JP2002068500A - Sheet supply device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the number of suppliable sheets per unit time by eliminating the influence of the time required to pick up the sheet. SOLUTION: This sheet supply device 10 is composed of a sheet stacking means 11 by which sheets are stacked, a sheet supplying means 13 to supply sheets S from the stacking means, a sheet correcting means to convey each sheet supplied by the supplying means, receive the leading edge of the sheet and convey farther upon correcting an eventual skew, and a sheet supply control means 50 to allow the sheet supplying means to perform supplying motion for the following sheet so that the front part of the following sheet S2 is overlapped on the rear part of the foregoing sheet S1 whose leading edge is received by the sheet correcting means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding apparatus for feeding a sheet, and a sheet feeding apparatus provided in a main body.
The present invention relates to an image forming apparatus such as a copier, a printer, a facsimile, and a multifunction machine for forming an image on a sheet supplied by the sheet supply apparatus.

[0002]

2. Description of the Related Art As shown in FIG. 7, for example, a sheet feeding device is provided in a main body 102 of a printer 101 which is an example of an image forming apparatus, and a photosensitive drum 121 on which a toner image is formed and a toner image formed on a sheet. Transfer charger 12 for transferring to
2, sheets are continuously supplied one by one.

[0003] That is, the sheet supply device 110 is provided with a sheet storage unit 11 provided in a main body 102 of the printer 101.
When the sheets S are supplied between the photosensitive drum 121 and the transfer charger 122 from 1, the sheets S stacked on the sheet storage unit 111 are sent out one by one by the pickup roller 113 of the first sheet feeding unit. Then, the sheet is fed to the second sheet feeding unit on the downstream side in the sheet conveying direction. Then, the sheet feeding device 110 feeds the sheet to the registration roller pair 118 on the downstream side in the sheet conveyance direction by the conveyance roller pair 117 of the second sheet feeding unit. Registration roller pair 11
8 is a photoreceptor drum 121 after correcting the skew of the sheet.
The sheet is supplied between the transfer charger 122 and the transfer charger 122.

FIG. 8A is a diagram showing a standby state before sheet supply. As shown in FIG. 8A, the sheet feeding device 110 is a top sheet S1 among a plurality of sheets S stacked and stored on the sheet storage unit 111.
The pickup roller 113 that feeds the sheets S one by one is made to stand by above the stored sheets S.

On the downstream side of the pickup roller 113 in the sheet conveying direction, a feed roller 114 for feeding the sheet S fed from the sheet storage unit 111 by the pickup roller 113 to a second feeding unit, and a feed roller 114 The sheet storage unit 111
When a plurality of sheets S sent out from are overlapped,
A retard roller 115 that rotates in a direction opposite to the rotation direction of the feed roller 114 and separates the sheet into one sheet is provided.

[0006] In such a configuration, the sheet feeding device 110 moves the uppermost sheet S1
8B, the pickup roller 113 is moved to the uppermost sheet S among the plurality of sheets S stacked and stored on the sheet storage unit 111 as shown in FIG.
Move to the position where it touches 1 and rotate. Then, the uppermost sheet S1 is moved to the pickup roller 113.
The feed roller 114 and the retard roller 11
No. 5 nip. At this time, when a plurality of sheets S are stacked, the sheets S are separated one by one by the feed roller 114 and the retard roller 115 and supplied to the second feeding unit.

Further, as shown in FIG. 8C, the sheet S1 sent from the first feeding unit is stopped while being conveyed by the pair of conveying rollers 117 of the second feeding unit. The resist is abutted against the roller pair 118 and the resist is removed (skew is corrected). Therefore, the sheet S1 has a loop shape. At that time, the conveying roller pair 11
7 stops. Then, the sheet S <b> 1 is conveyed between the photosensitive drum 121 and the transfer charger 122 by the registration roller pair 118 which has started rotating.

[0008]

By the way, the conventional sheet feeding apparatus employs a pickup roller 11 of a first feeding section.
While the sheet S1 sent out by No. 3 is conveyed by the conveying roller pair 117 of the second feeding section, the sheet S1 is brought into contact with the stopped registration roller pair 118 to remove the resist (correct skew). ing.

For this reason, the sheet supply device is provided with the sheet S1.
A sheet is conveyed between the photosensitive drum 121 and the transfer charger 122 by the registration roller pair 118 that has started rotating. It is supposed to. Then, in order to start the supply of the succeeding sheet S2, it is necessary to pick up and feed the subsequent sheet S2 from the first feeding unit after the registration roller pair 118 starts conveying the preceding sheet S1. There is.

As described above, in the conventional sheet feeding apparatus, after the preceding sheet S1 starts to be conveyed by the pair of registration rollers 118, the pickup roller 113 is moved to the plurality of sheets stacked and stored on the sheet storage section 111. Of the sheets S, since the sheet S2 is moved to a position in contact with the uppermost sheet S2 and the supply of the sheet S2 is started, the interval between the sheets is widened according to the moving time of the pickup roller 113, and the sheet The supply number could not be increased.

Also, when the sheet S slips between the feed roller 114 and the retard roller 115 and the sheet S, it also causes an increase in the interval between the sheets.

In order to narrow the interval between the spread sheets, it is conceivable to temporarily increase the sheet conveying speed so that the preceding sheet S1 can catch up with the succeeding sheet S2.

In addition, it is necessary that the succeeding sheet S2 can catch up with the sheet storage section 111 on a short conveying path. To achieve this, a great increase in speed is required, and the transport motor needs to be large. Conversely, if the transport path is lengthened, the speed can be slightly increased, but the apparatus itself needs to be large.

(Purpose) The present invention eliminates the influence of the time required for picking up the sheets and avoids the influence of the sliding of the sheets at the part where the sheets are separated, so that the interval between the sheets is always maintained constant. It is another object of the present invention to provide a sheet supply apparatus in which the number of sheets supplied per unit time is increased, and an image forming apparatus including the sheet supply apparatus.

[0015]

In order to achieve the above object, a sheet feeding apparatus according to the present invention comprises a sheet stacking means on which sheets are stacked, a sheet feeding means for feeding the sheets from the sheet stacking means, After receiving the leading edge of the sheet while transporting the sheet supplied by the sheet supply unit and correcting the skew of the sheet, the sheet straightening unit that transports the sheet, and the leading edge received by the sheet straightening unit are received. Sheet supply control means for causing the sheet supply means to perform the supply operation of the succeeding sheet so that the front part of the succeeding sheet overlaps the rear part of the preceding sheet.

The sheet feeding apparatus according to the present invention may further comprise, between the sheet feeding means and the sheet correcting means, at least one of a rear part of the preceding sheet and a front part of the succeeding sheet in a thickness direction of the sheet. Escape area is provided.

The sheet feeding apparatus according to the present invention further comprises a rear end of the preceding sheet bent between the sheet feeding means and the sheet correcting means in a thickness direction of the preceding sheet. Sheet interference avoiding means for avoiding interference of the front end of the succeeding sheet with the sheet.

The sheet feeding apparatus according to the present invention may further comprise, between the sheet feeding means and the sheet correcting means, at least one of a rear part of the preceding sheet and a front part of the succeeding sheet in a thickness direction of the sheet. Sheet interference avoidance in which a relief area to be released and a rear portion of the preceding sheet are bent in a thickness direction of the preceding sheet to enter the relief area to avoid interference of a front end of the succeeding sheet with a rear end of the preceding sheet. Means.

[0019] The sheet supply device of the present invention may further comprise: a sheet supply unit configured to overlap the sheet supplied by the sheet supply unit between the sheet supply unit and the escape area.
There is provided a sheet separating means for separating the sheet and supplying only one sheet.

In the sheet feeding apparatus according to the present invention, the sheet feeding means has a rotating body which rotates in contact with the sheet.

In the sheet feeding apparatus according to the present invention, the sheet straightening means is conveyed by a pair of sheet conveying rotary members pressed against each other to pinch and rotate and convey the sheet while rotating. And a pair of sheet correction rotating bodies that convey the sheet while pinching and rotating the sheet after the front end of the sheet is stopped and temporarily stopped.

In the sheet feeding apparatus according to the present invention, the sheet separating means includes a driving rotator, and a driven rotator which is pressed against the driving rotator and is driven to rotate. The driven rotator rotates in a direction to reversely feed the sheet.

In order to achieve the above object, an image forming apparatus according to the present invention includes any one of the above-described sheet supply apparatuses and image forming means for forming an image on a sheet supplied by the sheet supply apparatus. I have.

(Operation) In the sheet feeding apparatus of the present invention, the sheet feeding means feeds the sheet from the sheet stacking means to the sheet correcting means. The sheet straightening unit receives the leading end of the sheet while conveying the sheet supplied by the sheet feeding unit, and corrects the skew of the sheet.
The sheet is conveyed. In the meantime, the sheet supply control unit causes the sheet supply unit to perform a supply operation of the subsequent sheet, and overlaps a front portion of the succeeding sheet with a rear portion of the preceding sheet whose leading end is received by the sheet correction unit.

When the sheet feeding apparatus of the present invention is provided with a relief area, when the front part of the succeeding sheet is overlapped on the rear part of the preceding sheet, one of the sheets escapes to the relief area, and the rear end of the preceding sheet and the succeeding sheet Abutment with the tip of the camera is avoided.

When the sheet feeding apparatus of the present invention is provided with the sheet interference avoiding means, when the front part of the succeeding sheet is overlapped with the rear part of the preceding sheet, one of the sheets is urged in one direction by the sheet interference avoiding means. However, abutting between the trailing edge of the preceding sheet and the leading edge of the succeeding sheet is avoided.

When the sheet feeding apparatus of the present invention is provided with a relief area and sheet interference avoiding means,
When the front portion of the succeeding sheet is overlapped, one of the sheets is urged in one direction by the sheet interference avoiding means to enter the escape area, and abutment between the trailing edge of the preceding sheet and the leading edge of the succeeding sheet is avoided. Is done.

If the sheet feeding device of the present invention is provided with the sheet separating means, the sheet feeding device of the present invention separates the sheets and feeds only one sheet when the sheets fed by the sheet feeding means overlap. .

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a sheet feeding apparatus according to an embodiment of the present invention and a printer which is an image forming apparatus provided with the sheet feeding apparatus in a main body will be described.

First, a printer provided with a sheet feeding device in a main body will be described with reference to FIG.
The sheet feeding device will be described based on FIG. The sheet feeding device can be provided not only in a printer but also in other image forming apparatuses such as a copying machine and a facsimile.

(Printer) In FIG. 1, a printer (image forming apparatus) 1 has a sheet storage section (sheet loading means) in which a predetermined number of sheets S can be loaded and stored in one side of a main body 2.
11, a feeding cassette 27 capable of stacking and storing a predetermined number of sheets S and being detachably attached to the main body 2 is provided at a lower portion in the main body 2.

The sheet supply device 10 sequentially supplies sheets S one by one between a photosensitive drum 21 and a transfer charger 22 provided in the main body 2 of the printer 1. When the sheets S stacked on the sheet storage unit 11 are fed out one by one by the pickup roller 13 of the first feeding unit, the sheets S supplied from the sheet storage unit 11 are disposed on the second side on the downstream side in the sheet conveyance direction. The sheet is fed into the sheet feeding unit, and is brought into contact with the nip of the registration roller pair 18, which is the skew correction unit on the downstream side in the sheet conveyance direction and is stopped rotating, by the conveying roller pair 17 of the second feeding unit. . When the sheet S is skewed, the sheet S is straightened straight by the registration roller pair 18 and the conveyance roller pair 17.

Next, the registration roller pair 18 is rotated at a timing relative to the latent image formed on the photosensitive drum 21 constituting the image forming means, and is moved between the photosensitive drum 21 and the transfer charger 22. The sheet is fed, and the toner image on the photosensitive drum is transferred onto the sheet S.

Thereafter, the sheet S is sent to a fixing device 24 by a conveyor belt 23, and is subjected to a fixing process for fixing the already transferred toner image on the sheet surface. And loaded.

(Sheet Feeding Apparatus) In FIGS. 2 to 6, the sheet feeding apparatus 10 is designed to sequentially feed the sheets S one by one between the photosensitive drum 21 and the transfer charger 22 as described above. Has become.

The sheet supply device 10 is provided with a plurality of sheets S
And a pickup roller (sheet supply means) 13 for feeding the uppermost sheet S1 one by one from a sheet storage unit 11 in which sheets are stacked and stored.
3, a feed roller 14 for feeding the sheet S1 fed from the sheet storage unit 11 to the second feed unit, and a sheet roller 1 disposed opposite to the feed roller 14,
When a plurality of sheets S1 sent from the sheet stacking unit 1 overlap, a retard roller 15 and the like which rotate in a direction to return the sheets to the sheet storage unit 11 and separate the sheets into one sheet are provided. The feed roller 14 and the retard roller 15 constitute a sheet separating unit. Pickup roller 13
Rotates together with the feed roller 14.

In the case where the sheet S1 is supplied from the sheet storage section 11, in FIG. 2, the pickup roller 13 is applied to the uppermost sheet S1 of the plurality of sheets S stacked and stored on the sheet storage section 11. When the sheet S1 moves until it comes into contact with the sheet and starts rotating, the uppermost sheet S1 is conveyed by the pickup roller 13 to the nip between the feed roller 14 and the retard roller 15, and is supplied to the second feeding unit. At this time, when a plurality of sheets S are supplied in a superposed state, only the uppermost sheet S1 is fed by the feed roller 1.
4 and is separated by the retard roller 15 and supplied to the second feeding unit.

Further, as shown in FIG. 3, the sheet S1 sent from the sheet storage unit 11 of the first feeding unit is
The conveying roller pair 17 of the feeding section rotates, and conveys to the stopped registration roller pair 18. A sheet detection sensor 19 such as an optical sensor that detects the leading end of the sheet S1 is disposed near the upstream side of the registration roller pair 18. The sheet detection sensor 19 is connected to a CPU (sheet supply control unit) 50. Transport roller pair 17,
The registration roller pair 18 and the sheet detection sensor 19 constitute a sheet correcting unit.

The detection signal of the sheet detection sensor 19 is CP
The data is input to U50. The CPU 50
After the sheet detection sensor 19 detects the leading edge of the sheet, the rotation of the registration roller pair 18 is stopped until a predetermined time has elapsed. However, the conveying roller pair 17 continues to rotate, and conveys the intermediate portion of the sheet S. Therefore, the sheet S is
After being curved (forming a loop), the tip is strongly pressed against the pair of registration rollers 18 to remove the resist (correct skew). At the time when a predetermined amount of loop is formed, the conveying roller pair 17 is controlled by a control signal of the CPU 50.
Stop the rotation of.

When the trailing edge of the preceding sheet S1 has passed through the nip between the feed roller 14 and the retard roller 15,
The PU 50 sends the subsequent sheet S to the pickup roller 13.
2 is started. Then, when the leading end of the succeeding sheet S2 overlaps the rear end of the preceding sheet stopped by the pair of conveying rollers 17 by a certain distance, the feed roller feeds the feed roller. 14 and pickup roller 13
Stop the rotation of.

Here, as shown in FIG.
In order to prevent the rear end of the sheet 1 from hitting the front end of the succeeding sheet S2, a space 2 for releasing the sheet is provided at the entrance of the second feeding section.
8 and a convex rear regulating guide 16 projecting downward to guide the rear portion of the preceding sheet S1 by pushing it into the space 28. Therefore, the rear part of the preceding sheet S1 is pushed by the rear regulating guide 16 and pushed into the space 28, and the rear part of the preceding sheet S1 and the front part of the succeeding sheet S2 surely overlap with each other, and Collision can be avoided.

Thereafter, the preceding sheet S1 is fed between the photosensitive drum 21 and the transfer charger 22 by the registration roller pair 18 which has started rotating according to the control signal of the CPU 50. The succeeding sheet S2 is fed again when a space between the succeeding sheet S1 and the preceding sheet S1 becomes a predetermined amount.

Accordingly, the sheet feeding device 10 eliminates the influence of the time for picking up the sheet S2 from the sheet storage means 11 and removes the sheet from the influence of the sliding of the sheet by the feed roller 14 and the retard roller 15. It is possible to feed between the photosensitive drum 21 and the transfer charger 22 at regular intervals, thereby increasing the number of sheets to be fed per unit time and speeding up the image processing of the printer.

Although the trailing end regulating guide 16 is formed in a rib shape from one side of the conveying path, the trailing end regulating guide 16a may be formed over the entire length of the sheet in the width direction (FIG. 5). ). Further, the rear part of the preceding sheet S1 may be pushed into the space 28 by an elastic sheet interference avoiding member (sheet interference avoiding means) 16b (FIG. 6) such as Mylar.

The sheet supply device of the above embodiment is adapted to supply sheets from the sheet storage section 11, and conveys the sheet S from the feed cassette (sheet stacking means) 27 to the conveying roller pair 17. Then, during the conveyance, the rear part of the preceding sheet and the front part of the succeeding sheet may overlap. Further, the space, the rear end regulating guide, and the sheet interference avoiding member may be provided in the middle of the space.

[0046]

According to the sheet feeding apparatus of the present invention, the front portion of the succeeding sheet is overlapped with the rear portion of the preceding sheet, so that the succeeding sheet can be transported in advance and the sheet feeding means can be provided. Irrespective of the time required to start feeding sheets, the sheets can be sequentially fed while keeping the interval between the sheets always at a predetermined interval, and the number of sheets fed per unit time can be increased.

When the sheet feeding device of the present invention is provided with the sheet separating means, when the sheets fed by the sheet feeding means are overlapped, the sheets can be separated and only one sheet can be fed. When the sheet separation unit slips with respect to the sheet and the feeding time is lost, the sheet feeding unit is configured to convey the succeeding sheet in advance, so that the interval between the sheets is reduced. Can be always supplied at a predetermined interval and sheets can be sequentially supplied, and the number of sheets supplied per unit time can be increased.

When the sheet feeding apparatus of the present invention is provided with a relief area, when the front part of the succeeding sheet is overlapped with the rear part of the preceding sheet, one of the sheets escapes to the relief area, and the trailing edge of the preceding sheet and the trailing edge of the succeeding sheet. The sheet can be smoothly conveyed by avoiding abutment with the leading edge.

When the sheet feeding device of the present invention is provided with the sheet interference avoiding means, when the front part of the succeeding sheet is superimposed on the rear part of the preceding sheet, one sheet is urged in one direction by the sheet interference avoiding means. Abutting of the trailing edge of the preceding sheet with the leading edge of the succeeding sheet can be avoided, and the sheet can be transported smoothly.

When the sheet feeding apparatus of the present invention is provided with a relief area and sheet interference avoiding means,
When the front part of the succeeding sheet is overlapped, one sheet is urged in one direction by the sheet interference avoiding means, and is caused to enter the escape area, thereby avoiding abutment between the trailing edge of the preceding sheet and the leading edge of the succeeding sheet. In addition, the sheet can be transported smoothly.

The image forming apparatus of the present invention is provided with the above-mentioned sheet feeding device capable of always feeding the sheets while keeping the interval between the sheets at a predetermined interval, so that the image is reliably formed on the sheets. And an image can be formed on the sheet at high speed.

[Brief description of the drawings]

FIG. 1 is a schematic front sectional view of a printer which is an image forming apparatus provided with a sheet feeding device according to an embodiment of the present invention.

FIG. 2 is a schematic front sectional view of the sheet feeding device according to the embodiment of the present invention.

FIG. 3 is an explanatory diagram illustrating an operation of the sheet feeding apparatus according to the embodiment of the present invention.

FIG. 4 illustrates a sheet feeding device according to an embodiment of the present invention.
FIG. 13 is a diagram of another embodiment of a portion on the downstream side of the transport roller pair.

FIG. 5 illustrates a sheet supply device according to an embodiment of the present invention.
FIG. 13 is a diagram of another embodiment of a portion on the downstream side of the transport roller pair.

FIG. 6 illustrates a sheet feeding device according to an embodiment of the present invention.
FIG. 13 is a diagram of another embodiment of a portion on the downstream side of the transport roller pair.

FIG. 7 is a schematic front sectional view of a printer which is an image forming apparatus provided with a conventional sheet supply device.

FIG. 8 is a diagram illustrating the operation of the sheet feeding apparatus of FIG. 7; (A) is a state diagram before sheet supply starts. (B) is a state diagram during sheet supply. (C) is a diagram showing a state in which the skew of the sheet is being corrected.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 printer (image forming apparatus) 2 main body 10 sheet feeding device 11 sheet storage unit (sheet stacking unit) 13 pickup roller (sheet feeding unit) 14 feed roller (sheet separating unit) 15 retard roller (sheet separating unit) 16 trailing end regulation Guide (sheet interference avoiding means) 16a Rear end regulation guide (sheet interference avoiding means) 16b Sheet interference avoiding member (sheet interference avoiding means) 17 Transport roller pair (sheet correcting means) 18 Registration roller pair (sheet correcting means) 19 Sheet detection Sensor (sheet correcting unit) 21 Photoconductor drum (image forming unit) 22 Transfer charger 27 Feeding cassette (sheet stacking unit) 28 Space (escape area) 50 CPU (sheet feeding control unit)

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3F101 FA01 FB01 FB02 FC11 LA02 LA07 LB03 3F102 AA11 AB01 BA02 BA07 BB02 DA08 EA03 FA08 3F343 FA02 FB02 FC01 FC15 GA02 GB01 GC01 GD01 JA01 JD09 KA04 KA11 LC03 MB13 MC08 MC23

Claims (9)

[Claims] 1. A sheet stacking unit on which sheets are stacked, a sheet supply unit for supplying the sheet from the sheet stacking unit, and a receiving end of the sheet while conveying the sheet supplied by the sheet supply unit. Sheet straightening means for conveying the sheet after correcting the skew of the sheet, and the sheet feeding means so that the front part of the succeeding sheet overlaps the rear part of the preceding sheet whose leading end is received by the sheet straightening means. And a sheet supply control means for causing the subsequent sheet supply operation to be performed. 2. A relief area is provided between said sheet supply means and said sheet straightening means to allow at least one of a rear part of said preceding sheet and a front part of said succeeding sheet to escape in a thickness direction of said sheet. The sheet feeding device according to claim 1, wherein: 3. A front part of the succeeding sheet interferes with a rear end of the preceding sheet by bending a rear part of the preceding sheet in a thickness direction of the preceding sheet between the sheet feeding means and the sheet correcting means. 2. The sheet feeding apparatus according to claim 1, further comprising a sheet interference avoiding unit for avoiding the problem. 4. An escape area between the sheet supply means and the sheet straightening means for allowing at least one of a rear part of the preceding sheet and a front part of the succeeding sheet to escape in a thickness direction of the sheet; Sheet interference avoiding means for bending a rear portion of the preceding sheet in a thickness direction of the preceding sheet to enter the escape area to avoid interference of a front end of the succeeding sheet with a rear end of the preceding sheet. The sheet feeding device according to claim 1, wherein: 5. When a plurality of sheets supplied by said sheet supply means overlap between said sheet supply means and said relief area, said sheet separation means separates said sheet and supplies only one sheet. The sheet feeding device according to claim 2, further comprising: 6. The sheet feeding apparatus according to claim 1, wherein the sheet feeding unit has a rotating body that rotates in contact with the sheet. 7. The sheet straightening means, comprising: a pair of sheet conveying rotary members pressed against each other for pinching and rotating and conveying the sheet; and a tip of the sheet conveyed by the sheet conveying rotary member to rotate. 5. The sheet correction rotating body pair, which stops and temporarily receives the sheet, and conveys the sheet while nipping and rotating the sheet, and a sheet correction rotating body pair. 6. Sheet feeding device. 8. The sheet separating means includes: a driving rotating body;
A driven rotator that is driven in rotation by being pressed against the driving rotator, wherein the driven rotator rotates in a direction to reversely feed the sheet when the sheets are supplied in an overlapping manner. Item 6. A sheet feeding device according to item 5. 9. A sheet supply apparatus according to claim 1, further comprising: an image forming unit configured to form an image on a sheet supplied by the sheet supply apparatus. Image forming apparatus.