roller pair, and the sheet is conveyed by a predetermined amount in the upstream direction, In a sheet stacking / feeding device that stacks a plurality of sheets on the sheet storage guide portion such that the upper ones are sequentially shifted toward the upstream side at a predetermined interval with respect to the lower ones, the sheet is placed on the downstream side of the conveying roller pair. A guide that allows the sheet to be conveyed when the sheet is conveyed in the downstream direction and guides the rear end of the sheet toward the sheet storage guide portion when the sheet is conveyed in the upstream direction Having a member A sheet stacking and feeding device characterized by: