JP4453949B2 - Paper skew correction mechanism - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sheet skew correction mechanism that corrects skew of a sheet being conveyed in an image forming apparatus such as a printer, a facsimile machine, or a copying machine.
[0002]
[Prior art]
In an image forming apparatus such as a printer, skew (skew) in which a sheet is conveyed obliquely in the middle of conveyance is often caused.
Conventionally, in order to straighten the sheet in the conveyance direction, correction is performed by a method in which the sheet is conveyed obliquely in advance and abutted against a reference member, or by a width adjusting mechanism as disclosed in Japanese Patent Laid-Open No. 2000-16640. The method is known.
[0003]
[Problems to be solved by the invention]
However, in the case of oblique conveyance, a long conveyance path is necessary. In the case of the width adjusting mechanism, as shown in FIG. 1, when the width of the sheet 50 is adjusted during the conveyance of the sheet 50, that is, the left and right side fences 51 and 52 are slid to narrow the interval, the sheet 50. For example, damage 53 may occur due to the side edge of the side fence 52 being pushed at a corner on the downstream side of the side fence 52. Therefore, it is necessary to temporarily stop the conveyance of the paper 50 and then adjust the width. If it does so, printing time will become long.
[0004]
SUMMARY OF THE INVENTION An object of the present invention is to provide a paper skew correction mechanism capable of correcting paper skew by a simple mechanism without reducing the linear speed of paper conveyance of the image forming apparatus and damaging the paper. There is to do.
[0005]
[Means for Solving the Problems]
In order to achieve such an object, the present invention is characterized in that a pressing member that elastically presses the rear end portion of one side edge of the paper is provided on one of the left and right side fences that perform width adjustment.
[0006]
The pressing member may be provided on the side fence on the pressing side opposite to the reference side among the left and right side fences. In that case, if the side fence on the pressing side protrudes obliquely toward the upstream side, it is easy to press the side edge of the paper.
[0007]
The pressing member may be flexible due to its own elasticity or may be biased by another elastic member.
[0008]
The shape of the pressing member is preferably circular at a portion in contact with the rear end portion of the one side edge of the paper so as not to bend the one side edge of the paper.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described in detail with reference to the drawings.
[0010]
FIG. 2 is a plan view of an example of the sheet skew correction mechanism according to the present invention, and FIG. 3 is a side view. This skew feeding correction mechanism is installed between a paper feeding mechanism and a printing mechanism (not shown) in the image forming apparatus, corrects skew feeding of paper fed from the paper feeding mechanism, and guides it to the printing mechanism.
[0011]
The sheet skew correction mechanism includes both side fences 1 and 2 on the reference side and the holding side, a side fence detection sensor 3 that detects the reference position of the reference side fence 1, and a conveyance roller 5 that rotates integrally with the drive shaft 4. And a follower roller 6 that follows this, a paper detection sensor 7 that detects paper upstream of the conveying roller 5, a side fence drive motor 8, a drive pulley 9 driven by the motor 8, and a guide pulley 10 A belt 11 that is hung between the drive pulley 9 and the guide pulley 10 to link the side fences 1 and 2; a paper guide plate 12; and a pressing member 13 that is attached to the pressing side fence 2. Consists of.
[0012]
Both side fences 1 and 2 can slide left and right while staying parallel along a rail (not shown), and are simultaneously slid in the left and right direction by the belt 11 by driving the motor 8.
[0013]
The pressing member 13 has its base end fixed to the inner side surface of the pressing side fence 2 and protrudes obliquely from the inner side surface of the side fence 2 toward the upstream side, and can be bent by its own elasticity. . The tip portion 13a of the pressing member 13 is circular.
[0014]
The pressing member 13 itself is not elastic (flexible), but the base end of the pressing member 13 is pivotally supported by the holding side fence 2 so that the pressing member 13 is supported by a separately prepared elastic member. By urging, the pressing member 13 may be indirectly given elasticity.
[0015]
Next, the operation will be described.
First, the motor 8 is rotated clockwise to slide both side fences 1 and 2. When the side fence detection sensor 3 detects the reference side fence 1, the motor 8 is stopped and the reference side fence 1 is set as a reference. Set to position.
[0016]
Next, as shown in FIG. 4, when the paper P transported by a paper feeding mechanism (not shown) is detected by the paper detection sensor 7, the transport roller 5 is moved to a driving means (not shown) via the drive shaft 4. Rotate. Then, after a certain time T0 has elapsed from the time point when the paper is detected by the paper detection sensor 7, that is, when the paper P is transported to a position where it is sandwiched between the transport roller 5 and the driven roller 6, the motor 8 is rotated clockwise to rotate both side fences. Bring 1 and 2 closer.
[0017]
At the same time that the reference side fence 1 slides to the left, the holding side fence 2 slides to the right. However, since the pressing member 13 protrudes from the holding side fence 2, the pressing member 13 However, as shown in FIG. 5, the rear end portion (upstream side) of the left edge of the sheet P being conveyed is pressed rightward. As a result, the sheet P tilts around the nip portion between the transport roller 5 and the driven roller 6. Further, since the tip end portion 13a of the pressing member 13 that contacts the left edge of the paper P is circular, the paper P is pressed rightward without damaging the left edge of the paper P.
[0018]
When the two side fences 1 and 2 are further approached, the reference side fence 1 presses the rear end portion of the right edge of the paper P being conveyed, and as shown in FIG. The bend is caused by elasticity, and the inclination of the paper P is corrected.
[0019]
When T1 elapses after the motor 8 starts rotating, when the motor 8 stops, the paper P is adjusted to the center.
[0020]
Between the time when the paper P is tilted and the time when the tilt is corrected, the pressing member 13 elastically pushes the rear end of the left edge of the paper P, and the reference side fence 1 lags behind this. Since the rear end portion of the right edge is pushed, the front end portion of the paper P is not damaged or bent.
The sheet P whose inclination is corrected in this way is conveyed along the reference side fence 1 to a printing mechanism (not shown) as it is.
[0021]
Note that the time T0 is set so that the pressing member 13 presses the rear end of the side edge of the paper P in accordance with the conveyance speed of the paper P. The time T1 is set for each size so that the paper P is centered in accordance with the width size of the paper P.
[0022]
【The invention's effect】
As described above, according to the present invention, it is possible to correct the skew of a sheet with a simple mechanism without reducing the linear speed of sheet conveyance of the image forming apparatus and without damaging the sheet.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a problem of a conventional example.
FIG. 2 is a plan view of an example of a paper skew correction mechanism according to the present invention.
FIG. 3 is a side view thereof.
FIG. 4 shows the operation of the sheet skew correction mechanism, in a state where the sheet is conveyed until it is sandwiched between the conveying roller and the driven roller.
FIG. 5 is a state in which the rear end portion of the left edge of the sheet is pressed by the pressing member of the pressing side fence and the sheet is inclined.
FIG. 6 is a state in which the trailing edge of the right edge of the sheet is pushed by the reference side fence and the sheet is straightened.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Reference | standard side fence 2 Holding | pressing side fence 3 Side fence detection sensor 4 Drive shaft 5 Carrying roller 6 Driven roller 7 Paper detection sensor 8 Side fence drive motor 9 Drive pulley 10 Guide pulley 11 Belt 13 Press member 13a Tip part

Claims (6)

In a paper skew correction mechanism having a transport roller for transporting paper and left and right side fences slidable to the left and right to hold the paper from right and left, one of the left and right side fences has a rear edge on one side edge of the paper A sheet skew correction mechanism comprising a pressing member that elastically presses the portion. The paper skew correction mechanism according to claim 1, wherein the pressing member is provided on a side fence on a pressing side opposite to a reference side among the left and right side fences. The sheet skew correcting mechanism according to claim 2, wherein the pressing member is provided so as to project obliquely from the side fence on the pressing side toward the upstream side. 4. The skew feeding correcting mechanism according to claim 1, wherein the pressing member is flexible by its own elasticity. The paper skew feeding correction mechanism according to claim 1, wherein the pressing member is biased by an elastic member. 6. The skew feeding correcting mechanism according to claim 1, wherein the pressing member is circular at a portion in contact with a rear end portion of one side edge of the sheet.

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