JPH0289768A - Structure for retaining paper of image forming device - Google Patents

Abstract

PURPOSE:To restrain the curling up of a sheet of a paper smoothly without inconvenience by bringing retainer pieces made of a flexible material with the top face of a sheet of paper from the front end center portion thereof to both side portions in order. CONSTITUTION:The front end both side portions of a sheet of paper is in a largely curled up condition due to the heating by a fixing device, and the front end center portion in which the degree of curling up is less is first brought into contact with a central retainer piece 52 and retained from above. Thereby, the degree of curling upon both side portions gets less to some extent. In this condition, the front end both side portions are then brought into contact with both retainer pieces 51, 53 to restrain the curling up thereof. Thus, the sheet of paper is sent to a forwarding roller 46 with the curling up thereof being restrained from the center portion to both side portions.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a paper holding structure that suppresses curling of paper transported in an image forming apparatus such as a copying machine.

[Conventional technology]

For example, in an image forming apparatus that requires paper conveyance, such as a copying machine, the paper is nipped between a conveyance roller or a conveyance roller and another member, and the paper is transported by the rotation of the O-roller. Many methods such as transportation are used.

An example thereof is shown in FIG. In the figure, 101 is an intermediate tray, and this intermediate tray 101 is provided in a reverse feed path from the downstream side of the fixing device to the paper feed side in, for example, a double-sided copying machine or a composite copying machine, and is provided with a pair of transport rollers 102, 10.
It plays the role of temporarily stocking the paper that has been reversed by the third or other paper. A forward feed roller 104 and a presser plate 105 that are close to the upper surface of the intermediate tray 101 are disposed on the downstream side of the intermediate tray 101, and a stopper 106 that is configured to be able to rise and fall freely, and a refeed A paper roller 107 and a registration roller pair 108 are provided. The presser plate 105 is configured to be rotatable about a shaft 109.

In such a structure, after fixing, the pair of transport rollers 102
．． The paper conveyed to the intermediate tray 101 by the intermediate tray 103 is nipped between the upper surface of the intermediate tray 101 and the feed roller 104 which is rotationally driven, and is nipped until the tip δ touches the stopper 106 in an upright state. By being forward-fed, the sheets are sequentially stocked on the intermediate tray 101. At this time, the end portion (the right end portion in FIG. 6) of the presser plate 105 comes into contact with the top surface of the paper sheet, thereby preventing the leading edge portion of the stocked paper sheet from springing up.

[Problem to be solved by the invention]

In a general double-sided copying machine, the paper is sent back to the intermediate tray 101 after once passing through the fixing device.

In this fixing device, one side of the paper containing moisture in advance is heated at a high temperature, so that the paper is carried into the intermediate tray 101 in a curled state. This curl is particularly noticeable at both edges of the leading edge of the paper P shown in FIG.
There is an inconvenience that jams may occur due to poor nipping between the two.

Further, even if the sheet passes through the forward feed roller 104, the curled portion remains upside down on the presser plate 104.
05 may press it down from above and bend it. Such inconvenience may occur not only in the intermediate stock section but also in other conveyance paths such as the discharge roller pair.

Further, even if the presser plate 105 is provided in front of the advance roller 10/I in the above structure, there is a risk that the paper may be bent for the same reason as described above.

In view of these circumstances, it is an object of the present invention to provide a paper holding structure that can suppress the curling of paper transported in an image forming apparatus without causing any inconvenience and prevent the occurrence of jams, etc. do.

[Means to solve the problem]

The present invention provides a paper presser structure that presses the paper being conveyed in an image forming apparatus from the top and suppresses the curling of the paper, in which a presser piece made of a flexible material is provided in the conveyance path of the paper. It is arranged so that it contacts the top surface sequentially from the central part of the tip to both sides.

[For production]

According to the above configuration, first, the central portion of the leading edge of the paper, which is relatively less warped, comes into contact with the presser piece, and thereby the warping of both side portions as well as the central portion is somewhat suppressed. Thereafter, by sequentially contacting the presser pieces from the center to both sides, the leading edge of the paper is smoothly pressed to both sides without bending.

〔Example〕

A first embodiment of the present invention will be described based on FIGS. 1(a) and 2(b) and FIG.

FIG. 2 shows a double-sided copying mode (image forming apparatus) 1 having the structure of the present invention. This copying machine 1 is equipped with a contact glass 2 and a document holder 3 on its top surface, paper cassettes 4 to 6 for feeding paper are installed on one side of the main body, and a paper ejection tray 7 is installed on the other side. has been done.

Inside the copying machine 1, as image forming means, a photosensitive drum 8, a main charging device 9, a developing device 10, a transfer device @11,
Separation bag @12, static eliminator 13, cleaning device 14,
An optical system 15 and a fixing device 16 are provided. The optical system 15 includes an exposure lamp 21 and various mirrors 22 to 2.
5 and a lens 26, a part of which moves back and forth in the left-right direction in the figure to expose and scan the document on the contact glass 2. The fixing device 16 fixes the transferred toner image by heating one side of the paper at a high temperature.

The paper conveyance mechanism of this copying machine 1 includes a paper feed mechanism 27, a conveyance belt 28, a switching mechanism 29, and a reverse feed mechanism 30.

The paper feeding mechanism 27 includes a paper feeding roller 31 corresponding to each of the paper cassettes 4 to 6, a plurality of pairs of transport rollers 32, a guide plate 33, a pair of registration rollers 34, and the like. Feed paper at the appropriate timing.

The switching mechanism 29 includes a path switching plate 35, a reverse feed roller 36, and a reversing path 3a, and when the path switching plate 35 is switched to the position indicated by the solid line or the two-dot chain line in the figure, the paper is transferred from the pair of transport rollers 38. 11, a path for directly guiding the paper to the paper roller pair 39, and carrying the paper -q into the reversing path 37;
A passage is formed for carrying out the inverted state to the reverse feed structure 30.

The reverse feeder vA30 forms a return path from the switching mechanism 29 to the paper feed side, and has a pair of conveyor rollers 41, 43.
An intermediate tray 42 for docking paper is provided on the downstream side of the paper.

As shown in FIG. 1, guide plates 44 and 45 are provided above the intermediate tray 42, and on the downstream side of the intermediate tray 42, a forward feed roller 46, a presser plate 47, and a stopper 44 are provided.
8, four refeed rollers, a pair of registration rollers 50, etc. are provided. These structures are the same as those shown in FIG. 6 above.

Further, above the intermediate tray 42, three presser pieces 51 to 53 for pressing the paper from above are arranged side by side in the width direction of the paper. The 8 presser pieces 51 to 53 are made of a thin flexible material such as polyester film and are formed into a rectangular planar shape, and their upper ends are fixed to the lower surface of the guide plate 44, so that It is vertically installed above the intermediate tray 42 in a state of being inclined toward the downstream side in the paper conveyance direction. Moreover, the center presser piece 52 is different from the presser pieces 52 on both sides.
1.53 is attached at a position on the upstream side in the paper conveyance direction, and both presser pieces 51.
It is in contact at a position upstream of 53 in the paper conveyance direction.

Next, the operation of this structure will be explained. When the double-sided copying mode 7j is selected in the copying machine 1, the paper that has passed through the fixing device 16 is reversely conveyed through the switching mechanism 29, and carried onto the intermediate tray 42 by the pair of conveying rollers 41 and 43.

At this time, the paper is heated by the fixing device 16, and as shown in FIG. 7, both sides of the leading edge are greatly warped. They make contact and are pressed down from above.

As a result, the warpage on both sides is reduced to some extent. Then, in this state, both presser pieces 51 are attached to both sides of the tip.
．． 53, and its warpage is suppressed. In this way, the paper is sent to the advance roller 46 with curling suppressed from the center to both sides. Therefore, the paper is smoothly nipped between the advance roller 46 and the intermediate tray 42, and the paper is smoothly nipped! The paper is transported to the paper feeding mechanism 27 side by the paper refeeding roller 49 and the pair of registration rollers 50 without causing any disturbance.

As described above, with this structure, first the leading edge of the paper is held down at the center where there is less curling, and then the both sides are held down, so the leading edge of the paper is There is no inconvenience of bending due to being pressed down from above while it is turned over, and warping can be smoothly suppressed.

Next, a second embodiment will be described based on FIGS. 3(a) and 3(b). In the first embodiment, the order of contact with the paper is adjusted by the mounting positions of the eight presser pieces 51 to 53, but here the order of contact with the paper is adjusted by the attachment angles of the presser pieces 51 to 53. Specifically, a protrusion 44a having an inclined surface at an angle close to the vertical direction is formed on the lower surface of the guide plate 44.
is provided, and the upper end of the central presser piece 52 is fixed to the inclined surface thereof. Note that the presser pieces 51 and 53 on both sides are directly fixed to the F surface of the guide plate 44 as in the previous embodiment, and have a mounting angle closer to horizontal than the presser piece 52.

Even in this structure, because the mounting angles are different, the central presser piece 52 comes into contact with the paper earlier on the upstream side than the other presser pieces 51 and 53, so that the same effect as in the first embodiment can be obtained. Can be done.

In addition, in the present invention, the number of presser pieces is not limited, and may be 8.
The above effect can be obtained as long as the presser piece sequentially contacts both sides from the center of the sheet.

Next, a third embodiment will be explained based on FIG. 4 (a>(b). In the first and second embodiments, a plurality of presser pieces 5
1 to 53 are used, but in this embodiment, the above effect is obtained by a single presser piece 54 having a special shape.

That is, the presser piece 54 has a rectangular planar coverage portion 54a extending from the lower surface of the guide plate 44 to the intermediate tray 42F;
It has a substantially triangular holding part 54b whose width becomes wider as it approaches the forward feed row 546 side, and the entire area of this holding part 54b is in substantially contact with the intermediate tray 42.
The end portion of the mounting portion 54a is fixed to the lower surface of the guide plate 44 as in the first embodiment.

According to such a structure, the contact area between the leading edge of the paper and the presser portion 54b continuously expands from the center of the leading edge to both sides, and curling can be smoothly suppressed as in each of the above embodiments. It will be held in

Note that in the present invention, the direction of inclination of the presser piece is not particularly limited;
It may be made to be inclined toward the upstream side in the paper conveyance direction. For example, as shown in FIGS. 5(a) and 5(b) as a fourth embodiment, a protrusion 45a having an inclined surface inclined upstream in the paper conveyance direction is provided on the upper surface of the guide plate 45, and this protrusion 4
A similar effect can be obtained by fixing the upper end of a triangular presser piece 55, which has a wider width as it approaches the forward reroller 46, like the presser piece 54 described above, to the presser piece 5a. However, in this case, it is preferable to curl the tip end 55a of the presser piece 55 upward in advance in order to allow the center portion of the leading edge of the paper to enter smoothly below the presser piece 55.

Note that the location where the structure of the present invention is applied is not limited to such an intermediate stock section; for example, in the copying machine shown in FIG. This makes it possible to effectively prevent jams and the like from occurring at the discharge roller pair 39.

〔Effect of the invention〕

As described above, the present invention provides a presser piece made of a q-flexible material,
Since the leading edge is brought into contact with the upper surface of the paper sequentially from the center to both sides, it is possible to smoothly counter the curling of the paper without any inconvenience, and prevent jams etc. at the 1-ra during conveyance. This has the effect of preventing its occurrence.

[Brief explanation of drawings]

FIG. 1(a) is a plan view of the paper holding structure according to the first embodiment of the present invention, FIG. 1(b) is a side view of the interpolation structure, and FIG.
The figure is a diagram of the body structure of a copying machine equipped with an interpolation structure, and Figure 3 (
4(a) is a plan view of the paper holding structure in the second embodiment, FIG. 4(b) is a side view of the interposed structure, and FIG. 4(a) is a plan view of the paper holding structure in the third embodiment. 5(b) is a side view of the interpolation structure, FIG. 5(a) is a plan view of the paper holding structure in the fourth embodiment, and FIG.
FIG. 6 is a side view of a conventional paper holding structure, and FIG. 7 is a perspective view showing a curled state of paper conveyed in an image forming apparatus. 1... Copying machine (image forming apparatus) main body, presser pieces 51 to 55.

Claims (1)

[Claims] 1. A paper presser structure that presses the paper conveyed in an image forming apparatus from above and suppresses the curling of the paper, in which a presser piece made of a flexible material is placed in the conveyance path of the paper on the upper surface of the paper. 1. A paper holding structure for an image forming apparatus, characterized in that the paper holding structure is disposed so as to sequentially contact from the central part of the leading end to both sides thereof.