JP6186909B2 - Paper transport device, control method for paper transport device, and image forming apparatus - Google Patents

Description

  The present invention relates to a sheet conveying apparatus, a method for controlling the sheet conveying apparatus, and an image forming apparatus.

  Conventionally, there are endless belts on the top and bottom, and the endless belt conveys the paper (printing surface on the upper side) and conveys the paper, and a heat sink is provided inside the upper endless belt to cool the paper in the paper conveyance process. A cooling device has been proposed as one of paper conveying devices. In such a sheet conveying apparatus, the endless belt may be displaced in the width direction (direction including the sheet surface) orthogonal to the sheet conveying direction. If the misalignment becomes excessive, rotation of the endless belt will be hindered. Therefore, the paper transport device executes steering control to return the endless belt to a predetermined position (equilibrium position) when the misalignment occurs. (See Patent Document 1).

JP 2009-63861 A

  However, conventionally, in a paper conveying apparatus having upper and lower endless belts, control has been performed so that each endless belt is independently returned to the equilibrium position, so that each endless belt is returned to the equilibrium position during paper conveyance. At this time, if the moving speed and moving direction of the upper and lower endless belts are different, the paper is rubbed.

  The present invention has been made to solve such a conventional problem, and an object of the present invention is to control a sheet conveying apparatus and a sheet conveying apparatus that can prevent a situation in which a sheet is rubbed. A method and an image forming apparatus are provided.

In order to achieve the above object, a paper transport device according to the present invention is a paper transport device that sandwiches paper between upper and lower endless belts and transports the paper by rotating the upper and lower endless belts. Steering means for moving the upper and lower endless belts in the width direction by inclining the upper and lower endless belts in the width direction, and paper determination means for determining whether paper exists between the upper and lower endless belts; Control means for controlling the steering means, and deviation amount detection means for detecting a deviation amount from the equilibrium position of the upper and lower endless belts in the width direction , wherein the control means is a deviation by the deviation amount detection means. in the case where the detected amounts is determined that the endless belt of the upper and lower are displaced in different directions with respect to the equilibrium position, for the When the sheet between the upper and lower endless belt is determined to exist by the judgment means, and wherein the controlling the steering means to move the endless belt of the upper and lower at the same speed and the same direction in the width direction To do.

  According to this paper conveying apparatus, when it is determined that paper is present between the upper and lower endless belts, the steering means is controlled to move the upper and lower endless belts in the width direction at the same speed and in the same direction. When a sheet is present between the endless belts, the relative positions of the upper and lower endless belts are maintained, and the sheet is not rubbed. Particularly, since the upper and lower endless belts are moved in the width direction at the same speed and in the same direction, only one of the endless belts does not move unexpectedly due to a difference in frictional force between the upper and lower endless belts. Accordingly, it is possible to prevent a situation where the paper is rubbed.

  Further, in the paper conveying apparatus according to the present invention, the control means is an equilibrium position that is an appropriate position of the upper and lower endless belts when the paper judging means judges that paper is present between the upper and lower endless belts. It is preferable to repeat the operation of moving the upper and lower endless belts in the width direction at the same speed and in the same direction centering on.

  According to this sheet conveying apparatus, the upper and lower endless belts are reciprocated around the equilibrium position because the upper and lower endless belts are repeatedly moved in the width direction at the same speed and in the same direction around the equilibrium position. It will be. As a result, the movement of the upper and lower endless belts can be prevented from stopping during the sheet conveyance, and even when a long sheet is conveyed in the sheet conveyance direction, a situation in which the sheet is rubbed can be prevented. it can.

Further, in the paper transport device according to the present invention, when the control unit determines that the upper and lower endless belts are shifted in the same direction with respect to the equilibrium position by detecting the shift amount by the shift amount detection unit, after the endless belt remote from the equilibrium position of the upper and lower endless belt is moving the upper and lower endless belt so as to reach an equilibrium position at the same speed in the width direction, the endless belt is not in equilibrium position after movement It is preferable to repeat the operation of moving the upper and lower endless belts in the width direction at the same speed so as to reach the equilibrium position.

According to the paper conveying apparatus, if the upper and lower endless belt is determined to be shifted in the same direction, the upper and lower endless belt as the endless belt remote from the equilibrium position of the upper and lower endless belt reaches the equilibrium position Are moved in the width direction at the same speed, and then the upper and lower endless belts are moved in the width direction at the same speed so that the endless belts that are not in the equilibrium position reach the equilibrium position after the movement. For this reason, the upper and lower endless belts are alternately moved so as to reach the equilibrium position, and it is possible to prevent the sheet from being rubbed while the upper and lower endless belts are close to the proper positions. .

Further, in the paper conveying device according to the present invention, the control means is configured such that the upper and lower endless belts are displaced in different directions with respect to the equilibrium position by detecting the deviation amount by the deviation amount detection means. movement limit where the first distance between the endless belt and the equilibrium position farther from the equilibrium position of the endless belt is present on both sides in the width direction of the endless belt and the upper and lower endless belts closer from the equilibrium position If it is determined that the position is greater than the second distance between the endless belt and the closer movement limit position, the upper and lower endless belts are moved toward the closer movement limit position by the second distance. The endless belt closer to the equilibrium position is moved to the closer movement limit position by moving at a speed, and then the upper and lower endless belts are reciprocated between the movement limit positions at the same speed. It is preferable.

According to the paper conveying apparatus, and the upper and lower endless belts are displaced in different directions, a first distance between the equilibrium position from the endless belt of the equilibrium position and the farther one of the upper and lower endless belt, close to the equilibrium position If it is determined that the endless belt is larger than the second distance between the endless belt and the closer movement limit position, the upper and lower endless belts are moved at the same speed by the second distance toward the closer movement limit position. To move the endless belt closer to the equilibrium position to the closer movement limit position, and then the upper and lower endless belts are reciprocated between the movement limit positions at the same speed. Therefore, when the second distance is larger than the first distance and the endless belt far from the equilibrium position cannot be moved to the equilibrium position, the far endless belt is moved as close to the equilibrium position as possible, and then reciprocally travels. Will move. Therefore, even in a situation where the endless belt cannot be moved to the equilibrium position, it is possible to prevent the sheet from being rubbed while alternately moving the upper and lower endless belts to an appropriate position as much as possible.

Further, in the paper conveying device according to the present invention, the control means is configured such that the upper and lower endless belts are displaced in different directions with respect to the equilibrium position by detecting the deviation amount by the deviation amount detection means. movement limit where the first distance between the endless belt and the equilibrium position farther from the equilibrium position of the endless belt is present on both sides in the width direction of the endless belt and the upper and lower endless belts closer from the equilibrium position When it is determined that the position is equal to or less than the second distance between the position where the endless belt is closer to the movement limit position, the endless belt far from the equilibrium position among the upper and lower endless belts reaches the equilibrium position. After the upper and lower endless belts are moved in the width direction at the same speed, the upper and lower endless belts are moved in the width direction at the same speed so that the endless belt that is not in the equilibrium position reaches the equilibrium position after the movement. It is preferable to repeat the operation of moving the.

According to the paper conveying apparatus, and the upper and lower endless belts are displaced in different directions, a first distance between the equilibrium position from the endless belt of the equilibrium position and the farther one of the upper and lower endless belt, close to the equilibrium position When it is determined that the endless belt is smaller than the second distance between the endless belt and the movement limit position closer to the endless belt, the endless belt farther from the equilibrium position among the upper and lower endless belts may reach the equilibrium position. First, the upper and lower endless belts are moved in the width direction at the same speed, and then the upper and lower endless belts are moved in the width direction at the same speed so that the endless belts that are not in the equilibrium position reach the equilibrium position after the movement. . Thus, even when the upper and lower endless belts are displaced in different directions, if the upper and lower endless belts can be alternately moved to the equilibrium position due to the distance to the movement limit position, as described above. By alternately moving to the equilibrium position, it is possible to prevent the sheet from being rubbed while the upper and lower endless belts are in a state close to the proper position.

  In the paper transport device according to the present invention, the control means detects the deviation amount by the deviation amount detection means when the paper judgment means judges that there is no paper between the upper and lower endless belts. When it is determined that at least one of the upper and lower endless belts is displaced from the equilibrium position, it is preferable to control the steering means to move the upper and lower endless belts to the equilibrium position.

  According to this paper transport device, when it is determined that at least one of the upper and lower endless belts is displaced from the equilibrium position when there is no paper between the upper and lower endless belts, the steering means is controlled to Move the endless belt to the equilibrium position. For this reason, in a situation where there is no paper between the upper and lower endless belts and the paper cannot be rubbed, the upper and lower endless belts are returned to their proper positions, and the endless belts are not rubbed without causing the paper to be rubbed. An appropriate position can be obtained.

  In the paper transport device according to the present invention, the control means may be arranged on the upstream side of the upper and lower endless belts even when the paper judging means determines that paper is present between the upper and lower endless belts. When the rear end side of the paper is positioned in the front unit that sandwiches and conveys the paper, the control of the steering means is preferably prohibited.

  According to this paper transport device, even if it is determined that paper is present between the upper and lower endless belts, the rear end of the paper in the front unit that sandwiches and transports the paper on the upstream side of the upper and lower endless belts When the side is located, control of the steering means is prohibited. For this reason, the rear end of the paper is positioned in the front unit, and the situation where the paper is swung can be prevented by controlling the steering means and moving the endless belt in the width direction.

Further, the control method of the paper transport device according to the present invention is the control method of the paper transport device that sandwiches the paper by the upper and lower endless belts and transports the paper by rotating the upper and lower endless belts. A sheet determining step for determining whether or not a sheet exists between the belts, and steering means for moving the upper and lower endless belts in the width direction by inclining the upper and lower endless belts in a width direction perpendicular to the sheet conveyance direction. and a control step of controlling, and a shift amount detection step of detecting a shift amount from the equilibrium position of the upper and lower endless belt in the width direction, in the control step, by detecting the shift amount in the shift amount detecting process when the upper and lower endless belt is determined to be displaced in different directions with respect to the equilibrium position, the upper in the sheet determination step When the paper between the endless belt is determined to exist, the controls the steering means and moving the endless belt of the upper and lower at the same speed and the same direction in the width direction.

  According to this control method of the paper transport device, when it is determined that paper is present between the upper and lower endless belts, the steering means is controlled to move the upper and lower endless belts in the width direction at the same speed and in the same direction. Therefore, when a sheet exists between the upper and lower endless belts, the relative positions of the upper and lower endless belts are maintained, and the sheet is not rubbed. In particular, since the upper and lower endless belts are moved in the width direction at the same speed and in the same direction, the upper and lower endless belts continue to move in the width direction during the paper transport process, and the difference in frictional force between the upper and lower endless belts, etc. Only one endless belt will not move unexpectedly. Accordingly, it is possible to prevent a situation where the paper is rubbed.

Further, the image forming apparatus according to the present invention is configured such that the sheet is sandwiched between upper and lower endless belts, and the upper and lower ends in the width direction orthogonal to the sheet conveying direction of the sheet conveying apparatus that conveys the sheets by rotating the upper and lower endless belts. the control means for controlling the steering means for moving the endless belt of the upper and lower in the width direction by tilting the endless belt, and the paper determining means for determining whether the paper between the upper and lower endless belt is present, the A deviation amount detecting means for detecting a deviation amount from an equilibrium position of the upper and lower endless belts in the width direction, and the control means detects the deviation amount by the deviation amount detecting means so that the upper and lower endless belts are when it is determined that the shift in different directions with respect to the equilibrium position, the sheet between the upper and lower endless belts by said sheet determination means When it is determined that standing, the controls the steering means and moving the endless belt of the upper and lower at the same speed and the same direction in the width direction.

  According to this image forming apparatus, when it is determined that paper is present between the upper and lower endless belts, the steering means is controlled to move the upper and lower endless belts in the width direction at the same speed and in the same direction. When a sheet is present between the endless belts, the relative positions of the upper and lower endless belts are maintained, and the sheet is not rubbed. In particular, since the upper and lower endless belts are moved in the width direction at the same speed and in the same direction, the upper and lower endless belts continue to move in the width direction during the paper transport process, and the difference in frictional force between the upper and lower endless belts, etc. Only one endless belt will not move unexpectedly. Accordingly, it is possible to prevent a situation where the paper is rubbed.

  According to the present invention, it is possible to provide a paper transport device, a control method for the paper transport device, and an image forming apparatus that can prevent the paper from being rubbed.

1 is a configuration diagram schematically illustrating an image forming system including a sheet conveying device according to an embodiment. FIG. 2 is an enlarged view showing details of a sheet cooling unit shown in FIG. 1. FIG. 3 is a perspective view illustrating details of a sheet cooling unit illustrated in FIG. 2. FIG. 4 is a perspective view showing how the upper endless belt moves during operation of the first steering mechanism shown in FIG. 3. It is process drawing which shows the control method of the paper conveying apparatus which concerns on this embodiment. 6 is a flowchart illustrating a method for controlling the sheet conveying device according to the present embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments.

  FIG. 1 is a configuration diagram schematically illustrating an image forming system including a sheet conveying device according to the present embodiment. The image forming system 1 includes a paper feeding device 1A, an image forming device 1B, and a paper conveying device 1C.

  The paper feeding device 1A feeds the paper P to the image forming apparatus 1B, and selects the paper P requested by the image forming apparatus 1B from the plurality of trays Tr1 to Tr3, and selects the selected paper P Is supplied to the image forming apparatus 1B.

  The image forming apparatus 1B is an electrophotographic image forming apparatus such as a copying machine. The image forming apparatus 1B is a so-called tandem color image forming apparatus that forms a full-color image by arranging a plurality of photoconductors facing a single intermediate transfer belt in the vertical direction.

  The image forming apparatus is mainly composed of the document reading device 2, the main control unit 3, and the image forming units 10Y, 10M, 10C, and 10K, and these are housed in one casing. The document reading device 2 scans and exposes an image of a document with an optical system of a scanning exposure device, reads the reflected light with a line image sensor, and obtains an image signal. The image signal is subjected to processing such as A / D conversion, shading correction, and compression, and then input to the main control unit 3 as image data. Note that the image data input to the main control unit 3 is not limited to the data read by the document reading device 2, for example, data received from a personal computer connected to the image forming device 1 </ b> B or another image forming device. It may be stored in a portable recording medium such as a USB memory.

  The image forming units 10Y, 10M, 10C, and 10K are an image forming unit 10Y that forms a yellow (Y) image, an image forming unit 10M that forms a magenta (M) image, and an image that forms a cyan (C) image. The forming unit 10C includes an image forming unit 10K that forms a black (K) image.

  The image forming unit 10Y includes a photosensitive drum 21Y, a charging unit (not shown) arranged around the photosensitive drum 21Y, a developing device 22Y, an optical writing unit 15Y, and the like. Similarly, the image forming units 10M, 10C, and 10K include photosensitive drums 21M, 21C, and 21K, charging units (not shown) arranged around the photosensitive drums 21M, 21C, and 21K, developing devices 22M, 22C, and 22K, and optical writing units 15M, 15C, 15K, etc.

  The surfaces of the photosensitive drums 21Y, 21M, 21C, and 21K are uniformly charged by the charging unit, and the photosensitive drums 21Y, 21M, and 21K are scanned and exposed by the optical writing units 15Y, 15M, 15C, and 15K. Latent images are formed at 21C and 21K. Further, the developing devices 22Y, 22M, 22C, and 22K develop the latent images on the photosensitive drums 21Y, 21M, 21C, and 21K by developing with toner. Thus, an image (toner image) of a predetermined color corresponding to any one of yellow, magenta, cyan, and black is formed on the photosensitive drums 21Y, 21M, 21C, and 21K. The toner images formed on the photosensitive drums 21Y, 21M, 21C, and 21K are sequentially transferred to predetermined positions on the intermediate transfer belt 24, which is a belt-like intermediate transfer body, by a primary transfer roller (not shown). The

  The image composed of each color transferred onto the intermediate transfer belt 24 is transferred by the secondary transfer roller 26 to the paper P conveyed at a predetermined timing. The secondary transfer roller 26 is a roller-like rotating member, and is disposed in pressure contact with the intermediate transfer belt 24 to form a nip (transfer nip portion). Transcript.

  Further, the image forming apparatus 1B includes a paper feed tray Tr4. Therefore, the image forming apparatus 1B can form an image on the paper P stored in the paper feed tray Tr4. The paper P accommodated in the paper feed tray Tr4 is sent out to the transport path in the image forming apparatus 1B, like the paper P of the paper feed device 1A, and is transferred to the transfer nip portion by a plurality of pairs of rollers. The image composed of each color conveyed and transferred onto the intermediate transfer belt 24 is transferred by the secondary transfer roller 26.

  Further, the sheet P on which the image is transferred as described above is supplied to the sheet conveying apparatus 1C. The sheet conveying apparatus 1C conveys the sheet P from the image forming apparatus 1B and discharges the sheet P to the sheet discharge tray 47, or reverses the sheet P by the reverse conveying unit 60 and re-feeds the conveying path 70 in the image forming apparatus 1B. Or to supply. The sheet conveying apparatus 1C includes a fixing device (front unit) 30, a sheet cooling unit 40, a control unit (sheet determining unit, control unit, deviation amount detecting unit) 50, a reverse conveying unit 60, and a discharge tray 47. And.

  The fixing device 30 is a device that performs a fixing process for fixing an image in a process of nipping and conveying the paper P conveyed from the transfer nip portion. The fixing device 30 includes a pair of fixing rollers 31 and 32 that constitute a nip (fixing nip portion) by being arranged in pressure contact with each other, and a fixing heater (not shown) that heats the fixing roller 31. Yes. Each of the fixing rollers 31 and 32 is configured to be rotatable, and at least one of the rollers (for example, the fixing roller 32) is rotationally driven through a driving motor that is a driving unit. The fixing heater is turned on when energized, and for example, a halogen lamp can be used. The fixing device 30 fixes the image on the paper P by performing pressure fixing with a pair of fixing rollers 31 and 32 and heat fixing with a fixing heater.

  In the present embodiment, the fixing device 30 is provided in the sheet conveying device 1C, but is not limited thereto, and may be provided in the image forming device 1B.

  The paper cooling unit 40 cools the paper P on which the image is fixed by the fixing device 30. FIG. 2 is an enlarged view showing details of the sheet cooling unit 40 shown in FIG. 1, and FIG. 3 is a perspective view showing details of the sheet cooling unit 40 shown in FIG.

  As shown in FIGS. 2 and 3, the sheet cooling unit 40 includes upper and lower endless belts 41 and 42, a heat sink 43, photo sensors 44 and 45, steering mechanisms (steering means) 46 and 47, and a sheet detection sensor. 48.

  The upper and lower endless belts 41 and 42 are respectively wound around a plurality of rollers, and are rotated together to sandwich and convey the paper P conveyed from the fixing device 30. The heat sink 43 is disposed in the upper endless belt 41. The heat sink 43 is in contact with the back surface side of the upper endless belt 41 and cools the paper P by radiating heat from the heat radiating fins in the process of transporting the paper P.

  As shown in FIG. 3, the first photosensor 44 is provided at both ends of the upper endless belt 41 and outputs a signal corresponding to the amount of deviation from the equilibrium position in the width direction of the upper endless belt 41. is there. Further, as shown in FIG. 2, a second photo sensor 45 is provided on the lower endless belt 42. The second photosensor 45 is also provided at both ends of the lower endless belt 42 and outputs a signal corresponding to the amount of deviation from the equilibrium position in the width direction of the upper endless belt 41. The equilibrium position is an appropriate position of the upper and lower endless belts 41 and 42. For example, when the intermediate position in the width direction of the upper and lower endless belts 41 and 42 matches the intermediate position of the rollers around which the upper and lower endless belts 41 and 42 are wound, the upper and lower endless belts 41 and 42 are in equilibrium positions. It can be said.

  The steering mechanisms 46 and 47 move the upper and lower endless belts 41 and 42 in the width direction by inclining the upper and lower endless belts 41 and 42 in the width direction (including the paper surface) orthogonal to the paper transport direction FD. is there. Among these, the 1st steering mechanism 46 is provided corresponding to the upper endless belt 41, and moves the upper endless belt 41 in the width direction. The second steering mechanism 47 is provided corresponding to the lower endless belt 42, and moves the lower endless belt 42 in the width direction.

  As shown in FIG. 3, in detail, the first steering mechanism 46 includes a step motor 46a, a worm gear 46b, a sector gear 46c, and a steering roller bearing 46d.

  The steering roller bearing 46d supports the roller shaft of the upper endless belt 41. The stepping motor 60 is a motor that can be driven clockwise and counterclockwise. The worm gear 46b rotates with the driving of the stepping motor 60, and the sector gear 46c swings around the axis with the rotation of the worm gear 46b. The steering roller bearing 46d supports the roller shaft of the upper endless belt 41. The steering roller bearing 46d is connected to the sector gear 46c and operates as the sector gear 46c swings.

  In such a first steering mechanism 46, when the stepping motor 46a is driven counterclockwise in the first steering mechanism 46, the worm gear 46b rotates and the sector gear 46c swings upward about the axis. Accordingly, the steering roller bearing 46d moves upward.

  FIG. 4 is a perspective view showing how the upper endless belt 41 moves during the operation of the first steering mechanism 46 shown in FIG. When the steering roller bearing 46d moves upward, as shown in FIG. 4, the roller shaft of the upper endless belt 41 is tilted with the back side lowered, and the upper endless belt 41 is also tilted with the back side lowered. It becomes. That is, since the upper endless belt 41 is in a state where the tension on the back side is lower than that on the near side, the upper endless belt 41 gradually moves to the back side where the tension is low as the upper endless belt 41 rotates. The speed at which the upper endless belt 41 moves depends on the displacement amount D of the steering roller bearing 46d. That is, as the displacement amount D increases, the upper endless belt 41 moves to the rear side at a higher speed.

  Conversely, when the stepping motor 46a is driven clockwise, the worm gear 46b rotates and the sector gear 46c swings downward about the shaft. Accordingly, the steering roller bearing 46d moves downward. For this reason, the roller shaft of the upper endless belt 41 is slightly inclined toward the front side, and the upper endless belt 41 is also inclined toward the front side. That is, the upper endless belt 41 is in a state where the tension on the near side is lower than that on the far side, so that the upper endless belt 41 gradually moves to the near side having a lower tension as the upper endless belt 41 rotates.

  Further, the second steering mechanism 47 also includes a step motor, a worm gear, a fan-shaped gear, and a steering roller bearing, like the first steering mechanism 46, and the lower endless belt 42 is driven by the step motor. By tilting the roller shaft, the lower endless belt 42 is moved to the near side or the far side.

  Reference is again made to FIGS. 1 and 2. The paper detection sensor 48 is provided on the upstream side of the upper and lower endless belts 41 and 42, for example, and outputs a signal to that effect when the paper P is present.

  The control unit 50 controls the entire sheet conveying apparatus 1C, and includes a sheet determination function, a control function, and a deviation amount detection function. The sheet determination function determines whether or not the sheet P exists between the upper and lower endless belts 41 and 42. This sheet determination function determines whether or not the sheet P exists between the upper and lower endless belts 41 and 42 based on a signal from the sheet detection sensor 48, for example. Note that the determination method of the paper P by the paper determination function is not limited to this, and may be determined from, for example, the torque of the rollers that rotate the upper and lower endless belts 41 and 42, or other methods. May be.

  The control function is a function for controlling the steering mechanisms 46 and 47. In particular, in the present embodiment, when the sheet determination function determines that the sheet P exists between the upper and lower endless belts 41 and 42, the steering mechanism. By controlling 46 and 47, the upper and lower endless belts 41 and 42 are moved in the same direction and at the same speed in the width direction.

  Thus, when the paper P exists between the upper and lower endless belts 41 and 42, the relative positions of the upper and lower endless belts 41 and 42 are maintained, and the paper P is not rubbed. In particular, since the upper and lower endless belts 41 and 42 are moved in the width direction at the same speed and in the same direction, the upper and lower endless belts 41 and 42 continue to move in the width direction in the process of transporting the paper P. Only one of the endless belts 41 and 42 does not move unexpectedly due to a difference in frictional force between the belts 41 and 42. That is, when the control is not performed as described above, one of the endless belts 41 and 42 may move in the width direction due to a difference in frictional force between the upper and lower endless belts 41 and 42. In such a case, the paper P is rubbed. However, in the present embodiment, the upper and lower endless belts 41 and 42 are moved in the width direction at the same speed and in the same direction, so that one of the endless belts 41 and 42 may unexpectedly move in the width direction. It is possible to prevent the paper P from being rubbed.

  In the present embodiment, the sheet cooling unit 40 includes a heat sink 43, and the heat sink 43 is in contact with the upper endless belt 41. For this reason, when the displacement amount D of the first steering mechanism 46 and the second steering mechanism 47 is the same, the movement speed of the lower endless belt 42 tends to be higher than that of the upper endless belt 41. . For this reason, the control unit 50 moves both the upper and lower endless belts 41 and 42 in the same direction and at the same speed in consideration of such a tendency.

  The shift amount detection function is a function for detecting the shift amount from the equilibrium position of the upper and lower endless belts 41, 42 in the width direction, and detects the shift amount from the balance position based on the signals from the photosensors 44, 45. It is a function to do.

  The reverse conveyance unit 60 is a path through which the paper P conveyed from the paper cooling unit 40 is conveyed after being switched back. The paper P that has been switched back by the reverse conveyance unit 60 is conveyed to the refeed conveyance path 70 of the image forming apparatus 1B. The sheet P conveyed to the refeed conveyance path 70 is conveyed again to the transfer nip portion, and the toner image is transferred. As a result, printing is performed on both sides of the paper P.

  In addition, when the sheet determination function determines that the sheet P is present between the upper and lower endless belts 41 and 42, the control function performs the upper and lower movements around the equilibrium position that is the appropriate position of the upper and lower endless belts 41 and 42. The operation of moving the endless belts 41 and 42 in the width direction at the same speed and in the same direction is repeated. For this reason, the upper and lower endless belts 41 and 42 are reciprocated around the equilibrium position. Thereby, it is possible to prevent the movement of the upper and lower endless belts 41 and 42 from stopping during the sheet conveyance, and even when the long sheet P is conveyed in the sheet conveyance direction FD, the sheet is rubbed. Can be prevented.

  In addition, the control function varies the control method of the sheet conveying apparatus 1C based on the detection result of the deviation amount by the deviation amount detection function.

  Next, a control method of the sheet conveying apparatus 1C according to the embodiment of the present invention will be described. FIG. 5 is a process diagram showing a control method of the sheet conveying apparatus 1C according to the present embodiment, where (a) shows a first example, (b) shows a second example, and (c) shows. A third example is shown.

  As shown in FIG. 5, the process of moving the upper and lower endless belts 41 and 42 in the same direction and at the same speed in this embodiment is roughly classified into three cases. First, the first example shown in FIG. 5A is a case where the upper and lower endless belts 41 and 42 are displaced in the same direction from the equilibrium position. Based on the signals from the photosensors 44 and 45, the controller 50 determines that the upper and lower endless belts are displaced in the same direction with respect to the equilibrium position (first step).

  Next, the control unit 50 identifies an endless belt far from the equilibrium position among the upper and lower endless belts 41 and 42. In the example illustrated in FIG. 5A, the lower endless belt 42 is far from the equilibrium position, and the control unit 50 identifies the lower endless belt 42. In the example shown in FIG. 5A, the lower endless belt 42 is farther from the equilibrium position, but it goes without saying that the upper endless belt 41 may be farther from the equilibrium position. .

  Next, the control unit 50 moves the upper and lower endless belts 41 and 42 at the same speed in the width direction so that the identified lower endless belt 42 reaches the equilibrium position (second step). When the lower endless belt 42 reaches the equilibrium position, the control unit 50 moves the upper endless belt 41 that is not in the equilibrium position after movement to the equilibrium position at the same speed in the width direction (the first speed). 3 steps).

  Next, when the upper endless belt 41 reaches the equilibrium position, the control unit 50 repeats the same operation as in the third step. That is, in a state where the upper endless belt 41 has reached the equilibrium position, the controller 50 moves the lower endless belt 42 that is not in the equilibrium position at the same speed in the width direction so as to reach the equilibrium position (fourth). Process). Thereafter, the third step and the fourth step are repeated.

A second example shown in FIG. 5B is a case where the upper and lower endless belts 41 and 42 are displaced in different directions with respect to the equilibrium position. First, the control unit 50 calculates the first distance X1 between the endless belt 42 far from the equilibrium position and the equilibrium position based on the signals from the photosensors 44 and 45. Next, based on the signals from the photosensors 44 and 45, the control unit 50 determines the movement limit positions existing on both ends in the width direction of the endless belt 41 closer to the equilibrium position and the upper and lower endless belts 41 and 42. Of these, the second distance X2 is calculated from the movement limit position (movement limit position on the right side in the figure) closer to the endless belt 41. Then, the control unit 50 compares the first distance X1 and the second distance X2, and determines that the first distance X1 is larger (first step).

  Next, the control unit 50 moves the upper and lower endless belts 41 and 42 toward the closer movement limit position (the movement limit position on the right side in the drawing) at the same speed by the second distance X2 (second step). When the upper and lower endless belts 41 and 42 move by the second distance X2, the control unit 50 reciprocates the upper and lower endless belts 41 and 42 at the same speed between the movement limit positions (third step). -5th process).

  More specifically, the control unit 50 calculates a third distance X3 between the upper endless belt 41 that is farther from the equilibrium position and the equilibrium position, based on signals from the photosensors 44 and 45. Next, based on the signals from the photosensors 44 and 45, the control unit 50 determines the lower endless belt 42 closer to the equilibrium position and the movement limit position closer to the endless belt 42 (on the left side in the figure). The fourth distance X4 with respect to the movement limit position) is calculated. Then, the control unit 50 compares the third distance X3 and the fourth distance X4, and determines that the third distance X3 is larger (third process).

  Next, the control unit 50 moves the upper and lower endless belts 41 and 42 at the same speed by the fourth distance X4 toward the closer movement limit position (the movement limit position on the left side in the figure) (fourth step).

  After the movement, the control unit 50 calculates a fifth distance X5 between the lower endless belt 42 far from the equilibrium position and the equilibrium position based on the signals from the photosensors 44 and 45. Next, based on the signals from the photosensors 44 and 45, the control unit 50 moves the upper endless belt 41 closer to the equilibrium position and the movement limit position closer to the upper endless belt 41 (the movement on the right side in the figure). A sixth distance X6 with respect to the limit position is calculated. Then, the control unit 50 compares the fifth distance X5 and the sixth distance X6 and determines that the fifth distance X5 is larger (fourth step).

  Next, the control unit 50 moves the upper and lower endless belts 41 and 42 toward the closer movement limit position (the movement limit position on the right side in the drawing) at the same speed by the sixth distance X6 (fifth step). Thereafter, the fourth step and the fifth step are repeated. In FIG. 5B, the third distance X3 and the fifth distance X5, and the fourth distance X4 and the sixth distance X6 are theoretically the same, so the third distance X3 and the fourth distance X4 are calculated. Then, the distance need not be calculated.

A third example shown in FIG. 5C is a case where the upper and lower endless belts 41 and 42 are displaced in different directions with respect to the equilibrium position. First, the control unit 50 calculates the first distance X1 between the endless belt 42 far from the equilibrium position and the equilibrium position based on the signals from the photosensors 44 and 45. Next, based on the signals from the photosensors 44 and 45, the control unit 50 determines the movement limit positions existing on both ends in the width direction of the endless belt 41 closer to the equilibrium position and the upper and lower endless belts 41 and 42. Of these, the second distance X2 is calculated from the movement limit position (movement limit position on the right side in the figure) closer to the endless belt 41. Then, the control unit 50 compares the first distance X1 and the second distance X2, and determines that the first distance X1 is smaller (first step).

  Next, the control unit 50 moves the upper and lower endless belts 41 and 42 toward the closer movement limit position (the movement limit position on the right side in the drawing) at the same speed by the first distance X1 (second step). As a result, the lower endless belt 42 far from the equilibrium position reaches the equilibrium position.

  Thereafter, the control unit 50 repeats the operation of moving the upper endless belt 41 that is not in the equilibrium position after the movement at the same speed in the width direction so as to reach the equilibrium position (third process to fifth process). Specifically, the control unit 50 calculates a third distance X3 between the upper endless belt 41 that is not in the equilibrium position and the equilibrium position, based on signals from the photosensors 44 and 45. Next, the control unit 50 calculates a fourth distance X4 between the lower endless belt 42 in the equilibrium position and the movement limit position on the left side in the drawing based on the signals from the photosensors 44 and 45. Then, the control unit 50 compares the third distance X3 and the fourth distance X4, and determines that the fourth distance X4 is larger (third process).

  Next, the control unit 50 moves the upper and lower endless belts 41, 42 at the same speed by the third distance X3 toward the movement limit position on the left side in the drawing (fourth step).

  After the movement, the control unit 50 calculates the fifth distance X5 between the lower endless belt 42 that is not in the equilibrium position and the equilibrium position, based on the signals from the photosensors 44 and 45. Next, the control unit 50 calculates a sixth distance X6 between the upper endless belt 41 at the equilibrium position and the movement limit position on the right side in the drawing based on the signals from the photosensors 44 and 45. Then, the control unit 50 compares the fifth distance X5 and the sixth distance X6 and determines that the sixth distance X6 is larger (fourth step).

  Next, the control unit 50 moves the upper and lower endless belts 41, 42 at the same speed by the fifth distance X5 toward the movement limit position on the right side in the drawing (fifth step). Thereafter, the fourth step and the fifth step are repeated. Also in FIG. 5C, the third distance X3 and the fifth distance X5, and the fourth distance X4 and the sixth distance X6 are theoretically the same, so the third distance X3 and the fourth distance X4 It is not necessary to calculate the distance after calculating.

  Next, a control method of the sheet conveying apparatus 1C according to the present embodiment will be described with reference to a flowchart. 6 is a flowchart showing a control method of the sheet conveying apparatus 1C according to the present embodiment. As shown in FIG. 6, first, the control unit 50 detects the amount of deviation from the equilibrium position of the upper and lower endless belts 41 and 42 based on the signals from the photosensors 44 and 45 (S1).

  Next, the control unit 50 determines whether or not at least one of the upper and lower endless belts 41 and 42 is displaced based on the amount of displacement detected in step S1 (S2). When it is determined that the upper and lower endless belts 41 and 42 are not shifted (S2: NO), the process proceeds to step S1.

  When it is determined that at least one of the upper and lower endless belts 41 and 42 is displaced (S2: YES), the control unit 50 determines whether or not the sheet P exists between the upper and lower endless belts 41 and 42 (S3). ).

  When it is determined that the sheet P exists between the upper and lower endless belts 41 and 42 (S3: YES), the control unit 50 determines whether or not the rear end side of the sheet P is located in the fixing device 30 as the front unit. Is determined (S4). When it is determined that the rear end side of the sheet P is located in the fixing device 30 (S4: YES), the processing illustrated in FIG. In other words, even when it is determined that the paper P exists between the upper and lower endless belts 41 and 42, the control unit 50 fixes and conveys the paper on the upstream side of the upper and lower endless belts 41 and 42. When the rear end side of the sheet P is located in the sheet 30, the control of the steering mechanisms 46 and 47 is prohibited. As a result, the steering mechanisms 46 and 47 are controlled to move the endless belts 41 and 42 in the width direction, thereby preventing the paper P from being twisted.

  When it is determined that the rear end side of the sheet P is not located in the fixing device 30 (S4: NO), the control unit 50 determines the upper and lower endless belts 41 and 42 based on the deviation amount detected in step S1. It is determined whether or not they are displaced in the same direction (S5). When it is determined that they are displaced in the same direction (S5: YES), the control unit 50 controls the steering mechanisms 46 and 47 to reciprocate the upper and lower endless belts 41 and 42 between the equilibrium positions (S6). That is, as shown in FIG. 5A, the control unit 50 controls the upper and lower endless belts 41 and 42 so that the endless belts 41 and 42 far from the equilibrium position reach the equilibrium position. , 42 are moved in the width direction at the same speed, and then the upper and lower endless belts 41, 42 are moved in the width direction at the same speed so that the endless belts 41, 42 that are not in the equilibrium position reach the equilibrium position after the movement. Repeat the operation. Thereafter, the process shown in FIG. 6 ends.

  On the other hand, when it is determined that the upper and lower endless belts 41 and 42 are not shifted in the same direction (S5: NO), that is, when the upper and lower endless belts 41 and 42 are determined to be shifted in different directions with respect to the equilibrium position. The control unit 50 determines whether or not the first distance X1 is greater than the second distance X2 (S7).

  When it is determined that the first distance X1 is greater than the second distance X2 (S7: YES), the control unit 50 controls the steering mechanisms 46 and 47 to move the upper and lower endless belts 41 and 42 between the movement limit positions. The reciprocation is performed (S8). That is, as shown in FIG. 5B, the control unit 50 moves the upper and lower endless belts 41 and 42 toward the closer movement limit position at the same speed by the second distance X2, and from the equilibrium position. The closer endless belts 41 and 42 are made to reach the closer movement limit position, and then the upper and lower endless belts 41 and 42 are reciprocated between the movement limit positions at the same speed. Thereafter, the process shown in FIG. 6 ends.

  When it is determined that the first distance X1 is not greater than the second distance X2 (S7: NO), the control unit 50 controls the steering mechanisms 46 and 47 to move the upper and lower endless belts 41 and 42 between the equilibrium positions. The reciprocation is performed (S6). That is, as shown in FIG. 5C, the control unit 50 controls the upper and lower endless belts 41 and 42 so that the endless belts 41 and 42 far from the equilibrium position among the upper and lower endless belts 41 and 42 reach the equilibrium position. , 42 are moved in the width direction at the same speed, and then the upper and lower endless belts 41, 42 are moved in the width direction at the same speed so that the endless belts 41, 42 that are not in the equilibrium position reach the equilibrium position after the movement. Repeat the operation. Thereafter, the process shown in FIG. 6 ends.

  When it is determined that the sheet P does not exist between the upper and lower endless belts 41 and 42 (S3: NO), the control unit 50 controls the steering mechanisms 46 and 47 so that the upper and lower endless belts 41 and 42 are moved. Move to the equilibrium position (S10). Thereafter, the process shown in FIG. 6 ends.

  As described above, according to the sheet conveying apparatus 1C and the control method thereof according to the present embodiment, when it is determined that the sheet P exists between the upper and lower endless belts 41 and 42, the steering mechanisms 46 and 47 are controlled. Thus, when the sheet P is present between the upper and lower endless belts 41 and 42 in order to move the upper and lower endless belts 41 and 42 in the width direction at the same speed and in the same direction, the relative positions of the upper and lower endless belts 41 and 42 Is maintained, and the paper P is not rubbed. In particular, since the upper and lower endless belts 41 and 42 are moved in the width direction at the same speed and in the same direction, only one of the endless belts 41 and 42 moves unexpectedly due to a difference in frictional force between the upper and lower endless belts 41 and 42. I don't have to. Therefore, it is possible to prevent the paper P from being rubbed.

  In addition, since the operation of moving the upper and lower endless belts 41 and 42 in the width direction at the same speed and in the same direction around the equilibrium position is repeated, the upper and lower endless belts 41 and 42 are reciprocated around the equilibrium position. It will be. Accordingly, it is possible to prevent the movement of the upper and lower endless belts 41 and 42 from being stopped during the conveyance of the sheet, and the sheet P is rubbed even when the long sheet P is conveyed in the sheet conveyance direction FD. The situation can be prevented.

  Further, when it is determined that the upper and lower endless belts 41 and 42 are displaced in the same direction, the upper and lower endless belts 41 and 42 of the upper and lower endless belts 41 and 42 are arranged so that the endless belts 41 and 42 far from the equilibrium position reach the equilibrium position. After the endless belts 41 and 42 are moved at the same speed in the width direction, the upper and lower endless belts 41 and 42 are moved at the same speed in the width direction so that the endless belts 41 and 42 that are not in the equilibrium position after the movement reach the equilibrium position. Repeat the movement with. Therefore, the upper and lower endless belts 41 and 42 are alternately moved so as to reach the equilibrium position, and the paper P is rubbed while the upper and lower endless belts 41 and 42 are in a state close to an appropriate position. The situation can be prevented.

  Further, the upper and lower endless belts 41 and 42 are shifted in different directions, and the first distance X1 between the equilibrium position and the far endless belts 41 and 42 between the upper and lower endless belts 41 and 42 is equal to the equilibrium position. When it is determined that the endless belts 41 and 42 closer to the position are larger than the second distance X2 between the endless belts 41 and 42 and the movement limit position where the endless belts 41 and 42 are closer, the upper and lower endless belts 41 and 42 are closer to each other. Are moved at the same speed by the second distance X2 toward the movement limit position, and the endless belts 41, 42 closer to the equilibrium position are made to reach the movement limit position closer to the movement position, and then the upper and lower endless belts 41, 42 are moved. Are reciprocated between both movement limit positions at the same speed. Therefore, when the second distance X2 is larger than the first distance X1 and the endless belts 41 and 42 far from the equilibrium position cannot be moved to the equilibrium position, the far endless belts 41 and 42 are set to the equilibrium position as much as possible. It moves so that it may approach, and a reciprocating movement will be performed after that. Therefore, even in a situation where the endless belts 41 and 42 cannot be moved to the equilibrium position, the upper and lower endless belts 41 and 42 are alternately moved to an appropriate position to prevent the sheet P from being rubbed. it can.

  Further, the upper and lower endless belts 41 and 42 are shifted in different directions, and the first distance X1 between the equilibrium position and the far endless belts 41 and 42 between the upper and lower endless belts 41 and 42 is equal to the equilibrium position. When it is determined that the endless belts 41 and 42 closer to the position are smaller than the second distance X2 between the endless belts 41 and 42 and the movement limit position closer to the endless belt 41, 42, the balanced position of the upper and lower endless belts 41, 42 After moving the upper and lower endless belts 41 and 42 at the same speed in the width direction so that the endless belts 41 and 42 farther from the end reach the equilibrium position, the endless belts 41 and 42 that are not in the equilibrium position after the movement are balanced. The operation of moving the upper and lower endless belts 41 and 42 in the width direction at the same speed so as to reach the position is repeated. In this way, even when the upper and lower endless belts 41 and 42 are displaced in different directions, the upper and lower endless belts 41 and 42 can be alternately moved to the equilibrium position due to the distance to the movement limit position. Thus, by alternately moving to the equilibrium position as described above, it is possible to prevent the sheet P from being rubbed while the upper and lower endless belts 41 and 42 are close to the proper positions.

  When it is determined that at least one of the upper and lower endless belts 41 and 42 is deviated from the equilibrium position when the sheet P is not present between the upper and lower endless belts 41 and 42, the steering mechanisms 46 and 47 are controlled. Thus, the upper and lower endless belts 41 and 42 are moved to the equilibrium position. For this reason, in a situation where the paper P does not exist between the upper and lower endless belts 41 and 42 and the paper P cannot be rubbed, the upper and lower endless belts 41 and 42 are returned to their proper positions. The endless belts 41 and 42 can be set to appropriate positions without causing rubbing.

  Even when it is determined that the sheet P exists between the upper and lower endless belts 41 and 42, the sheet P is inserted into the fixing device 30 that sandwiches and conveys the sheet P on the upstream side of the upper and lower endless belts 41 and 42. When the rear end side of P is located, control of the steering mechanisms 46 and 47 is prohibited. For this reason, the rear end of the paper P is positioned in the fixing device 30, and the steering mechanism 46, 47 is controlled to move the endless belts 41, 42 in the width direction, thereby preventing the paper P from being twisted. can do.

  As described above, the sheet conveying apparatus and the method for controlling the sheet conveying apparatus according to the present invention have been described based on the embodiments. However, the present invention is not limited to this, and changes can be made without departing from the spirit of the present invention. May be added.

  For example, in the above embodiment, the sheet conveying apparatus 1 </ b> C includes the heat sink 43 and has a cooling function for the sheet P, but is not limited thereto, and may be a belt-type sheet conveying apparatus that does not include the heat sink 43. The sheet conveying apparatus 1C may be another apparatus such as a belt-type gloss increasing apparatus or a belt-type fixing apparatus as long as the sheet P is conveyed by the upper and lower endless belts 41 and 42.

  Furthermore, the image forming apparatus 1B according to the present embodiment includes at least one of a belt-type paper conveyance device (with or without a cooling function), a belt-type gloss increasing device, and a belt-type fixing device. In the case of performing the above control, it goes without saying that the image forming apparatus 1B corresponds to the sheet conveying apparatus in the present invention.

  Further, in the above-described embodiment, the sheet conveying apparatus 1C itself includes the control unit 50, and the control unit 50 executes the above control. However, the present invention is not limited to this, and the sheet conveying apparatus 1C includes the photosensors 44 and 45 and the steering mechanisms 46 and 47. The main control unit 3 of the image forming apparatus 1B may include a sheet determination mechanism, a deviation amount detection function, and a control function, and execute control according to these functions.

  In addition, in the above embodiment, the fixing device 30 is illustrated as a front unit existing on the upstream side of the upper and lower endless belts 41 and 42. However, the present invention is not limited to this. A pair of rollers for conveyance may be used.

DESCRIPTION OF SYMBOLS 1 Image forming system 1A Paper feeding apparatus 1B Image forming apparatus 1C Paper conveying apparatus 2 Original reading apparatus 3 Main control part 10Y, 10M, 10C, 10K Image forming part 15Y, 15M, 15C, 15K Optical writing part 21Y, 21M, 21C, 21K Photosensitive drums 22Y, 22M, 22C, 22K Developing device 24 Intermediate transfer belt 26 Secondary transfer roller 30 Fixing device 31, 32 Fixing roller 40 Paper cooling unit 41 Upper endless belt 42 Lower endless belt 43 Heat sink 44 , 45 Photo sensor 46, 47 Steering mechanism 46a Step motor 46b Worm gear 46c Fan-shaped gear 46d Steering roller bearing 50 Control unit (control means)
60 Reverse conveyance section 70 Re-feed conveyance path FD Paper conveyance direction P Paper Tr1 to Tr4 Tray

Claims (9)

In a paper transport device that sandwiches a paper sheet between upper and lower endless belts and transports the paper sheet by rotating the upper and lower endless belts,
Steering means for moving the upper and lower endless belts in the width direction by inclining the upper and lower endless belts in the width direction perpendicular to the paper conveyance direction;
Paper judging means for judging whether paper is present between the upper and lower endless belts;
Control means for controlling the steering means;
A displacement amount detecting means for detecting a displacement amount from an equilibrium position of the upper and lower endless belts in the width direction ,
When the control means determines that the upper and lower endless belts are displaced in different directions with respect to the equilibrium position by detecting the amount of deviation by the deviation amount detection means, the upper and lower endless belts are detected by the paper determination means. when the sheet is determined to exist between the control the steering means, the sheet conveying apparatus characterized by moving the endless belt of the upper and lower at the same speed and the same direction in the width direction. When the paper determining means determines that paper is present between the upper and lower endless belts, the control means moves the upper and lower endless belts around an equilibrium position that is an appropriate position of the upper and lower endless belts. The sheet conveying apparatus according to claim 1, wherein an operation of moving in the same direction and in the same direction in the width direction is repeated. Wherein, when the upper and lower endless belts by detecting the shift amount by the shift amount detecting means determines that the deviation in the same direction with respect to the equilibrium position, far from the equilibrium position of the upper and lower endless belt The upper and lower endless belts are moved at the same speed in the width direction so that the endless belt on one side reaches the equilibrium position, and then the upper and lower endless belts that are not in the equilibrium position after the movement reach the equilibrium position. The sheet conveying apparatus according to claim 2, wherein the operation of moving the endless belt in the width direction at the same speed is repeated. Wherein, by detecting the shift amount by the shift amount detection means, wherein which the upper and lower endless belt displaced in different directions with respect to the equilibrium position, the endless farther from the equilibrium position of the upper and lower endless belt Movement in which the first distance between the belt and the equilibrium position is closer to the endless belt among the movement limit positions existing at both ends in the width direction of the endless belt closer to the equilibrium position and the upper and lower endless belts. If it is determined that it is greater than the second distance between the limit position, the upper and lower endless belts are moved at the same speed by the second distance toward the closer movement limit position, and are closer to the equilibrium position. The endless belt on one side is made to reach the closer movement limit position, and then the upper and lower endless belts are reciprocated between the two movement limit positions at the same speed. Paper transport device. Wherein, by detecting the shift amount by the shift amount detection means, wherein which the upper and lower endless belt displaced in different directions with respect to the equilibrium position, the endless farther from the equilibrium position of the upper and lower endless belt Movement in which the first distance between the belt and the equilibrium position is closer to the endless belt among the movement limit positions existing at both ends in the width direction of the endless belt closer to the equilibrium position and the upper and lower endless belts. When it is determined that the distance is equal to or less than the second distance between the upper limit end position and the upper endless belt, the upper and lower endless belts are aligned in the width direction so that the endless belt far from the equilibrium position reaches the equilibrium position. After the movement at the speed, the operation of moving the upper and lower endless belts at the same speed in the width direction so that the endless belt that is not in the equilibrium position reaches the equilibrium position after the movement is repeated. The sheet conveying device according to claim 2, wherein When the paper determining means determines that there is no paper between the upper and lower endless belts, the control means detects at least one of the upper and lower endless belts by detecting the deviation amount by the deviation amount detecting means. 6. The apparatus according to claim 1 , wherein when it is determined that the position is deviated from the position, the steering means is controlled to move the upper and lower endless belts to the equilibrium position. 6. Paper transport device. Even if the control unit determines that a sheet exists between the upper and lower endless belts, the control unit includes a front unit that sandwiches and conveys the sheet on the upstream side of the upper and lower endless belts. The paper conveying apparatus according to any one of claims 1 to 6, wherein when the rear end side of the paper is positioned, control of the steering unit is prohibited. In a control method of a paper transporting apparatus that sandwiches a paper by upper and lower endless belts and transports the paper by rotating the upper and lower endless belts,
A paper judgment step for judging whether paper is present between the upper and lower endless belts;
A control step of controlling steering means for moving the upper and lower endless belts in the width direction by inclining the upper and lower endless belts in the width direction perpendicular to the paper conveyance direction;
A displacement amount detecting step for detecting a displacement amount from an equilibrium position of the upper and lower endless belts in the width direction ,
In the control step, when it is determined that the upper and lower endless belts are displaced in different directions with respect to the equilibrium position by detecting the amount of deviation in the deviation amount detection step, the upper and lower endless belts in the paper determination step. when the sheet is determined to exist between the control method of the paper conveying apparatus, wherein the controlling the steering means to move the endless belt of the upper and lower at the same speed and the same direction in the width direction. The paper is sandwiched between upper and lower endless belts, and the upper and lower endless belts are inclined by tilting the upper and lower endless belts in the width direction perpendicular to the paper transport direction of the paper transport device that transports the paper by rotating the upper and lower endless belts. Control means for controlling steering means for moving the belt in the width direction;
Paper judging means for judging whether paper is present between the upper and lower endless belts;
A displacement amount detecting means for detecting a displacement amount from an equilibrium position of the upper and lower endless belts in the width direction ,
When the control means determines that the upper and lower endless belts are displaced in different directions with respect to the equilibrium position by detecting the amount of deviation by the deviation amount detection means, the upper and lower endless belts are detected by the paper determination means. when the sheet is determined to exist between the control the steering means, the image forming apparatus characterized by moving the endless belt of the upper and lower at the same speed and the same direction in the width direction.

Images