JP2009208951A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device with a simple constitution capable of quickly releasing a jam without tearing sheets and retaining them in the device as torn pieces when the sheets are recovered. <P>SOLUTION: A jam canceling part 16 installed to one part of a conveying path 2 of this image forming device has a pair of guide plates 20, 21 continued to front and rear guide plates 10, 11 when sheets are conveyed, a drive roller 13 and a driven roller 14 provided to a pair of guide plates 20, 21, and drive means for normally rotating a drive shaft 22, driving the drive roller and coveying the sheets when the sheets are conveyed, and for reversely rotating the drive shaft 22 and rotating the pair of guide plates 20, 21 when the jam is released. The jammed sheets are removed from the conveying path without being torn, and taken up, so as to quickly release the jam. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus provided with a conveyance path for conveying a sheet. In particular, when a sheet is jammed in the conveyance path, the sheet can be easily pulled out of the conveyance path and easily taken out of the apparatus. The present invention relates to an image forming apparatus having such a structure.

  In image forming apparatuses (printers, etc.) that have been reduced in size in response to consumer needs in recent years, if paper is jammed (contains a jam) in the conveyance path within the apparatus, it is necessary to remove the jammed paper. There is almost no space in the housing of the apparatus to insert the paper, and it may be difficult to remove the jammed paper and clear the error.

  Therefore, as disclosed in Patent Document 1 below, the paper transport path is unitized so that it can be drawn out of the housing of the apparatus, and the paper jammed in the transport path is pulled out of the apparatus and processed together with the unit. An invention of an image forming apparatus aimed at achieving the above has been proposed.

  Further, in Patent Document 2 below, a part of the sheet conveying means that forms the sheet conveyance path can be opened together with the open panel, and when the jam occurs, the opening panel can be opened to process the jammed sheet in the conveyance path. An invention of an image forming apparatus is proposed.

  Further, in Patent Document 3 below, when a paper jam occurs in the paper transport path, the jammed paper is moved by manually turning a rotary knob that interlocks the image forming unit and the transport unit. There has been proposed an invention of an image forming apparatus which is discharged outside the apparatus.

  FIGS. 11 to 14 relate to an image forming apparatus in which a part of the sheet conveyance path is opened so that a jammed sheet can be processed, and is based on an idea similar to the image forming apparatus described in Patent Document 2. It is. FIG. 11 is an internal structural view schematically showing the entire structure of such a conventional printer, and FIG. 12 is an enlarged view showing a state where the release door of the jam release portion of the transport path is closed. 13 is an enlarged view showing a state where the release door of the jam release unit is opened, and FIG. 14 is an enlarged view showing a state where the release door of the jam release unit is opened and the paper is pulled out.

  The image forming apparatus shown in FIG. 11 forms an image on a plurality of paper feed trays 1, a transport path 2 that transports paper fed from each paper feed tray 1, and a paper transported along the transport path 2. An inkjet head 3 as image forming means, a paper discharge roller 4 for discharging the paper conveyed along the transport path 2 after image formation, and a paper discharged outside by the paper discharge roller 4 A paper discharge tray 5 to be stacked is provided.

In the middle of the conveyance path 2, in this example, the conveyance path 2 between the inkjet head 3 and the paper discharge roller 4, a jam release unit 6 is provided. As shown in FIG. 12, a release window 9 that can be opened and closed by a door 8 is provided on the front side of the housing 7 of the apparatus. When the door 8 is opened, the transport path 2 inside the housing 7 is released. It can be seen that the window 9 is arranged along the vertical direction on the right side of the window 9, and a jam release portion 6 is provided in this portion. The conveyance path 2 is configured by a pair of guide plates 10 and 11 arranged with a gap through which the paper P passes. However, in the jam release unit 6, the right guide plate 11 is connected to the upstream and downstream guide plates 11. Although it is a continuous fixed guide plate, a part of the left guide plate 10 facing the fixed guide plate is an open / close guide plate 10a that is rotatable leftward about the rotation fulcrum 12 at the lower end. The jam release unit 6 is provided with a conveying roller 15 including a driving roller 13 provided on the fixed guide plate 11 and a driven roller 14 provided on the open / close guide plate 10a. In addition, as shown in FIG. 12, the conveyance roller 15 is provided also in the upstream and downstream conveyance path | route 2 of the jam cancellation | release part 6, respectively, and the jam release part 6 and the conveyance roller 15 of the upstream conveyance path | route 2 and In between, a sensor 30 for detecting a jam by detecting the paper P is provided. The sensors 30 are provided not only at this position but at a plurality of important points in the transport path 2.
Using the signal from the sensor 30, it is detected that a jam has occurred, and if it is determined that the paper P is in the jam release unit 6, the door 8 of the housing 7 is opened with the apparatus stopped. Then, the release window 9 is opened, and the open / close guide plate 10a of the jam release unit 6 is opened as shown in FIG.
JP 2000-137356 A Japanese Patent Laid-Open No. 10-48898 JP-A-6-186810

  According to the image forming apparatus described in Patent Document 1, when a unitized conveyance path is pulled out of the apparatus at the time of jam, a sheet exists across the unit and upstream or downstream thereof. When the paper is pulled out, the paper is torn and a part of the paper on the transport path in the apparatus is separated from the part in the unit. The piece of paper remaining in the apparatus cannot be detected by the jam detection sensor, but remains in the conveyance path, thereby hindering subsequent conveyance of the paper.

  According to the image forming apparatus described in Patent Document 2, a hinge mechanism or the like that connects the open panel and the housing is provided in order to be able to open a part of the paper transport unit having a considerable weight together with the open panel. There is a need to have sufficient strength, etc., and it is necessary to firmly configure the opening mechanism, and a shock absorbing damper is required in the mechanism part that repeatedly opens and closes the opening panel, etc. When actually configured as a product, there is a problem that the cost becomes expensive.

  According to the image forming apparatus described in Patent Document 3, the jammed paper cannot be moved in the transport path by turning the dial depending on the jam state, and the jam may not be released. Even if it is possible to release the jam, there is a problem that it takes a long time to discharge the jam to the outside of the apparatus, and it is impossible to respond to a request for quick jam release.

  Further, according to the image forming apparatus shown in FIGS. 11 to 14, when a jam occurs, the door 8 of the housing 7 is opened to open the release window 9, and the open / close guide plate of the jam release unit 6 as shown in FIG. When the paper P that is jammed by opening 10a is forcibly pulled out from the transport path 2 by hand, only the portion of the paper P in the jam release unit 6 is collected, and the upstream and downstream transport of the jam release unit 6 is performed. There is a problem that a part of the sheet P existing in the path 2 remains as a torn sheet piece P ′ and cannot be collected.

  The present invention solves the above-described problems, and even when a jammed sheet exists across the upstream or downstream side of the jam release unit, the sheet is torn at the time of collecting the sheet and placed in the apparatus. An image that remains as a piece of paper and does not obstruct the subsequent conveyance of the paper, is simple in configuration, can be manufactured at low cost, and can be quickly cleared in a short time. An object is to provide a forming apparatus.

An image forming apparatus according to claim 1 is provided.
In an image forming apparatus having a transport path for transporting paper,
A part of the transport path is provided as a part of the transport path independent of the front and rear transport paths, and is rotatable between the front and rear transport paths in a direction crossing the surface of the transported paper. A jam release unit;
Drive means for rotating the jam release section to wind the paper around the jam release section when a jam occurs;
It is characterized by comprising.

The image forming apparatus according to claim 2 is the image forming apparatus according to claim 1,
The jam release unit is characterized in that it can move outward from between the front and rear transport paths.

The image forming apparatus according to claim 3 is the image forming apparatus according to claim 1 or 2,
The jam release unit is provided with a conveyance unit for conveying a sheet, and the sheet is conveyed by the conveyance unit when the jam release unit conveys a sheet continuous with the preceding and following conveyance paths, and the jam release unit is At the time of winding the paper rotating between the transport paths, the transport means rotates the jam release unit without transporting the paper.

An image forming apparatus according to claim 4 is the image forming apparatus according to any one of claims 1 to 3,
A sensor provided in the vicinity of the transport path for detecting paper;
Based on the detection signal of the paper detected by the sensor, the size of the paper to be transported, and information regarding the timing of transporting the paper, it is determined that a paper jam has occurred in the transport path, and the jam is detected. Detecting the position of a sheet relating to a jam that partially exists in the release unit, and pulling out the sheet from the conveyance path adjacent to the jam release unit and winding it on the jam release unit according to the detected position of the sheet Control means for calculating the number of rotations of the jam release unit required for
It is characterized by comprising.

  According to the image forming apparatus of the first aspect, when a jam occurs in the conveyance path and at least a part of the paper related to the jam is in the jam release unit, the driving unit is driven to move the jam release unit. The paper is rotated and turned around the front and rear conveyance paths, and the paper is wound around the jam release unit and collected.

  According to the image forming apparatus described in claim 2, in the effect of the image forming apparatus according to claim 1, after the paper relating to the jam is wound around the jam release unit and collected, the jam release unit is further moved back and forth. It is possible to move to the outside where it is easy to collect by manual operation from between the transport paths.

  According to the image forming apparatus described in claim 3, in the effect of the image forming apparatus according to claim 1 or 2, the driving of the conveying unit is performed at the time of paper conveyance in which the jam release unit is continuous with the front and rear conveyance paths. Thus, the paper in the transport path can be transported. When a jam occurs and the conveyance of the paper is stopped and the paper related to the jam is collected, the driving unit rotates the jam release unit between the front and rear conveyance paths to wind the paper related to the jam around the jam release unit. take.

According to the image forming apparatus described in claim 4, in the effect of the image forming apparatus according to any one of claims 1 to 3,
Based on the detection signal of the sheet detected by the sensor, the size of the sheet to be transported, and information on the timing of transporting the sheet, it is determined that a jam has occurred in the transport of the sheet within the transport path, and the jam clearing unit Jam release unit required to detect the position of the paper related to the jam that is partially present, and to pull out the paper from the conveyance path adjacent to the jam release unit and wind it on the jam release unit according to the detected paper position Therefore, the paper relating to the jam can be wound around the jam release unit and quickly collected at the minimum necessary number of rotations.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention which are considered best by patent applicants at the time of filing to implement the present invention will be described with reference to FIGS.
FIG. 1 is a schematic internal structure diagram of the image forming apparatus according to the embodiment. FIG. 2 is an external view (a) of the image forming apparatus according to the embodiment with the exterior cover closed, and an external view of the image forming apparatus with the cover open. FIG. 3 is a side view showing details of the jam release unit in the embodiment, and FIGS. 4 to 6 are side views showing sheet winding by the jam release unit of the embodiment. A broken circle shown in the center of each of FIGS. 3 to 6 indicates the jam release window 19. 7 is a front view of the jam release portion in the pull-out position in the embodiment, FIG. 8 is a perspective view of the jam release portion in the pull-out position in the embodiment, and FIG. 9 is a pull-out position in which the paper is wound in the embodiment. FIG. 10 is a block diagram showing a configuration of the image forming apparatus according to the embodiment.

  The image forming apparatus of this example shown in FIG. 1 has the same basic structure as the image forming apparatus in the background art described with reference to FIG. 11, and the configuration of the jam release unit of the transport path 2 is different. The other parts shall be illustrated and described in the background art to avoid repeated illustration and description.

  This image forming apparatus has a jam release unit 16 in the conveyance path 2 between the inkjet head 3 and the paper discharge roller 4. As shown in FIGS. 2B, 3 to 6, 8, and 9, a circular release window 19 is provided on the front side of the casing 7 of the apparatus, and FIGS. As shown in b), the release window 19 can be opened and closed by an exterior cover 40 that is openably and closably provided on the front surface of the casing 7 of the apparatus. When a jam occurs, if the exterior cover 40 is opened, the jam release unit 16 (not shown in FIG. 2) on the transport path inside the housing 7 can be accessed via the release window 19.

  As shown in FIG. 3, the conveyance path 2 has a pair of guide plates 10 and 11 arranged with a gap through which the paper P passes, and further, a sheet between the pair of guide plates 10 and 11. A plurality of pairs of transport rollers 15 each including a driving roller 13 and a driven roller 14 that sandwich and transport P are provided at an appropriate interval.

  As shown in FIG. 3, the jam release unit 16 of this example configured as a part of the conveyance path 2 includes a pair of guide plates 20 and 21 separated from the upstream and downstream guide plates 10 and 11. Furthermore, it has a conveying roller 15 comprising a driving roller 13 and a driven roller 14 which are arranged in a through-hole portion provided in the guide plates 20 and 21 and which are opposed to each other between the pair of guide plates 20 and 21. Yes. As shown in FIG. 3, the jam release unit 16 drives the driving force of the driving roller 13 during the conveyance of the sheet in which the pair of guide plates 20 and 21 are continuous with the upstream and downstream guide plates 10 and 11 as shown in FIG. Thus, the sheet P is sandwiched between the driven roller 14 and conveyed inside the pair of guide plates 20 and 21. The jam release unit 16 is configured such that the pair of guide plates 20 and 21 is centered on the drive shaft 22 of the drive roller 13 between the upstream and downstream guide plates 10 and 11 during the jam release operation shown in FIGS. The paper P is wound around the outside of the pair of guide plates 20 and 21 by being rotated by the same drive source as the drive roller 13, and is extracted from the transport path 2 and collected.

  As shown in FIGS. 7 and 8, the jam release unit 16 moves from between the upstream and downstream guide plates 10 and 11 when the operator pulls the handle 23 to pull the release window of the housing 7. It is comprised so that it can draw out from 19. That is, as shown in FIG. 7, the frame 24 of the housing 7 is provided with a base 25 that is movable in the above-described pulling direction, and a motor 26 as a driving means is mounted on the base 25. A motor gear 27 provided at one end of the rotating shaft of the motor 26 meshes with a jam release gear 28 and a paper transport gear 29 provided on the drive shaft 22 provided with the drive roller 13, respectively. The drive shaft 22 is supported by the frame 24 of the housing 7 so as to be movable in the pull-out direction. The jam release gear 28 and the paper transport gear 29 are respectively connected to the drive shaft 22 via a one-way clutch whose power transmission directions are opposite to each other. The jam release gear 28 includes a driven roller that contacts the drive roller 13. The pair of guide plates 20 and 21 provided with 14 are attached.

  According to the above configuration, when the motor 26 rotates forward, the drive shaft 22 is driven, the drive roller 13 rotates in the transport direction of the paper P, and the transport of the paper P is performed. Further, when the motor 26 rotates in the reverse direction, the drive roller 13 is not driven and the drive shaft 22 rotates in the reverse direction of the motor 26, so that the pair of guide plates 20 and 21 together with the drive roller 13 and the driven roller 14. The paper P is rotated around the drive shaft 22, that is, the entire jam release unit 16 is rotated, and the paper P is taken up.

  As shown in FIG. 7, an encoder 35 is provided at the other end of the rotating shaft of the motor 26, and a sensor 36 for detecting the encoder 35 is provided on the base 25. Is configured to receive a signal from the sensor 36, detect the position in the rotation direction of the jam release unit 16 that rotates when the jam is released, and use it for controlling the rotation.

  In addition, as shown in FIG. 3, the conveyance roller 15 is provided also in the upstream and downstream conveyance path | route 2 of the jam cancellation | release part 16, respectively, and the jam release part 16 and the conveyance roller 15 of the downstream conveyance path | route 2 and Between the two, a sensor 30 for detecting a jam by detecting a sheet is provided. The sensors 30 are not limited to this position, and are provided at a plurality of important points in the transport path 2.

The control means of the image forming apparatus of this example recognizes the current position of the paper P from the detection signal obtained from each sensor 30 and the like, the conveyance timing of the paper P, the size of the paper P, etc. It is possible to recognize the fact and further detect whether or not at least a part of the paper P related to the jam exists in the jam release unit 16.
Specifically, as shown in FIG. 10, the control means 50 includes a memory 51 that stores a control program and data, and a CPU 52 that performs control using signals from various sensors and data in the memory 51. Have. More specifically, the CPU 52 compares the detection result of the paper P by the sensor 30 and other necessary signals and data, and the like, and includes a detection result comparison unit 53 that determines the jam of the paper P in the transport path 2. A detection unit 54 and a rotation number calculation unit 55 that recognizes the position in the rotation direction of the jam release unit 16 that rotates when the jam is released using a signal from the sensor 36 that detects the encoder 35 and calculates the rotation number. is doing. Then, the control unit 50 controls the motor 26 as described above using the jam detection result by the jam detection unit 54 and the calculated value by the rotation number calculation unit 55, and thereby rotates the jam release unit 16. (When a jam occurs), the conveyance roller 15 is driven to convey the paper P in the conveyance path 2 (at the time of normal image formation). In addition, during normal image formation, the control unit 50 drives the inkjet head 3 to form an image on the paper P in synchronization with the conveyance of the paper P, and drives the paper discharge roller 4 to discharge the paper P. The tray 5 is discharged. As shown in FIGS. 10 and 2, the image forming apparatus of this example has a display unit 56 on the upper surface side of the housing 7, and the control unit 50 displays an alarm at the time of jam on the display unit 56. In addition, information necessary for normal image forming work is displayed.

  When the jam is detected, the control unit stops the apparatus, and when at least a part of the paper P related to the jam exists in the jam release unit 16, the winding operation of the paper P by the jam release unit 16 is optimized. It can be executed at the rotational speed, and a predetermined alarm can be issued on the display unit 56 to prompt the user to manually pull out the jam release unit 16 and remove the paper P.

Next, the operation of the above configuration will be described.
When the image forming apparatus performs a normal image forming operation, the jam release unit 16 is located at a paper transport position continuous to the front and rear transport paths 2 as a part of the transport path 2 of the paper P as shown in FIG. In this state, the motor 26 rotates forward to rotate the drive shaft 22 in the same direction, and the drive roller 13 is rotated in the direction in which the paper is transported, so that the paper P sent through the transport path 2 is jammed. 16 is sent forward. The pair of guide plates 20 and 21 are fixed by a lock mechanism (not shown) while the motor is rotating forward to transport the paper P, so that the pair of guide plates 20 and 21 do not rotate.

  When the control unit detects the occurrence of a jam and detects that at least a part of the jammed paper is present in the jam release unit 16, the operation of the image forming apparatus is stopped and the jam is released by the jam release unit 16. Move to release operation. That is, by rotating the motor 26 in the reverse direction and rotating the drive shaft 22 provided with the drive roller 13 in the reverse direction, the pair of guide plates 20 and 21 and the driven roller 14 are rotated in the same direction. That is, the entire jam release unit 16 rotates in the reverse direction of the motor 26.

  As shown in FIGS. 4 to 6, the sheet P that has existed across the upstream and downstream sides of the jam release unit 16 is wound around the outer side of the pair of rotating guide plates 20, 21, and the front and rear transport paths 2. It will be drawn from. The drawing direction of the paper P does not make a large angle with respect to the guiding direction of the paper P by the transport path 2, so that the paper P is not torn and remains in the transport path 2.

  As shown in FIG. 6, when the paper P is wound around the jam release unit 16, the control unit displays on the display unit or the like that the winding is completed. The user who has confirmed the display opens the door of the housing 7 to open the release window 19, puts his hand into the housing 7 through the release window 19 and grasps the handle, and as shown in FIG. Pull it out. Then, the paper P wound around the jam release unit 16 is manually removed, and the jam release unit 16 is stored in the housing 7 and returned to the paper transport position.

  In this example, in the winding of the paper P by the jam release unit 16 described above, the longer dimension is set according to the length of the paper P protruding from the jam release unit 16 to the upstream or downstream conveyance path 2. The minimum necessary number of rotations of the jam release unit 16 necessary for winding can be determined, and control can be performed so that winding of the paper P is completed quickly.

That is, as shown in part in FIG. 3, the numerical conditions or dimensions in this example are expressed as follows.
V: paper transport speed T: time from detection of paper by the sensor to stop of the driving roller of the jam release unit L1: paper transport distance of the jam release unit L2: distance from the sensor to the jam release unit L3: jam release unit half Length of winding of one side (upstream side or downstream side) of the sheet by rotation L4: Length of the sheet A: Length of the sheet that is advanced (downstream side) ahead of the jam release portion when the sheet is stopped B: Sheet Length of paper (upstream side) that has not reached the jam release area when stopped

As defined above,
A = V × T-L1-L2
B = L4-V × T + L2
So,

When A> B (or A ≧ B), (A / L3) × (1/2) is the rotation speed of the jam release unit,
In the case of A <B (or A ≦ B), (B / L3) × (1/2) is the rotation speed of the jam release unit.
For example, in the case of A> B, if A = 15 cm and L3 = 10 cm, from (A / L3) × (1/2) = 0.75, one rotation is the number of rotations of the jam release unit. .
For example, in the case of A <B, if B = 30 cm and L3 = 8 cm, from (B / L3) × (1/2) = 1.875, two rotations are the number of rotations of the jam release unit. .
Note that, as in the example described above, the number of revolutions is calculated by rounding up the decimal part.

  In the calculation of the number of rotations of the jam release unit, L1, L2, and L3 are numerical values fixed in the apparatus. If the paper length L4 and the paper conveyance speed V are determined by the operating conditions, the control unit recognizes when the jam occurs. A and B can be calculated from the time T by the above formula, and the required minimum number of rotations can be calculated.

  In the embodiment described above, the jam release unit is provided in the middle of the sheet conveyance path vertically disposed downstream of the image forming unit. However, the location where the jam can occur is not limited to this, and the position where the jam release unit is provided. Is not limited to this position. In addition, the image forming apparatus to which the present invention is applied is not limited to an ink jet recording apparatus, and is applicable to all types of image forming principles having a transport path that may cause a paper jam to transport the paper. Needless to say.

FIG. 1 is a schematic internal structure diagram of an image forming apparatus according to an embodiment of the present invention. FIG. 2A is an external view of the image forming apparatus according to the embodiment in a state in which an exterior cover is closed, and FIG. 2B is an external view of the state in which the exterior cover is open. FIG. 3 is a side view showing details of the jam release unit in the same embodiment. FIG. 4 is a side view showing the paper winding operation by the jam release unit of the embodiment. FIG. 5 is a side view showing the paper winding operation by the jam release unit of the embodiment. FIG. 6 is a side view showing the paper winding operation by the jam release unit of the embodiment. FIG. 7 is a front view of the jam release unit in the drawer position in the same embodiment. FIG. 8 is a perspective view of the jam release unit in the drawer position in the same embodiment. FIG. 9 is a perspective view of the jam release unit in the drawer position where the sheet is wound in the embodiment. FIG. 10 is a block diagram showing the configuration of the image forming apparatus of the embodiment. FIG. 11 is an internal structural view schematically showing the entire structure of a conventional printer that can open a part of the paper transport path and process paper jammed. 12 is an enlarged view showing a state in which the release door of the jam release unit is closed in the printer shown in FIG. FIG. 13 is an enlarged view showing a state where the release door of the jam release unit is opened. FIG. 14 is an enlarged view showing a state where the release door of the jam release unit is opened and the paper is pulled out.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 ... Conveyance path | route 3 ... Inkjet head as image formation means 7 ... Housing | casing 10,11 ... Guide plate of conveyance path | route 13 ... Drive roller 14 ... Follow-up roller 15 ... Conveyance roller 16 ... Jam release part 19 ... Release window 20,21 ... Jam release part guide plate 22 ... Drive shaft 26 ... Motor 28 as drive means 28 ... Jam release gear 29 ... Paper transport gear 30 ... Sensor 50 ... Control means P ... Paper

Claims (4)

In an image forming apparatus having a transport path for transporting paper,
A part of the transport path is provided as a part of the transport path independent of the front and rear transport paths, and is rotatable between the front and rear transport paths in a direction crossing the surface of the transported paper. A jam release unit;
Drive means for rotating the jam release section to wind the paper around the jam release section when a jam occurs;
An image forming apparatus comprising: The image forming apparatus according to claim 1, wherein the jam release unit is movable outward from between the front and rear transport paths. The jam release unit is provided with a conveyance unit for conveying a sheet, and the sheet is conveyed by the conveyance unit when the jam release unit conveys a sheet continuous with the preceding and following conveyance paths, and the jam release unit is 3. The image forming apparatus according to claim 1, wherein when the paper is rotated between the transport paths, the transport unit rotates the jam release unit without transporting the paper. A sensor provided in the vicinity of the transport path for detecting paper;
Based on the detection signal of the paper detected by the sensor, the size of the paper to be transported, and information regarding the timing of transporting the paper, it is determined that a paper jam has occurred in the transport path, and the jam is detected. Detecting the position of a sheet relating to a jam that partially exists in the release unit, and pulling out the sheet from the conveyance path adjacent to the jam release unit and winding it on the jam release unit according to the detected position of the sheet Control means for calculating the number of rotations of the jam release unit required for
The image forming apparatus according to claim 1, further comprising: