JP2832914B2 - Paper transport device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet conveying device, and more particularly, to a sheet conveying device for conveying a sheet to a sheet placing portion of an image forming apparatus.

2. Description of the Related Art A conventional image forming apparatus, for example, a copying machine having a double-sided copying function and an image editing function (masking and trimming functions) generally has an intermediate tray.
The intermediate tray temporarily stores the copied paper,
This is for re-supplying the paper to an image forming unit including a photosensitive drum or the like. Above the intermediate tray, a downstream end of a paper transport path through which the paper that has passed through the image forming unit and the fixing device is transported is disposed. At the downstream end of the paper transport path, a paper transport device for guiding the paper toward the intermediate tray is provided.

A conventional paper transport device includes a pair of rollers for sending out the paper in the horizontal direction, and a guide plate for guiding the paper coming out of the roller obliquely downward to the intermediate tray. In this paper transport apparatus, the paper fed laterally from the rollers abuts on the lower surface of the guide plate and is guided obliquely downward toward the intermediate tray. As a result, the paper is placed on the intermediate tray from the paper transport path via the paper transport device.

[Problems to be solved by the invention]

In the above-described conventional paper transport apparatus, the paper fed in the horizontal direction is only guided by the guide plate that comes into contact from above. However, some papers have a curl that curves downward. When a sheet having such a curl is conveyed, the leading end of the sheet is curled downward while being guided by a guide plate after being sent out from a roller. As a result, the paper is no longer placed flat on the intermediate tray, causing a conveyance failure such as a paper jam.

SUMMARY OF THE INVENTION An object of the present invention is to provide a sheet transport device that can reliably place a sheet having a downward curl on an intermediate tray in a flat state.

[Means for solving the problem]

A paper transport device according to the present invention is a paper transport device for transporting a sheet that has passed through a fixing device that heats and fixes a toner image formed on a sheet in an image forming apparatus to a sheet placement unit. The apparatus includes a sending member for sending the sheet in the lateral direction, a pair of support members for supporting both sides of the sheet coming out of the sending member from below,
A tip end position on the downstream side in the sheet conveyance direction is located below the support member, and a holding member for holding down a central portion of the sheet coming out of the sending-out member is provided.

In another aspect of the present invention, in the image forming apparatus,
The sheet transport device is configured to discharge a sheet on which an image is formed by the image forming unit and to convey the sheet to a sheet placement unit for re-feeding the sheet to the image forming unit. The apparatus includes a feeding member for feeding the sheet in the horizontal direction, and a feeding member for supporting both sides of the sheet coming out of the feeding member from below.
A pair of supporting members, a tip end position on the downstream side in the sheet conveying direction is located below the supporting member, and a holding member for holding down a central portion of the sheet coming out of the feeding member downward; The paper sheet that has passed between the pressing member and the holding member is carried out to the sheet mounting portion from the leading end positions of both members.

[Action]

In the sheet transport device according to the present invention, the sheet is sent out in the horizontal direction by the sending member. The fed sheet is supported from below by a pair of support members on both sides, and the central portion is pressed down by the pressing member. As a result, the paper is in a state in which the central portion is bent downward as viewed in the paper transport direction. Therefore, even if the paper has a curl habit, the paper is deformed into a gutter shape by the pressing plate and the support plate, thereby suppressing the curl of the paper. As a result, the sheet is securely placed on the intermediate tray in a flat state.

〔Example〕

FIG. 1 is a schematic longitudinal sectional view of a copying machine employing an embodiment of the present invention.

In FIG. 1, a document holder 11 that can be freely opened and closed is provided at an upper portion of the copying machine 10. On the right side of the copying machine 10 in the figure, a bypass table 12 and three kinds of paper feed cassette cases 13 are arranged. The output tray is located on the left side of the copying machine 10
14 are located.

A photoconductor drum 16 is disposed substantially at the center of the copying machine 10. Around the photosensitive drum 16, the main charging device 1
7, erase cell array 18, one pair of developing device 19, transfer device 2
0, a separating device 21 and a cleaning device 22 are sequentially arranged. In addition, an optical exposure device 23 is arranged in an upper space of the copying machine 10. The image forming unit 15 includes the photosensitive drum 16, various members surrounding the photosensitive drum 16, and the exposure device 23.

A paper feed path 24 is arranged between the bypass table 12 and the transfer device 20. On the downstream side of the separation device 21 in the sheet conveyance direction, a sheet discharge conveyance device 25 and a fixing device 26 are sequentially arranged. Between the fixing device 26 and the discharge tray 14,
A sheet transport path branching device 27 is provided. Branching device 27
A sheet reversing device 28 is disposed above the sheet reversing device. Copier
In the lower space of 10, an intermediate tray 30 is arranged.
Above the left side of the intermediate tray 30 in FIG.
Is arranged. A paper transport path 32 is disposed between the right end of the intermediate tray 30 in the figure and the middle of the paper transport path 24. The paper passing through the fixing device 26 is supplied to the intermediate tray 30 by the paper transport paths 31 and 32, and the paper is transported from the intermediate tray 30 to the image forming unit 15.

The branching device 27 is provided with a path 27a for directly supplying the sheet coming out of the fixing device 26 to the sheet conveying path 31, and a path 27b for supplying the sheet from the fixing device 26 to the reversing device 28 and discharging the sheet to the discharge tray 14. And The two paths 27a and 27b are selected alternatively. Further, a branching claw 33 for switching the sheet conveyance direction to the discharge tray 14 side or the reversing device 28 side is provided at the downstream end of the path 27b. The branching device 27 adjacent to the upstream end of the paper transport path 31
Is provided with a path 27c for receiving a sheet from the reversing device 28. On the downstream side of the paper transport path 31, first and second paper distribution devices 34 and 35 and a paper transport device 36 according to the present invention are provided. The first sheet distribution device 34 arranged at the most upstream side opens downward when the sheet size is the largest, and guides the sheet to the intermediate tray 30 side. The second sheet distribution device 35 is opened downward when a sheet of a smaller size is conveyed, and guides the sheet to the intermediate tray 30 side.

The paper transporting device 36 moves the paper transporting path 31 along an arrow X in FIG.
A pair of rollers 40 for further feeding out the paper that has passed in the direction (lateral direction), a guide plate 41 disposed downstream of the rollers 40, and for pressing the central portion of the paper coming out of the rollers 40 And a pair of support plates 43 for supporting both sides of the sheet from below.

One end of the guide plate 41 is fixed to a fixed wall plate 44 arranged near the upper roller 40. The guide plate 41 is
It is smoothly curved from the wall plate 44 and extends obliquely downward. As is apparent from FIGS. 3 and 4, the guide plate 41 is a substantially rectangular plate-like member. The upper end of the holding plate 42 is fixed to the wall plate 44. The pressing plate 42 extends vertically downward from the wall plate 44, and has a trapezoidal shape having a narrow lower end as shown in FIG. The holding plate 42
It is made of a flexible resin, and can be bent by being pressed by the sheet sent out from the roller 40. As shown in FIG. 2, the base of the support plate 43 is fixed to a fixing bracket 45 arranged on the upstream side of the roller 40. The support plate 43 extends horizontally from the bracket 45 toward the roller 40, and extends obliquely downward along the guide plate 41 while slightly bending. The support plate
Reference numeral 43 is disposed laterally of the roller 40 as shown in FIGS. 3 and 4, and is formed in a belt shape. In addition, each roller
The reference numeral 40 is provided integrally with the central shaft 46, and is driven to rotate in a direction indicated by an arrow in FIG. 2 by a drive source (not shown) connected to the central shaft 46.

The intermediate tray 30 shown in FIG. 1 includes a tray main body 50 extending in a substantially horizontal direction, a side regulating plate 51 disposed on both sides of the tray main body 50 (sides in a direction perpendicular to the sheet of FIG. 1), A roller 52 is provided at the end of the sheet conveyance path 32 for holding and conveying the sheet.

 Next, the operation of the above embodiment will be described.

When the copying operation is started, the sheet selected from the bypass tray 12 or the sheet cassette 13 is conveyed to the image forming unit 15 through the sheet conveyance path 24. On the other hand, the original placed below the original holder 11 is scanned by the exposure device 23. The image information based on the scanning is transferred to the photosensitive drum 16.
Is transferred as an electrostatic latent image. The electrostatic latent image on the photosensitive drum 16 is developed by the developing device 19 and is transferred to a sheet by the transfer device 20. The sheet on which the image has been transferred is subjected to a fixing process by the fixing device 26.

The sheet subjected to the fixing process is discharged to the discharge tray 14 through the branching device 27 in the normal one-sided copy mode. On the other hand, in the screen copy mode, the fixed paper is temporarily stored in the reversing device 28 from the branch 27. Then, the sheet is sent from the reversing device 28 to the sheet transport path 31. In the edit mode in which a plurality of document images are combined on the same screen, the fixed sheet is supplied to the sheet transport path 31 through the path 27a of the branching device 27.

In the paper transport device 31, a first paper distribution device 34, a second paper distribution device 35, or a paper transport device 36 operates according to the size of the transported paper. In the case of the largest size paper, the first paper distribution device 34 opens downward. As a result, the sheet is lowered from the first sheet distribution device 34 and placed on the intermediate tray 30. If a smaller sheet is conveyed, the second sheet distribution device 35
Opens downward. Thus, the sheet descends from the second sheet distributing device 35 and is placed on the intermediate tray 30. In these cases, the paper distribution devices 34 and 35 guide the paper so as to support it from below, so that there is no problem due to the curl of the paper. When the smallest size paper is conveyed, the first and second paper distribution devices
The paper is supplied to the paper transport device 36 after passing through 34 and 35.

In the sheet conveying device 36, the sheet conveyed in the X direction in FIG. 2 is further fed forward (laterally) by the rollers 40. Then, the leading end of the sheet comes into contact with the pressing plate 42, and the pressing plate 42 curves as shown in FIG. On the other hand, both sides of the sheet (both sides in the direction perpendicular to the plane of FIG. 5) are supported by the support plate 43 from below. As a result, both sides of the sheet are supported by the support plate 43 from below, and the center portion is
As a result, the sheet is deformed into a gutter shape having a central portion bent downward as shown by A in FIG. Therefore, even if the sheet has a downward curl, the sheet is prevented from curling due to the deformation of the sheet as shown in A.

When the paper is further conveyed by the rollers 40 and the rear end of the paper passes through the rollers 40, the central portion of the paper is further deflected downward by the pressing force of the pressing plate 42 downward,
The paper comes off the support plate 43. Then, it is placed on the intermediate tray 30 in a flat state.

The sheet placed on the intermediate tray 30 is supplied to the image forming unit 15 by rollers 52 at a predetermined timing. The sheet supplied to the image forming section is subjected to a predetermined image forming process, and further, is subjected to a fixing process by a fixing device 26, and then is discharged to a discharge tray 14.

[Other embodiments]

(A) Even when a relatively narrow sheet of paper is handled by the sheet conveying device 36, when the action of the holding plate 42 and the supporting plate 43 is unnecessary, the holding plate 42 may be formed in an inverted trapezoidal shape as shown in FIG. Instead, a pair of right and left holding plates from which the central portion is removed may be used. The pair of left and right pressing plates have a space between them so that the vertically long paper can pass therebetween. In this case, the vertically long paper does not contact the pressing plate 42 and the support plate 43, and It is placed on the intermediate tray 30 while being guided by the guide plate 41 as in the related art. For example, this configuration
This can be applied to a case where the sheet transporting device 36 is set to handle sheets of landscape A4 size and portrait B5 size. Here, the A4 size paper sheet is processed by the holding plate 42 and the support plate 43, and is securely placed on the intermediate tray 30 in a flat state. Further, the sheet of the vertical B5 plate is guided by the guide plate 41 and placed on the intermediate tray 30 as before, without being affected by the press plate 42 and the support plate 43.

(B) The paper transport device according to the present invention is not limited to the case where the paper is transported to the intermediate tray, but may be applied to the case where the paper is transported to a discharge tray, for example. Further, the first and second paper distribution devices 34, 3
5, the paper transport device according to the present invention may be employed.

〔The invention's effect〕

Since the paper conveying device according to the present invention includes the above-described pressing member and the supporting member, it is possible to reliably place the paper having the curl on the intermediate tray in a flat state. Thus, the occurrence of jam can be suppressed.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view of a copying machine adopting an embodiment of the present invention, FIG. 2 is a longitudinal sectional view of the paper transporting apparatus, FIG. 3 is a view taken in the direction of arrow III in FIG. Is a sectional view taken along the line IV-IV in FIG. 2,
FIG. 5 is a diagram corresponding to FIG. 2 showing an operating state. 10: Copier, 30: Intermediate tray, 36: Paper transport device, 40: Roller, 42: Pressing plate, 43: Support plate.

Claims (2)

(57) [Claims] 1. A sheet transport device for transporting a sheet having passed through a fixing device for heating and fixing a toner image formed on a sheet in an image forming apparatus to a sheet placing portion, wherein the sheet is transported in a lateral direction. A delivery member for delivering, a pair of support members for supporting both sides of the sheet coming out of the delivery member from below, and a leading end position on the downstream side in the sheet conveyance direction below the support member. And a pressing member for pressing down a central portion of the sheet coming out of the sending-out member. 2. An image forming apparatus, wherein a sheet on which an image is formed by an image forming unit is discharged, and the sheet is conveyed to a sheet mounting unit for re-feeding the sheet to the image forming unit. A sending member for sending out the sheet in the lateral direction; a pair of supporting members for supporting both sides of the sheet coming out of the sending member from below; and a downstream side in the sheet conveying direction. And a pressing member for pressing down a central portion of the sheet coming out of the sending-out member, wherein a leading end position of the pressing member is located below the supporting member, and the paper passes between the supporting member and the pressing member. A sheet transporting device that transports the extracted sheet from the leading end positions of both members to a sheet placement section.