JP3254500B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for transferring a toner image on a photoreceptor such as an electronic copying machine onto recording paper.

[0002]

2. Description of the Related Art For example, in an image forming apparatus such as a copying machine,
The image of the original is exposed on a photoreceptor, the image on the photoreceptor is developed to form a toner image, the toner image on the photoreceptor is transferred to recording paper by a transfer processing unit, and further, by a fixing unit. In some cases, the toner image is fixed on recording paper by heating and pressing, and the recording paper is discharged to a sorter or the like. At the subsequent stage of the fixing unit, a straight transport path for transporting the recording paper sent from the fixing unit without reversing, a reversing transport path for reversing and transporting the recording paper sent from the fixing unit, the straight transport path and the reverse transport In some cases, the recording paper is discharged from the merged discharge path.

[0003]

As described above, even if the transport path at the subsequent stage of the fixing unit is different from the straight transport path and the reverse transport path, the transport speed of the recording paper in the merge discharge path is constant. By the way, the required conveyance speed of the recording paper in the two systems of the straight conveyance path and the reverse conveyance path may be different. For example, in the straight conveyance path, the recording sheet sent from the fixing unit is conveyed without being inverted, guided to the merge discharge path, and discharged through the merge discharge path.When the conveying speed in the merge discharge path is increased, Because the straight transport path is short, it straddles both the fixing section and the merging and discharging path, and the recording paper is pulled to convey at different transport speeds, and the roller mark at the fixing section adheres to the recording paper, This may have adverse effects such as wrinkling of the paper. For this reason, the transport speed of the merged discharge path is set to be the same as the transport speed in the fixing unit, and is low.

For example, in a reversing conveyance path, a recording sheet sent from a fixing unit is switched back, conveyed, guided to a merge discharge path, and discharged through the merge discharge path. The path has a long reversing conveyance path for switching back the recording paper. Therefore, in order to increase the productivity, the transport speed of the reverse transport path is increased, and therefore, the discharge speed of the merged discharge path is set in the same manner, and the speed is high.

[0005] In the case where a straight transport path and a reverse transport path are provided, for example, it is conceivable to set the transport speed of the merging and discharging path to an intermediate speed between the two. Even if it is set, when the paper is conveyed on the straight conveyance path, it is unavoidable that the recording paper is pulled and the roller mark adheres to the fixing section as described above. Since the transport speed of the discharge path is slow, the recording paper loops to give stress and productivity is reduced.

It is conceivable to provide a dedicated discharge path for each of the straight transport path and the reverse transport path. However, there are disadvantages such as a complicated mechanism and an increase in cost.

The present invention has been made in view of the above points, has a simple structure, is low in cost, and transports a recording sheet under optimal conditions according to the transport of a straight transport path and a reverse transport path. It is another object of the present invention to provide an image forming apparatus in which the reliability of recording sheet feeding is improved.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a transfer processing section for transferring a toner image on a photoreceptor to recording paper, and a recording apparatus in which the toner image is transferred by the transfer processing section. A fixing section for fixing the toner image on the sheet, a straight conveyance path for conveying the recording sheet sent from the fixing section without reversing the sheet, a reversing conveyance path for reversing and conveying the recording sheet sent from the fixing section; In an image forming apparatus including a merging and discharging path for discharging a recording sheet by merging a straight conveying path and a reverse conveying path, a conveying unit capable of changing a conveying speed of the merging and discharging path,
And a controller configured to control the transport unit in accordance with the transport speed of the straight transport route and the transport speed of the reverse transport route to change the transport speed of the merged discharge route.

[0009]

According to the present invention, when the recording sheet is conveyed from the fixing section through the straight conveyance path, the conveyance speed of the merge discharge path is changed according to the conveyance speed of the straight conveyance path. Further, when the recording sheet is transported from the fixing unit through the reverse transport path, the transport speed of the merge discharge path is changed according to the transport speed of the reverse transport path. In this way, the recording paper is transported under optimal conditions in accordance with the transport in the straight transport path and the reverse transport path.

[0010]

Next, an embodiment of the image forming apparatus of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic configuration diagram of the image forming apparatus.

The image forming apparatus 1 includes an apparatus main body 2 and
The apparatus has a sheet feeding unit 3 connected to one of the apparatus main body 2 and a sorter unit 4 connected to the other of the apparatus main body 2. A photoreceptor 5 is provided on the apparatus main body 2 so as to be rotatable in the direction of an arrow, and a document glass 6 is attached to an upper portion of the apparatus main body 2. An automatic document reversing document feeder 7 is provided on the upper portion of the document glass 6. By simply setting a two-sided document, the document can be automatically reversed and both sides can be copied. An optical system including a light source 8, mirrors 9, 10, 11, 12, a lens 13, and the like are arranged below the original glass 6, and the optical system
The image of the document set thereon is exposed on the photoconductor 5.

Around the photoreceptor 5, a charging electrode 20, a developing unit 21, a transfer electrode 22, a separation electrode 23, and a cleaning unit 24 are arranged, and an image exposed on the photoreceptor 5 by an optical system is formed. After development, the toner image is transferred and recorded on a recording sheet. The transfer processing unit 25 including the transfer electrode 22 and the separation electrode 23 is provided in the automatic double-side transfer device 30.
The automatic double-side transfer device 30 further includes a storage tray 3.
1, a transport section 32, and a transport path 33 are provided. These transfer electrode 22, separation electrode 23, storage tray 31,
The transport unit 32 and the transport path 33 are unitized integrally with the gantry 40. A rail 41 is provided on the gantry 40,
The rail 41 is slidably engaged with a rail 42 of the apparatus main body 2 so that the automatic duplex transfer device 30 can be pulled out to the front side.

In the automatic double-side transfer device 30, when the recording paper is transferred to one side of the recording paper, the recording paper transferred to one side is sent to the transport unit 32 through the separation claw 34, and the transport unit 3
2 to the fixing unit 50. In the fixing section 50, fixing rollers 51 and 52 are disposed vertically facing each other, and a discharge section 60 is provided at a stage subsequent to the fixing section 50. The discharge unit 60 includes a two-sided transfer conveyance path A for reversing the recording paper sent from the fixing unit 50 and conveying the recording paper to the automatic double-side transfer device 30, and a straight conveyance for conveying the recording paper sent from the fixing unit 50 without reversing it. Path B and reversing transport path C for reversing and transporting the recording paper sent from fixing unit 50
And a merging discharge path D for discharging the recording paper by merging the straight conveying path B and the reverse conveying path C.

The recording paper discharged from the merging and discharging path D is sent to a sorter section 4, where the sorter section 4
The page alignment and the sorting of the recording paper are automatically performed.

When transferring to both sides of the recording sheet, the recording sheet which has been reversed on the double-sided transfer conveyance path A and transferred to one side is temporarily stored in the storage tray 31 from the paper feeding mechanism 35 of the automatic double-side transfer apparatus 30. You. This recording paper is stored in tray 3
1 is fed by a paper feed mechanism 35, conveyed by a conveyance path 33, and sent again to the transfer electrode 22 and the separation electrode 23, where transfer and separation are performed on the opposite surface of the recording paper. The sheet is sent to the transport section 32 via the separation claw 34, and is sent from the transport section 32 to the fixing section 50, and further from the straight transport path B or the reverse transport path A of the discharge section 60 to the sorter section 4 from the merge discharge path D.

Below the apparatus main body 2, three paper feed units 80, 81 and 82 are arranged.
Recording papers are stored at 0, 81, and 82, respectively.
Paper feed rollers 83, 84 and 85 are arranged in each of the paper feed units 80, 81 and 82, and intermittently feed recording paper by rotation of a paper feed drive motor (not shown) connected to each of them. Each paper feed unit 80, 81,
The recording paper sent out from the paper feed path 86
From 87 and 88, the paper is sent to the conveyance path 33 of the automatic duplex transfer device 30.

A paper feed unit 3 connected to the apparatus main body 2
, Three paper feed units 90, 91, 92 are vertically arranged, and the paper feed units 90, 91, 92 respectively store recording paper. Paper feed rollers 93, 94, and 95 are arranged in each of the paper feed units 90, 91, and 92, and intermittently feed recording paper by rotation of a paper feed drive motor (not shown) connected to each of them. The recording paper sent from each of the paper feed units 90, 91, and 92 is conveyed from conveyance paths 96, 97, and 98 to conveyance path 99, respectively.
Through the transfer path 33 of the automatic double-side transfer device 30.

Next, the discharge section of the image forming apparatus will be described in detail. FIG. 2 is a schematic configuration diagram of a front surface of the discharge unit, and FIG. 3 is a schematic configuration diagram of a rear surface of the discharge unit.

In the discharge section 60, guide plates 700, 701, 702, 703, 70 for reversing the recording sheet sent from the fixing section 50 and conveying the sheet to the automatic double-side transfer apparatus 30.
4, 722, and 723, and a guide plate 71 that conveys recording paper sent from the fixing unit 50 to the sorter unit 4.
0, 711 are provided, and the recording paper is
Guide plates 720 and 721 that convey from 0 and 703 to guide plates 710 and 711 are arranged. Further, a switching guide 730 is provided between the guide plate 702 and the guide plate 711, and the conveyance path of the recording paper can be switched by the operation of the switching guide 730.

A driving roller 740 is provided on the entry side of the guide plate 700.
However, the driven roller 741 is disposed to face the entry side of the guide plate 710, and the driving roller 740 is rotated by driving means (not shown), and the driven roller 741 is rotated in conjunction with the rotation. A winding sensor 746 is provided at a stage preceding the driven roller 741.
Are detected, and it is detected that the recording paper is wound around the fixing rollers 51 and 52 of the fixing unit 50. Further, a fixing exit sensor 747 is disposed near the driven roller 741,
Detecting conveyance of recording paper.

The drive roller 74 is provided at the exit side of the guide plate 720.
8 is also a driven roller 749 on the exit side of the guide plate 710.
Are arranged facing each other. Gear 7 of drive roller 748
50 is meshed with a drive gear 751, and a pulley 752 provided on this shaft and a pulley 754 of a paper discharge motor 753 are connected by a timing belt 755. Therefore, the pulley 752 is rotated via the timing belt 755 by the driving of the paper discharge motor 753, whereby the drive roller 748 is rotated by the drive gear 751 on the shaft, and the driven roller 749 is rotated in conjunction therewith. A paper exit sensor 793 is disposed near the driven roller 749, and detects that the recording paper is discharged.

The drive roller 756 and the driven roller 743 are provided on the guide plate 700 side, and the drive roller 75 is provided on the guide plate 720 side.
7 and a driven roller 744 are arranged. Drive roller 7
The gear 759 provided on the shaft of the gear 40 meshes with the connecting gear 760, and the gear 760 meshes with the driving gear 762 provided on the shaft of the driving roller 756, and the driving roller 756 is interlocked with the driving roller 740. Rotate. The driving gear 763 of the driving roller 757 is
1 and rotates in conjunction with the drive roller 748.

Driving rollers 770 and 771 are arranged on the entrance side and exit side of the guide plate 701, and driven rollers 772 and 773 are arranged to be driven by the respective driving rollers 770 and 771. These respective drive rollers 772, 7
A pulley 774, 775 on the shaft of 73 and a drive gear 776
A timing belt 778 is stretched over a pulley 777 on the shaft of the
The drive rollers 770 and 771 rotate forward or reverse through the timing belt 778 in the forward or reverse rotation of 76, and the driven rollers 772 and 773 rotate in conjunction with this.
Rotates.

A forward rotation clutch gear 780 is connected to the drive gear 776.
The forward clutch gear 780 has a reverse clutch gear 7
The forward clutch gear 780 and the reverse clutch gear 781 are provided so as to be freely movable on the shaft. A forward clutch 782 is provided on the shaft of the forward clutch gear 780, and a reverse clutch 783 is provided on the shaft of the reverse clutch gear 781. A forward clutch pulley 784 is provided on the shaft of the forward clutch gear 780, and a reverse clutch pulley 785 is provided on the shaft of the reverse clutch gear 781. A timing belt 788 is stretched between the forward clutch pulley 784, the reverse clutch pulley 785, and the pulley 787 of the reverse motor 786, and the rotation of the reverse motor 786 causes the shaft of the forward clutch 784 and the reverse clutch pulley 78 to rotate.
The five axes rotate in the same direction in conjunction with each other. Forward rotation clutch 7
82 or the reverse clutch 783 is selectively operated, so that each shaft and the forward clutch gear 780 are operated.
Alternatively, the reverse clutch gear 781 is selectively connected to rotate integrally. As a result, the drive gear 776 rotates forward or backward, whereby the drive rollers 770 and 771 rotate forward or reverse via the timing belt 778, and the driven rollers 772 and 773 rotate in conjunction with this.

A reversing sensor 7 is provided near the driving roller 770.
Reference numeral 91 is disposed to detect a reversal state of the recording paper. A reversing exit sensor 792 is provided near the driving roller 771.
And detects that the recording paper is conveyed to the automatic double-side transfer device 30.

As described above, the double-sided transfer conveyance path A for reversing the recording sheet sent from the fixing unit 50 and conveying the recording sheet to the automatic double-side transfer device 30 is provided by the guide plates 700, 701, and 70.
2, 703, 704, 722, 723 and the switching guide 7
30, the recording paper is formed by a driving roller 740, a driven roller 741, a driving roller 7
The sheet is conveyed by the operation of the driven roller 56 and the driven roller 743, the driving roller 770 and the driven roller 772, and the driving roller 771 and the driven roller 773.

A straight transport path B for transporting the recording paper sent from the fixing section 50 without reversing the recording paper is formed by the guide plates 710 and 711 and the switching guide 730, and the recording paper is driven by a driving roller 740 constituting transport means.
And driven by the operation of the driven roller 741.

A reversing conveyance path C for reversing and conveying the recording paper sent from the fixing unit 50 is provided on the guide plate 70.
0, 701, switching guide 730 and guide plates 702, 7
03, 704, 722, 723, 720 and 721, and the recording paper constitutes a conveying means. The driving roller 740 and the driven roller 741, the driving roller 756 and the driven roller 743, the driving roller 770 and the driven roller 772, and the driving roller. The recording paper is conveyed by the operation of the driven roller 757 and the driven roller 743.
4. The sheet is conveyed by the reverse rotation of the driving roller 770 and the driven roller 772 and the driving roller 771 and the driven roller 773.

A merging discharge path D for discharging the recording paper by merging the straight conveyance path A and the reverse conveyance path C is formed by a path 790 leading to the sorter section 4, and the recording paper is driven by a driving roller 748 which constitutes a conveying means. And driven by the operation of the driven roller 749.

Winding sensor 746, fixing outlet sensor 74
7. The detection information of the paper discharge exit sensor 755, the reversing sensor 770 and the reversing exit sensor 792 is input to the control means 795. The control means 795 determines the transport motor 743, the switching guide 730, the forward clutch 782, and the reverse clutch 78 based on the detection information and the information from the operation device.
3. Control the paper discharge motor 753 and the reversing motor 786.

Next, the operation of the discharge section 60 of the image forming apparatus will be described in detail with reference to FIG.

When the reverse discharge mode for reversing the recording paper and discharging it to the sorter unit 4 is selected, the switching guide 730 switches to the reverse discharge path C, and the recording paper is fixed in the reverse discharge mode in the reverse discharge mode. 50 from the fixing outlet sensor 74
When 7 is turned on, the forward rotation clutch 782 is turned on, and the paper discharge motor 753 rotates at high speed.

When the recording paper is conveyed, the fixing outlet sensor 747 is turned off, the reversing sensor 791 is turned on, and the forward clutch 782 is turned off and the reverse clutch 783
Is turned on, whereby the driving rollers 770 and 771 and the driven rollers 772 and 773 rotate in the reverse direction and are conveyed in the opposite direction.
Further, the sheet is inverted and conveyed by the operation of the driving roller 757 and the driven roller 744. The recording paper is further discharged by a paper discharge motor 7.
Drive roller 748 and driven roller 749 driven by 86
Is discharged to the sorter unit 4 through the passage 790. At this time, the paper discharge outlet sensor 793 is turned on and the reversing sensor 791 is turned off, and a predetermined time after the reverse rotation clutch 78
3 is turned off, and after a predetermined time, the forward rotation clutch 782
Turns on to prepare for the next transport. In the reverse discharge mode, the discharge motor 753 rotates at a high speed according to the transport speed (720 mm / sec) in the reverse discharge path C, and is transported from the merge discharge path D to the sorter unit 4.

On the other hand, when the straight discharge mode for directly discharging the recording paper to the sorter unit 4 without reversing the recording paper is selected, the switching guide 730 is switched to the straight discharge path B, and the recording paper is switched in the straight discharge mode. Is transported from the fixing unit 50, and when the fixing exit sensor 747 is turned on, the paper discharge motor 753 rotates at a low speed. With this paper discharge motor 753, the drive roller 748 and the driven roller 749 move at the transport speed of the straight transport path B (427 mm / sec).
Rotates at a low speed in accordance with
Transported to

As described above, when the recording sheet is transported from the fixing section 50 through the straight transport path B, the transport speed of the merge discharge path D is changed according to the transport speed of the straight transport path B. Further, when the recording sheet is transported from the fixing section 50 through the reverse transport path C, the transport speed of the merge discharge path D is changed according to the transport speed of the reverse transport path C. As described above, the recording paper can be conveyed under the optimal conditions because the conveyance speed of the merge discharge path D can be changed according to the conveyance of the straight conveyance path B and the reverse conveyance path C.

[0036]

As described above, according to the present invention, the conveying means capable of changing the conveying speed of the merging and discharging path, and the conveying means are controlled according to the conveying speed of the straight conveying path and the conveying speed of the reverse conveying path. And control means for changing the transport speed of the merged discharge path, so that the transport can be performed at an optimal transport speed at a low speed when transporting the straight transport route and at a high speed when transporting the reverse transport route. Therefore, without lowering the productivity of the reverse transport, and even when transporting on the straight transport path, it is possible to transport without generating roller marks and without wrinkles or the like on the recording paper, The reliability of feeding is improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus.

FIG. 2 is a schematic configuration diagram of a front surface of a discharge unit.

FIG. 3 is a schematic configuration diagram of a back surface of a discharge unit.

FIG. 4 is described in detail based on a time chart at the time of reverse conveyance.

[Explanation of symbols]

 5 Photoreceptor 25 Transfer processing section 50 Fixing section B Straight transport path C Reverse transport path D Merging discharge path

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 15/00 B65H 29/20 B65H 29/58 B65H 29/60 B65H 43/00

Claims (1)

(57) [Claims] A transfer unit configured to transfer the toner image on the photosensitive member onto a recording sheet; a fixing unit configured to fix the toner image on the recording sheet onto which the toner image has been transferred by the transfer processing unit; A straight transport path for transporting the recording paper without reversing it, a reverse transport path for reversing and transporting the recording paper sent from the fixing unit, and discharging the recording paper by merging the straight transport path and the reverse transport path An image forming apparatus having a merging and discharging path, wherein the conveying means is configured to change the conveying speed of the merging and discharging path, and the conveying means is controlled according to the conveying speed of the straight conveying path and the conveying speed of the reverse conveying path. An image forming apparatus comprising: a control unit configured to control and change a transport speed of the merged discharge path.