JP6487296B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus, and is suitable for application to an image forming apparatus such as a printer or a copier using an electrophotographic system.

  Conventionally, in an image forming apparatus using an electrophotographic system, toner corresponding to a print image is transferred to a medium, and the toner is fixed to the medium by heat and pressure in a fixing device. In such an image forming apparatus, a driving roller that has a driving force and always rotates and a detection roller that does not have a driving force and is rotated by the driving roller are provided downstream of the fixing device in the transport direction. In some cases, the detection of the rotation of the detection roller detects the occurrence of a jam (jam) of long paper (for example, see Patent Document 1).

  In such an image forming apparatus, regardless of whether or not a long sheet is sandwiched between the drive roller and the detection roller, the detection roller is always driven to rotate along with the drive roller that rotates by itself. For this reason, the conventional image forming apparatus can detect the occurrence of the jam because the rotation of the detection roller stops when the jam occurs when the long paper is sandwiched between the driving roller and the detection roller.

JP-A-6-167907

  However, in such an image forming apparatus, since the detection roller rotates even when the long paper is not sandwiched between the driving roller and the detection roller, the leading end of the long paper discharged from the fixing device is fixed to the fixing roller. Even if the leading end does not reach the driving roller and the detection roller, the detection roller continues to rotate. For this reason, the conventional image forming apparatus cannot detect a jam that occurs after the leading end of the long sheet is discharged from the fixing device and before the driving roller and the detection roller are reached.

  The present invention has been made in consideration of the above points, and intends to propose an image forming apparatus capable of improving reliability.

In order to solve such a problem, in the image forming apparatus of the present invention, the conveyance path for conveying the long paper along the longitudinal direction and the fixing device for heating the long paper are arranged downstream of the conveyance direction of the long paper. It is arranged, has no driving force, is arranged to face the idle roller that is in contact with the long paper that is conveyed on the conveying path, and is opposed to the idle roller across the conveying path, and has no driving force, A detection roller that rotates in contact with a long sheet conveyed through the conveyance path, a rotation detection sensor unit that detects rotation of the detection roller, and an idle roller and a detection roller that are arranged near the upstream side in the conveyance direction; A drive roller unit having a discharge roller having a driving force and a pinch roller that is arranged to face the discharge roller across the conveyance path and rotates in contact with a long sheet that has no driving force and is conveyed through the conveyance path; The outer peripheral surface of the detection roller and the pinch roller The circumferential surface so as to overlap.

  As a result, the present invention can rotate the detection roller and the idle roller only when the conveyed long paper comes into contact with the detection roller and the idle roller. It is possible to detect that a jam has occurred on the long paper before the leading end of the paper reaches the detection roller and the idle roller.

  According to the present invention, since the detection roller and the idle roller can be rotated only when the conveyed long paper contacts the detection roller and the idle roller, the long paper discharged from the fixing device. It is possible to detect the occurrence of a jam on the long sheet before the leading end of the sheet reaches the detection roller and the idle roller, and thus it is possible to realize an image forming apparatus capable of improving the reliability.

1 is a left side view illustrating a configuration of an image forming apparatus. It is a left view which shows the structure (1) of a discharge | emission sensor part. It is a top view which shows the structure (2) of a discharge sensor part. It is a left view which shows a front end winding jam. It is a left view which shows jam with conveyance. It is a left view which shows a bellows jam during conveyance.

  Hereinafter, modes for carrying out the invention (hereinafter referred to as embodiments) will be described with reference to the drawings.

[1. Embodiment]
[1-1. Configuration of image forming apparatus]
As shown in FIG. 1, the image forming apparatus 1 includes a feeder 10, a cutter unit 12, and an image forming unit 14, and a control unit 16 is provided. The control unit 16 is mainly configured by a CPU (Central Processing Unit), and reads a predetermined program from a storage unit such as a ROM (Read Only Memory), a RAM (Random Access Memory), a hard disk drive, or a flash memory. By executing this, the image forming apparatus 1 is comprehensively controlled.

  The feeder 10 is provided in front of the cutter unit 12, holds the long paper P, which is a long paper, in a roll shape, and conveys the long paper P to the cutter unit 12. The cutter unit 12 is provided in front of the image forming unit 14, and includes a paper feed roller 20, a transport roller 22, and an auto cutter 24. The paper feed roller 20 and the transport roller 22 are provided in a transport path 26 through which the long paper P is transported. The paper feed roller 20 and the transport roller 22 are in contact with the long paper P and rotate to rotate the long paper P into the image forming unit 14. Transport toward Based on the control of the control unit 16, the auto cutter 24 cuts a predetermined portion of the long paper P along a conveyance width direction that is a left-right direction orthogonal to the conveyance direction of the long paper P. The transport path 26 transports the long paper P along the longitudinal direction using the right end in the transport path 26 as a transport position reference in the transport width direction.

  The image forming unit 14 includes an image forming unit 28, an intermediate transfer unit 30, a conveyance roller 32, a fixing device 34, a discharge roller 36, a pinch roller 37, a discharge roller 38, a pinch roller 39, and a discharge sensor unit 40.

  The conveyance roller 32 is provided in the conveyance path 26 and conveys the long paper P by rotating in contact with the long paper P. The image forming unit 28 primarily transfers the toner image to the intermediate transfer belt 42 in the intermediate transfer unit 30 based on the control of the control unit 16. The intermediate transfer unit 30 includes an intermediate transfer belt 42, a secondary transfer counter roller 44, a secondary transfer roller 46, and the like. The toner image transferred to the intermediate transfer belt 42 is transferred to the secondary transfer counter roller 44 and the secondary transfer roller 44. An image is formed on the long paper P by secondary transfer onto the long paper P by the transfer roller 46.

  As shown in FIG. 2, the fixing device 34 includes a heating belt 49 provided with a heater 48 inside, and a fixing belt 50 that presses the long paper P against the heating belt 49. The fixing device 34 fixes the toner image on the long paper P by sandwiching the long paper P between the heating belt 49 and the fixing belt 50 and melting the toner with heat and pressurizing the toner.

  The discharge roller 36, the pinch roller 37, the discharge roller 38, and the pinch roller 39 (FIG. 1) are arranged on the downstream side in the conveyance direction of the long paper P with respect to the fixing device 34, and sandwich the long paper P on which the toner image is fixed. Then, it is conveyed and discharged to the outside of the image forming apparatus 1. The discharge sensor unit 40 is arranged on the downstream side in the conveyance direction with respect to the fixing device 34, and detects whether or not the long paper P discharged from the fixing device 34 is normally conveyed.

[1-2. Configuration of sensor unit]
As shown in FIGS. 2 and 3, the discharge sensor unit 40 includes an upstream sensor unit 51 and a downstream sensor unit 52. The discharge sensor unit 40 is disposed in the vicinity of the right end of the conveyance path 26 that is the conveyance position reference.

[1-3. Configuration of upstream sensor section]
The upstream sensor unit 51 is provided in the vicinity of the downstream side in the conveyance direction with respect to the fixing device 34, and includes a discharge sensor lever 54 and a first sensor 56.

  The discharge sensor lever 54 is a rod-shaped member having a substantially W shape in side view, and a non-passing state position indicated by a solid line in FIG. 2 with a pivot fulcrum 54A provided on the lower side of the conveyance path 26 as an axis, and FIG. It is configured to be rotatable to a passing state position indicated by a broken line. The discharge sensor lever 54 has a long paper contact portion 54B that protrudes from the lower side to the upper side of the transport path 26 in the non-passing state position, and is formed on the upper end portion. The detector part 54C which shields is formed in the lower end part. Further, the discharge sensor lever 54 is biased by a biasing member (not shown) from the passing state position toward the non-passing state position.

  The first sensor 56 as a lever detection sensor is provided on the rotation path of the detector unit 54C in the discharge sensor lever 54, and the light emitting unit and the light receiving unit are moved left and right across a groove through which the detector unit 54C passes. It is a U-shaped optical sensor arranged. The first sensor 56 detects a bright state in which the light receiving unit receives light from the light emitting unit when the detector unit 54C does not block the optical axis in the passing state position, while the detector unit 54C in the non-passing state position. Is blocking the optical axis, it detects a dark state in which the light receiving unit is not receiving light from the light emitting unit, and sends the detection result to the control unit 16 (FIG. 1) as a lever detection result. Based on the acquired lever detection result, the control unit 16 determines whether or not the long paper P discharged from the fixing device 34 is normally conveyed downstream in the conveying direction of the fixing device 34.

  The discharge sensor lever 54 is in a non-passing state position when the leading end of the long paper P has not reached, and when the long paper P is conveyed and the leading end abuts, the discharging sensor lever 54 passes from the non-passing state position to the passing state position. , And then the leading end of the long paper P passes through the discharge sensor lever 54 to be in a conveying state in which the long paper P is continuously conveyed, and the lower side of the long paper P is the long paper. As long as it is in contact with the contact portion 54B, the passing state position is maintained.

[1-4. Configuration of downstream sensor unit]
The downstream sensor unit 52 is provided in the vicinity of the downstream side in the transport direction with respect to the upstream sensor unit 51, and includes a drive roller unit 58 and a rotation detection sensor unit 60. The drive roller unit 58 includes a discharge roller 36 and a pinch roller 37.

  The discharge roller 36 is attached so as to be rotatable at a predetermined interval in the left-right direction around a discharge roller shaft 36 </ b> S extending along the conveyance width direction below the conveyance path 26. The discharge roller 36 actively rotates when a driving force is transmitted from an actuator (not shown).

  The pinch roller 37 rotates at a position facing each discharge roller 36 across the conveyance path 26, with a pinch roller shaft 37S extending in the left-right direction on the upper side of the conveyance path 26 and movable in the vertical direction. It is attached as possible. Each of the pinch rollers 37 is pressed against the discharge roller 36 by an urging member which is a compression spring (not shown). The pinch roller 37 is not given a rotating driving force from the actuator, and is rotated by the rotation of the discharge roller 36 by being pressed against the discharge roller 36.

  As a result, the drive roller unit 58 rotates toward the detection roller clamping portion 70 where the idle roller 68 and the detection roller 66 come into contact with each other by rotating the discharge roller 36 and the pinch roller 37 while sandwiching the long paper P. Then, the long paper P is transported along the transport path 26.

  The rotation detection sensor unit 60 includes a driven roller unit 62 and a rotation detection sensor unit 64. The driven roller unit 62 includes a detection roller 66 and an idle roller 68.

  The idle roller 68 is rotatably attached to a central portion between the discharge rollers 36 arranged in the left-right direction around an idle roller shaft 68S extending in the left-right direction below the transport path 26. The idle roller 68 is not provided with an actively rotating driving force from the actuator, and is rotated by the long paper P when the long paper P contacts the outer peripheral surface. Further, the idle roller 68 has a position where it overlaps with the discharge roller 36 in a side view, that is, the upstream end in the transport direction on the outer peripheral surface of the idle roller 68 is the downstream end in the transport direction on the outer peripheral surface of the discharge roller 36. It is disposed in the vicinity of the discharge roller 36 so as to be located upstream of the transport direction.

  The detection roller 66 extends along the left-right direction on the upper side of the conveyance path 26, and has a detection roller shaft 66S that can move in the vertical direction. The detection roller 66 faces the idle roller 68 across the conveyance path 26 and is aligned in the left-right direction. A central portion between the pinch rollers 37 is rotatably attached. The detection roller 66 is pressed against the idle roller 68 by a biasing member that is a compression spring (not shown). In addition, the detection roller 66 is not provided with an actively rotating driving force from the actuator, and is rotated by the rotation of the idle roller 68 across the long paper P when pressed against the idle roller 68. . Further, the detection roller 66 overlaps with the pinch roller 37 in a side view, that is, the upstream end in the transport direction on the outer peripheral surface of the detection roller 66 is the downstream end in the transport direction on the outer peripheral surface of the pinch roller 37. It is arranged in the vicinity of the pinch roller 37 to such an extent that it is located upstream of the conveying direction. On the left side surface of the detection roller 66, there is provided a detection roller gear 66G in which a gear meshing with a slit disk 72 described later is formed on the outer peripheral surface.

  In this way, the detection roller 66 and the idle roller 68 do not rotate with each other, and are rotated by the long paper P only when it contacts the long paper P.

  Further, since the discharge sensor unit 40 includes the idle roller 68 in the central portion between the adjacent discharge rollers 36 and the detection roller 66 in the central portion between the adjacent pinch rollers 37, for example, the adjacent discharge rollers 36 and When the long paper P passes through the drive roller unit 58 and the rotation detection sensor unit 60, compared to the case where the idle roller 68 and the detection roller 66 are arranged on the downstream side in the conveyance direction on either outer side of the pinch roller 37. Can be prevented from skewing.

  The rotation detection sensor unit 64 is a so-called rotary encoder, and includes a slit disk 72 and a second sensor 74.

  The slit disk 72 is attached to the upper side of the downstream side of the detection roller 66 in the transport direction so as to be rotatable with respect to an axis along the left-right direction. A gear that meshes with the detection roller gear 66G is formed on the outer peripheral surface of the slit disk 72. As a result, the slit disk 72 rotates in synchronization with the detection roller 66. In addition, slits that allow light to pass therethrough are formed on the side surfaces of the slit disk 72 at predetermined intervals.

  The second sensor 74 is provided on the rotation path of the slit disk 72, and is a U-shaped optical sensor in which a light emitting part and a light receiving part are arranged on the left and right sides of a groove through which the slit disk 72 passes. It is. The second sensor 74 detects a bright state in which the light receiving unit receives light from the light emitting unit when the slit disk 72 does not block the optical axis, while when the slit disk 72 blocks the optical axis. The light receiving unit detects a dark state where light from the light emitting unit is not received, and sends the detection result to the control unit 16 as a slit disk detection result. Based on the obtained slit disk detection result, the control unit 16 detects the rotational displacement of the slit disk 72, that is, the rotational displacement of the detection roller 66 that rotates in synchronization with the slit disk 72. As a result, the control unit 16 detects that the long paper P that has passed through the upstream sensor unit 51 is normally conveyed downstream in the conveyance direction of the upstream sensor unit 51.

  As described above, the image forming apparatus 1 can detect the leading end portion of the long paper P by the downstream sensor unit 52 and can also detect an abnormality during the conveyance of the long paper. A discharge roller 38 and a pinch roller 39 configured in substantially the same manner as the discharge roller 36 and the pinch roller 37 are provided downstream of the downstream sensor unit 52 in the transport direction.

[1-5. Paper jam detection control]
In such a configuration, in a state in which the leading end portion of the long paper P does not pass through the fixing device 34, the control unit 16 detects the non-passing state position of the discharge sensor lever 54 based on the lever detection result and also detects the detection roller. An unrotated state in which 66 is not rotating is detected.

  Subsequently, the control unit 16 determines whether or not the discharge sensor lever 54 is in the passing state position based on the lever detection result after a predetermined time has elapsed since the printing operation was started. Here, when the printing operation is not performed and the non-passing state position is maintained after a predetermined time elapses, it is discharged from the fixing device 34 as shown in FIG. There is a possibility that a leading end winding jam in which the leading end portion of the long paper P is wound around the heating belt 49 or the fixing belt 50 may occur. In this case, the control unit 16 determines that the leading end winding jam has occurred, and stops the conveyance of the long paper P.

  On the other hand, when the passage position is reached after a predetermined time has elapsed from the start of the printing operation, the control unit 16 determines that the long paper P has been normally conveyed from the fixing device 34 to the upstream sensor unit 51. To do. Subsequently, the control unit 16 detects the rotation of the slit disk 72 until the predetermined time elapses after the discharge sensor lever 54 reaches the passing state position based on the slit disk detection result, and the leading edge of the long paper P is detected. It is determined whether the part has reached the detection roller clamping part 70 in the downstream sensor part 52. Here, when the detection roller 66 does not rotate after the discharge sensor lever 54 reaches the passing state position until a predetermined time elapses, a long length is detected between the upstream sensor unit 51 and the detection roller clamping portion 70. The paper P may be jammed. In this case, the control unit 16 determines that a jam has occurred, and stops the conveyance of the long paper P.

  On the other hand, when the rotation of the detection roller 66 is detected during a predetermined time after the discharge sensor lever 54 reaches the passing state position, the control unit 16 is long from the upstream sensor unit 51 to the detection roller clamping portion 70. It determines with the front-end | tip part of the paper P having been normally conveyed. Subsequently, based on the lever detection result and the slit disk detection result, the control unit 16 determines whether or not the discharge sensor lever 54 keeps the passing state position and the rotation speed of the detection roller 66 keeps a predetermined value or more. .

  Here, when the rotation speed of the detection roller 66 becomes less than a predetermined value or when the rotation of the detection roller 66 stops, the transport direction is greater than the leading edge of the long paper P as shown in FIG. More than the leading edge of the long paper P between the fixing belt 34 and the detection roller clamping portion 70 as shown in FIG. There is a possibility that a bellows jam or the like during the conveyance in which the upstream side in the conveyance direction buckles in a bellows shape. In this case, the control unit 16 determines that the winding jam during conveyance or the bellows jam during conveyance occurs, and stops the conveyance of the long paper P.

[1-6. Effect]
In the conventional image forming apparatus, the detection roller is always driven to rotate along with the drive roller that rotates by itself regardless of whether or not the long sheet is sandwiched between the drive roller and the detection roller. For this reason, the conventional image forming apparatus can detect the occurrence of the jam because the rotation of the detection roller stops when the jam occurs in the state where the long paper is sandwiched between the driving roller and the detection roller. . However, in the conventional image forming apparatus, since the detection roller rotates even when the long paper is not sandwiched between the driving roller and the detection roller, the leading end portion of the long paper discharged from the fixing device is the fixing device. Thus, the detection roller continues to rotate even if it does not reach the drive roller and the detection roller. For this reason, the conventional image forming apparatus cannot detect a jam caused by the winding of the leading end of the long paper.

  On the other hand, the image forming apparatus 1 is transported without applying a driving force to actively rotate the detection roller 66 and the idle roller 68 in the driven roller unit 62 whose rotation is detected by the rotation detection sensor unit 64. The detection roller 66 and the idle roller 68 are rotated only when the long paper P to be in contact with the detection roller 66 and the idle roller 68. For this reason, the image forming apparatus 1 can prevent the detection roller 66 from rotating when the long paper P is not conveyed between the detection roller 66 and the idle roller 68. Accordingly, when the image forming apparatus 1 detects that the leading end of the long paper P does not reach the detection roller clamping portion 70 even after a predetermined time has elapsed after the start of printing, the image forming apparatus 1 is caused by the winding of the leading end of the long paper P. It can be determined that a jam has occurred.

  Here, since the long paper P heated by the fixing device 34 has no stiffness and tends to bend with a light load, the long paper P is not easily driven by the idle roller 68 and the detection roller 66 which do not have a driving force to rotate. When the paper is sandwiched, the slit disk detection result may become unstable due to the vibration of the long paper P. On the other hand, in the image forming apparatus 1, a discharge roller 36 having a rotational driving force and a pinch roller 37 that rotates with the discharge roller 36 are disposed in the vicinity of the upstream side in the transport direction with respect to the idle roller 68 and the detection roller 66. I did it. For this reason, the image forming apparatus 1 can stabilize the slit disk detection result by holding the long paper P between the discharge roller 36 and the pinch roller 37 and stably conveying the long paper P. In addition, since the image forming apparatus 1 can send out the long paper P in the transport direction by the discharge roller 36 and the pinch roller 37, the long paper P is buckled by the load of the idle roller 68 and the detection roller 66. It is possible to prevent a paper feed failure from occurring.

  Here, the long paper P heated by the fixing device 34 tends to be easily deformed at the leading end portion, and therefore, the leading end portion tends to be wound around the heating belt 49 or the fixing belt 50. On the other hand, in the image forming apparatus 1, the upstream sensor unit 51 is provided between the fixing device 34 and the downstream sensor unit 52. As a result, the image forming apparatus 1 can detect the leading end winding jam at an early stage, and while the leading end of the long paper P is slightly wound around the heating belt 49 or the fixing belt 50, the long paper P is handed to the operator. Since it can be removed, it is possible to prevent the heating belt 49 or the fixing belt 50 from being damaged by the leading end winding jam.

  In the above configuration, the image forming apparatus 1 is disposed downstream of the conveyance path 26 for conveying the long paper P along the longitudinal direction and the fixing unit 34 for heating the long paper P in the conveyance direction of the long paper P. An idle roller 68 that does not have a driving force and abuts on the long paper P conveyed along the conveyance path 26 and rotates by being driven, and is opposed to the idle roller 68 across the conveyance path 26. A detection roller 66 that does not have a driving force and contacts and rotates with the long paper P conveyed along the conveyance path 26 and a second sensor 74 that detects the rotation of the detection roller 66 are provided. As a result, the image forming apparatus 1 can rotate the detection roller 66 and the idle roller 68 only when the long paper P being conveyed contacts the detection roller 66 and the idle roller 68. It is possible to detect that a jam has occurred in the long paper P before the leading end of the long paper P discharged from 34 reaches the detection roller 66 and the idle roller 68.

[2. Other Embodiments]
In the above-described embodiment, the discharge sensor lever 54 that rotates when the long paper P comes into contact with the long paper contact portion 54B, and the first sensor that detects the detector portion 54C of the discharge sensor lever 54. The case where the upstream wrap jam is detected by the upstream sensor unit 51 including 56 has been described. The present invention is not limited to this, and various types of sensors for detecting the long paper discharged from the fixing device detect the leading edge of the long paper and detect the upstream side of the long paper in the transport direction. And you may go.

  In the above-described embodiment, the case where the discharge sensor unit 40 is arranged in the vicinity of the left end set as the transport position reference in the transport path 26 has been described. The present invention is not limited to this, and the discharge sensor unit 40 may be arranged at various positions in the transport width direction in the transport path.

  Further, in the above-described embodiment, the case where the slit disk 72 is rotated by transmitting the rotational force of the detection roller 66 to the slit disk 72 via the detection roller gear 66G formed on the detection roller 66 has been described. The present invention is not limited to this, and the rotational force of the detection roller 66 may be transmitted to the slit disk 72 by other various power transmission methods.

  Furthermore, in the above-described embodiment, the case where the rotation of the detection roller 66 is detected by the rotation detection sensor unit 64 including the slit disk 72 and the second sensor 74 has been described. The present invention is not limited to this, and the rotation of the detection roller 66 may be detected by other various sensors.

  Further, in the above-described embodiment, the present invention is applied to the image forming apparatus 1 that is an intermediate transfer method in which the toner image primarily transferred from the image forming unit 28 to the intermediate transfer belt 42 is secondarily transferred to the long paper P. Said about the case. The present invention is not limited to this, and the present invention may be applied to a direct transfer type image forming apparatus that directly transfers a toner image from an image forming unit to a long sheet.

  Further, in the embodiment described above, image formation is performed by the conveyance path 26 as the conveyance path, the idle roller 68 as the idle roller, the detection roller 66 as the detection roller, and the second sensor 74 as the rotation detection sensor. The case where the image forming apparatus 1 as an apparatus is configured has been described. However, the present invention is not limited to this, and the image forming apparatus may be configured by a conveyance path having various configurations, an idle roller, a detection roller, and a rotation detection sensor.

  The present invention can also be used in an image forming apparatus that conveys a long medium.

  DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 10 ... Feeder, 12 ... Cutter unit, 14 ... Image forming unit, 16 ... Control part, 20 ... Paper feed roller, 22 ... Conveyance roller, 24 ... Auto cutter, 26... Conveyance path 28... Image forming section 30... Intermediate transfer section 32... Conveyance roller 34 34 Fixing device 36... Discharge roller 36 S. Discharge roller shaft 37. , 37S: pinch roller shaft, 38: discharge roller, 39: pinch roller, 40: discharge sensor, 42: intermediate transfer belt, 44: secondary transfer counter roller, 46: secondary transfer roller , 48... Heater, 49... Heating belt, 50 .. fixing belt, 51... Upstream sensor section, 52 .. downstream sensor section, 54... Discharge sensor lever, 54A. Paper paper , 54C... Detector section, 56... First sensor, 58... Driving roller section, 60... Rotation detection sensor unit, 62. , 66S ... detection roller shaft, 66G ... detection roller gear, 68 ... idle roller, 68S ... idle roller shaft, 70 ... detection roller clamping part, 72 ... slit disk, 74 ... second sensor, P ... ... long paper.

Claims (8)

A transport path for transporting long paper along the longitudinal direction;
An idle that is arranged on the downstream side in the conveyance direction of the long paper with respect to the fixing device that heats the long paper, does not have a driving force, and rotates in contact with the long paper conveyed through the conveyance path Laura,
A detection roller that is disposed opposite the idle roller across the conveyance path, has no driving force, and rotates in contact with the long paper conveyed through the conveyance path;
A rotation detection sensor unit for detecting rotation of the detection roller ;
It is arranged near the idle roller and the detection roller on the upstream side in the conveying direction, and is arranged opposite to the discharging roller having a driving force and the discharging roller across the conveying path, and has no driving force. A drive roller section having a pinch roller that rotates in contact with the long paper transported through the transport path;
Have
An image forming apparatus in which an outer peripheral surface of the detection roller and an outer peripheral surface of the pinch roller overlap . The image forming apparatus according to claim 1, further comprising an upstream sensor unit that is provided between the fixing device and the idle roller and the detection roller, and detects an arrival of the leading end of the long paper and a conveying state. Wherein the rotation of the detection roller detection result of the rotation detecting sensor unit and, according to claim 2, further comprising a control unit for controlling the conveyance of the long paper based on the detection result of the long paper in the upstream sensor unit Image forming apparatus. The image forming apparatus according to claim 3 , wherein when the leading edge of the long paper is not detected by the upstream sensor unit within a predetermined time, the control unit stops the conveyance of the long paper. When the rotation detection sensor unit does not detect rotation of the detection roller within a predetermined time after the upstream sensor unit detects the leading edge of the long paper in the upstream sensor unit, the control unit conveys the long paper. The image forming apparatus according to claim 4 , wherein the image forming apparatus is stopped. The control unit, when detecting the rotation of the detection roller in the rotation detection sensor unit, stops the conveyance of the long paper when detecting that the rotation speed of the detection roller has decreased to a predetermined value or less. Item 6. The image forming apparatus according to Item 5 . The image according to claim 2 , wherein the upstream sensor unit includes a lever that rotates about a fulcrum when it contacts the long paper, and a lever detection sensor that detects a rotation state of the lever. Forming equipment. The detection roller is disposed in a central portion between the pinch rollers adjacent to each other in the rotation axis direction,
The idle roller is disposed in a central portion between the discharge rollers adjacent in the rotation axis direction.
The image forming apparatus according to claim 1.

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