JP2901365B2 - Paper transport device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper conveying device,
In particular, the present invention relates to a sheet transport device including a guide plate having ribs.

[0002]

2. Description of the Related Art Conventionally, a paper conveying apparatus is provided in an image forming apparatus such as a copying machine or a printer. Some of such paper transport apparatuses include a guide plate having ribs, and for example, those described in Japanese Utility Model Laid-Open No. 63-17149 and Japanese Utility Model Laid-Open No. 63-42641 are known.

On the other hand, there is a guide plate 1 in which a notch 2a is formed in a rib 2 of a guide plate 1 as shown in FIG. Notch 2a
Are formed in order to allow escape from other members (not shown), for example, to avoid interference with a reversing mechanism for reversing the sheet 3. Notch 2a and rib 2
Corner 2c on the downstream side in the transport direction formed by the paper contact surface 2b of
The paper 3 is chamfered in an arc shape for smooth conveyance.

[0004]

However, in such a conventional paper conveying apparatus, since the notch 2a is formed in the rib 2, the leading end of the paper 3 curled toward the notch 2a has a corner. Even if the sheet 3 is relatively abutted on the inner side and is chamfered in an arc shape, it is impossible to avoid the occurrence of a broken edge or a jam of the sheet 3, and the sheet 3 cannot be transported smoothly.

Therefore, the present invention is to make the paper transport smoothly by making the height of the rib adjacent to the downstream side in the transport direction across the notch lower than the height of the rib adjacent to the upstream side. It is an issue.

[0006]

According to a first aspect of the present invention, there is provided a guide plate having a rib extending in a sheet conveying direction, and a sheet size on which the rib is conveyed. In addition to being formed corresponding to the
A paper transport device in which one or more notches are formed in each rib, wherein the height of a rib adjacent to the downstream side in the transport direction across the notch is lower than the height of a rib adjacent to the upstream side. According to a second aspect of the present invention, in addition to the configuration of the first aspect, each of the ribs of the guide plate is curled by a predetermined amount according to the paper size of the paper to be guided. According to a third aspect of the present invention, in addition to the configuration of the first or second aspect, one of the surfaces of the sheet is an image forming surface. The guide plate is provided so as to face the image forming surface of the sheet.

[0007]

According to the first aspect of the present invention, when the leading end of the sheet passes through the notch, the leading end of the sheet curls toward the notch, and the leading end of the sheet is downstream of the notch. By contacting the shallow portion and chamfering the downstream corner formed by the cutout of the rib into an arc shape, the edge break and the jam of the sheet are prevented.

According to the second aspect of the present invention, in addition to the function of the first aspect, a large curl of the ear at both corners of the sheet does not pass over the rib, that is, the curl of the ear is prevented from entering the notch. Is done. In the invention according to claim 3, claim 1
Alternatively, in addition to the function of the second aspect, when one surface of the sheet is the image forming surface, the sheet curls toward the image forming surface side, so that the sheet is reliably guided by the guide plate provided on the same side.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIGS. 1 to 7 are diagrams showing an embodiment of a sheet conveying device according to the present invention, which is an example in which the present invention is applied to a conveyance reversing section on the downstream side of a fixing unit of an image forming apparatus. First, the configuration will be described.

In FIGS. 1 to 5, reference numeral 11 denotes a guide plate.
The guide plate 11 has a rib 13 extending along the transfer direction of the transfer paper (paper) 12. A plurality of ribs 13 are formed according to the size of the transfer paper 12 as shown in FIG. That is, there are several sizes of transfer paper 12 to be conveyed, and a plurality of ribs 13 are formed so as to correspond to the size of each transfer paper 12. Further, each rib 13 has one or a plurality of notches, and in this embodiment, five notches 13a to 13e.
Are formed. Corners on the downstream side in the transport direction formed by the notches 13a to 13e and the transfer paper contact surface 13f of the rib 13 are transfer papers.
12 is chamfered in an arc shape to make the transfer smooth. Notches 13a to 13e are formed to escape interference with the reversing mechanism 14, and 15 is a transport drive roller, 16
Is a transport driven roller, 17 is a reversing claw, 18 is a reversing drive roller,
19 is a reverse driven roller.

The heights af of the ribs 13 divided by the notches 13a-13e are as follows: a>b>c>d> e
> F. That is, the height of the rib 13 adjacent on the downstream side in the transport direction across the cutouts 13a to 13e is lower than the height of the rib 13 adjacent on the upstream side. Also,
As shown in FIG. 4, the outermost rib that contacts the transfer paper 12
The positions of the ribs 13 are arranged so as to be closer to the center of the transfer paper 12 by the dimension F from the side end of the transfer paper 12, and this relationship is established regardless of the size of the transfer paper 12. Have been. The dimension F is determined by F = (allowable curl amount E) + (allowable lateral resist) + (allowable skew). The ears 12a at both corners of the leading end of the transfer paper 12 are the most curled portions, and the amount of curl in this portion is substantially determined according to the size of the transfer paper. Therefore, the dimension F is determined by setting the allowable curl amount E to an appropriate value and considering the allowable lateral resist and the allowable skew. That is, the guide plate 11
Each of the ribs 13 is arranged so as to avoid the ears 12a at both ends of the transfer paper tip which curl by a predetermined amount according to the paper size of the transfer paper 12 to be guided. Further, when one surface 12b of the transfer paper 12 is an image forming surface as shown in FIG.
Is provided so as to face the image forming surface 12b.

On the other hand, on the upstream side of the guide plate 11, components of the following image forming process are arranged. In FIG. 5, reference numeral 21 denotes a paper feed cassette, 22 denotes a photosensitive member, 23 denotes an exposure unit, 24 denotes a developing unit, 25 denotes a fixing unit, and 26 denotes a transfer / separation unit. To briefly explain these operations, first, the transfer paper 12 placed on the paper feed cassette 21 is fed to the transfer / separator 26. The latent image exposed on the photoreceptor 22 by the exposure unit 23 is developed by the developing unit 24 and transferred to the transfer paper 12 by the transfer / separation unit 26. Next, the developed image on the transfer paper 12 is fixed by the fixing device 25, and the surface on which the developed image is fixed is the image forming surface 12b of the transfer paper 12. Next, the transfer paper 12 is fed to the guide plate 11.

Next, the operation will be described. The transfer paper 12 conveyed from the fixing device 25 is conveyed downstream by the left rotation of the conveyance drive roller 15 in FIG. After the conveyed transfer paper 12 comes off the conveyance driving roller 15, the reversing driven roller 19 presses the reversing driven roller 19 by a solenoid (not shown). At this time, the reversing claw 17 is tilted rightward in FIG. 1 by a solenoid (not shown), and is conveyed to the paper passage B on the reversing exit side. Here, the leading end of the transfer paper 12 is
13e, the respective heights a to f of the ribs 13 divided by the notches 13a to 13e are a>b>c>d>
e> f, the leading edge of the transfer paper 12 has a corner K formed by the notches 13a to 13e and the paper passing surface 13f as shown in FIG.
Contact the relatively shallow side. Note that the broken line in FIG. 6 indicates a conventional cutout shape, and in the related art, the leading end of the transfer paper 12 abuts on the relatively deep side of the corner. Each force F for sending the transfer paper 12 to the downstream side when the leading end of the transfer paper 12 contacts the deep side and the shallow side of the corner K
The magnitude relationship between F1 and F2 (the force in the tangential direction of each contact portion) is F1 <F2 as shown in FIG. This relationship is clear if the contact force of the transfer paper 12 is the same and the contact force is divided into the normal direction and the tangential direction.

As described above, in the present embodiment, when the leading edge of the transfer sheet 12 passes through the notches 13a to 13e, Abuts on the relatively shallow portions of the notches 13a to 13e, so that the force for feeding the transfer paper 12 to the downstream side can be increased as compared with the conventional one. Therefore, it is possible to prevent the transfer paper 12 from breaking or jamming, and the transfer paper 12
12 can be transported smoothly. Further, since the transfer paper 12 to be conveyed is of any paper size and the ribs 13 are arranged so as to avoid the ears 12b at both ends of the transfer paper 12, the ears 12b are notched 13a to 13c. 13e can be prevented from passing over, and the curl of the ear 12b is notched
13a to 13e can be prevented from entering. Therefore, it is possible to prevent the transfer paper 12 from being skewed, bent, and to be jammed, so that the transfer paper 12 can be transported more smoothly. Further, the guide plate 11 is connected to the image forming surface 12 of the transfer paper 12.
The transfer sheet 12 can be reliably guided by the guide plate 11 because the transfer sheet 12 is provided so as to oppose the transfer sheet b.

[0015]

According to the first aspect of the present invention, the height of the rib adjacent to the downstream side in the transport direction across the notch is smaller than the height of the rib adjacent to the upstream side. Ear breaks and jams can be prevented, and paper can be transported smoothly. According to the invention described in claim 2,
In addition to the effect of the first aspect, it is possible to prevent the curl of the ear portion from entering the notch, and it is possible to further smoothly transport the paper.

According to the third aspect of the invention, in addition to the effects of the first or second aspect, the sheet can be reliably guided by the guide plate disposed on the side on which the sheet curls.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of a sheet conveying device according to the present invention.

FIG. 2 is a front view of the guide plate shown in FIG.

FIG. 3 is an enlarged front view of a main part of the guide plate shown in FIG. 2;

FIG. 4 is a view showing an arrangement of ribs of the guide plate shown in FIG. 2;

FIG. 5 is a schematic diagram of an image forming unit arranged on the upstream side in the transport direction of the paper transport device shown in FIG. 1;

FIG. 6 is an enlarged view showing a shape of a rib of the guide plate shown in FIG. 2;

FIG. 7 is a diagram illustrating the operation of the paper transport device in FIG. 1;

FIG. 8 is a view showing a cut-out shape of a guide plate of a conventional sheet conveying device.

[Explanation of symbols]

 11 Guide plate 12 Transfer paper (paper) 12a Ear 12b Image forming surface 13 Rib

Claims (3)

(57) [Claims] A guide plate having ribs extending along a sheet conveying direction, wherein a plurality of the ribs are formed corresponding to a sheet size to be conveyed, and one or more ribs are provided for each rib. A sheet conveying device having a notch formed therein, wherein the height of a rib adjacent to the downstream side in the conveying direction across the notch is lower than the height of a rib adjacent to the upstream side. . 2. The paper transport according to claim 1, wherein the ribs of the guide plate are arranged so as to avoid the both ends of the paper leading edge which are curled by a predetermined amount according to the paper size of the paper to be guided. apparatus. 3. The sheet according to claim 1, wherein when one surface of the sheet is an image forming surface, a guide plate is provided so as to face the image forming surface of the sheet. Transport device.