JP5772383B2 - Paper feeding device, image reading device, and image forming device - Google Patents

Description

  The present invention relates to a paper feeding device, and more particularly to an image forming device such as a paper feeding device, an image reading device, an electrophotographic copying machine, or a printer that feeds stacked sheets of originals one by one.

  In general, in an image reading apparatus that optically reads a document image, as shown in FIG. 4, a plurality of documents D stacked on a sheet feed tray are picked up by rotation of a pickup roller 122, and a sheet feed roller 123a. The sheet is fed in the direction of arrow B (provided with a roller not shown) on the lower side, and conveyed to the registration roller pair 125 via the intermediate conveyance roller pair 124. When feeding is started, the registration roller pair 125 is in a rotation stopped state, and the leading edge of the document D is conveyed by the leading edge of the document D conveyed from the intermediate conveying roller pair 124 against the nip portion of the roller pair 125. Is curved and skew is corrected. When a curve is formed at the leading end of the document D, the intermediate conveyance roller pair 124 is temporarily stopped from rotating. Thereafter, the registration roller pair 125 and the intermediate conveyance roller pair 124 are rotationally driven in synchronization with each other, and the document D is conveyed in the direction of arrow B while maintaining the curvature.

  Specifically, as shown in FIG. 5A, the leading edge of the document D1 that has skewed during pick-up strikes the nip portion of the resist roller pair 125 that has stopped (see FIG. 5B). At this time, a curving c is generated at the front end portion of the document D1 by the transport force applied from the pair of intermediate transport rollers 124, and skew is corrected. Thereafter, the registration roller pair 125 and the intermediate conveyance roller pair 124 are rotationally driven in synchronization with each other, so that the document D1 is conveyed in a state where the curve c is held as shown in FIG. After registration, the roller pair 124 and 125 are driven synchronously to hold the curvature c of the document D1. If only the registration roller pair 125 is rotationally driven and the rotation of the intermediate conveyance roller pair 124 is stopped, the registration is performed. This is to prevent the registered original D1 from receiving a load at the intermediate conveyance roller pair 124 and returning the registered original D1 to the original skew state.

  By the way, originals of the same size are set on the paper feed tray, but sometimes different sizes of originals are set simultaneously (hereinafter referred to as a mixed loading mode). In this specification, different sizes mean that the lengths in the direction orthogonal to the paper feeding direction are different. That is, even if the A4 size is the same, the size varies depending on whether the long side or the short side is set in the paper feeding direction.

  In the mixed loading mode, as shown in FIG. 4, since the large-size document D is guided by the side regulating plates 131a and 131b on the basis of the center, there is little possibility of skewing during pickup. However, since only one side of the small-sized document D1 is guided by the side regulating plate 131a, the document D1 often flows to the non-regulating side and skews greatly. When the skewed small-size document D1 hits the registration roller pair 125 and is registered, as shown in FIG. 6, the amount of curvature of the side portion preceded by the skew is larger than that of the other side portion. It becomes a state. The various rollers 122 to 125 are composed of short rollers on the premise that the document is conveyed in the axial direction on the basis of the center, so that the leading end of the skewed small-size document D1 hits the registration roller pair 125. At this time, the original D1 cannot rotate in the direction of the arrow B ′ (see FIG. 4) around the central portion of the intermediate conveyance roller pair 124. If the grip force of the intermediate conveyance roller pair 124 is strong, the intermediate conveyance roller Since the pair 124 and the registration roller pair 125 are synchronously rotated, the document D1 is wrinkled between the rollers 124 and 125.

  In Patent Document 1, when a sheet is conveyed by a pair of registration rollers, the formed deflection (curvature) is not lost, and the amount of deflection is excessive so that wrinkles do not occur. Controlling the rotation speed is described. Here, since it is not intended to eliminate the deflection itself, it is difficult to prevent wrinkles from occurring on a small-size sheet that is skewed relatively large.

JP 2000-108482 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide a paper feeding device, an image reading device, and an image forming device that can prevent wrinkles due to skewing on a once registered paper.

The paper feeding device according to the first aspect of the present invention is:
A sheet feeding unit that picks up the stacked sheets and feeds them in one direction, an intermediate conveyance unit that conveys the fed sheets in one direction, and a sheet that is conveyed by the intermediate conveyance unit by applying the leading edge of the sheet. A sheet feeding device comprising: registration means for aligning
The intermediate transport means is configured to be driven to rotate when a force in the transport direction is applied from the sandwiched paper,
After the leading edge of the sheet transported from the intermediate transporting unit comes into contact with the resisting unit that has stopped rotating, the rotation of the intermediate transporting unit is stopped, and a predetermined amount of paper is placed between the registering unit and the intermediate transporting unit. Forming a curved portion of
If the size of the paper to be fed is constant, after the curved portion is formed, the registration means and the intermediate conveyance means are synchronously driven to convey the paper,
When the sizes of the papers to be fed are different, after forming the curved portion, the registration unit is rotated and the intermediate conveyance unit conveys the sheets without being rotated.
It is characterized by.

  In the paper feeding device according to the first embodiment, the intermediate transport means is configured to be driven to rotate when a force in the transport direction is applied from the sandwiched paper, and the size of the paper to be fed is different. After the curved portion is formed, the registration unit is rotated, and the intermediate conveyance unit conveys the sheet without being rotated. Therefore, the curvature of the registered sheet is eliminated and wrinkles are generated. Is prevented.

The sheet feeding device according to the second aspect of the present invention is:
A sheet feeding unit that picks up the stacked sheets and feeds them in one direction, an intermediate conveyance unit that conveys the fed sheets in one direction, and a sheet that is conveyed by the intermediate conveyance unit by applying the leading edge of the sheet. A sheet feeding device comprising: registration means for aligning
The intermediate transport means is configured to be driven to rotate when a force in the transport direction is applied from the sandwiched paper,
After the leading edge of the sheet transported from the intermediate transporting unit comes into contact with the resisting unit that has stopped rotating, the rotation of the intermediate transporting unit is stopped, and a predetermined amount of paper is placed between the registering unit and the intermediate transporting unit. Forming a curved portion of
If the size of the paper to be fed is constant, after the curved portion is formed, the registration means and the intermediate conveyance means are synchronously driven to convey the paper,
When the size of the paper to be fed is different, after the curved portion is formed, the registration means and the intermediate conveyance means are driven to rotate, but the intermediate conveyance means conveys the paper so that the curved state of the paper is eliminated. Making the speed slower than the conveying speed of the resist means,
It is characterized by.

  In the sheet feeding device according to the second embodiment, the intermediate conveying unit is configured to be driven to rotate when a force in the conveying direction is applied from the sandwiched paper, and the size of the fed paper is different. After the curved portion is formed, the registration means and the intermediate conveyance means are rotationally driven, but the conveyance speed of the intermediate conveyance means is made slower than the conveyance speed of the registration means so as to eliminate the curved state of the sheet. Thus, the curvature of the registered paper is eliminated and the generation of wrinkles is prevented.

An image reading apparatus according to a third aspect of the present invention includes any one of the paper feeding apparatuses according to the first and second aspects. An image forming apparatus according to a fourth aspect of the present invention includes the image reading device.

  According to the present invention, it is possible to prevent wrinkles due to skewing from occurring once on a registered sheet, particularly for a small-sized sheet in which sheets of different sizes are mixedly loaded.

1 is a perspective view showing an external appearance of an image forming apparatus. It is a schematic block diagram which shows an image reading apparatus. 2A and 2B are diagrams illustrating a sheet feeding unit of the image reading apparatus, in which FIG. 3A is an explanatory diagram viewed from a side surface, and FIG. It is explanatory drawing which shows the paper feeding state in an image reading apparatus. FIG. 6 is an explanatory diagram illustrating a paper feeding state in the image reading device as time elapses. FIG. 6 is a perspective view showing a curved state of a skewed document.

  Hereinafter, embodiments of a paper feeding device, an image reading device, and an image forming device according to the present invention will be described with reference to the accompanying drawings.

  FIG. 1 shows a digital copying machine equipped with an image reading device (scanner) 3. In this copying machine, an image of a document placed on the platen glass 10 (see FIG. 2) of the image reading device 3 is read by a reading optical system 50 described below moving immediately below the platen glass 10. . Further, the originals placed on the paper feed tray 21 of the original conveying unit 20 are automatically fed and conveyed one by one, and the reading optical system 50 in which the image is stationary through the reading glass 40 will be described below. It is read by the sheet through method.

  The developed image read by the image reading device 3 is transferred as a toner image on the transfer material fed from the paper feeding unit 5 by a known electrophotographic process in the printing unit 4. Thereafter, the transfer material is fixed with toner and discharged to the discharge unit 6.

  FIG. 2 shows the image reading device 3 and its original transport unit 20. The reading optical system 50 is known per se, and includes a lamp 53, mirrors 54, 55, and 56, an imaging lens (not shown), and an imaging unit (CCD color sensor) 58. The lamp 53 and the mirror 54 are mounted on the first slider 51, and the mirrors 55 and 56 are mounted on the second slider 52, and are movable in the sub-scanning direction Y, respectively. Reading of a document image by the sheet-through method is performed in a state where the optical system 50 is stationary at a reading position A shown in FIG.

  The document conveying unit 20 includes a sheet feeding tray 21, a pickup roller 22, a sheet feeding roller 23a and a separating roller 23b, an intermediate conveying roller pair 24, a registration roller pair 25, reading unit roller pairs 26 and 27, and a discharge. It is composed of partial roller pairs 28 and 29 and a discharge tray 30.

A plurality of documents are placed on the tray 21 with the image surface facing upward and regulated by the side regulation plates 31a and 31b according to the center reference. First, the uppermost document is picked up by the pickup roller 22 in the direction of arrow B, and is fed from the nip portion with the paper roller 23b by the rotation of the paper feed roller 23a. Thereafter, the document is conveyed from the intermediate conveyance roller pair 24 that is rotationally driven to the registration roller pair 25 (see FIG. 3, the document is indicated by a symbol D).

  The registration roller pair 25 is in a rotation stopped state at the beginning of the paper feeding operation, and the leading edge of the document D is curved when the leading edge of the document D conveyed from the intermediate conveying roller pair 24 abuts against the nip portion of the roller pair 25. The skew is corrected. When a curve is formed at the leading end of the document D, the intermediate conveying roller pair 24 is temporarily stopped from rotating. Thereafter, the registration roller pair 25 and the intermediate conveyance roller pair 24 are rotationally driven in synchronization with each other, and the document D is conveyed in the direction of the arrow B while maintaining the curvature. Hereinafter, such a document conveying operation is referred to as a normal mode.

  By the way, if skew is generated in the document fed as described above and the document is conveyed in the normal mode, the document may be wrinkled. In order to solve this problem, the document conveying unit 20 is driven in any of the following control examples 1 to 4 to eliminate the bending between the roller pairs 24 and 25 to prevent wrinkles. As a premise thereof, the intermediate conveying roller pair 24 is configured to be driven and rotated when a force in the conveying direction B is applied from the document pinched at the nip. Specifically, a one-way clutch is incorporated in each of the roller pair 24 so that the original can be conveyed in the direction of arrow B by the registration roller pair 25 even when the roller pair 24 stops rotating.

(Control example 1)
If the size of the document to be fed is constant, after the curved portion is formed, the registration roller pair 25 and the intermediate conveyance roller pair 24 are synchronously driven to convey the document (normal mode). When the sizes of the fed documents are different (mixed mode), after the curved portion is formed, the registration roller pair 25 is rotationally driven, and the intermediate conveyance roller pair 24 is not rotationally driven and conveys the original. To do. In the mixed loading mode, the user inputs that fact on the operation panel. In the mixed loading mode, a large document is placed on the tray 21 by the side regulation plates 31a and 31b on the center reference, and a small document is placed on the tray 21 with one side regulated by the side regulation plate 31a. Placed on top.

  In the mixed loading mode of Control Example 1, only the registration roller pair 25 is driven to rotate after the curved portion is formed. For this reason, the document conveyed by the registration roller pair 25 is free from bending and no wrinkles are generated. The curvature is eliminated and the original can be conveyed without damaging the original by the intermediate conveyance roller pair 24 being driven to rotate in the conveyance direction B by the one-way clutch.

(Control example 2)
If the size of the document to be fed is constant, after the curved portion is formed, the registration roller pair 25 and the intermediate conveyance roller pair 24 are synchronously driven to convey the document (normal mode). When the sizes of the fed documents are different (in the mixed loading mode), the curved state of the document is solved by rotating the registration roller pair 25 and the intermediate conveyance roller pair 24 after the curved portion is formed. In addition, the conveyance speed of the intermediate conveyance roller pair 24 is made slower than the conveyance speed of the registration roller pair 25.

  Even in the mixed loading mode of the control example 2, in the conveyance state after forming the curved portion, the curved state of the document is canceled and the generation of wrinkles is prevented.

(Control example 3)
In the control example 3, a skew amount detecting means for detecting the skew amount of the document is provided immediately before the registration roller pair 25 is conveyed. For example, as shown in FIG. 3B, sensors 32 a and 32 b for detecting the leading edge of the document are provided in a direction orthogonal to the conveyance direction B. The sensors 32a and 32b are arranged so as to detect the skew of the document of the minimum size corresponding to the size of the document assumed to be the minimum size. The minimum size means, for example, a case where the long side is transported along the transport direction B with a B5 size.

  Regardless of whether the size of the fed document is constant or different, the skew amount detected by the sensors 32a and 32b is a predetermined value (for example, a specific value out of a deviation of 2 to 3 mm on both sides of the document). In the case of within the dimension (2), after the curved portion is formed, the registration roller pair 25 and the intermediate conveyance roller pair 24 are synchronously rotated to convey the document (normal mode). When the skew amount detected by the sensors 32a and 32b exceeds the predetermined value, the registration roller pair 25 is driven to rotate and the intermediate conveyance roller pair 24 is driven to rotate after the curved portion is formed. Transport the document without any problems.

  In the control example 3, when the detected skew amount exceeds a predetermined value, only the registration roller pair 25 is driven to rotate after the curved portion is formed. For this reason, the document conveyed by the registration roller pair 25 is free from bending and no wrinkles are generated. The curvature is eliminated and the original can be conveyed without damaging the original by the intermediate conveyance roller pair 24 being driven to rotate in the conveyance direction B by the one-way clutch. If the detected skew amount is within a predetermined value, there is no possibility that the document will be wrinkled even if it is operated in the normal mode.

(Control example 4)
Also in the control example 4, sensors 32a and 32b for detecting the skew amount of the document are provided immediately before the registration roller pair 25 is conveyed. The skew amount detected by the sensors 32a and 32b is within a predetermined value (for example, a deviation of 2 to 3 mm on both sides of the document) regardless of whether the size of the fed document is constant or different. After the curved portion is formed, the registration roller pair 25 and the intermediate conveyance roller pair 24 are synchronously rotated to convey the original (normal mode). When the skew amount detected by the sensors 32a and 32b exceeds the predetermined value, the registration roller pair 25 and the intermediate conveyance roller pair 24 are driven to rotate after the curved portion is formed. The conveyance speed of the intermediate conveyance roller pair 24 is made slower than the conveyance speed of the registration roller pair 25 so as to eliminate the state.

  In the control example 4, when the detected skew amount exceeds a predetermined value, the curved state of the document is canceled in the conveyance state after forming the curved portion, and the generation of wrinkles is prevented.

  The paper feeding device, the image reading device, and the image forming device according to the present invention are not limited to the above-described embodiments, and can be variously changed within the scope of the gist.

  As described above, the present invention is useful for a paper feeding device, an image reading device, and an image forming device, and in particular, can prevent a wrinkle caused by skewing from occurring once on a registered paper. Are better.

DESCRIPTION OF SYMBOLS 3 ... Image reading device 20 ... Document conveyance part 22 ... Pickup roller 23a ... Paper feed roller 24 ... Intermediate conveyance roller pair 25 ... Registration roller pair 32a, 32b ... Document front end detection sensor D, D1 ... Document

Claims (4)

A sheet feeding unit that picks up the stacked sheets and feeds them in one direction, an intermediate conveyance unit that conveys the fed sheets in one direction, and a sheet that is conveyed by the intermediate conveyance unit by applying the leading edge of the sheet. A sheet feeding device comprising: registration means for aligning
The intermediate transport means is configured to be driven to rotate when a force in the transport direction is applied from the sandwiched paper,
After the leading edge of the sheet transported from the intermediate transporting unit comes into contact with the resisting unit that has stopped rotating, the rotation of the intermediate transporting unit is stopped, and a predetermined amount of paper is placed between the registering unit and the intermediate transporting unit. Forming a curved portion of
If the size of the paper to be fed is constant, after the curved portion is formed, the registration means and the intermediate conveyance means are synchronously driven to convey the paper,
When the sizes of the papers to be fed are different, after forming the curved portion, the registration unit is rotated and the intermediate conveyance unit conveys the sheets without being rotated.
A paper feeder characterized by. A sheet feeding unit that picks up the stacked sheets and feeds them in one direction, an intermediate conveyance unit that conveys the fed sheets in one direction, and a sheet that is conveyed by the intermediate conveyance unit by applying the leading edge of the sheet. A sheet feeding device comprising: registration means for aligning
The intermediate transport means is configured to be driven to rotate when a force in the transport direction is applied from the sandwiched paper,
After the leading edge of the sheet transported from the intermediate transporting unit comes into contact with the resisting unit that has stopped rotating, the rotation of the intermediate transporting unit is stopped, and a predetermined amount of paper is placed between the registering unit and the intermediate transporting unit. Forming a curved portion of
If the size of the paper to be fed is constant, after the curved portion is formed, the registration means and the intermediate conveyance means are synchronously driven to convey the paper,
When the size of the paper to be fed is different, after the curved portion is formed, the registration means and the intermediate conveyance means are driven to rotate, but the intermediate conveyance means conveys the paper so that the curved state of the paper is eliminated. Making the speed slower than the conveying speed of the resist means,
A paper feeder characterized by. An image reading apparatus comprising the sheet feeding device according to claim 1 . An image forming apparatus comprising the image reading device according to claim 3 .

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