JP4336258B2 - Paper reversing and conveying apparatus and image forming apparatus having the same - Google Patents

Description

   BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus (electrophotographic apparatus) such as a copying machine or a printer, and more particularly to a sheet reversing and conveying apparatus of an image forming apparatus provided with a reversing conveying system for forming images on both sides of a sheet. .

   An electrophotographic apparatus such as a copying machine or a printer transports a sheet fed from a sheet feeding device by a roller, transfers a toner image formed on an image carrier to the sheet, fixes it through a fixing device, and discharges the sheet. It is configured to let you.

  In this electrophotographic apparatus, in addition to adopting a mechanism for discharging the sheet on which the image is formed only on the first side toward the discharge tray as it is, the sheet is reversed by a switchback mechanism in the sheet reversing and conveying apparatus. Some employ a mechanism for recording and discharging the second surface.

  However, there may be a problem that the sheet sent out from the sheet reversing and conveying apparatus is not accurately conveyed along the reference position (lateral registration) in the sheet width direction. For example, a large number of conveyance rollers are arranged in the paper conveyance path from the paper feeding device to the fixing device, and a large number of conveyance rollers and a switchback mechanism are arranged in the paper reverse conveyance device. In addition, a structure in which a plurality of roller members are skewered with respect to the shaft is used.

  In the paper transport device and the paper reverse transport device, there is a tendency that a uniform transport action cannot be exhibited in the width direction of the paper due to the elasticity of the roller member, the difference in diameter, etc., and the paper has a reference position in the width direction. May not be able to be matched in a state of sliding accurately.

  Therefore, in order to solve the above-described problems, it has been proposed to provide a sheet aligning device at a predetermined position in the sheet conveying path as disclosed in, for example, Japanese Utility Model Publication No. 1-166654 (Patent Document 1).

  In this conventional example, an oblique roller is disposed upstream of the sheet conveyance path, and is moved in a direction away from the reference position while conveying the sheet. Thereafter, the alignment roller member disposed at the downstream portion of the oblique roller is used to correct the sheet so that the sheet is aligned with the reference position, and the sheet can be fed out in the aligned state for the next stage. ing. Therefore, by using the sheet aligning device as described above, the sheet can be conveyed toward the next processing stage in a state in which the sheet is aligned.

Further, as disclosed in Japanese Patent Application Laid-Open No. 2002-326768 (Patent Document 2), it is possible to move the sheet according to the size of the sheet and a width-shifting unit such as an oblique roller that conveys the sheet obliquely into the sheet reversing and conveying apparatus. Some have a paper abutting member to align the lateral registration of the paper.
Japanese Utility Model Publication No. 1-166654 JP 2002-326768 A

  However, in order to use the sheet aligning apparatus as described above, it is necessary to form a long sheet conveyance path, and there is a problem that it cannot be easily applied to an apparatus for reducing the size. In addition, it is necessary to provide sheet aligning means such as a width adjusting device such as an oblique roller and a movable abutting member, which further complicates the mechanism of the device and leads to an increase in cost.

  Therefore, in the conventional paper reversing and conveying apparatus described above, it is necessary to provide another means for aligning the paper in the paper reversing and conveying apparatus, and there are many obstacles to simplifying the configuration of the paper reversing and conveying apparatus. There is.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a sheet reversing / conveying apparatus and an image forming apparatus equipped with the same, which can eliminate such drawbacks of the prior art and can easily reduce the size, simplification, and cost of the apparatus. There is.

In order to achieve the above object, the first means of the present invention provides a paper width direction reference position restriction that guides the paper to the paper processing unit by setting the position in the width direction of the supplied paper as the paper width direction reference position. Members,
A reversible reverse roller,
A first paper guide that forms a paper reverse path from the paper processing unit to the reverse roller;
A second paper guide that forms a paper reversing path from the reversing roller to the paper width direction reference position regulating member;
The sheet whose one surface is processed by the sheet processing unit is guided again to the sheet width direction reference position regulating member side through the first paper guide, the reverse roller and the second paper guide, and the other is processed by the sheet processing unit. In the paper reversing and conveying apparatus for processing the surface of
The length L1 in the transport direction on the side corresponding to the paper width direction reference position regulating member of the first paper guide is made longer than the length L2 in the transport direction on the opposite side of the paper guide (L1> L2).
In addition, the length L4 in the transport direction on the side corresponding to the paper width direction reference position regulating member of the second paper guide is made shorter than the length L5 in the transport direction on the opposite side of the paper guide (L4 < L5),
The sheet fed from the sheet processing unit is conveyed toward the reversing roller while being guided by the first paper guide, so that the trailing edge of the sheet is separated from the sheet width direction reference position regulating member. The paper is skewed
The skewed paper is conveyed in reverse by the reverse roller in an inclined state,
The reversely conveyed paper is further guided by the second paper guide, so that the paper is skewed in a direction in which the leading edge of the paper is separated from the paper width direction reference position regulating member. It is characterized by.

According to a second means of the present invention, in the first means, at least one of the first and second paper guides is constituted by a plurality of slidable plate members, and the plurality of plate members. The length in the transport direction can be adjusted by the slide .

According to a third means of the present invention, in the second means, the length of the paper guide in the transport direction is adjusted by the size or thickness of the paper .

According to a fourth means of the present invention, in the first to third means, an oblique roller is provided for aligning the position in the width direction of the sheet with the sheet reference position together with the sheet width direction reference position regulating member. It is a feature.

The fifth means of the present invention is reversible with a paper width direction reference position regulating member that guides the paper to the paper processing unit by setting the position in the width direction of the supplied paper as the paper width direction reference position. A reversing roller; a first paper guide that forms a paper reversing path from the paper processing unit to the reversing roller; and a second paper that forms a paper reversing path from the reversing roller to the paper width direction reference position regulating member. A paper guide, and the paper whose one side is processed by the paper processing unit is again guided to the paper width direction reference position regulating member side through the first paper guide, the reverse roller, and the second paper guide. A paper reversing and conveying device for processing the other side in the paper processing unit ;
In the image forming apparatus including the sheet processing unit for forming an image on the sheet, the sheet reversing and conveying apparatus is a sheet reversing and conveying apparatus of first to fourth means. .

  The present invention is configured as described above, so that jamming at the reference position regulating member in the paper width direction is less likely to occur, and it is not necessary to provide a preliminary shift mechanism, thereby reducing the size, simplification, and cost of the apparatus. It can be easily achieved.

 Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a partial perspective view of a sheet reversing and conveying apparatus according to the first embodiment of the present invention, FIG. 2 is a front view of the sheet reversing and conveying apparatus, and FIG. 4 is a bottom view of the vicinity of the lateral registration member of the sheet reversing and conveying apparatus, FIG. 5 is a top view of the paper guide, and FIG. 6 is a schematic configuration diagram of the image forming unit.

  A sheet fed from a sheet feeding device (not shown) is conveyed by a conveyance roller 1, and then the sheet width direction is aligned by an oblique roller 2 and a lateral registration member (paper width direction reference position regulating member) 3. The paper traveling direction is aligned and sent to the image forming unit 5.

 As shown in FIG. 6, cyan, magenta, yellow, and black printing units 22 are arranged in the image forming unit 5 along the rotation direction of the intermediate transfer belt 21. Each printing unit 22 includes a photoreceptor 23, a charging unit 24, an exposure unit 25, a developing unit 26, and a transfer unit 27. The toner image formed on the surface of the photoconductor 23 is sequentially transferred to the intermediate transfer belt 21 that rotates from the lower side to the upper side on the side surface of the printing unit 22 to obtain a full-color image.

 A re-transfer unit 28 is provided on the upper portion of the intermediate transfer belt 21, and the full-color image formed on the intermediate transfer belt 21 is transferred to the sheet sent from the registration roller 4 and then fixed by the fixing unit 29. System.

 The paper P1 on which the image is formed on the first surface in the image forming unit 5 in this way is a pair of upper and lower paper guides 9 in which the conveying roller 7 is formed in the direction of the arrow 6 shown in FIG. Is conveyed and guided, and is fed in the direction of arrow 11 until the trailing edge of the sheet reaches the reverse switching point 10. Reference numeral 17 denotes a paper guide.

  When the trailing edge of the sheet reaches the reversal switching point 10, the reversing roller 8 starts reversing and conveys the sheet in the direction of the arrow 12. The sheet P2 conveyed in the direction of the arrow 13 is again aligned with the sheet reference position by the oblique roller 2 and the lateral registration member 3, and then aligned in the sheet traveling direction by the registration roller 4, and the image forming unit 5 is aligned. After the image is formed on the second surface, the image is discharged in the direction of the arrow 18 as shown in FIG.

  However, in the bottom view of FIG. 4, the sheet edge, the sheet reference position, and the reference surface (inner surface) of the lateral resist member 3 when the sheet is conveyed in the direction of the arrow 14 are on the same straight line. In this case, there is no problem if it is displaced in the direction away from the lateral resist member 3, but if it is slightly displaced toward the lateral resist member 3, it will hit the lateral resist member 3 and cause problems such as folding of the front end of the paper or jamming.

  Here, it is theoretically possible to convey the paper so that it is not displaced at all, but it is extremely difficult to actually carry out since highly accurate parts are required. Therefore, as described above, in the conventional paper reversing / conveying device, a width adjusting device such as an oblique roller, an abutting member that can be moved according to the paper size, and the reversing roller of the switchback mechanism are shifted when reversing the paper. A preliminary shift mechanism is provided. However, with this mechanism, there has been a problem of increasing the size, complexity, and cost of the entire apparatus as described above.

  In the present invention, in order to solve this problem, the peripheral length of the paper guide 9 in the paper reversing conveyance path is changed in the paper width direction. In other words, as shown in FIGS. 1 and 5, the circumference of the paper guide 9 (the length in the transport direction) is the side corresponding to the reference position (lateral registration member 3) in the paper width direction in the paper width direction (that is, the side). On the same side, the circumferential length L1 on the front side in FIG. 1 is longer than the circumferential length L2 on the opposite side (that is, the back side in FIG. 1) (L1> L2).

 In the case of this embodiment, the upper and lower paper guides 9 both have a circumferential length difference, but the lower paper guide 9 with which the paper P1 mainly contacts must have at least a circumferential length difference. In the case of this embodiment, as shown in FIG. 5, the difference (ΔL) between the circumferential length L1 and the circumferential length L2 is designed to be about 4 to 5 mm with respect to the lateral width L3 of the paper guide 9 being 300 mm.

  The leading edge of the paper P1 sent out by the transport roller 7 is transported to the reverse roller 8 while being guided by the paper guide 9. Here, the sheet P1 is moved forward on the reversing roller 8d side (see FIG. 1) due to the difference in the circumferential length of the paper guide 9 in the sheet width direction, that is, the difference in the sliding resistance of the paper guide 9 in the sheet width direction. The rear end of the paper is skewed in a direction away from the reference position in the paper width direction (the inner surface of the lateral resist member 3).

  The skewed sheet is conveyed by being reversed and conveyed by the reversing roller 8 while maintaining the state inclined by a predetermined angle θ with respect to the reference position in the sheet width direction (the inner surface of the lateral resist member 3), as shown in FIG. In this way, the corner 19 at the leading edge of the sheet passes through a straight line separated from the reference position in the sheet width direction (the inner surface of the lateral resist member 3), and is sent to the oblique roller 2.

  Therefore, in the horizontal registration alignment, which is the next step, the paper P2 hits the horizontal registration member 3 and is aligned at the reference position, but problems such as folding of the front end of the paper or jamming do not occur.

  FIG. 7 is a partial perspective view of a sheet reversing and conveying apparatus according to the second embodiment of the present invention, and FIG. 8 is a top view of a paper guide used in the present embodiment. As shown in FIG. 1, in addition to the configuration in which the circumferential length of the paper guide 9 in front of the reverse roller 8 in the paper reverse conveying apparatus is changed in the paper width direction, in this embodiment, as shown in FIGS. In addition, a difference is also provided in the circumferential length of the paper guide 16 after the reversing roller 8.

  That is, as shown in FIG. 7 and FIG. 8, the peripheral length of the paper guide 16 is set in the paper width direction, and the peripheral length L4 on the side corresponding to the reference position (lateral registration member 3) side in the paper width direction is set on the opposite side. Is shorter than the circumferential length L5 (L4 <L5).

  Then, the leading end of the paper P1 sent out by the reversing roller 8 is guided by the paper guide 16 and conveyed to the conveying roller 15. Here, due to the difference in the circumferential width of the paper guide 16 in the paper width direction, the reverse roller 8a side advances as shown in FIG. 7, and the leading edge of the paper is separated from the paper width direction reference position (the inner surface of the lateral resist member 3). Skewed in the direction, that is, tilted by a predetermined angle θ, and is sent to the oblique roller 2 as it is.

  In this embodiment, a difference is provided in the circumferences of both the paper guide 9 and the paper guide 16, but a circumference difference can be provided only in the paper guide 16.

  FIG. 9 is a partial perspective view of a sheet reversing / conveying apparatus according to the third embodiment of the present invention, and FIG. 10 is a view for explaining the peripheral length adjustment of a paper guide used in the embodiment. In the paper reversing and conveying apparatus according to the present embodiment, the paper guide 17 is constituted by a plurality of plate members 17a to 17d, and the paper guide 17 (plate members 17a to 17a to 17b) is manually or by driving means such as a motor depending on the size and thickness of the paper. 17d) is configured such that one side (for example, the side corresponding to the lateral resist member 3) slides in the direction of the arrow 18 so that the peripheral length of the paper guide 17 is changed. FIG. 10A shows a state in which the plate members 17a to 17d are opened to the outside to increase the circumference, and FIG. 10B shows a state in which the plate members 17a to 17d are contracted to the inside to shorten the circumference. Yes.

  This slide mechanism can also be applied to the paper guide 9 or the paper guide 16.

  In the above-described embodiment, the case where the paper reversing and conveying apparatus is applied to the image forming apparatus has been described. However, the present invention is not limited to this, and for example, paint is applied to both sides of the paper or light is irradiated. The paper reversing and conveying apparatus of the present invention can be applied to other paper processing such as.

1 is a partial perspective view of a sheet reversing and conveying apparatus according to a first embodiment of the present invention. It is a front view of the paper reversing and conveying apparatus. FIG. 6 is a top view of the vicinity of a lateral resist member of the paper reversing and conveying apparatus. FIG. 6 is a bottom view of the vicinity of a lateral resist member of the paper reversing and conveying apparatus. It is a top view of a paper guide used in the paper reversing and conveying apparatus. FIG. 2 is a schematic configuration diagram of an image forming unit in an image forming apparatus including the paper reversing conveyance device. FIG. 6 is a partial perspective view of a sheet reversing and conveying apparatus according to a second embodiment of the present invention. It is a top view of a paper guide used in the paper reversing and conveying apparatus. FIG. 10 is a partial perspective view of a sheet reversing and conveying apparatus according to a third embodiment of the present invention. It is a figure for demonstrating the circumference adjustment of the paper guide used for the paper reverse conveyance apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 7, 15: Conveyance roller, 2: Oblique roller, 3: Horizontal registration member, 4: Registration roller, 5: Image formation part, 6: Paper conveyance direction, 8: Reversing roller, 9, 16, 17, Paper guide 10: Reverse switching point, 11-14: Paper transport direction, 17a-17d: Plate material, 18: Paper discharge direction, 19: Corner part, 21: Intermediate transfer belt, 22: Printing unit, 23: Photoconductor, 24: Charging means, 25: exposure means, 26: developing means, 27: transfer means, 28: retransfer means, 29: fixing means, P1, P2: paper, L1, L2, L4, L5: perimeter of paper guide, ΔL : Circumference difference of the paper guide, L3, L6: width of the paper guide.

Claims (5)

A paper width direction reference position regulating member that guides the paper to the paper processing unit by setting a position in the width direction of the supplied paper as a paper width direction reference position;
A reversible reverse roller,
A first paper guide that forms a paper reverse path from the paper processing unit to the reverse roller;
A second paper guide that forms a paper reversing path from the reversing roller to the paper width direction reference position regulating member;
The sheet whose one surface is processed by the sheet processing unit is guided again to the sheet width direction reference position regulating member side through the first paper guide, the reverse roller and the second paper guide, and the other is processed by the sheet processing unit. In the paper reversing and conveying apparatus for processing the surface of
The length L1 in the transport direction on the side corresponding to the paper width direction reference position regulating member of the first paper guide is made longer than the length L2 in the transport direction on the opposite side of the paper guide (L1> L2).
In addition, the length L4 in the transport direction on the side corresponding to the paper width direction reference position regulating member of the second paper guide is made shorter than the length L5 in the transport direction on the opposite side of the paper guide (L4 < L5),
The sheet fed from the sheet processing unit is conveyed toward the reversing roller while being guided by the first paper guide, so that the trailing edge of the sheet is separated from the sheet width direction reference position regulating member. The paper is skewed
The skewed paper is conveyed in reverse by the reverse roller in an inclined state,
The reversely conveyed paper is further guided by the second paper guide, so that the paper is skewed in a direction in which the leading edge of the paper is separated from the paper width direction reference position regulating member. A sheet reversing and conveying apparatus characterized by 2. The paper reversing and conveying apparatus according to claim 1, wherein at least one of the first and second paper guides is composed of a plurality of slidable plates, and is conveyed by sliding the plurality of plates. A sheet reversing / conveying device characterized in that the length in the direction is adjustable . 3. The paper reversing and conveying apparatus according to claim 2 , wherein the length of the paper guide in the conveying direction is adjusted according to the size or thickness of the paper. 4. The sheet reversing and conveying apparatus according to claim 1, further comprising an oblique roller that aligns a position of the sheet in the width direction with the sheet reference position together with the sheet width direction reference position regulating member. A paper reversing / conveying device. A sheet width direction reference position regulating member that guides the sheet to the sheet processing unit by setting the position in the width direction of the supplied sheet as a sheet width direction reference position, a reversible reversing roller, and the sheet processing unit A first paper guide that forms a paper reversing path to the reversing roller; and a second paper guide that forms a paper reversing path from the reversing roller to the paper width direction reference position regulating member, Then, the sheet whose one side is processed is guided again to the sheet width direction reference position regulating member side through the first paper guide, the reverse roller and the second paper guide, and the other side is processed by the sheet processing unit. A paper reversing and conveying device,
In the image forming apparatus comprising the paper processing unit for forming an image on the paper ,
The image forming apparatus according to claim 1, wherein the sheet reversing and conveying apparatus is the sheet reversing and conveying apparatus according to claim 1.

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