JP2002372816A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent unfixed toner from adhering to other parts in jamming disposal of a sheet. SOLUTION: A copying machine 30 is equipped with a pair of resist rollers 11 carrying the sheet, a pair of pre-transfer rollers 10 carrying the sheet carried by the pair of rollers 11 to a downstream side, a top sensor 23 detecting an abnormal state in carrying the sheet in the copying machine, a carrying frame 12 capable of turning while supporting the pair of rollers 10, and a control part 21 actuating at least either the pair of rollers 11 or the pair of rollers 10 based on the detection operation of the top sensor 23 and carrying the sheet by a specified distance so that looseness may be formed on the sheet stopped extending over the roller pairs 11 and 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a copying machine for forming an image on a sheet, a laser beam printer, an ink jet printer, a facsimile machine, and an image forming apparatus such as a multifunction machine having a plurality of these functions.

[0002]

2. Description of the Related Art Examples of an image forming apparatus for forming an image on a sheet include a copying machine, a laser beam printer, an ink jet printer, a facsimile machine, and a multifunction machine having a plurality of these functions.

A copying machine generally has a reading function of reading an image of a document or the like, and copies an image on a sheet based on the read image information. recent years,
Many copying machines have a function of receiving image information sent from outside with a communication function and the like and forming an image on a sheet based on the image information.

[0004] A printer is generally an external device,
For example, an image is formed on a sheet based on image information sent from a device such as a computer.

Further, a facsimile machine is generally
A reading function and a communication function for reading an image of a document or the like are provided, and the read image information is sent to the outside, and an image is formed on a sheet based on the image information sent from the outside.

In recent years, a multifunction peripheral having a plurality of functions of a copier, a printer, and a facsimile has been commercialized in recent years.

Conventionally, in an image forming apparatus of this type, for example, an electrophotographic image forming apparatus, a roller pair commonly called a registration roller pair is arranged upstream of a photosensitive drum.

The registration roller pair is rotatably supported on the front plate and the rear plate of the apparatus main body. The registration roller pair temporarily receives the sheet sent from the sheet supporting means such as a cassette or the like at the nip portion, corrects the skew of the sheet tip (skew correction), and then adjusts the image position of the rotating photosensitive drum. It is responsible for adjusting the feeding timing so that the leading edge of the sheet fits the feeding.

In order to correct skew, the registration roller pair is set to a high roller pressure (roller pressing force) (about 2K).
g or more). Further, the registration roller pair requires a clutch, such as an electromagnetic clutch, which coaxially turns on and off the transmission of the rotational force from the drive source in order to temporarily stop the sheet. For this reason, in general, the pair of registration rollers is mounted on a front plate and a rear plate having sufficient strength to support a high roller pressure and to support a heavy clutch.

As described above, the registration roller pair needs to be firmly attached to the front plate and the rear plate. For this reason, in the conventional image forming apparatus, when a sheet jam occurs between a registration roller pair and a transfer unit that transfers a toner image from a photosensitive drum to a sheet, so-called jam occurs, a process of removing the jam sheet (hereinafter, referred to as a process) (Referred to as “jam clearing”), it is difficult to separate the rollers of the pair of registration rollers to open the sheet conveying path and make it easy to remove the sheet. Therefore, a conventional image forming apparatus is often configured to open a sheet conveying path on the downstream side of the registration roller pair. in this case,
The user can open the sheet conveyance path, manually rotate the pair of registration rollers, and send out and take out the jammed sheet to perform the jam processing.

[0011]

However, in the conventional image forming apparatus, when a paper jam occurs, the user may push the transfer unit side with the rear end side of the sheet strongly and slightly sandwiched between the pair of registration rollers. Since the sheet is opened, the leading end side of the sheet may rub against a member of the apparatus main body as the sheet is released. At this time, if there is an unfixed toner image formed at the transfer section and not yet fixed to the sheet at the leading end side of the sheet, the unfixed toner image is transferred to a member such as a guide for guiding the sheet of the apparatus body. May adhere to For this reason,
In a conventional image forming apparatus, when a user ends a jam process and forms an image again, a toner image adhered to a member such as a guide adheres to a new sheet and is formed on a new sheet. There is a problem that the resulting image becomes dirty.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus in which an unfixed toner image of a sheet stopped at a transfer section during a jam processing is prevented from adhering to other components.

[0013]

In order to achieve the above object, an image forming apparatus according to the present invention comprises a first sheet conveying means for conveying a sheet, and the sheet conveyed by the first sheet conveying means. A second sheet conveying unit that conveys the sheet to the downstream side, a conveyance abnormality detecting unit that detects a sheet conveyance abnormal state in the image forming apparatus, and the first sheet conveying unit and the second sheet conveying unit. Supporting either one of the first sheet conveying means and the second sheet conveying means based on the detection of the rotatable rotating member and the conveyance abnormality detecting means, and operating at least one of the first sheet conveying means and the second sheet conveying means. ,
Control means for conveying the sheet a predetermined distance so as to form a slack in the sheet stopped over the first sheet conveying means and the second sheet conveying means.

In the image forming apparatus of the present invention, the rotating member is
The first sheet conveying means and the second sheet conveying means are provided so as to be rotatable around a fulcrum arranged on the upstream side in the sheet conveying direction along the sheet conveying path. The second sheet conveying means is disposed at a position where the distance from the means is widened, and a sheet conveying path between the first conveying means and the second conveying means can be opened.

In the image forming apparatus of the present invention, the rotating member is
The first sheet conveying means and the second sheet conveying means are provided so as to be rotatable around a fulcrum arranged on the upstream side in the sheet conveying direction along the sheet conveying path. The first sheet conveying means is provided at a position where the distance between the first conveying means and the second conveying means is widened, and a sheet conveying path between the first conveying means and the second conveying means can be opened.

The image forming apparatus of the present invention is provided with sheet detecting means for detecting that a sheet is straddling the first sheet conveying means and the second sheet conveying means,
The control unit does not operate the first conveyance unit and the second conveyance unit when the sheet detection unit does not detect the sheet, and does not operate the first conveyance unit when the sheet detection unit detects the sheet. Means for activating at least one of the means and the second transport means.

The control means of the image forming apparatus according to the present invention comprises:
By operating both the first sheet conveying means and the second sheet conveying means, and making the first sheet conveying means larger in sheet conveyance amount than the second sheet conveying means, The sheet is conveyed a predetermined distance so as to form a slack in a sheet stopped over the first sheet conveying means and the second sheet conveying means.

In the image forming apparatus according to the present invention, the control unit includes:
The second sheet conveying means is operated in reverse to move the sheet at a predetermined distance so as to form a slack in the sheet stopped over the first sheet conveying means and the second sheet conveying means. It is designed to be transported.

To achieve the above object, an image forming apparatus according to the present invention comprises a first sheet conveying means for conveying a sheet,
Second sheet conveying means for conveying the sheet conveyed by the first sheet conveying means to a downstream side, and image forming means for forming an image on the sheet conveyed by the second sheet conveying means A guiding unit for guiding the sheet conveyed by the second sheet conveying unit to the image forming unit; a conveying abnormality detecting unit for detecting a sheet conveying abnormal state in the image forming apparatus; A rotation member having a sheet conveyance unit and the guide unit, the rotation member being rotatable in a direction away from the image forming unit along the sheet conveyance path with an upstream side in a sheet conveyance direction as a fulcrum; Control means for operating the first sheet conveying means based on the detection of the detecting means to convey the sheet by a predetermined distance to the downstream side.

In the image forming apparatus according to the present invention, the second sheet conveying means may be configured such that the first sheet conveying means and the second sheet are provided when the rotating member is rotated in a direction away from the image forming means. The predetermined distance that the first sheet conveying means conveys the sheet is provided at a position where the distance from the conveying means is widened, and is a distance exceeding the widened distance.

The image forming apparatus of the present invention detects that a sheet is straddling between the first conveying means and the second conveying means between the second conveying means and the image forming means. Sheet detection means for performing the control, the control means,
When the sheet detecting unit does not detect the sheet, the first conveying unit and the second conveying unit are not operated, and when the sheet detecting unit detects the sheet, the first conveying unit and the second conveying unit are not operated. At least one of the transfer means is operated.

The sheet detecting means of the image forming apparatus of the present invention has a function of detecting a sheet conveyance abnormality.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A copying machine which is an image forming apparatus according to an embodiment of the present invention will be described below with reference to FIGS.

In the following description, the dimensions, materials, shapes, relative positions, and the like of the components described are merely examples, and unless otherwise specified, the scope of the present invention is limited thereto. Not something.

(Copier of First Embodiment) FIG. 1 is a diagram showing a main part of a copier and a cross-sectional view along a sheet conveying direction. The copying machine 30 includes a laser scanner (not shown) that irradiates a laser beam to the photosensitive drum (image forming unit) 1 based on image information obtained from an external device or image information of a document read by an image reading device. I have. A latent image is formed on the photosensitive drum 1 by this laser scanner. The copying machine 30 also includes a developing device 3 for developing the latent image into a toner image.

On the other hand, a sheet conveying path 25 for guiding the sheet P sent from a sheet supporting portion such as a cassette (not shown) to the photosensitive drum 1 has a pair of registration rollers (first sheet conveying means) 11 and a pre-transfer roller. A roller pair (second sheet conveying means) 10 is provided. These roller pairs 1
Numerals 0 and 11 feed the sheets separated and fed one by one from the sheet support unit into the nip between the photosensitive drum 1 and the transfer roller 6.

The transfer roller 6 is supported by the transfer arm 7 and is urged by a spring 19 to the photosensitive drum 1 at a predetermined pressure. The transfer roller 6 and the spring 19 are connected to the transfer unit 1.
6. The transfer section 16 transfers the toner image from the photosensitive drum 1 to the sheet P. The toner image remaining on the photosensitive drum 1 after the transfer is removed by the cleaner 2. As a result, the surface of the photosensitive drum 1 is cleaned, and the photosensitive drum 1 is used for the next image formation.

The fixing device 4 is disposed downstream of the transfer roller 6. Between the transfer roller 6 and the fixing device 4, a conveyance guide 26 for guiding the sheet P on which the toner image has been transferred to the fixing device 4 is provided. In the fixing device 4, the fed sheet is heated and pressed to fix a toner image. The sheet on which the toner image has been fixed is further conveyed and discharged outside the apparatus by a discharge roller pair (not shown).
Thus, the image formation by the copying machine 30 ends.

The image forming operation of the copying machine 30 is controlled by a control section (control means) 21. The control unit 21 controls the registration roller pair 11 based on the detection of a sheet by a top sensor (sheet detection unit) 23 that detects whether or not the sheet P has reached between the photosensitive drum 1 and the transfer unit 16. The rotation of the registration roller pair motor 20 to be rotated is controlled, the rotation of the pre-transfer roller pair motor 22 for rotating the pre-transfer roller pair 10 is controlled,
Further, the rotation of a motor (not shown) for rotating another pair of rollers is controlled. Top sensor 2
When the sheet P is detected in Step 3, it is determined that the sheet P straddles the registration roller pair 11 and the pre-transfer roller pair 10.

In addition to the function of detecting the leading edge of the sheet, the top sensor 23 has a jam detecting function of detecting that a sheet has jammed.

The registration roller pair motor 20 and the pre-transfer roller pair motor 22 are separated from each other.
A common motor may be used. In this case, it is necessary to provide a clutch between the common motor and each roller pair so that the rotation of one roller pair can be stopped while the other roller pair is stopped.

In the copying machine 30, when a sheet jam (jam) occurs during conveyance, the user needs to remove the jammed sheet. Therefore, it is necessary to secure a space between the photosensitive drum 1 and the fixing device 4 for removing the jammed sheet. Therefore, when the distance between the photosensitive drum 1 and the fixing device 4 is short, the roller base 17 for holding the pre-transfer roller pair 10, the transfer unit 16, and the transport guide 26 are connected to the transport frame 1.
2 so that these members 17, 16, and 26 can move integrally.

The transport frame 12 is provided with a sheet transport path 25
Is provided rotatably at a rotation fulcrum (fulcrum) 12a disposed upstream along the sheet conveying direction. Transport frame 12
Is closed when the guide member 24 on the apparatus main body side is closed.
Form a sheet transport path 25.

The transport frame 12 is normally held at a closed position by a cam 15. The user can use the handle 14
Is rotated in the direction of arrow A, the holding of the transport frame 12 by the cam 15 is released, and the transport frame 12
As shown in FIG. The space B for removing the jammed sheet by opening the sheet conveying path 25 by rotating the conveying frame 12 can be secured.

Next, the operation at the time of jam clearance will be described with reference to the flowchart shown in FIG. Jam processing is
The jam removal procedure differs depending on where the sheet is jammed.

First, a sensor which is an abnormality detecting means for detecting an abnormal state of sheet conveyance provided in a plurality of sheet conveying paths of the entire copying machine 30, for example, a jam detection sensor (not shown) , One of which is detected) (S1).
01), the copying machine 30 enters a jam processing task.

As described above, when any one or a plurality of the jam detection sensors (not shown) detects a jam, the control unit 21 controls the pair of registration rollers for conveying the sheet. The motor 20 and the pre-transfer roller pair motor 22 are turned off (S102), and the sheet P is stopped at that position. When the sheet detection sensor detects a jam, the control unit 21 stops the operation of the entire copying machine.

If there is no jammed sheet in the transfer unit 16,
That is, the top sensor (sheet detecting means) 23
In the F state (S103), the user moves the handle 14 with the arrow A
By rotating in the direction, the transport frame (rotating member) 1
2 rotates around the rotation fulcrum 12a, and can secure a jam clearance space B near the transfer unit 16. At this time, since the sheet does not straddle between the pair of registration rollers 11 and the pair of pre-transfer rollers 10, the sheet can be removed as it is without moving even if the transport frame 12 is rotated.

In (S103), if the jammed sheet is on the transfer roller 6, the top sensor 23 is turned on. At this time, the control section 21 rotates the registration roller pair motor 20 by a fixed amount and stops it (S104, S1).
05), and feed the sheet slightly downstream. For example, about 2
Feed in about 0 mm. The feeding distance is defined as L3. Then, a sufficient loop (slack) is formed between the registration roller pair 11 and the pre-transfer roller pair 10.

As a result, even if the transport frame 12 is rotated in the jam clearing operation, the sheet sandwiched between the registration roller pair 11 and the pre-transfer roller pair 10 moves by the distance L3, but (L2−L1 ) <L3, the sheet on the transfer roller 6 hardly moves. The distance L1 is set between the nip 11a of the registration roller pair 11 and the nip 1 of the pre-transfer roller pair 10 during the normal operation in FIG.
0a. As shown in FIG. 2, the distance L2 is between the nip 11a of the pair of registration rollers 11 and the nip 1 of the pair of pre-transfer rollers 10 when the transport frame 12 is rotated.
0a.

Since the copying machine 30 of the present embodiment is set to have such a distance relationship, the unfixed portion of the toner image does not come into contact with the transfer guide (guide means) 9.
The transfer guide 9 is not stained by the toner.

In the copying machine 30 of this embodiment, the unfixed toner image of the sheet when the sheet straddling the pair of registration rollers 11 and the pair of pre-transfer rollers 10 is jammed is transferred to the transfer guide 9.
Not only can be prevented from adhering to the sheet, but also the sheet is jammed in a conveyance path other than the conveyance path between the registration roller pair 11 and the pre-transfer roller pair 10, so that the user can see the inside of the copying machine. When another sheet is straddled between the registration roller pair 11 and the pre-transfer roller pair 10 when the transport frame 12 is opened, the unfixed toner image of the sheet does not adhere to the transfer guide 9. You can also

Accordingly, the copying machine 30 of the present embodiment
Since the transfer guide 9 is not stained by the unfixed toner image during the jam processing, a new sheet after the jam processing is not stained, and a high-quality image is formed immediately after the jam processing. Sheets can be provided.

Further, in the copying machine 30 of the present embodiment, the distance between the registration roller pair 11 and the pre-transfer roller 10 is reduced from the distance L1 to the distance L2 by rotating the transport frame 12 by the user during the jam processing. Even if the sheet spreads, the registration roller pair 11 is rotated to form a loop (slack) on the sheet, so that the sheet is hardly pulled by the fixing roller pair 10 and the registration roller pair 11. Has become. For this reason, the copying machine 30 does not damage the jam sheet. In addition, the sheet is loosened, so that the jam can be easily removed.

Further, in the copying machine 30 of the present embodiment, a loop (slack) is formed between the registration roller pair 11 and the pre-transfer roller pair 10 by rotating only the registration roller pair 11. By rotating the pair of rollers 11 and the pair of pre-transfer rollers 10 to operate the pair of registration rollers 11 for a longer time than the pair of pre-transfer rollers 10 or by increasing the conveyance speed of the pair of registration rollers 11, The loop (slack) may be formed by increasing the sheet conveyance amount.

The transport frame 12 is rotatably supported on a pivot 12a located at the upstream end.
Even in the case where the transfer guide 9 is rotatably supported on a rotation fulcrum (not shown) located downstream of the transfer roller 6, the transfer guide 9 may be stained by unfixed toner during jam processing. However, by forming a loop (slack) on the sheet as in the present embodiment, the transfer guide 9 is not stained by unfixed toner. Therefore, the present invention can be applied not only to a copying machine having a transport frame having a rotation fulcrum on the upstream end side, but also to a copying machine having a transport frame having a rotation fulcrum on the upstream end side. it can.

(Copier of Second Embodiment) Next, an example in which the present invention is applied to a copier 130 having a vertical sheet conveying section will be described with reference to FIGS. FIG. 4 shows a state where the sheet conveyance path 125 is opened to remove the jammed sheet P. FIG. 5 is a diagram illustrating a state in which the side plate 122 (rotating member) is closed.

The copier 130 of the present embodiment includes the fixing device 10
6 is provided on the apparatus body 131, and the registration roller pair 102 is provided on the side plate 122. When the side plate 122 is opened, the distance L4 between the registration roller pair 102 and the fixing device 106 becomes longer.

At the lower portion of the apparatus main body 131 of the copying machine 130, a cassette 100 as sheet supporting means for supporting sheets is provided. The sheet sent from the cassette 100 is supplied to the sheet transport path 1 provided substantially vertically.
An image is formed by being sent along the line 25. A registration roller pair (first sheet conveying means) 102, a transfer unit 104, and a fixing device 106 are sequentially arranged along the sheet conveying path 125. An automatic image reading device 108 for automatically reading an image of a document is provided at an upper portion of the apparatus main body 131.

The transfer section 104 includes a photosensitive drum 110 and a transfer roller 112 which is urged against the photosensitive drum 110 with a predetermined pressure. A latent image is formed on the photosensitive drum 110 by the laser beam emitted from the laser scanner 114. The latent image is developed into a toner image by the developing device 116. The toner image is transferred to the sheet by the transfer roller 112.

The sheet on which the toner image has been transferred is
The sheet is fixed by a pair of fixing rollers (second sheet conveying means) 118 and discharged to a discharge space A between the automatic image reading apparatus 108 and an upper portion of the apparatus main body 131 by a pair of discharge rollers 120.

The side plate 122 of the copying machine 130 is rotatably provided at a rotation fulcrum (fulcrum) 122a on the upstream side (lower side in the drawing) in the sheet conveyance direction along the sheet conveyance path 125. The side plate 122 is provided with the registration roller pair 102 and the transfer roller 112. When the side plate 122 is closed, the transfer roller 112 is the transfer roller 6 of the first embodiment.
In the same manner as described above, the spring is urged toward the photosensitive drum 110 by a spring (not shown). With this configuration, when a sheet is jammed in the sheet conveyance path 125 (jam occurs), the user opens the side plate 122 as shown in FIG. 4 and removes the sheet P stopped on the sheet conveyance path 125. be able to.

In the sheet conveying path from the cassette 100 to the discharge roller pair 120, a plurality of jam detecting sensors (transport abnormal state detecting means) (not shown) are provided to detect jamming of sheets (jam indicated by reference numeral 123). The sensing sensor is one of them). Also, the copier 130
Has a control means (control means) 121 for rotating the pair of registration rollers 102 by a predetermined amount when the jam detection sensor detects a sheet jam.

The image forming operation of the copying machine 130 is controlled by the control unit 1
21. Control unit 12
1 controls the rotation of the registration roller pair motor 126 that rotates the registration roller pair 102, controls the rotation of the fixing roller pair motor 128 that rotates the fixing roller pair 118, and controls the other roller pair. The rotation of a motor (not shown) to be rotated is controlled.

The jam detection sensor 123 has a jam detection function for detecting that a sheet has jammed, a function for detecting the leading edge of the sheet, and a registration roller pair 102 and a fixing roller pair 118. It also has a function of detecting a sheet straddling the.

A plurality of jam detecting sensors (not shown) provided in the sheet conveying path of the entire copying machine 130 are provided.
Is one of the jam detection sensors), the copier 130 detects
Enter the jam handling task.

The control unit 121 stops the registration roller pair motor 126 and the fixing roller pair motor 128 of the fixing roller pair 118, and stops the rotation of the registration roller pair 102 and the fixing roller pair 118.

At this time, when the jam detecting sensor 123 detects that the sheet is stopped in the middle of the sheet conveying path 125 across the registration roller pair motor 126 and the fixing roller pair 118, the control unit 121 The sheet is fed downstream by rotating the roller pair 102 by a predetermined amount.

As a result, a slack is formed in the sheet that is stopped between the fixing roller pair 118 and the registration roller pair 102. In this case, the distance is longer than the difference between the distance between the fixing roller pair 118 and the registration roller pair 102 when the side plate 122 is closed and the distance between the fixing roller pair 118 and the registration roller pair 102 when the side plate 122 is opened. By rotating the pair of registration rollers 102 to feed the sheet, the sheet P is surely slackened. The sheet feed amount at this time is a feed amount corresponding to the distance L3 of the copying machine 30 in the first embodiment.

The copier 130 of the present embodiment is capable of performing not only the sheet jam processing when the sheet straddling the registration roller pair 102 and the fixing roller pair 118 is jammed, but also the registration roller pair 102 and the fixing roller pair 118. When the sheet is jammed in another conveyance path other than the above conveyance path and the user opens the side plate 122 to see the inside of the copying machine,
Even if another sheet straddles the registration roller pair 102 and the fixing roller pair 118, the sheet can be easily removed.

As described above, the copying machine 130 of the present embodiment
When the jam occurs, the registration roller pair 102 is rotated to form a loop (slack) in the sheet, so that the fixing roller pair 118 and the registration roller pair 102 pull the sheet when the side plate 122 is opened. The sheet is hardly generated, so that the sheet can be prevented from being damaged. In addition, the sheet is loosened, so that the jam can be easily removed.

The side plate 122 is rotatably supported by a rotation fulcrum 122a located at the upstream end, but is rotatably supported by a rotation fulcrum (not shown) located downstream of the transfer roller 112. Even when supported, the registration roller pair 102
May be rotated to form a loop (slack). Therefore, the present invention can be applied not only to a copying machine having a transport frame having a rotation fulcrum on the upstream end side but also to a copying machine having a transport frame having a rotation fulcrum on the downstream end side. it can.

The fixing roller pair 118 may be provided on the side plate 122, and the registration roller pair 102 may be provided on the apparatus main body 131. Also in this case, when a jam occurs, the registration roller pair 102 is rotated to form a loop (slack) on the sheet, thereby making it easier to perform the jam processing.

Further, in the copying machine 130 of this embodiment, a loop (slack) is formed between the registration roller pair 102 and the fixing roller pair 118 by rotating only the registration roller pair 102. By rotating the pair 102 and the fixing roller pair 118, the registration roller pair 10
2 is operated for a longer time than the fixing roller pair 118,
The loop (bending) may be formed by increasing the conveyance speed of the registration roller pair 102 to increase the conveyance amount of the sheet of the registration roller pair 102. Alternatively, the fixing roller pair 118 is rotated in the reverse direction without rotating the registration roller pair 102, and the loop (bending) is performed.
May be formed. Further, the registration roller pair 102
Is rotated forward, the fixing roller pair 118 is rotated reversely,
The above-mentioned loop (bending) may be formed.

The present invention is not limited to the above embodiment. For example, in the above embodiment, a copying machine which is an electrophotographic image forming apparatus has been described. The present invention can be applied to an ink jet printer or the like that forms an image according to the present invention, and the present invention is not limited to a copying machine alone.

[0066]

According to the image forming apparatus of the present invention, by forming a slack in the sheet between the first conveying means and the second conveying means, it is possible to prevent the sheet from being damaged during the jam processing. . Also, by loosening the sheet,
Jams can be easily removed.

The image forming apparatus of the present invention forms a slack in the sheet between the first conveying means and the second conveying means, so that the toner adhered to the sheet even when the rotating member is opened. No ink or ink adheres to the members on the main body of the device.
It is possible to provide a sheet on which a high-quality image is formed even after the jam processing.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part of a copier as an image forming apparatus according to a first embodiment of the present invention, taken along a sheet conveying direction.

FIG. 2 is a diagram illustrating a state where a jammed sheet is removed in the copying machine of FIG. 1;

FIG. 3 is a flowchart for explaining the operation of the copying machine when a sheet is jammed;

FIG. 4 is a diagram illustrating a state where a sheet jammed in a vertical conveyance unit is removed in a copying machine that is an image forming apparatus according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a state in which a side plate is closed in the copying machine of FIG. 4;

[Explanation of symbols]

P Sheet A Sheet discharge space B Space L1 Distance from nip of registration roller pair to nip of pre-transfer roller pair during normal operation L2 From nip of registration roller pair to nip of pre-transfer roller pair during rotation of transport frame L3 Difference between distance L2 and distance L1 L4 Distance between registration roller pair and fixing device 1 Photosensitive drum (image forming means) 6 Transfer roller 7 Transfer arm 9 Transfer guide (guide means) 10 Roller pair before transfer (second 10a Nip 11 Registration roller pair (first sheet conveyance unit) 11a Nip 12 Transport frame (rotating member) 12a Rotation fulcrum (fulcrum) 16 Transfer unit 20 Motor for registration roller pair 21 Control unit (control) Means) 22 Motor for roller pair before transfer 23 Top sensor (conveyance abnormality detecting means, sheet detecting means) 2 Sheet transport path 30 Copier (image forming apparatus) 102 Registration roller pair (first sheet transport unit) 104 Transfer unit 106 Fixing unit 110 Photosensitive drum 112 Transfer roller 118 Fixing roller pair (second sheet transport unit) 121 Control unit (Control means) 122 Side plate (rotating member) 122a Rotating fulcrum (fulcrum) 123 Jam detection sensor (transport abnormality detecting means, sheet detecting means) 125 Sheet transport path 126 Motor for registration roller pair 128 Motor for fixing roller pair 130 Copy Machine (image forming apparatus) 131 Apparatus main body

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 21/14 G03G 21/00 372 F term (Reference) 2H027 DC04 DC14 ED16 EK09 EK10 HA04 2H072 AB07 CA01 CA02 CB09 EA16 EA18 3F048 AA02 AA04 AA05 AB01 BA14 BB02 BD03 CC01 DA07 DB11 DC05 DC09 EA03 EB36 3F049 AA04 DA11 DA12 EA22 EA29 LA02 LA05 LA07 LB03 3F102 AA02 AA10 AA11 AB01 BA02 BB02 CA01 CB01 DA08 EA03 FA03

Claims (10)

[Claims] A first sheet conveying means for conveying a sheet; a second sheet conveying means for conveying the sheet conveyed by the first sheet conveying means to a downstream side; Conveyance abnormality detection means for detecting a sheet conveyance abnormality state; a rotatable rotating member that supports one of the first sheet conveyance means and the second sheet conveyance means; Activating at least one of the first sheet conveying means and the second sheet conveying means on the basis of the detection by the abnormality detecting means, and straddling the first sheet conveying means and the second sheet conveying means. An image forming apparatus comprising: a control unit configured to convey a sheet at a predetermined distance so as to form a slack in a stopped sheet. 2. The rotating member is provided so as to be rotatable around a fulcrum arranged on the upstream side in the sheet conveying direction along the sheet conveying path, and when the member is turned, the first member is turned to the first position. The second sheet conveying means is disposed at a position where the distance between the sheet conveying means and the second sheet conveying means is widened, and a sheet between the first conveying means and the second conveying means is provided. The image forming apparatus according to claim 1, wherein the transport path is openable. 3. The rotating member is provided so as to be rotatable around a fulcrum disposed on an upstream side in a sheet conveying direction along a sheet conveying path, and when the member is turned, the first member is turned on. The first sheet conveying means is disposed at a position where the distance between the sheet conveying means and the second sheet conveying means is widened, and a sheet between the first conveying means and the second conveying means is provided. The image forming apparatus according to claim 1, wherein the transport path is openable. 4. A sheet detecting means for detecting that a sheet is straddling between the first sheet conveying means and the second sheet conveying means, wherein the control means comprises: When the sheet detecting means does not detect the sheet, the first conveying means and the second conveying means are not operated, and when the sheet detecting means detects the sheet, the first conveying means and the second conveying means are not operated.
4. The method according to claim 1, wherein at least one of the first conveying means and the second conveying means is operated.
Item 10. The image forming apparatus according to item 1. 5. The control means activates both the first sheet conveying means and the second sheet conveying means,
And, by making the first sheet conveying means larger in sheet conveyance amount than the second sheet conveying means,
2. A sheet transported by a predetermined distance so as to form a slack in a sheet stopped over the first sheet transporting means and the second sheet transporting means.
The image forming apparatus according to claim 1. 6. The control means reversely operates the second sheet conveying means to form slack in a sheet stopped over the first sheet conveying means and the second sheet conveying means. The image forming apparatus according to any one of claims 1 to 4, wherein the sheet is conveyed by a predetermined distance so as to perform the operation. 7. A first sheet conveying means for conveying a sheet, a second sheet conveying means for conveying the sheet conveyed by the first sheet conveying means to a downstream side, and the second sheet. Image forming means for forming an image on the sheet conveyed by conveying means, guiding means for guiding the sheet conveyed by the second sheet conveying means to the image forming means, and sheet in the image forming apparatus Transport abnormality detecting means for detecting a transport abnormal state of the second sheet transport means and the guide means,
A rotating member rotatable in a direction away from the image forming unit with the upstream side in the sheet conveying direction as a fulcrum along the sheet conveying path; and the first sheet based on the detection of the conveyance abnormality detecting unit. An image forming apparatus comprising: a control unit that operates a conveying unit to convey the sheet to a downstream side by a predetermined distance. 8. The method according to claim 8, wherein the second sheet conveying unit is configured to control an interval between the first sheet conveying unit and the second sheet conveying unit when the rotating member rotates in a direction away from the image forming unit. The image forming apparatus according to claim 7, wherein the predetermined distance at which the first sheet conveying means conveys the sheet is a distance exceeding the widened distance. . 9. A sheet detecting means for detecting that a sheet is straddling between the first conveying means and the second conveying means between the second conveying means and the image forming means. The control means does not operate the first conveyance means and the second conveyance means when the sheet detection means has not detected a sheet, and when the sheet detection means has detected a sheet, the control means 9. The image forming apparatus according to claim 7, wherein at least one of the first transport unit and the second transport unit is operated. 10. The image forming apparatus according to claim 9, wherein said sheet detecting means has a function of detecting a sheet conveyance abnormality.