JP2003155145A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device for improving jam processing performance in a sheet carrying part. SOLUTION: When jam is generated at any place within this device while carrying a sheet P by a pair of resist rollers 8, the carrying of the sheet P by the pair of the resist rollers 8 is continued till a rear end of the sheet P passes the pair of resist rollers 8.

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 such as a copying machine, a facsimile, a laser beam printer, etc., and more particularly to a technique related to jamming a sheet.

[0002]

2. Description of the Related Art An example of a conventional laser beam printer (hereinafter referred to as "LBP") using an electrophotographic system is shown in FIG.

The illustrated LBP is a four-drum full-color type LBP, and 50Y, 50M, 50C, and 50K are photosensitive drums, and each image forming is provided with a developer (toner) of each color of yellow, magenta, cyan, and black. It is provided for each station.

Photosensitive drums 50Y, 50M, 50C, 5
A latent image is formed on the surface of 0K by exposure with laser light emitted from the corresponding laser scanner devices 51Y, 51M, 51C, and 51K. This latent image
Toner images are formed by being developed by developing materials of yellow, magenta, cyan, and black, respectively. 52
Is an intermediate transfer belt, and each photosensitive drum 50Y, 50M, 5
The toner images of each color formed by 0C and 50K are primarily transferred.

A sheet P, which is a transfer material, is stacked on the sheet feeding cassette 53. The sheet P is fed by the paper feed roller 54, conveyed by the feed / retard roller pair 55, the conveyance roller pairs 56, 57, and conveyed to the registration roller pair 59 which is stopped. After the skew of the sheet P is corrected by the pair of registration rollers 59, the sheet P is conveyed to the secondary transfer device 60 at a predetermined timing to transfer the toner image on the intermediate transfer belt 52, and then the sheet of the secondary transfer device 60 is transferred. The secondary transfer roller 60 a and the intermediate transfer belt 52 convey the toner image to the fixing device 61 to fix the toner image. The sheet P that has passed through the fixing device 61 is
The sheet is conveyed by the pair of sheet discharge rollers 62 and 63 and discharged and stacked on the sheet discharge tray 64.

When the sheet P is jammed in the sheet feeding portion of the color LBP, the right door 70 is rotated in the direction of arrow D as shown in FIG. The upper side of the sheet path is opened apart from 57a. Therefore, the user can remove the jam sheet relatively easily by using this space.

[0007]

However, the above-mentioned color LBP has the following problems. That is, depending on the jam occurrence position of the sheet P, for example, when the leading edge of the jam sheet P'is present in front of the registration roller pair 59 (upstream side) as shown in FIG. To release the seat P '
It can be easily removed by grasping the tip.

However, in order to prevent the unfixed toner on the sheet P'from adhering to the registration roller pair 59, the registration roller pair 58 has a reverse rotation preventing mechanism (not shown), and the registration roller pair is only in the direction of arrow E. As shown in FIG. 5, when the jammed sheet P ′ is sandwiched by the registration roller pair 59, the jammed sheet P ′ is held even if the rear end of the sheet P ′ is grasped and pulled. In some cases, it could not be pulled out from the registration roller pair 59, and it took time to clear the jam. Further, if the jam sheet P'is pulled by force, the sheet P'may be damaged or the torn sheet P'may remain in the apparatus main body.

An object of the present invention is to solve the above-mentioned problems of the prior art and to provide an image forming apparatus having improved jam handling property in the sheet conveying section.

[0010]

To achieve the above object, an image forming apparatus of the present invention comprises an image carrier, a transfer unit for transferring a toner image carried on the image carrier to a sheet, and a sheet. Fixing means for fixing the transferred toner image on the sheet, correcting skew of the conveyed sheet, and nipping and conveying the sheet in synchronization with the toner image carried on the image carrier. If a jam occurs at any place in the apparatus while the resist means and the sheet are conveyed by the resist means, the sheet is conveyed by the resist means until the trailing edge of the sheet passes through the resist means. And a control means for continuing the operation.

The control means stops the driving of the fixing means, the image carrier and the transfer means when a jam occurs at any place in the apparatus while the sheet is conveyed by the registration means, In addition, after releasing the nip of the fixing unit and separating the transfer unit and the image carrier, the registration unit is driven after waiting for the trailing edge of the sheet to pass through the registration unit. You should stop it.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be illustratively described in detail below with reference to the drawings. In addition,
Here, a color LBP will be described as an example of the image forming apparatus, but the present invention can be preferably applied to other image forming apparatuses such as electrophotographic copying machines, printers, and facsimiles.

FIG. 1 is a sectional view showing a schematic structure of a collar LBP according to an embodiment of the present invention.

First, the schematic structure of the color LBP will be described with reference to FIG. In FIG. 1, 1 is a color LBP
At the lower part of the apparatus, a sheet cassette 2 as a sheet storage means is equipped so as to be drawn out. As the sheet cassette 2, a universal cassette or the like that can be exchanged for each sheet size or can accommodate sheets P of a plurality of sizes is used.

A feeding roller 3 as a feeding means has a half-moon shape and rotates in response to a feeding start signal to sequentially feed the sheets P stacked in the sheet cassette 2. A pair of retard rollers 4 separates and conveys the sheets P sent by the feeding roller 3 one by one.

The sheet P separated and conveyed by the retard roller pair 4 is conveyed by the conveying roller pair 5 and the conveying roller 6.
And is driven by the driven roller 7. The transport roller pair 5 and the transport roller 6 are provided on the apparatus main body side, and the drive is transmitted by a driving unit (not shown) to be rotationally driven. The driven roller 7 is rotatably attached to the right door 9, and the driven roller 7 is configured to come into pressure contact with / separate from the transport roller 6 according to the opening / closing operation of the right door 9.

Reference numeral 8a is a pre-registration sensor for detecting the edge of the sheet P. A pair of registration rollers 8 serves as registration means, and is intermittently controlled by a clutch mechanism (not shown). The registration roller pair 8 is not driven by the clutch mechanism, but starts rotation after correcting skew of the sheet P and synchronizing with the intermediate transfer belt 12 to transfer the sheet P to the secondary transfer portion. It is nipped and conveyed toward 13.

Next, the structure of the image forming means will be described. 20Y, 20M, 20C and 20K are photosensitive drums.
Developing means 21Y, 21M provided with developing materials (toners) of yellow, magenta, cyan, and black, respectively.
21C and 21K are provided for each image forming station.

Each photosensitive drum 20Y, 20M, 20C, 2
A latent image is formed on the surface of 0K by exposure with laser light emitted from the corresponding laser scanner devices 22Y, 22M, 22C, and 22K. This latent image
The developing device 21Y, 21M, 21C, 21K develops the toner image. Reference numeral 12 denotes an intermediate transfer belt as an image carrier that carries a toner image, and the toner image for each color formed on the surface of each photosensitive drum 20Y, 20M, 20C, 20K is primarily transferred.

The toner image primarily transferred to the intermediate transfer belt 12 is secondarily transferred to the sheet P conveyed by the registration roller pair 8 in the secondary transfer portion 13. Here, the secondary transfer roller 11 constitutes a transfer means for transferring the toner image carried on the intermediate transfer belt 12 onto the sheet.

The sheet P to which the toner image is secondarily transferred is
The toner image is fixed by being sandwiched between the intermediate transfer belt 12 and the secondary transfer roller 11 and conveyed to a fixing device 14 as a fixing means. The sheet P that has passed through the fixing device 14 is conveyed by the pair of discharge rollers 15 and 16 and the discharge tray 1
7 is discharged and loaded.

Next, the jam processing operation in the color LBP1 will be described.

A series of jam processing operations described below is C
It is executed by the control unit 30 including a PU and a memory.

When a jam occurs at any place in the sheet conveying path in the apparatus, the control means 30 first separates the secondary transfer roller 11 from the intermediate transfer belt 12 by a driving mechanism (not shown). Next, the driving of the fixing device 14 and the intermediate transfer belt 12 is stopped. Next, the lower roller 14b of the fixing device 14 is separated from the upper roller 14a by a separation mechanism (not shown).

At this time, the registration roller pair 8 and the conveyance roller pairs 5, 6 and 7 arranged upstream of the registration roller pair 8 continue to be driven, and at least the trailing end of the sheet P being conveyed is the registration roller pair 8. Continue to rotate until it passes through the nip part of. Since the sheet size can be determined in advance by the sheet cassette 2, the rotation time of the registration roller pair 8 and the conveyance roller pairs 5, 6, and 7 is determined by the time management after the pre-registration sensor 8a detects the leading edge of the sheet. The drive stop time is determined.

Next, when the trailing edge of the sheet P passes through the nip portion of the registration roller pair 8, the control means 30 stops the driving of the registration roller pair 8 and the conveyance roller pairs 5, 6 and 7. At this time, the sheet P is released from the nipping of the registration roller pair 8, and is stopped in a accordion-like corrugated state between the secondary transfer portion 13 and the registration roller pair 8. Then, the user opens the right door 9 and seats P
It can be easily grasped and removed.

Even if the sheet P is located between the secondary transfer portion 13 and the fixing device 14, the secondary transfer roller 11
Is separated from the intermediate transfer belt 12, and the fixing device 1
Since the lower roller 14b of No. 4 is separated from the upper roller 14a, the jam processing can be performed without damaging the device or the sheet P even if the sheet P is pulled to the upstream side (right door 9 side).

Although the above embodiment has been described for the case of feeding the cassette, the same effect can be obtained even if an optional feeder or the like is connected. Further, the above-mentioned embodiment is
Although the color LBP has been described as the image forming apparatus,
The present invention is not limited to this, and can be applied to other devices such as a copying machine and a facsimile device.

[0029]

As described above, according to the present invention, when a jam occurs, the sheet conveyance by the registration means is continued until the trailing edge of the sheet passes through the registration means. Since it is released from the pinch, it is possible to easily perform jam processing without damaging the sheet.

When a jam occurs, if the nip of the fixing means is released and the transfer means and the image carrier are separated from each other, the device parts and the sheet will be damaged when the sheet is taken out from the apparatus. It is possible to effectively prevent the jamming and further facilitate the jam processing.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a schematic configuration of a collar LBP according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a schematic configuration of a conventional collar LBP.

FIG. 3 is an explanatory diagram showing a jam processing operation in a conventional color LBP.

FIG. 4 is an explanatory diagram when a jam occurs in a conventional color LBP.

FIG. 5 is an explanatory diagram when a jam occurs in a conventional color LBP.

[Explanation of symbols]

1 color LBP (image forming device) 2 sheet cassette 3 feeding rollers 4 retard roller pair 5 Transport roller pair 6 transport rollers 7 Driven roller 8 Registration roller pair (resist means) 8a Pre-registration sensor 9 Right door 11 Secondary transfer roller (transfer means) 12 Intermediate transfer belt (image carrier) 13 Secondary transfer part 14 Fixing device (fixing means) 14a Upper roller 14b Lower roller 15, 16 Paper ejection roller pair 17 Output tray 20Y, 20M, 20C, 20K Photosensitive drum 21Y, 21M, 21C, 21K developing means 22Y, 22M, 22C, 22K laser scanner device 30 control means P sheet

Continued front page    F-term (reference) 2H027 DC15 DC16 DE07 ED17 EE05                       EK10 EK11                 2H072 AA02 AA13 AA24 AB07 BA12                       CA01 CA02 CB09 EA11 EA19                 3F048 AA02 AA04 AA05 AB01 BA14                       BB02 BD05 DA07 EA03 EA12                 3F102 AA02 AB01 BA02 BB02 CA03                       CB01 DA08 EA03

Claims (2)

[Claims] 1. An image carrier, transfer means for transferring the toner image carried on the image carrier onto a sheet, and fixing means for fixing the toner image transferred onto the sheet onto the sheet. A registration unit that corrects skew of the sheet and holds and conveys the sheet by synchronizing with the toner image carried on the image carrier, and one of the inside of the apparatus while the sheet is conveyed by the registration unit. An image forming apparatus comprising: a control unit that continues the conveyance of the sheet by the registration unit until a trailing edge of the sheet passes the registration unit when a jam occurs at a place. 2. The control means stops driving the fixing means, the image carrier and the transfer means when a jam occurs at any place in the apparatus while the sheet is being conveyed by the registration means. And releasing the nip of the fixing means and separating the transfer means and the image carrier from each other, waiting for the trailing edge of the sheet to pass through the registration means, The image forming apparatus according to claim 1, wherein the driving is stopped.