JP2009241284A - Image forming apparatus and conveying device for continuous paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain continuous paper from being more damaged due to retained foreign matter as compared with a configuration that the continuous paper is held to apply tension, when the tension is applied to the continuous paper to be conveyed. <P>SOLUTION: An image forming apparatus includes: a conveying part which conveys the continuous paper P in a conveying direction A; an image forming part which is provided to the upstream side from the conveying part in the conveying direction A and forms an image on the continuous paper P; a position fixing roll 71 which is arranged in contact with the first surface of the continuous paper P on the upstream side from the image forming part in the conveying direction A; and a position movable roll 72 which is arranged in contact with the second surface of the continuous paper P on the upstream side from the position fixing roll 71 in the conveying direction A and applies the tension, without holding the continuous paper P by the position fixing roll 71 and the position movable roll 72. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that forms an image on continuous paper and a continuous paper transport device that transports the continuous paper.

In recent years, for example, an image forming apparatus that employs an electrophotographic image forming process and forms an image on a long continuous sheet as a recording medium has been used.
As a technique described in the publication, a transport unit that transports continuous paper is provided downstream of the image forming unit that forms an image on continuous paper in the transport direction of the continuous paper, and further upstream of the image forming unit in the transport direction of the continuous paper. A technique has been proposed in which a pair of rolls that sandwich continuous paper is provided and a predetermined tension is applied to the continuous paper that passes through the image forming unit (see Patent Document 1).

Japanese Patent Laid-Open No. 2005-262738

  An object of the present invention is to suppress the continuous paper from being damaged by a staying foreign substance, as compared with a configuration in which tension is applied by sandwiching the continuous paper when tension is applied to the conveyed continuous paper.

The invention according to claim 1 is a transport unit that transports continuous paper in a predetermined transport direction, an image forming unit that is provided upstream of the transport unit in the transport direction and forms an image on the continuous paper, and Tension applying means for applying tension to the continuous paper transported in the transport direction upstream of the image forming unit in the transport direction, and the tension applying means contacts one surface of the continuous paper A first contact member; and a second contact member that contacts the other surface of the continuous paper on the upstream side of the first contact member in the transport direction, and is between the first contact member and the continuous paper. The image forming apparatus is characterized in that tension is applied to the continuous paper transported by the transport unit by a dynamic frictional force acting and a dynamic friction force acting between the second contact member and the continuous paper.
The invention according to claim 2 further includes a position changing unit that changes a relative positional relationship between the first contact member and the second contact member, and the position changing unit includes the first contact member and the continuous paper. 2. The image forming apparatus according to claim 1, wherein the tension applied to the continuous paper is variable by changing a contact area between the second contact member and the continuous paper. .
According to a third aspect of the present invention, in the image forming apparatus according to the second aspect, the position changing unit moves the second contact member while fixing the position of the first contact member. .
According to a fourth aspect of the present invention, the first contact member and the second contact member are rotating bodies that rotate, and a drive unit that rotationally drives at least one of the first contact member or the second contact member. The tension applying means moves the second contact member to a position where the continuous sheet is sandwiched between the second contact member and the first contact member, and the drive unit 4. The image formation according to claim 2, wherein at least one of the first contact member and the second contact member is driven to transport the continuous sheet in a direction opposite to the transport direction. 5. Device.
According to a fifth aspect of the present invention, the tension applying means further includes a third contact member that sandwiches the continuous sheet together with the second contact member by the movement of the second contact member, and the second contact member and the third contact member The contact member is a rotating body that rotates, and further includes a drive unit that rotationally drives at least one of the second contact member and the third contact member. The tension applying unit includes the position changing unit, The second contact member is moved to a position where the continuous paper is sandwiched between the second contact member and the third contact member, and the drive unit moves at least one of the first contact member and the second contact member. 4. The image forming apparatus according to claim 2, wherein the continuous sheet is conveyed in a direction opposite to the conveying direction by being driven.
The invention according to claim 6 further includes a drive unit that intermittently rotates the first contact member and the second contact member in the transport direction of the continuous paper by the transport unit. The image forming apparatus according to any one of 1 to 5.
The invention according to claim 7 is provided on the upstream side in the transport direction with respect to the image forming unit and on the downstream side in the transport direction with respect to the first contact member, and in a direction orthogonal to the transport direction of the continuous paper. The positioning part further includes a positioning part, and the positioning part is formed in a curved shape and guides the continuous paper by bringing the continuous paper into contact with the outer surface, and the continuous paper in contact with the outer surface of the guide member A skew rotating body that rotates in contact with the surface of the sheet and applies a conveying force in the oblique direction of the conveying direction to the continuous sheet, and the continuous sheet conveyed in the oblique direction by the skew rotating body. 7. The image forming apparatus according to claim 1, further comprising an abutting member against which one side end is abutted.
According to an eighth aspect of the present invention, the side edge detection unit that detects the position of the side edge of the continuous sheet fed from the positioning unit and the position changing unit are controlled to vary the tension applied to the continuous sheet. The image forming apparatus according to claim 7, further comprising: a tension setting unit that sets the continuous sheet according to a detection result of the side edge detection unit. It is.

The invention according to claim 9 is a transport unit that transports continuous paper in a predetermined transport direction, and a tension applying unit that applies tension to the continuous paper transported in the transport direction upstream of the transport unit in the transport direction. The tension applying means contacts a first contact member that contacts one surface of the continuous paper and the other surface of the continuous paper upstream of the first transport member in the transport direction. A second contact member, and is conveyed by the conveying unit by a dynamic friction force acting between the first contact member and the continuous paper and a dynamic friction force acting between the second contact member and the continuous paper. A continuous paper transport device that applies tension to the continuous paper.
The invention according to claim 10 further includes a position changing unit that changes a relative positional relationship between the first contact member and the second contact member, and the position changing unit includes the first contact member and the continuous sheet. The continuous paper transport device according to claim 9, wherein a tension applied to the continuous paper is variable by changing a contact area between the second contact member and the continuous paper. It is.
The invention according to claim 11 is characterized in that the position changing unit moves the second contact member while fixing the position of the first contact member. It is.

According to the first aspect of the present invention, the continuous paper can be prevented from being damaged by the staying foreign matter as compared with the configuration in which the continuous paper is sandwiched and tension is applied.
According to the second aspect of the invention, the tension applied to the continuous paper can be adjusted.
According to the third aspect of the present invention, since the positional variation of the continuous paper conveyance path is suppressed at the location where the tension is applied, the posture of the continuous paper sent toward the image forming unit can be stabilized. .
According to the fourth aspect of the present invention, it is possible to transport the continuous paper in the direction opposite to the transport direction without adding a new configuration.
According to the fifth aspect of the present invention, continuous paper can be transported in the direction opposite to the transport direction without adding a new configuration.
According to the sixth aspect of the present invention, since the contact position between the first contact member and the second contact member and the continuous sheet is changed, uneven wear of the first contact member and the second contact member can be suppressed.
According to the seventh aspect of the present invention, it is possible to correct the positional deviation in the direction orthogonal to the conveyance direction of the continuous paper.
According to the eighth aspect of the invention, it is possible to apply a tension suitable for correcting the positional deviation in the direction orthogonal to the conveying direction of the continuous paper to the continuous paper.
According to the ninth aspect of the present invention, it is possible to suppress the continuous paper from being damaged by the staying foreign matter as compared with the configuration in which the continuous paper is sandwiched and tension is applied.
According to the tenth aspect of the present invention, the tension applied to the continuous paper can be adjusted.
According to the eleventh aspect of the present invention, it is possible to stabilize the posture of the continuous sheet fed from the first contact member toward the transport unit as compared with the case where the first contact member is moved.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
<Embodiment 1>
FIG. 1 is a diagram illustrating an overall configuration of an image forming apparatus 10 to which the exemplary embodiment is applied. The image forming apparatus 10 has a function of forming a toner image on a long continuous paper P that is transported in the transport direction A (sub-scanning direction). The image forming apparatus 10 conveys the continuous paper P in a direction opposite to the conveyance direction A (reverse conveyance direction B), for example, after stopping the image formation operation and before starting the next image formation operation. It also has a function to do. In the image forming apparatus 10 according to the present embodiment, so-called pinless paper in which perforations are not formed is used as the continuous paper P.

  The image forming apparatus 10 includes an image forming unit 20 that forms an image on the continuous paper P, and a fixing unit that is provided on the downstream side in the transport direction A as viewed from the image forming unit 20 and heat-fixes the image formed on the continuous paper P. 30, provided downstream of the fixing unit 30 in the transport direction A, and provided on the upstream side of the transport direction A with respect to the transport unit 40 for applying driving force to the continuous paper P, and forming an image. A feeding unit 50 that applies tension to the continuous paper P passing through the unit 20 together with the transport unit 40 and corrects the positional deviation of the continuous paper P in the direction orthogonal to the transport direction A (main scanning direction), and each of these units. And a control unit 60 for controlling the operation. The image forming apparatus 10 according to the present embodiment includes an engine casing 12 and a stacker casing 14, and the image forming unit 20, the sending unit 50, and the control unit 60 are connected to the engine casing 12. The fixing unit 30 and the transport unit 40 are respectively attached to the stacker casing 14. Further, upstream of the feeding unit 50 in the transport direction A, an age roll 68 for supplying continuous paper P sent from a paper feeding device (not shown) is provided. Further, a transport roll for transporting the continuous paper P is appropriately provided in the transport path of the continuous paper P as necessary. In the following description, the surface of the continuous paper P on which image formation is performed by the image forming unit 20 is referred to as a first surface, and the back surface thereof is referred to as a second surface.

  The image forming unit 20 includes a photosensitive drum 21 that rotates in the direction of the arrow in the drawing, a charger 22 that charges the photosensitive drum 21 to a predetermined potential, and a downstream side of the charging drum 22 in the rotational direction of the photosensitive drum 21. An exposure device 23 that exposes the photosensitive drum 21 after charging, a developing device 24 that develops the exposed photosensitive drum 21 with toner on the downstream side of the exposure device 23 in the rotation direction of the photosensitive drum 21, and a developing device 24. The transfer unit 25 transfers the toner image formed on the photosensitive drum 21 to the first surface of the continuous paper P at the downstream side of the rotation direction of the photosensitive drum 21, and the rotation of the photosensitive drum 21 more than the transfer unit 25. And a cleaner 26 for cleaning the transferred photosensitive drum 21 on the downstream side in the direction and on the upstream side in the rotational direction of the photosensitive drum 21 with respect to the charger 22. In this embodiment, the image forming unit 20 forms an image by a so-called electrophotographic method, but any other method such as an ink jet method may be adopted.

  The fixing unit 30 includes a flash lamp 31 that extends along a direction orthogonal to the conveyance direction A of the continuous paper P and is arranged in a row in the conveyance direction A. The flash lamp 31 is disposed in a non-contact manner so as to face the first surface of the continuous paper P, and is configured to light up intermittently.

  The transport unit 40 includes a driving roll 41 that rotates clockwise and counterclockwise in the figure, a winding roll 42 that is attached to the right side of the driving roll 41 in the figure and that defines the winding amount of the continuous paper P around the driving roll 41, A drive roll 41 is provided on the upper side in the figure, and is provided with a pinch roll 43 that sandwiches the continuous paper P together with the drive roll 41. In the present embodiment, the drive roll 41 is in contact with the second surface of the continuous paper P, and the winding roll 42 and the pinch roll 43 are in contact with the first surface of the continuous paper P. Here, the drive roll 41 is connected to a main drive motor 44 (see FIG. 5 described later) for rotationally driving the roll. The drive roll 41 is driven to rotate in the counterclockwise direction in the figure when the continuous paper P is conveyed in the conveyance direction A, and in the clockwise direction in the figure when conveyed in the reverse conveyance direction B. . In the following description, the rotation of the main drive motor 44 when the drive roll 41 is rotated counterclockwise in the figure is referred to as normal rotation, and the main drive motor 44 when the drive roll 41 is rotated clockwise in the figure. This rotation is called reverse rotation. Further, the winding roll 42 and the pinch roll 43 are configured to be rotated at the same speed as the rotation speed of the drive roll 41 via the continuous paper P. The pressure of the pinch roll 43 against the drive roll 41 is determined in advance so as to suppress slippage between the drive roll 41 and the pinch roll 43 and the continuous paper P. For this reason, the ideal transport amount that the continuous paper P will be transported by the rotation of the drive roll 41 and the actual transport amount that the continuous paper P is actually transported are suppressed from shifting due to the above-mentioned slip. The

Next, the configuration of the delivery unit 50 will be described in detail.
FIG. 2 is a perspective view of the configuration of the delivery unit 50 as viewed obliquely from the upper left of FIG. 1, and FIG. 3 is a side view of the delivery unit 50 viewed from the front side of FIG. FIG. 4 is a development view for explaining the conveyance path of the continuous paper P in the delivery unit 50. In FIG. 4, description of a separation claw 73 and a conveyance guide 74 which will be described later is omitted.
The feeding unit 50 cooperates with the transport unit 40 (see FIG. 1) to apply tension to the continuous paper P passing through the image forming unit 20, and the tension applying unit 70 in the transport direction A more than the tension applying unit 70. A misalignment correction unit 80 that is disposed on the downstream side and corrects misalignment of the continuous paper P in a direction (main scanning direction) orthogonal to the transport direction A, and is disposed on the downstream side in the transport direction A from the misalignment correction unit 80. And a side edge detection sensor 90 that detects the position of one side edge of the continuous paper P in the main scanning direction. The tension applying unit 70 also has a function of applying a driving force to the continuous paper P when the continuous paper P is transported in the reverse transport direction B, as will be described later.

  The tension applying unit 70 is disposed on the upstream side in the transport direction A with respect to the position fixing roll 71 as an example of the first contact member that rotates clockwise and counterclockwise in FIG. 3 includes a position movable roll 72 as an example of a second contact member that rotates clockwise and counterclockwise. Here, the position fixing roll 71 is disposed so as to be in contact with the first surface of the continuous paper P, and the position movable roll 72 is disposed so as to be in contact with the second surface of the continuous paper P. For example, as illustrated in FIG. 3, the conveyance path of the continuous paper P passes between the position fixing roll 71 and the position movable roll 72 between the rotation axis of the position fixing roll 71 and the rotation axis of the position movable roll 72. It straddles the axis V. Thereby, in the vicinity of the position fixing roll 71 and the position movable roll 72, the conveyance path of the continuous paper P is substantially S-shaped. The position fixing roll 71 has a diameter of 19.5 mm, and an electroless nickel plating layer is formed on the outer peripheral surface thereof. On the other hand, the diameter of the position movable roll 72 is 20.0 mm which is larger than that of the position fixed roll 71, and a ceramic sprayed layer is formed on the outer peripheral surface thereof. The outer peripheral surface of the position movable roll 72 is set to have a higher coefficient of friction with the continuous paper P than the outer peripheral surface of the position fixing roll 71.

  The position fixing roll 71 and the position movable roll 72 are connected to a sub drive motor 75 (see FIG. 5 described later) as an example of a drive unit that rotationally drives them. The position fixing roll 71 is driven to rotate in the clockwise direction in the drawing when the continuous paper P is conveyed in the conveyance direction A, and in the counterclockwise direction when it is conveyed in the reverse conveyance direction B. On the other hand, the position movable roll 72 rotates counterclockwise in the figure when transporting the continuous paper P in the transport direction A and clockwise when transporting the continuous paper P in the reverse transport direction B. Driven. In the following description, the rotation of the sub drive motor 75 when the position fixing roll 71 is rotated in the clockwise direction in the figure and the position movable roll 72 is rotated in the counterclockwise direction in the figure is referred to as normal rotation. The rotation of the sub drive motor 75 when the 71 is rotated counterclockwise in the drawing and the position movable roll 72 is rotated clockwise in the drawing is referred to as reverse rotation.

  In the tension applying unit 70, the position of the rotation shaft of the position fixing roll 71 is fixed. On the other hand, the position of the rotation shaft of the position movable roll 72 is movable along an axis V connecting the rotation axis of the position fixed roll 71 and the rotation axis of the position movable roll 72. The inter-axis distance L with respect to the position movable roll 72 can be changed. The position movable roll 72 is connected to a movement motor 76 (see FIG. 5 described later) for moving the position of the rotation shaft of the position movable roll 72 via a worm gear (not shown). In the following description, the rotation of the movement motor 76 when the position movable roll 72 is moved closer to the position fixed roll 71 is referred to as normal rotation, and the rotation of the movement motor 76 when the position movable roll 72 is moved away from the position fixed roll 71. Called reversal. Here, FIG. 3 shows a state in which the position movable roll 72 is disposed at the reference position with respect to the position fixing roll 71, and the inter-axis distance L at this time is the reference inter-axis distance L0. In the present embodiment, the distance L between the axes is set to be larger or smaller than the reference distance L0 by the moving motor 76. The moving motor 76 and the worm gear in the present embodiment are examples of the position changing unit in the present invention.

  The tension applying unit 70 further includes a separation claw 73 that extends in a direction orthogonal to the conveyance direction A and is disposed in contact with the position fixing roll 71. The separation claw 73 is made of, for example, a polyester film or the like, and is attached so that the tip portion of the separation claw 73 contacts the rotation direction when the position fixing roll 71 rotates counterclockwise in FIG. Yes. Further, the tension applying unit 70 further includes a conveyance guide 74 disposed so as to cover the position movable roll 72. The conveyance guide 74 is attached at a position where it does not come into contact with the position movable roll 72 when it moves.

  The misregistration correction unit 80 as an example of the positioning unit has a curved shape in a U shape, and a curved guide 81 as an example of a guide member in which a conveyance path of the continuous paper P is formed on the outer surface. A fan-shaped side guide plate 82 as an example of an abutting member attached to the front side of the curved guide 81 so as to cover the conveyance path, and a direction orthogonal to the conveyance direction A at a substantially central portion of the conveyance direction A of the curved guide 81. A plurality of skew rolls 83 (83a to 83d) that are attached to the openings (four locations in this example) obliquely with respect to the transport direction A and rotate clockwise and counterclockwise in FIG. And. Here, the skew roll 83 is attached to the curved guide 81 so that the downstream side is closer to the side guide plate 82 than the upstream side in the transport direction A. Further, the skew roll 83 is disposed so that the outer peripheral surface thereof slightly protrudes from the outer surface of the curved guide 81. The skew roll 83 receives a driving force by coming into contact with the transported continuous paper P. When the continuous paper P is transported in the transport direction A, the skew roll 83 is rotated clockwise in FIG. When transported to B, it rotates counterclockwise. In the present embodiment, the first surface of the continuous paper P is in contact with the outer surface of the curved guide 81 and the outer peripheral surface of the skew roll 83. Further, in the present embodiment, the position fixing roll 71 provided in the tension applying unit 70 and the upstream end portion in the conveyance direction A of the curved guide 81 provided in the position deviation correcting unit 80 are arranged close to each other. Yes.

  The side edge detection sensor 90 as an example of the side edge detection unit detects the position of the side edge on the side where the side guide plate 82 is attached, out of both side edges in the direction orthogonal to the conveyance direction A of the continuous paper P. Here, as the side edge detection sensor 90, various sensors such as a contact type or a non-contact type may be used. In this embodiment, for example, a laser is directed from the first surface side of the continuous paper P toward the continuous paper P. A so-called laser sensor is used to detect the position of the side edge of the continuous paper P by irradiating light in a band shape in the main scanning direction and detecting the position of the laser light received on the second surface side of the continuous paper P. ing.

  The side edge detection sensor 90 outputs the detection result of the edge of the continuous paper P sent from the misalignment correction unit 80 on the side guide plate 82 side as a voltage value E. Here, when the end position of the discharged continuous paper P coincides with the abutting surface of the side guide plate 82 (see FIG. 4), the side end detection sensor 90 uses the reference voltage value ES as the voltage value E. Is output. When the end position of the discharged continuous paper P is shifted from the abutting surface of the side guide plate 82 to the rear side (upper side in FIG. 4), the side end detection sensor 90 uses the reference voltage value as the voltage value E. A value larger than ES is output. On the other hand, when the end position of the discharged continuous paper P is shifted from the abutting surface of the side guide plate 82 to the front side (lower side shown in FIG. 4), the side end detection sensor 90 uses the voltage value E as a reference. A value smaller than the voltage value ES is output. Note that the magnitude of the voltage value E becomes larger or smaller than the reference voltage value ES as the deviation amount of the continuous paper P increases.

Next, an image forming operation by the image forming apparatus 10 shown in FIG. 1 will be described.
With the start of the image forming operation, the continuous paper P is transported in the transport direction A in a state where tension is applied to the transport direction A by the transport unit 40 and the tension applying unit 70. At this time, the misregistration correction unit 80 provided between the transport unit 40 and the tension applying unit 70 positions the continuous paper P in the main scanning direction using the tension applied to the continuous paper P, and the image forming unit. The continuous paper P is sent out toward the 20 transfer position.

  On the other hand, with the start of the image forming operation, in the image forming unit 20, the photosensitive drum 21 rotates in the direction of the arrow shown in FIG. By exposure, an electrostatic latent image is formed on the photosensitive drum 21. The electrostatic latent image formed on the photosensitive drum 21 is developed by the developing unit 24 to become a toner image, and is electrostatically transferred by the transfer unit 25 to the first surface of the continuous paper P passing through the transfer position. The residual toner remaining on the photosensitive drum 21 after the transfer is removed by the cleaner 26 to prepare for the next charging operation.

  Then, the continuous paper P to which the toner image is transferred passes through the fixing unit 30. At this time, the toner image on the first surface of the continuous paper P is heated by the opposing flash lamp 31 and fixed on the continuous paper P. Thereafter, the continuous paper P on which the toner image has been fixed passes through the transport unit 40 and is discharged to the outside of the image forming apparatus 10.

  FIG. 5 shows a block diagram related to the conveyance of the continuous paper P among the functions of the control unit 60 shown in FIG. The CPU 61 of the control unit 60 that functions as an example of a tension setting unit executes processing while appropriately exchanging data with the RAM 63 according to a program stored in the ROM 62. Further, various instructions from a user interface UI provided in the image forming apparatus 10 and side end detection information from the side end detection sensor 90 are input to the control unit 60 via the input / output interface 64. Further, the control unit 60 controls driving of the main drive motor 44, the sub drive motor 75, and the movement motor 76 via the input / output interface 64.

Next, the transport operation of the continuous paper P in the above-described image forming operation will be described in detail.
FIG. 6A shows an example of a timing chart of the conveying operation of the continuous paper P in the image forming operation. Now, the conveying operation of the continuous paper P in the image forming operation will be described with reference to FIGS.
The control unit 60 that has received an instruction to start an image forming operation from the user interface UI starts normal rotation of the main drive motor 44 while the sub drive motor 75 is stopped. At this time, the main drive motor 44 gradually increases the surface speed of the drive roll 41. As a result, the continuous paper P is pulled in the transport direction A by the frictional force acting between the drive roll 41 and the pinch roll 43. On the other hand, in the tension applying unit 70, since the sub drive motor 75 is stopped, the position fixing roll 71 is stopped in a state where the first surface of the continuous paper P is wound, and the position movable roll 72 is moved to the continuous paper P. It stops in the state which wound the 2nd surface. Thereby, predetermined frictional forces act between the position fixing roll 71 and the first surface of the continuous paper P and between the position movable roll 72 and the second surface of the continuous paper P, respectively. Therefore, between the transport unit 40 and the tension applying unit 70, the continuous paper P is pulled in the transport direction A by the transport unit 40 and is held by the tension applying unit 70. Tension is applied. The continuous paper P has a position where the frictional force acting between the driving roll 41 and the winding roll 42 and the pinch roll 43 is larger than the frictional force acting between the position fixing roll 71 and the position movable roll 72. While slipping between the fixed roll 71 and the position movable roll 72, the sheet begins to be conveyed in the conveyance direction A in a state where a predetermined tension is applied. As described above, the continuous sheet P is positioned in the sub-scanning direction at the transfer position of the image forming unit 20 by applying tension to the continuous sheet P in the transport direction A, that is, the sub-scanning direction by the transport unit 40 and the tension applying unit 70. Made.

  When the surface speed of the drive roll 41 reaches the target transport speed V1 of the continuous paper P, the main drive motor 44 controls the surface speed of the drive roll 41 to be constant at the transport speed V1. Further, as the surface speed of the drive roll 41 reaches the transport speed V <b> 1, the control unit 60 starts the normal rotation of the sub drive motor 75. At this time, the sub drive motor 75 gradually increases the speed of the position fixing roll 71 and the position movable roll 72, and when the surface speed of the position fixing roll 71 and the position movable roll 72 reaches the speed limit V2, these position fixing roll 71 The surface speed of the position movable roll 72 is controlled to be constant at the limit speed V2. However, since the diameter of the position movable roll 72 is larger than the diameter of the position fixed roll 71, the surface speed of the position movable roll 72 is actually slightly higher than the surface speed of the position fixed roll 71. Here, the speed limit V2 is set to be significantly lower than the transport speed V. As a result, the continuous paper P continues to be transported in the transport direction A in a state where a predetermined tension is applied while causing slippage between the position fixing roll 71 and the position movable roll 72. Here, in the present embodiment, when tension is applied to the continuous paper P, the position fixing roll 71 and the position movable roll 72 are arranged so as to be shifted with respect to the transport direction A so that these two rolls do not come into contact with each other. It has become. That is, a configuration in which the continuous paper P is sandwiched between the position fixing roll 71 and the position movable roll 72 is not employed. For this reason, even when foreign matter adheres to the position fixing roll 71 and the position movable roll 72, since there is nothing facing the foreign matter, it becomes difficult for the foreign matter to be pressed against the continuous paper P. This makes it easier for foreign objects to be transported downstream in the transport direction.

  The continuous paper P in which tension is applied to the continuous paper P by the transport unit 40 and the tension applying unit 70 is attached to the outer surface of the curved guide 81 and the curved guide 81 in a misalignment correcting unit 80 disposed between the two. The paper is conveyed in the conveyance direction A while being pressed against the skew feeding roller 83. Then, the continuous paper P is given a force in the oblique direction of the conveyance direction A, that is, toward the side guide plate 82 side by the skew roll 83, and the continuous paper P tries to move to the side guide plate 82 side while being conveyed. To do. When the end of the continuous paper P on the side guide plate 82 side comes into contact with the side guide plate 82 with the movement, further movement of the continuous paper P is restricted. As a result, the continuous paper P is transferred from the misalignment correction unit 80 to the image forming unit 20 in a state where the end on the side guide plate 82 side is aligned at substantially the same position, that is, in a state in which positioning is performed in the main scanning direction. Sent out to the position. Here, in the present embodiment, the skew roll 83 is in contact with the first surface of the continuous paper P. However, the positional deviation correction unit 80 is a member that sandwiches the continuous paper P from the second surface side together with the skew roll 83. Not equipped.

  Then, the toner image formed on the photosensitive drum 21 of the image forming unit 20 is transferred to the conveyed continuous paper P at the transfer position, and then the transferred toner image is fixed by the fixing unit 30. Thereafter, the sheet is discharged to the outside through the transport unit 40.

  When the series of image forming operations is completed, the control unit 60 stops the sub drive motor 75 while keeping the main drive motor 44 rotating forward. At this time, the sub drive motor 75 gradually decelerates the surface speeds of the position fixing roll 71 and the position movable roll 72 from the speed limit V2. Then, as the sub drive motor 75 stops, the control unit 60 stops the main drive motor 44 this time. At this time, the main drive motor 44 gradually decelerates the surface speed of the drive roll 41 from the transport speed V1. In this way, in the image forming apparatus 10 that has finished the image forming operation by stopping the rotation of the drive roll 41 after stopping the rotation of the position fixing roll 71 and the position movable roll 72, the conveyance unit 40 and the tension A state in which a predetermined tension is applied to the continuous paper P between the application unit 70 and the application unit 70 is maintained.

  In the above description, the position fixing roll 71 and the position movable roll 72 are controlled to be constant at the speed limit V2, but the present invention is not limited to this. For example, as shown in FIG. 6B, the position fixing roll 71 and the position movable roll 72 may be rotated intermittently by intermittently rotating the sub drive motor 75 at regular intervals. Also in this case, a predetermined tension is applied to the continuous paper P being transported between the transport unit 40 and the tension applying unit 70. Further, the position fixing roll 71 and the position movable roll 72 may be stopped without rotating. However, when the position fixing roll 71 and the position movable roll 72 are rotated continuously or intermittently, the contact portion between the continuous paper P being conveyed and the position fixing roll 71 and the position movable roll 72 changes. These local fixed rolls 71 and the movable movable roll 72 are less likely to cause uneven wear.

  In the image forming apparatus 10, as described above, the misregistration correction unit 80 is used to correct the deviation in the main scanning direction of the continuous paper P supplied to the transfer position of the image forming unit 20. However, if, for example, meandering occurs in the continuous paper P as the behavior of the conveyed continuous paper P changes, the misalignment correction unit 80 may not be able to correct the main scanning direction deviation of the continuous paper P as a result. Therefore, in the present embodiment, the position of one end in the main scanning direction of the continuous paper P discharged from the misregistration correction unit 80 when the image forming operation is executed is detected by the side edge detection sensor 90, and the detection result is determined according to the detection result. By changing the tension applied to the continuous paper P, the position deviation correction unit 80 adjusts the force in the main scanning direction applied to the continuous paper P (referred to as skew force), and the continuous paper P supplied to the transfer position is adjusted. The position in the main scanning direction is kept constant.

Now, the variable operation of the tension applied to the continuous paper P in the above-described image forming operation will be described in detail.
FIG. 7 shows a timing chart of the variable operation of the tension applied to the continuous paper P in the image forming operation. FIG. 8 is a diagram for explaining a variable operation of tension applied to the continuous paper P. Further, FIG. 9 is a diagram for explaining a contact state between the position fixing roll 71 and the position movable roll 72 and the continuous paper P in the variable tension operation for the continuous paper P.

  In the initial state, as shown in FIG. 3, in the tension applying unit 70, the position movable roll 72 is placed at the reference position with respect to the position fixing roll 71, and the inter-axis distance L is set to the reference inter-axis distance L0. Is done. When the position movable roll 72 is placed at the reference position as described above, the continuous paper P is wound around the position fixing roll 71 at the first winding angle θ1 as shown in FIG. Winding is performed at the second winding angle θ2. As a result, the continuous paper P comes into contact with the position fixing roll 71 with the first contact area S1, and comes into contact with the position movable roll 72 with the second contact area S2. Here, when the continuous paper P is wound around the position fixing roll 71, the first winding angle θ <b> 1 is the transport direction of the axial center of the position fixing roll 71 and the contact area of the position fixing roll 71 and the continuous paper P. An angle formed by both ends of A. In addition, the second winding angle θ <b> 2 is determined when the continuous paper P is wound around the position movable roll 72, and in the transport direction A of the axial center of the position movable roll 72 and the contact area between the position movable roll 72 and the continuous paper P. The angle between the two ends.

  For example, when the conveyed continuous paper P starts to meander in the direction away from the side guide plate 82, the voltage value E output from the side edge detection sensor 90 is the reference voltage value ES as shown in FIG. It will be higher than At this time, when the voltage value E exceeds a predetermined upper limit voltage value EH, the control unit 60 causes the moving motor 76 to rotate forward for a predetermined time. As a result, the position movable roll 72 moves from the reference position to the side closer to the position fixing roll 71, and as shown in FIG. 8A, the inter-axis distance L becomes the adjacent inter-axis distance L1 (L1 <L0). At a position (referred to as a proximity position). Thus, when the position movable roll 72 moves from the reference position to the close position, the first winding angle θ1 increases and the second winding angle θ2 also increases as shown in FIG. 9B. As a result, the first contact area S1 increases and the second contact area S2 also increases. Therefore, when the position movable roll 72 is placed at the close position, the position fixed roll 71 and the position movable roll 72 and the continuous paper P act between the position movable roll 72 and the continuous paper P as compared with the case where the position movable roll 72 is placed at the reference position. Dynamic friction force increases. In the present embodiment, the dynamic friction force generated by the tension applying unit 70 is a resistance force against the driving of the continuous paper P by the transport unit 40, and therefore the position movable roll 72 is moved from the reference position to the proximity position. As a result, the tension in the transport direction A applied to the continuous paper P increases between the transport unit 40 and the tension applying unit 70. When the tension applied to the continuous paper P increases in this way, the pressing force of the skew roll 83 against the continuous paper P increases in the misalignment correction unit 80. Then, the skew force applied to the continuous paper P from the skew roll 83 increases, and the continuous paper P tends to move to the side closer to the side guide plate 82. As a result, the positional deviation of the continuous paper P in the main scanning direction is suppressed.

  On the other hand, for example, when the conveyed continuous paper P starts to meander so as to strongly hit the side guide plate 82, the voltage value E output from the side edge detection sensor 90 is a reference value as shown in FIG. It becomes lower than the voltage value ES. At this time, when the output voltage value E falls below a predetermined lower limit voltage value EL, the control unit 60 reverses the moving motor 76 for a predetermined time. As a result, the position movable roll 72 moves from the reference position to the side farther from the position fixing roll 71, and the distance L between the axes becomes the distance L2 between the remote axes as shown in FIG. 8B (L2> L0). Stop at position (remote position). When the position movable roll 72 moves from the reference position to the remote position in this way, as shown in FIG. 9C, the first winding angle θ1 is decreased and the second winding angle θ2 is also decreased. As a result, the first contact area S1 and the second contact area S2 are reduced. Therefore, when the position movable roll 72 is placed at the remote position, the position movable roll 72 and the position movable roll 72 are operated between the continuous paper P and the position fixed roll 71 as compared with the case where the position movable roll 72 is placed at the reference position. The dynamic friction force becomes smaller. Accordingly, the tension in the transport direction A applied to the continuous paper P decreases between the transport unit 40 and the tension applying unit 70. Thus, when the tension applied to the continuous paper P is reduced, the pressing force of the skew roll 83 against the continuous paper P is reduced in the misalignment correction unit 80. Then, the skew force applied to the continuous paper P from the skew roll 83 decreases, and the continuous paper P tends to move away from the side guide plate 82. As a result, the positional deviation of the continuous paper P in the main scanning direction is suppressed.

  FIG. 10 is a graph showing the relationship between the first winding angle θ1 (°) of the continuous paper P around the position fixing roll 71 and the tension T (kgf) generated in the transport direction A. FIG. 10 shows the result of using continuous paper P having a width of 18 inches in the main scanning direction and a basis weight of 33 gsm, and 40 gsm having a width of 18 inches in the main scanning direction. The results when using the one having a basis weight of 2 are shown. From the figure, it is understood that the generated tension T increases by increasing the first winding angle θ1. As a matter of course, the generated tension T also increases when the second winding angle θ2 is increased.

  Here, when the friction coefficient of the position fixing roll 71 is μ1, the friction coefficient of the position movable roll 72 is μ2, and the weight of the continuous paper P is W, the position fixing roll 71 and the position movable roll 72 give the continuous paper P to the continuous paper P. The tension T is expressed by the following formula.

  In this equation (1), the friction coefficient μ1 of the position fixing roll 71, the friction coefficient μ2 of the position movable roll 72, and the weight W of the continuous paper P are constant values. Therefore, also from the above equation (1), the tension T increases if the first winding angle θ1 and the second winding angle θ2 are increased, and the tension decreases if the first winding angle θ1 and the second winding angle θ2 are decreased. It is understood.

  In the image forming apparatus 10 according to the present embodiment, after the image forming operation is finished, the continuous paper P is stopped while gradually decelerating. Therefore, the continuous paper P is the last in the image forming operation. A margin is generated between the image formation position and the transfer position. Also, when starting the next image forming operation, the continuous paper P is gradually increased and the transfer of the image is started after the continuous paper P reaches the transport speed V1, so that a blank is generated in the continuous paper P. . Therefore, in this image forming apparatus 10, the continuous paper P is moved in the reverse conveyance direction B by a predetermined distance between the end of the previous image forming operation and the start of the next image forming operation. Thus, it is possible to prevent the useless blank space from being generated in the continuous paper P.

Now, the reverse conveyance operation of the continuous paper P between the above-described image forming operations will be described in detail.
FIG. 11 shows a timing chart of the reverse conveyance operation of the continuous paper P between the image forming operations. FIG. 12 is a diagram for explaining the reverse conveyance operation of the continuous paper P.
After the main drive motor 44 is stopped along with the end of the image forming operation (see FIG. 6A), the control unit 60 causes the moving motor 76 to rotate forward. Accordingly, the position movable roll 72 arranged at the reference position, the proximity position or the remote position moves toward the position fixing roll 71 and comes into contact with the position fixing roll 71 as shown in FIG. (Referred to as contact position). As a result, the continuous paper P is sandwiched between the position fixing roll 71 and the position movable roll 72. When the position movable roll 72 reaches the contact position, the moving motor 76 stops.

  As the moving motor 76 stops, the control unit 60 starts reverse rotation of the sub drive motor 75. At this time, the sub drive motor 75 gradually increases the speed of the position fixing roll 71 and the position movable roll 72. As a result, the continuous paper P is pulled in the reverse conveyance direction B by the frictional force acting between the position fixing roll 71 and the position movable roll 72. On the other hand, since the main drive motor 44 is stopped in the transport unit 40, the drive roll 41, the winding roll 42, and the pinch roll 43 are stopped with the continuous paper P sandwiched therebetween. As a result, a frictional force acts between the driving roll 41, the winding roll 42 and the pinch roll 43 and the continuous paper P. Therefore, since the continuous paper P is pulled by the tension applying unit 70 and is held by the transport unit 40 between the tension applying unit 70 and the transport unit 40, a predetermined tension is applied to the continuous paper P. However, since the frictional force acting between the drive roll 41 and the pinch roll 43 is larger than the frictional force acting between the position fixing roll 71 and the position movable roll 72, the continuous paper P has the position fixing roll 71 and The continuous paper P is difficult to slide between the drive roll 41 and the pinch roll 43 while being held in a state of sliding between the position movable roll 72.

  When the surface speeds of the position fixing roll 71 and the position movable roll 72 reach the target reverse conveyance speed V3, the sub drive motor 75 keeps the surface speeds of the position fixing roll 71 and the position movable roll 72 constant at the reverse conveyance speed V3. To control. However, since the diameter of the position movable roll 72 is larger than the diameter of the position fixed roll 71, the surface speed of the position movable roll 72 is actually slightly higher than the surface speed of the position fixed roll 71. Further, as the surface speeds of the position fixing roll 71 and the position movable roll 72 reach the reverse transport speed V3, the control unit 60 starts the reverse rotation of the main drive motor 44. At this time, the main drive motor 44 gradually increases the surface speed of the drive roll 41, and when the surface speed of the drive roll 41 reaches the reverse limit speed V4, the surface speed of the drive roll 41 is constant at the reverse limit speed V4. To control. Here, the reverse speed limit V4 is set slightly lower than the reverse transport speed V3. As a result, the continuous paper P is transported in the reverse transport direction B in a state where a predetermined tension is applied while causing slippage between the position fixing roll 71 and the position movable roll 72. On the other hand, the continuous paper P hardly slips between the drive roll 41 and the pinch roll 43, or reverse in a state where less slip occurs than the slip generated between the position fixing roll 71 and the position movable roll 72. It is conveyed in the conveyance direction B.

  When a predetermined time elapses, the control unit 60 stops the main drive motor 44 while the sub drive motor 75 is reversed. At this time, the main drive motor 44 gradually decelerates the surface speed of the drive roll 41 from the reverse limit speed V4. Then, as the main drive motor 44 stops, the control unit 60 stops the sub drive motor 75. At this time, the sub drive motor 75 gradually decelerates the surface speeds of the position fixing roll 71 and the position movable roll 72 from the reverse conveyance speed V3. In this manner, the image forming apparatus that has completed the movement of the continuous paper P in the reverse transport direction B by stopping the rotation of the position fixing roll 71 and the position movable roll 72 after stopping the rotation of the drive roll 41 first. 10, a state in which a predetermined tension is applied to the continuous paper P is maintained between the tension applying unit 70 and the transport unit 40.

  Subsequently, as the auxiliary drive motor 75 stops, the control unit 60 reverses the movement motor 76 for a predetermined time. As a result, the position movable roll 72 placed at the contact position moves away from the position fixing roll 71 and stops at the reference position where the inter-axis distance L becomes the reference inter-axis distance L0 as shown in FIG. To do. At this time, when the position movable roll 72 moves from the contact position to the reference position, the contact state between the position fixing roll 71 and the position movable roll 72 and the continuous paper P changes, and as a result, the tension applied to the continuous paper P is increased. descend. For this reason, as the moving motor 76 stops, the control unit 60 rotates the main drive motor 44 forward for a predetermined time in a state where the sub drive motor 75 is stopped to restore the tension applied to the continuous paper P to the original state. Thus, a series of reverse conveyance operations is completed.

  By the way, when the continuous paper P is transported in the reverse transport direction B in this way, the continuous paper P may be adsorbed while being wound around the position fixing roll 71. This is because, for example, the continuous paper P charged by the transfer device 25 at the transfer position is rewound to the tension applying unit 70. In this embodiment, as shown in FIG. 3, the separation claw 73 is placed in contact with the position fixing roll 71, and the continuous paper P adsorbed on the position fixing roll 71 is peeled off by the separation claw 73. Therefore, it is difficult for jamming and the like due to sticking to occur. Since the position moving roll 72 is provided with a conveyance guide 74, the continuous paper P that has passed through the nip region between the position fixing roll 71 and the position movable roll 72 by being conveyed in the reverse conveyance direction B is conveyed. While being guided by the guide 74, it is transported in the reverse transport direction B (downward), and jamming or the like is unlikely to occur in this region.

  In this example, the reverse conveyance operation is executed starting from the fact that the main drive motor 44 is stopped along with the end of the image forming operation. However, the present invention is not limited to this. For example, the reverse conveyance operation may be executed starting from reception of the start time of the image forming operation from the user interface UI, and then the image forming operation may be started.

  Further, in the present embodiment, the stop position of the position movable roll 72 in the variable tension operation is set to the three positions of the reference position, the proximity position, and the remote position, but is not limited thereto. For example, a stop position is further provided between the reference position and the proximity position and between the reference position and the remote position, and the stop position is changed stepwise according to the voltage value E output from the side end detection sensor 90. May be.

Furthermore, in this Embodiment, although the tension | tensile_strength provision part 70 was comprised using the one position fixed roll 71 and the one position movable roll 72, it is not restricted to this.
FIG. 13 is a side view showing another configuration example of the delivery unit 50 including the tension applying unit 70. The misalignment correction unit 80 and the side edge detection sensor 90 in FIG. 13 are the same as those shown in FIG. In the delivery unit 50, the tension applying unit 70 includes three position fixing rolls 71 (first position fixing roll 71a, second position fixing roll 71b, and third position fixing roll 71c) and one position movable roll 72. Has been. The first position fixing roll 71a is fixed on the downstream side in the conveying direction A with respect to the position movable roll 72, and the second position fixing roll 71b is fixed on the downstream side in the conveying direction A with respect to the first position fixing roll 71a. The rolls 71c are arranged downstream of the second position fixing roll 71b in the transport direction A and upstream of the positional deviation correction unit 80, respectively. Here, the first position fixing roll 71a and the third position fixing roll 71c are in contact with the second surface of the continuous paper P so that the second position fixing roll 71b and the position movable roll 72 are in contact with the first surface of the continuous paper P. Each is arranged so as to come into contact. The positions of the rotation axes of the first position fixing roll 71a, the second position fixing roll 71b, the third position fixing roll 71c and the position movable roll 72 are set on the axis V, and the continuous paper P is conveyed. The route extends between the rolls. The position movable roll 72 is configured such that its rotation axis moves on the axis V.

  As apparent from the above equation (1), the tension applied to the continuous paper P is represented by multiplication of the number of rolls around which the continuous paper P is wound. Therefore, when the position fixing roll 71 is constituted by a plurality of rolls in this way, even if the friction coefficient of each roll is lowered, the overall tension is ensured.

  Further, for example, as shown in FIG. 14, a film-like banner member 91 formed of resin is provided on the upstream side in the transport direction A (downstream in the reverse transport direction B) from the tension applying unit 70. The curtain member 91 may be disposed so as to be in contact with the first surface, and the upstream end in the conveyance direction A may be fixed by the fixing member 92. In addition, from the viewpoint of preventing the continuous paper P from being adsorbed, it is preferable to use the banner member 91 that has been subjected to antistatic treatment. In the image forming apparatus 10 according to the present embodiment, when the continuous paper P is transported in the reverse transport direction B, the continuous paper P is loosened on the downstream side in the reverse transport direction B with respect to the tension applying unit 70. By providing the configuration, the weight of the trailing curtain member 91 is added to the continuous paper P, so that the slack is eliminated and the reverse transport operation is stabilized.

<Embodiment 2>
FIG. 15 is a side view of the delivery unit 50 according to the second embodiment. Here, the configurations of the misalignment correction unit 80 and the side edge detection sensor 90 in the present embodiment are the same as those in the first embodiment. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the tension applying unit 70 of the delivery unit 50, the position of the rotation shaft of the position fixing roll 71 is fixed, and the position of the rotation shaft of the position movable roll 72 is movable, as in the first embodiment. is there. However, in the present embodiment, the position of the rotation axis of the position movable roll 72 is movable along a locus line W having the rotation axis of the position fixing roll 71 as a center and a reference axis distance L0 as a radius. . The tension applying unit 70 further includes an opposing roll 77 as an example of a third contact member disposed above the position movable roll 72 and outside the locus line W. The opposing roll 77 is rotatable in the clockwise direction and the counterclockwise direction in the figure, and when the position movable roll 72 moves upward in the figure along the trajectory line W, it is in a position where it comes into contact with the position movable roll 72. It is attached. Here, FIG. 15 shows a state in which the position movable roll 72 is arranged at the first position with respect to the position fixed roll 71, and the position of the rotation axis of the position movable roll 72 at this time is the position of the position fixed roll 71. The direction is 45 ° diagonally downward to the right in the figure as seen from the rotation axis.

FIG. 16 is a diagram for explaining the variable operation of the tension applied to the continuous paper P in the present embodiment.
In the image forming operation, when the continuous paper P conveyed in the conveyance direction A meanders in the direction away from the side guide plate 82, the moving motor 76 (see FIG. 5) moves the position movable roll 72 from the first position to the opposing roll 77. Is moved to a side closer to, and stopped at a position (referred to as a second position) shown in FIG. When the position movable roll 72 is moved from the first position to the second position in this manner, the first winding angle θ1 and the first contact area S1 are increased, and the second winding angle θ2 and the second winding angle are increased as in the first embodiment. 2 The contact area S2 also increases. As a result, the tension applied to the continuous paper P increases, and the positional deviation of the continuous paper P in the main scanning direction is suppressed.

  On the other hand, when the continuous paper P transported in the transport direction A in the image forming operation meanders in a direction in which the continuous paper P strongly hits the side guide plate 82, the moving motor 76 (see FIG. 5) moves the position movable roll 72 from the first position. It moves to the side away from the opposing roll 77 and stops at a position (referred to as a third position) shown in FIG. Thus, when the position movable roll 72 moves from the first position to the third position, the first winding angle θ1 and the first contact area S1 decrease, and the second winding angle θ2 and the second contact, as in the first embodiment. Area S2 also decreases. As a result, the tension applied to the continuous paper P is reduced and the positional deviation of the continuous paper P in the main scanning direction is suppressed.

FIG. 17 is a diagram for explaining the reverse conveyance operation of the continuous paper P in the present embodiment.
When the continuous paper P is to be transported in the reverse transport direction B during the image forming operation, the moving motor 76 (see FIG. 5) fixes the position movable roll 72 from the first position, the second position, or the third position. It moves to the side approaching the roll 71 and stops at a position (referred to as a fourth position) in contact with the position fixing roll 71. As a result, as in the first embodiment, the continuous paper P is sandwiched between the position fixing roll 71 and the position movable roll 72. Then, the continuous paper P is conveyed in the reverse conveyance direction B by reversing the main drive motor 44 and the sub drive motor 75 in the same procedure as in the first embodiment. In the reverse conveyance operation, similarly to the first embodiment, after the reverse rotation of the main drive motor 44 and the sub drive motor 75 is stopped and the position movable roll 72 is moved to the first position by the moving motor 76, It is preferable to apply a predetermined tension to the continuous paper P by causing the main drive motor 44 to rotate forward for a predetermined time.

  In the first and second embodiments, the position of the position movable roll 72 is moved according to the meandering amount of the continuous paper P. However, the present invention is not limited to this. For example, the arrangement position of the position movable roll 72 may be determined according to the type of continuous paper P (for example, basis weight or main scanning direction length). Further, the position of the position movable roll 72 may be set manually, and the user may arbitrarily change the tension applied to the continuous paper P.

1 is a diagram illustrating an overall configuration of an image forming apparatus to which the exemplary embodiment is applied. FIG. 3 is a perspective view illustrating a configuration of a delivery unit according to the first embodiment. FIG. 3 is a side view of a delivery unit according to the first embodiment. FIG. 4 is a development view for explaining a continuous paper conveyance path in a delivery unit according to the first embodiment. It is a block diagram of a control part. 6 is a timing chart of a continuous sheet conveying operation in an image forming operation of the image forming apparatus. 6 is a timing chart of a variable operation of tension applied to continuous paper in an image forming operation. FIG. 6 is a diagram for explaining a variable tension operation in the first embodiment. It is a figure for demonstrating the contact state of the position fixed roll and position movable roll, and continuous paper in the variable operation of tension | tensile_strength. It is a graph which shows the relationship between the 1st winding angle of the continuous paper with respect to a position fixed roll, and the tension | tensile_strength (kgf) which generate | occur | produces in a conveyance direction. 6 is a timing chart of a reverse conveyance operation of continuous paper during an image forming operation. 6 is a diagram for explaining a reverse conveyance operation for continuous paper in Embodiment 1. FIG. It is a side view which shows the other structural example of a delivery part. It is a figure for demonstrating attachment of a banner member. It is a side view of the sending-out part which concerns on Embodiment 2. FIG. 10 is a diagram for explaining a variable tension operation in the second embodiment. FIG. 10 is a diagram for explaining the reverse conveyance operation of continuous paper in the second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Image forming apparatus, 20 ... Image forming part, 30 ... Fixing part, 40 ... Conveying part, 41 ... Drive roll, 42 ... Winding roll, 43 ... Pinch roll, 44 ... Main drive motor, 50 ... Sending part, 60 ... Control part 70 ... Tension applying part 71 ... Position fixing roll 72 ... Position movable roll 75 ... Sub driving motor 76 ... Moving motor 80 ... Position displacement correction part 81 ... Curving guide 82 ... Side guide plate 83: Skewed roll, 90: Side edge detection sensor, A: Transport direction, B: Reverse transport direction, L: Distance between axes of position-fixed roll and position-movable roll, P: Continuous paper, V: Axis, θ1 ... First winding angle, θ2 ... second winding angle, μ1 ... friction coefficient of position fixed roll, μ2 ... friction coefficient of position movable roll

Claims (11)

A transport unit for transporting continuous paper in a predetermined transport direction;
An image forming unit that is provided upstream of the transport unit in the transport direction and forms an image on the continuous paper;
Tension applying means for applying tension to the continuous paper transported in the transport direction upstream of the image forming unit in the transport direction;
The tension applying means includes a first contact member that contacts one surface of the continuous sheet, and a second contact member that contacts the other surface of the continuous sheet on the upstream side in the transport direction from the first contact member. The continuous paper transported by the transport unit by the dynamic frictional force acting between the first contact member and the continuous paper and the dynamic frictional force acting between the second contact member and the continuous paper. An image forming apparatus characterized by applying tension. A position changing unit that changes a relative positional relationship between the first contact member and the second contact member;
The position changing unit changes a tension applied to the continuous paper by changing a contact area between the first contact member and the continuous paper and a contact area between the second contact member and the continuous paper. The image forming apparatus according to claim 1.   The image forming apparatus according to claim 2, wherein the position changing unit moves the second contact member while fixing the position of the first contact member. The first contact member and the second contact member are rotating bodies that rotate,
A drive unit that rotationally drives at least one of the first contact member and the second contact member;
The tension applying unit moves the second contact member to a position where the continuous sheet is sandwiched between the second contact member and the first contact member, and the driving unit moves the second contact member to the first contact member. 4. The image forming apparatus according to claim 2, wherein the continuous sheet is conveyed in a direction opposite to the conveying direction by driving at least one of the second contact members. 5. The tension applying means further includes a third contact member that sandwiches the continuous paper together with the second contact member by movement of the second contact member,
The second contact member and the third contact member are rotating bodies that rotate,
A drive unit that rotationally drives at least one of the second contact member and the third contact member;
The tension applying unit moves the second contact member to a position where the continuous sheet is sandwiched between the second contact member and the third contact member, and the driving unit moves the second contact member to the first contact member. 4. The image forming apparatus according to claim 2, wherein the continuous sheet is conveyed in a direction opposite to the conveying direction by driving at least one of the second contact members. 5.   6. The drive unit according to claim 1, further comprising a drive unit that intermittently rotates the first contact member and the second contact member in the transport direction of the continuous sheet by the transport unit. The image forming apparatus described. A positioning unit that is provided upstream of the image forming unit in the transport direction and downstream of the first contact member in the transport direction and that positions the continuous paper in a direction orthogonal to the transport direction; ,
The positioning part is
A guide member that is curved and formed by bringing the continuous paper into contact with the outer surface;
A skew rotating body that rotates in contact with a surface of the continuous sheet that contacts the outer surface of the guide member, and applies a conveying force to the continuous sheet in an oblique direction of the conveying direction;
The image according to any one of claims 1 to 6, further comprising an abutting member against which one side end of the continuous sheet conveyed in the oblique direction by the skew rotating body is abutted. Forming equipment. A side edge detection unit that detects a position of the side edge of the continuous sheet fed from the positioning unit;
A tension setting unit that controls the position changing unit to variably set a tension applied to the continuous paper;
The image forming apparatus according to claim 7, wherein the tension setting unit changes a tension applied to the continuous sheet according to a detection result by the side edge detection unit. A transport unit for transporting continuous paper in a predetermined transport direction;
Tension applying means for applying tension to the continuous paper transported in the transport direction upstream of the transport unit in the transport direction;
The tension applying means includes a first contact member that contacts one surface of the continuous paper, and a second contact member that contacts the other surface of the continuous paper on the upstream side in the transport direction from the first transport member. The continuous paper transported by the transport unit by the dynamic frictional force acting between the first contact member and the continuous paper and the dynamic frictional force acting between the second contact member and the continuous paper. A continuous paper conveying device characterized by applying tension. A position changing unit that changes a relative positional relationship between the first contact member and the second contact member;
The position changing unit changes a tension applied to the continuous paper by changing a contact area between the first contact member and the continuous paper and a contact area between the second contact member and the continuous paper. The continuous paper conveying apparatus according to claim 9.   11. The continuous paper conveying apparatus according to claim 10, wherein the position changing unit moves the second contact member while fixing the position of the first contact member.

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