JP2012158456A - Paper meandering correcting device and image forming device provided with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper meandering correcting device capable of stably correcting meandering of paper even when the paper is special paper like the one which has an uneven thickness in the width direction of the paper and is apt to be unstable in paper conveyance performance.SOLUTION: A buffer mechanism part 8 arranged between first and second paper conveying mechanism parts is provided with: a first buffer arm 20 fixed to an end of a buffer drive shaft 17; a second buffer arm 30 rotatably held to the other end of the buffer drive shaft 17; buffer springs 23 elastically urging the buffer arms 20, 30; and a buffer shaft 31 which is arranged on the side of free ends of the buffer arms 20, 30 so that the free ends of the buffer arms 20, 30 can be vertically moved by rotation of the buffer drive shaft 17, and applies tension to continuous paper 5 by the movement of the buffer arms 20, 30. The angle of rotation of a buffer control motor 27 is controlled on the basis of a detection result by a paper meandering detection part, and meandering of the paper is corrected.

Description

  The present invention relates to a sheet meandering correction apparatus in an electrophotographic apparatus such as a laser printer, and an image forming apparatus including the same.

  A schematic configuration of a continuous paper printing apparatus using an electrophotographic system will be described with reference to FIG.

  When a print signal decomposed into dot data is transmitted from a host device (not shown), the laser beam is scanned over the surface of the photosensitive drum 1. The surface of the photosensitive drum 1 is uniformly charged by the charger 2 in advance, and the charge of the portion irradiated with the laser light escapes, and an electrostatic latent image based on the print signal is formed on the surface of the photosensitive drum 1. It is formed.

  A toner image is formed on the electrostatic latent image by the developing device 3 to form a toner image, and the toner image is conveyed to the position of the transfer unit 4 by the rotating photosensitive drum 1. A long continuous sheet (hereinafter abbreviated as “sheet”) 5 is fed to the position of the transfer unit 4 by a transport tractor 6 (or a transport roller) which is a sheet transport unit and is carried on the photosensitive drum 1. The toner image is transferred onto the paper 5 by the transfer device 4.

  The sheet 5 on which the toner image 12 has been transferred is fixed by heat and pressure between the heat roller 7 and the backup roller 10 while being given a certain tension by the buffer mechanism 8, and then discharged to the stacker 11. .

  The configuration of the conventional buffer mechanism unit 8 will be described with reference to FIGS. FIG. 9 is a schematic configuration diagram for explaining the configuration from the transport tractor 6 to the heat roller 7 of the conventional printing apparatus, FIG. 10 is a plan view of the conventional buffer mechanism unit 8, and FIG. It is a partial side view for demonstrating a motion of a buffer arm.

  As shown in FIGS. 8 and 9, the buffer mechanism unit 8 is installed between the transport tractor 6 corresponding to the first paper transport mechanism unit and the fixing mechanism unit corresponding to the second paper transport mechanism unit, and the transport tractor 6. And a mechanism for applying tension to the sheet 5 in order to absorb a difference in sheet conveyance speed between the fixing mechanism unit (heat roller 7 and backup roller 10).

  The buffer mechanism 8 is rotatably supported at both ends of a buffer drive shaft 19 shown in FIG. 10 by bearings (not shown) in a bearing holder 18 fixed to the frames 17 and 17. The frames 17 and 17 are arranged on both sides of the paper 5 in the width direction so as to face the paper conveyance direction X in parallel.

  At both ends of the buffer drive shaft 19, first and second buffer arms 20 and 21 extending in the paper feeding direction of the paper 5 are supported by screws 25, and the first and second buffer arms 20 and 21 are The buffer drive shaft 19 can be turned around.

  Buffer springs 23 are loosely fitted to both ends of the buffer drive shaft 19, one end of the buffer spring 23 is fixed to the frame 17, and the other end of the buffer spring 23 is connected to the first and second buffer arms 20, 21. ing.

  A buffer shaft 22 is attached to the tips of the first and second buffer arms 20 and 21, and the sheet 5 passes through the upper side of the buffer shaft 22 as shown in FIG. A tension is applied to the entire width of the sheet 5 through the first and second buffer arms 20 and 21 and the buffer shaft 22 by an upward elastic biasing force.

  When printing is stopped, the first and second buffer arms 20 and 21 are held at positions indicated by chain lines in FIG. This is because the tension of the first and second buffer arms 20 and 21 by the buffer spring 23 is regulated by the buffer position pin 29 attached to the frame 17. The rotation angles of the first and second buffer arms 20 and 21 are the same on both the left and right sides.

  As shown in FIG. 10, a buffer position gear 39 is attached to the first buffer arm 20 on the back side (upper side in the drawing) of the printing apparatus. The buffer position gear 39 is installed so as to mesh with the gear of the buffer position motor 38 attached to the frame 17.

  At the start of printing, the first and second buffer arms 20 and 21 are rotated to a predetermined angle (θ) as shown in FIG. 11 so that the tension applied to the paper 5 is constant from the start of paper conveyance. The buffer position motor 38 is controlled based on position information from the buffer position sensor 24 disposed at the end of the buffer drive shaft 19.

  Next, the conveyance tractor 6 and the heat roller 7 for feeding paper start driving at the same time, and at the same time, the excitation of the buffer position motor 38 is released. As a result, a certain tension is applied from the buffer shaft 22 to the paper 5 by the buffer spring 23.

  Further, during the printing operation, the heat roller drive motor 40 is set so that the detection angle of the buffer position sensor 24 falls within a preset range with respect to the transport tractor 6 (or transport roller) that feeds the paper at a constant speed. (See FIG. 9) adjusts the rotational speed of the heat roller 7 by finely accelerating / decelerating it.

  Further, the backup roller 10 is driven to rotate by the rotational driving of the heat roller 7. Accordingly, the conveyance speed of the paper 5 is controlled to be constant by the heat roller drive motor 40, the angles of the first and second buffer arms 20, 21 are kept constant, and a constant tension is applied to the paper 5.

  At this time, the paper 5 has a fiber distribution, thickness variation, or thermal shrinkage variation of the paper 5 itself, electrostatic sticking to the photosensitive drum 1, temperature distribution of the heat roller 7, heat roller 7 and the like. Depending on the balance of the nip pressure of the backup roller 10 and the like, the running performance may become unstable.

  In order to stabilize the running property of the paper, as described in Patent Document 1 (Japanese Patent No. 3738983), the paper meander detector 13 (see FIG. 9) mounted at the exit of the transport tractor 6 is used to make the paper The meandering state is monitored, and the meandering correction control is performed by varying the nip pressure of the backup roller 10 with respect to the heat roller 7 in accordance with the meandering state of the paper.

  Next, an outline of sheet meandering correction in the fixing mechanism will be described with reference to FIGS. 9 and 12 to 15. 12A and 12B are views for explaining the pressing mechanism of the backup roller 10 by the cam 14, FIGS. 13A and 13B are diagrams showing the shape of the cam 14, and FIGS. 14A and 14B are backup rollers 10. FIG. FIG. 15 is a conceptual diagram for explaining the rotation angle of the cam motor. FIG. 15 is a diagram showing a change in the nip width between the heat roller 7 and the backup roller 10 in accordance with the change in pressing force.

  As shown in FIG. 9, cams 14 a and 14 b are attached to both ends of the camshaft 9. The cams 14a and 14b have the same shape, but as shown in FIGS. 13A and 13B, the cam 14a installed on the front side of the printing apparatus (the lower side in the drawing in FIG. 9) and the printing apparatus The cam 14b installed on the back side (upper side in FIG. 9 in FIG. 9) is attached to the camshaft 9 with the cam surface slightly shifted in the circumferential direction, so that the cam 14a and the cam 14b are relative to each other. The relationship has a different aspect.

  As shown in FIGS. 9 and 12, the arm member 15 is disposed so as to be rotatable about the support shaft 15c so as to be adjacent to the cams 14a and 14b. The arm member 15 is disposed so that a part of the arm member 15 always has a cam abutting portion 15d that abuts against the cam surfaces of the cams 14a and 14b, and the first arm portion 15a. The second arm portion 15b is in contact with the rotation shaft of the first arm portion 15b, and the coil spring 16 is interposed between the first arm portion 15a and the second arm portion 15b.

  Since the arm member 15 is interposed between the backup roller 10 and the cams 14a and 14b, and the coil spring 16 is in a compressed state, the cam contact of the first arm portion 15a is caused by the elastic biasing force of the coil spring 16. The contact portion 15d is in elastic contact with the cam surfaces of the cams 14a and 14b. Therefore, the arm member 15 rotates about the support shaft 15c depending on the position of the cam surface.

  By rotating the cams 14 a and 14 b together with the cam shaft 9, the first arm 15 a moves according to the position of the cam surface, and presses the second arm portion 15 b against the heat roller 7 via the coil spring 16. When the pressing amount is large, the nip width between the heat roller 7 and the backup roller 10 is wide as shown in FIG. 14 (a), and when the pressing amount is small, the heat roller 7 and the backup roller 10 as shown in FIG. 14 (b). The nip width of the backup roller 10 becomes narrow.

Next, the paper meandering correction control based on the pressing amount of the backup roller 10 against the heat roller 7 will be described.
The microprocessor 34 shown in FIG. 9 takes in the detection result of the sheet running state from the sheet meandering detector 13 installed on the exit side of the transport tractor 6. Next, the microprocessor 34 performs various arithmetic processes 35, calculates the correction angle of the cam motor 33, and sends control information to the cam motor drive circuit 36. The cam motor drive circuit 36 rotates the cam shaft 33 by rotating the cam motor 33 by an appropriate angle (see FIG. 12), and varies the left and right pressing loads in the paper width direction by the cam 14. Such feedback control is performed. The cam motor 33 is composed of a stepping motor.

  As an example, when the paper meander detector 13 shown in FIG. 9 detects that the paper 5 meanders to the back side (upper side in the drawing) of the printing apparatus, the cam 14 is fixed in the A direction (see FIG. 12). Rotate within an angle. At this time, as shown in FIGS. 13A and 13B, the cams 14a and 14b have different shapes on the left and right. Therefore, the amount of movement of the cam 14a (front side of the device) on the arm 15a side (cam contact portion 15d) does not change, but the amount of movement of the cam 14b (device back side) on the far arm 15a side (cam contact portion 15d). Will be reduced.

  As a result, the pressing force of the cam 14a (the front side of the apparatus) against the arm 15a does not change, and the backup roller 10 is at the position (10a) as shown in FIG. The nip width is substantially maintained. On the other hand, the pressing force of the cam 14b (on the back side of the apparatus) against the arm 15a decreases, and as shown in FIG. 14B, the backup roller 10 moves back to the position (10b), and the heat roller 7 and the backup roller 10 The nip width is reduced. This makes it possible to correct the meandering of the sheet 5 toward the cam 14a (near the apparatus).

  The rotation angle of the cam motor 33 at this time, that is, the number of meandering correction steps (STEP) of the cam motor 33 is calculated by the microprocessor 34 in accordance with the amount of paper meander detected by the paper meander detector 13, as shown in FIG. Calculated by processing 35.

  In FIG. 15, the horizontal axis represents the amount of paper meander detected by the paper meander detector 13, and the vertical axis represents the number of meander correction steps (STEP) of the cam motor 33. Since the relationship between the amount of paper meandering and the number of meandering correction steps (STEP) of the cam motor is tabulated in advance, the meandering correction step (STEP) of the cam motor 33 based on the amount of paper meandering detected by the paper meandering detector 13. Number can be set. In the drawing, the solid line indicates the STEP for basic correction, and the chain line indicates the range of the correction STEP by the calculation process 35.

  Patent Document 2 (Japanese Patent No. 4328043) describes a configuration in which paper meander correction is performed by a meander control device mounted on a paper transport path.

  Patent Document 3 (Japanese Patent Application Laid-Open No. 2007-186301) discloses, as a printing apparatus that can significantly reduce the adjustment time for aligning with a pre-processing machine, a carrying-in means for carrying a web into a storage unit as a driving roller. And at least one pressing roller rotating in contact with the driving roller, and pressing force varying means for varying the pressing force of the pressing roller against the driving roller in a direction perpendicular to the web conveyance direction (web width direction). Are listed.

  Further, Patent Document 4 (Japanese Patent Application Laid-Open No. 2008-230734) discloses a traveling position in the sheet width direction by tilting the rotation axis of a reverse tension applying unit having a pressure adjusting unit and a rotating member that rotates as the continuous sheet travels. It is described that an inclination driving mechanism for changing the angle and that adjustment by the pressure adjusting means and correction by the inclination driving mechanism are sequentially performed.

  By the way, in recent printing business, the demand for special papers such as different thicknesses in the paper width direction is increasing. In the case of a sheet having a difference in thickness in the width direction, the tendency to meander in the direction in which the sheet thickness is thick occurs remarkably.

  On the other hand, in a printing apparatus, it is necessary to ensure a sufficient fixing strength, and there is a limit to lowering the pressing pressure of the heat roller 7 and the backup roller 10 that have a great influence on the fixing strength. In addition, it is necessary to set a limit for increasing the pressing pressure in consideration of damage to the paper. For this reason, in the conventional meandering correction control described in Patent Document 1, it may be difficult to stabilize the paper meandering.

  Further, as in Patent Documents 2 and 3, a configuration for correcting the meandering of the web is known, but Patent Documents 2 and 3 do not consider the relationship with the pressing force of the fixing mechanism unit.

  Further, in Patent Document 4, the configuration is such that the pressing on the paper and the inclination correction are sequentially performed. In addition to a configuration in which a plurality of control sensors are required, two or more correction units must be provided independently. The configuration becomes complicated.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a sheet meandering correction device capable of performing stable paper meandering correction even on special paper having a thickness difference in the paper width direction in which paper transportability tends to become unstable, and an image forming apparatus provided with the same Is to provide.

In order to achieve and achieve the above object, the first means of the present invention includes:
A first paper transport mechanism unit and a second paper transport mechanism unit disposed on the continuous paper transport path from the upstream side to the downstream side in the paper transport direction;
A buffer mechanism section provided between the first sheet transport mechanism section and the second sheet transport mechanism section for applying tension to the continuous sheet to absorb a sheet transport speed difference between the sheet transport mechanism sections;
A sheet meandering correction apparatus provided with a sheet meandering amount detecting unit that is provided between the first sheet conveying mechanism unit and the buffer mechanism unit on the upstream side in the sheet conveying direction and detects the meandering amount of the continuous sheet. It is.

The buffer mechanism unit
Frames disposed on both sides of the continuous sheet in the width direction in parallel with the sheet conveyance direction;
A buffer drive shaft rotatably supported between the frames;
A buffer control motor for rotationally driving the buffer drive shaft;
A buffer control motor control unit for controlling the rotation angle of the buffer control motor;
A first buffer arm having a base end fixed to one end of the buffer drive shaft;
A second buffer arm having a base end rotatably held on the other end side of the buffer drive shaft;
A buffer spring installed at both ends of the buffer drive shaft and elastically urging the first buffer arm and the second buffer arm in the rotational direction of the buffer drive shaft;
Free ends of the first buffer arm and the second buffer arm are movably installed in the vertical direction by rotation of the buffer drive shaft on the free ends of the first buffer arm and the second buffer arm, A buffer shaft that applies tension to the continuous paper by movement of the buffer arm and the second buffer arm, and
Based on the detection result from the paper meandering detection unit, the buffer control motor control unit controls the rotation angle of the buffer control motor to correct meandering of the continuous paper. It is.

According to a second means of the present invention, in the first means,
The first buffer arm and the second buffer arm have elongated holes formed on the free ends thereof, and both end portions of the buffer shaft are inserted into the elongated holes so as to be movable in the vertical direction. is there.

According to a third means of the present invention, in the first means,
A storage unit for storing a state of tension applied to continuous paper by the buffer mechanism unit;
When resuming the conveyance of the continuous sheet after the conveyance of the continuous sheet is stopped, the buffer control motor is controlled based on the tension state stored in the storage unit immediately before the conveyance of the continuous sheet is stopped. It is characterized by that.

The fourth means of the present invention is:
A paper transport mechanism for transporting continuous paper with the toner image transferred thereon;
A heat roller, a backup roller pressed to the heat roller side, and a roller pressing means for pressing the backup roller to the heat roller side, disposed on the downstream side of the paper conveyance mechanism unit in the paper conveyance direction; In the image forming apparatus provided with a fixing mechanism that fixes the toner image on the continuous paper while passing the continuous paper between the heat roller and the backup roller and sandwiching and conveying the continuous paper by rotation of both rollers.
A buffer mechanism portion of any one of the first to third means is provided between the paper transport mechanism portion and the fixing mechanism portion.

According to a fifth means of the present invention, in the fourth means,
The roller pressing means is
Frames disposed on both sides of the continuous paper in the width direction in parallel with the paper conveyance direction;
A camshaft that is rotatably supported between the frames and has a first cam and a second cam attached to both end portions;
A pressing force transmission member such as an arm member, which will be described later, interposed between one rotation shaft of the first cam and the backup roller and between the second cam and the other rotation shaft of the backup roller;
A cam motor for rotationally driving the cam shaft;
A cam motor control unit for controlling the rotation angle of the cam motor;
Based on the detection result from the paper meander detection unit,
Rotation angle control of the cam motor by the cam motor control unit in the fixing mechanism unit;
The buffer mechanism motor is configured to perform the rotation angle control of the buffer control motor by the buffer control motor control unit in parallel.

According to a sixth means of the present invention, in the fifth means,
A meandering amount storage means for storing a meandering amount of paper from the meandering detection unit;
Meandering amount average value calculating means for calculating the meandering amount average value;
Meandering amount change rate calculating means for calculating a meandering amount change rate from the meandering amount average value;
A driving amount calculating means for calculating a driving amount of the paper conveyance driving means based on the meandering amount change rate;
An offset amount calculating means for determining whether the position of the continuous sheet is away from a predetermined position;
Based on these calculation results,
Rotation angle control of the cam motor by the cam motor control unit in the fixing mechanism unit;
The buffer mechanism motor is configured to perform the rotation angle control of the buffer control motor by the buffer control motor control unit in parallel.

  The present invention is configured as described above, and even when a special sheet having a different thickness in the width direction of the sheet is used, the sheet meandering correction apparatus can stably convey the sheet without causing the sheet to meander. In addition, an image forming apparatus using the same can be provided.

It is a schematic block diagram for demonstrating the structure from the conveyance tractor of the printing apparatus which concerns on 1st Embodiment of this invention to a heat roller. It is a top view of the buffer mechanism part which concerns on 1st Embodiment of this invention. (A), (b), (c) is the partial side view and partial sectional view which show the connection of a buffer arm and a buffer shaft. (A), (b) has shown the state in which the both ends of the buffer shaft were twisted with respect to two buffer arms, and the state of the paper at the time of paper meander correction | amendment, a backup roller, and a buffer arm FIG. In this embodiment, it is a figure which shows the state which the buffer arm contact | abutted to the buffer position pin at the time of printing stop. (A), (b) is a figure which shows the control state of a cam motor and a buffer control motor in this embodiment. It is a schematic block diagram for demonstrating the structure from the conveyance tractor to the heat roller of the printing apparatus which concerns on 2nd Embodiment of this invention. It is a schematic block diagram of the continuous paper printing apparatus applied by embodiment of this invention. It is a schematic block diagram for demonstrating the structure from the conveyance tractor of the conventional printing apparatus to a heat roller. It is a top view of the conventional buffer mechanism part. It is a partial side view for demonstrating the motion of the buffer arm in the buffer mechanism part. It is a figure for demonstrating the press mechanism of the backup roller by a cam. (A), (b) is a figure which shows a cam shape. (A), (b) is a figure which shows the change of the nip width of a heat roller and a backup roller accompanying the change of the press of a backup roller. It is a conceptual diagram for demonstrating the example of a rotation angle of a cam motor.

  In the conventional paper meandering correction, there is no particular problem in the case of ordinary paper having no deviation in the paper thickness in the paper width direction. However, in some cases such as partially label-attached paper, there is a case where the correction cannot be made by the conventional correction on the fixing mechanism section side in the case where the thickness is uneven in the paper width direction.

  In this regard, for example, even if the thickness of the paper is detected by a sensor or the like, it is about 50 to 150 μm, so a highly accurate sensor is required, and the thickness of the paper during high-speed conveyance is sequentially detected. It is difficult. Also, if the paper to be used is the same type, a method of presetting the paper thickness and performing control based on the thickness can be considered. However, the above method is difficult to solve by the fact that the thickness of the paper actually varies, and the difference in the thickness of the paper may be partial.

  For this reason, in this embodiment, in addition to the paper meandering correction in the fixing mechanism part, the buffer mechanism part 8 installed between the transport tractor 6 and the fixing mechanism part can correct the inclination with respect to the paper in the paper width direction. Is introduced, and the meandering correction of the paper is performed by the inclination in the paper width direction.

  Next, embodiments of the present invention will be described with reference to the drawings. The schematic configuration of the continuous paper printing apparatus using the electrophotographic method according to this embodiment is the same as that shown in FIG.

  FIG. 1 is a schematic configuration diagram for explaining a configuration from a transport tractor 6 to a heat roller 7 of a printing apparatus according to an embodiment of the present invention. FIG. 2 is a plan view of a buffer mechanism unit 8 according to the embodiment of the present invention. FIGS. 3A, 3 </ b> B, and 3 </ b> C are a partial side view and a partial cross-sectional view showing the connection between the first and second buffer arms 20 and 30 and the buffer shaft 31.

  As shown in FIGS. 1 and 8, the buffer mechanism unit 8 is disposed between the transport tractor 6 and the fixing mechanism unit on the sheet transport path. The fixing mechanism unit includes a heat roller 7 and a backup roller 10, and the sheet 5 is conveyed while being sandwiched between the two. Therefore, the buffer mechanism unit 8 includes one of the conveyance tractors 6 (or conveyance rollers). Arranged between the paper transport mechanism and the other paper transport mechanism consisting of the heat roller 7 and the backup roller 10 to prevent the paper 5 from being damaged or loosened due to a transport speed difference occurring between the two paper transport mechanisms. Is provided to do.

(Paper meandering correction in the buffer mechanism)
First, the paper meandering correction in the buffer mechanism unit 8 will be described with reference to FIGS.
As shown in FIG. 2, frames 17 a and 17 b are arranged on both sides of the continuous sheet 5 in the width direction so as to be parallel to the sheet transport direction X.

  One end portion (end portion on the back side of the apparatus) of the buffer drive shaft 19 is supported by the frame 17b by a bearing holder 18 that incorporates a bearing (not shown). On the other hand, the other end (the front end of the apparatus) of the buffer drive shaft 19 is connected to one rotary shaft of the buffer control motor 27 of both shafts by a shaft fixing member such as a coupling 32 without slipping. Yes. Instead of the coupling 32, the end of the buffer drive shaft 19 may be processed and integrated with the motor shaft by screwing or the like to form a uniaxial configuration.

The other rotating shaft of the buffer control motor 27 is rotatably supported by a bearing holder 28, and the bearing holder 28 is fixed to the frame 17a. Therefore, the buffer drive shaft 19 is rotatably supported between the frame 17a and the frame 17b.
The buffer control motor 27 is rotationally driven by a predetermined angle by a buffer control motor drive circuit 37.

  As described above, the other rotating shaft of the buffer control motor 27 is fixed to the frame 17 a by the bearing holder 28. Thereby, the buffer control motor 27 can rotate in the swinging direction by the printing operation, and the positions of both ends in the paper width direction are fixed to the frame 17.

  The first and second buffer arms 20 and 30 extend along the conveyance direction X of the sheet 5, and the base end portion of the first buffer arm 20 on the back side of the apparatus is fixed to the buffer drive shaft 19 with a screw 25, A proximal end portion of the second buffer arm 30 on the front side is fixed to a rotation shaft of the buffer control motor 27.

  A buffer shaft 31 is attached to the free end side (tip end side) of the first and second buffer arms 20 and 30, and the buffer shaft 31 is connected to the free end side (tip end side) of the first buffer arm 20. The pin 26 is positioned at the center of the formed long hole 41. FIGS. 3A, 3B, and 3C are views showing a support structure of the buffer shaft 31 with respect to the buffer arm 20, and as shown in FIG. Is pivotable at a predetermined angle about the pin 26.

  Accordingly, both ends of the buffer shaft 31 can be twisted with respect to the first and second buffer arms 20 and 30, that is, the axis of the buffer shaft 31 is aligned with the axis of the buffer drive shaft 19 (the paper surface of FIG. 2). It becomes possible to be non-parallel (substantially perpendicular to). FIG. 4A is a diagram showing a state in which both ends of the buffer shaft 31 are twisted with respect to the first and second buffer arms 20 and 30.

  A buffer position pin 29 is provided on each of the frames 17a and 17b. As shown in FIGS. 2 and 5, the buffer position pin 29 is installed above the rotation area of the first and second buffer arms 20 and 30.

  Also, as shown in FIG. 2, buffer springs 23 are loosely fitted to both ends of the buffer drive shaft 19, one end of the buffer spring 23 is fixed to the frames 17a and 17b, and the other end of the buffer spring 23 is the first and first ends. Two buffer arms 20 and 30 are connected. Accordingly, the first and second buffer arms 20 and 30 are elastically biased in the rotational direction of the buffer drive shaft 19 by the buffer spring 23.

  The sheet 5 passes through the upper side of the buffer shaft 22, and is tensioned over the entire width of the sheet 5 through the first and second buffer arms 20, 30 and the buffer shaft 22 by the elastic biasing force of the buffer spring 23. It is the composition which gives.

  For this reason, when printing is stopped, the buffer control motor 27 is not excited, and the buffer control motor 27 is in a free state in which it can rotate with respect to the second buffer arm 30. Accordingly, since the force acting on the first and second buffer arms 20 and 30 is only the buffer springs 23, the force is pushed up by the buffer springs 23, and the first and second buffer arms 20 and 30 are respectively applied to the buffer position pins 29. It is still in the butted state (see FIG. 5). That is, the rotation angles of the buffer arms 20 and 30 with respect to the same buffer drive shaft 19 are equal, and the tension applied to the paper 5 by the abutment of the first and second buffer arms 20 and 30 against the buffer position pin 29 is increased. It is held at a position that is uniform in the paper width direction. The state in which the second buffer arm 30 is in contact with the buffer position pin 29 is shown in FIG. 5, and the buffer position pin 29 functions as a stopper pin.

  In printing, the buffer control motor 27 is excited at the start of the printing operation. By this excitation, the positions of the buffer control motor 27 and the second buffer arm 30 are fixed and integrated. In other words, in this state, the second buffer arm 30 is held integrally with the buffer drive shaft 19 to which the first buffer arm 20 is fixed by the screw 25 and the buffer control motor 27 having the buffer drive shaft 19 as the rotation axis. It becomes a state.

  Next, the second buffer arm 20 is moved to the reference position during printing by rotation of the buffer position motor 38 (see FIG. 2). This reference position is a position where a preset tension is applied by the buffer spring 23. Then, the first and second buffer arms 20 and 21 are rotated to a predetermined angle (θ ′) which is the above-described reference position so that the tension applied to the paper 5 is constant from the start of paper conveyance. The buffer position motor 38 is controlled based on position information from the buffer position sensor 24 disposed at the end of the buffer drive shaft 19.

  Since the buffer control motor 27 is always excited, the first and second buffer arms 20 and 30 maintain the relative positional relationship. As a result, the second buffer arm 30 is moved with the movement of the first buffer arm 20. Also move to the reference position.

  After the movement to the reference position is completed, the transport tractor 6 and the heat roller 7 that feed the paper start their operations, and at the same time, the excitation of the buffer position motor 38 is released to apply a constant tension to the paper 5. During this time, the buffer control motor 27 is in an excited state.

  In the meandering correction of the paper by the inclination in the paper width direction, the buffer control motor 27 is held in an excited state as shown in the rotation angle example (number of meander correction STEPs) of the buffer control motor 27 shown in FIG. Rotate a certain amount according to the amount of paper meandering. Thus, the paper meandering correction can be performed by giving an inclination in the width direction of the paper 5.

  Further, the tension applied to the paper 5 during printing is a buffer position sensor 24 (see FIG. 2) disposed at the end of the buffer drive shaft 19 with respect to the transport tractor 6 (or transport roller) that feeds the paper at a constant speed. ) Is controlled so as to finely accelerate and decelerate the speeds of the heat roller 7 and the backup roller 10 of the fixing mechanism unit by the heat roller drive motor 40 so that the detected angle falls within a preset range.

Next, details of the paper meandering correction in the buffer mechanism unit 8 will be described.
In the sheet correction mechanism using the cam 14 of the present embodiment, the shape of the cam 14 and the pressing of the backup roller 10 using the cam 14 are the same as those described above with reference to FIGS. This will be described with reference to FIG.

  As shown in FIG. 1, cams 14 a and 14 b are attached to both ends of the camshaft 9. The cams 14a and 14b have the same shape, but as shown in FIGS. 13A and 13B, the cam 14a installed on the front side of the printing apparatus (the lower side in the drawing in FIG. 1) and the printing apparatus The cam 14b installed on the back side (upper side in FIG. 1 in FIG. 1) is attached to the camshaft 9 with the cam surface being slightly displaced in the circumferential direction, so that the cams 14a and 14b are out of phase. It has a relationship.

  As shown in FIGS. 1 and 12, the arm member 15 is disposed so as to be rotatable about the support shaft 15c so as to be adjacent to the cams 14a and 14b. The arm member 15 is disposed so that a part of the arm member 15 always has a cam abutting portion 15d that abuts against the cam surfaces of the cams 14a and 14b, and the first arm portion 15a. The second arm portion 15b is in contact with the rotation shaft of the first arm portion 15b, and the coil spring 16 is interposed between the first arm portion 15a and the second arm portion 15b.

  Since the arm member 15 is interposed between the backup roller 10 and the cams 14a and 14b, and the coil spring 16 is in a compressed state, the cam contact of the first arm portion 15a is caused by the elastic biasing force of the coil spring 16. The contact portion 15d is in elastic contact with the cam surfaces of the cams 14a and 14b. Therefore, the arm member 15 rotates about the support shaft 15c depending on the position of the cam surface.

  By rotating the cams 14 a and 14 b together with the cam shaft 9, the first arm 15 a moves according to the position of the cam surface, and presses the second arm portion 15 b against the heat roller 7 via the coil spring 16. When the pressing amount is large, the nip width between the heat roller 7 and the backup roller 10 is wide as shown in FIG. 14 (a), and when the pressing amount is small, the heat roller 7 and the backup roller 10 as shown in FIG. 14 (b). The nip width of the backup roller 10 becomes narrow.

  The meandering state of the paper 5 is monitored by a paper meander detector 13 (see FIG. 1) mounted at the exit of the transport tractor 6. Based on the meandering amount in the paper width direction obtained by the paper meander detector 13, paper meandering control of the fixing mechanism is performed.

  Specifically, the microprocessor 34 shown in FIG. 1 corrects the meandering of the paper by rotating the cam member 15 by the cam motor 33 and varying the pressing pressure of the backup roller 10 against the heat roller 7 by various arithmetic processes 35. Is made.

  Further, the paper meandering correction amount calculation process 35 by the microprocessor 34 simultaneously performs the calculation process of the fixing mechanism unit by the cam motor 33 and the calculation of the buffer mechanism unit 8 by the buffer control motor 27 shown in FIG. That is, the paper meandering correction in the fixing mechanism and the paper meandering correction in the buffer mechanism 8 are performed simultaneously (performed in parallel). A curve indicated by a two-dot chain line shown in FIG. 6A indicates a control state of the prior art by the cam motor 33.

Next, an example of sheet meandering correction will be described.
When the paper meandering detector 13 detects that the paper meanders to the back side of the printing apparatus while the printing operation is being performed while monitoring the paper conveyance state, the microprocessor 34 By the arithmetic processing 35 in FIG. 4, the cam shaft 33 is rotated in the A direction by the cam motor 33 as shown in FIGS.

  With this rotation, the cams 14a and 14b are also rotated together by a certain angle in the downward A direction, so that the pressing state of each arm member 15 by the cams 14a and 14b is different on the left and right. That is, the pressing load does not change with the cam 14a on the front side of the printing apparatus, whereas the pressing load is reduced with the cam 14b on the back side of the printing apparatus, and the pressing amount of the nip portion between the heat roller 7 and the backup roller 10 is reduced. , It becomes smaller on the back side (see FIG. 14). Thus, as a result of the backup roller 10 being inclined and pressed against the heat roller 7, the paper 5 can be meandered to the front side (cam 14a side).

  At this time, the sheet meandering correction in the buffer mechanism unit 8 is synchronized with the meandering correction in the fixing mechanism unit by the cam motor 33 as shown in FIG. As shown, the cam motor 33 (cam 14) is rotated in the upward direction B in the opposite direction. By this control, the tension applied to the front side portion of the paper 5 can be reduced and the paper 5 can be corrected to the front side.

  In FIG. 4, δ is the amount of twist of the paper 5 on the buffer shaft 31, 5a indicated by a solid line is the edge of the paper 5 on the front side of the apparatus, 5b indicated by an alternate long and short dash line is the edge of the paper 5 at the back of the apparatus, and a solid line 10a indicates the end of the backup roller 10 on the front side of the apparatus, and 10b indicates the end of the backup roller 10 on the back side of the apparatus.

  By performing the meandering correction of the fixing mechanism unit and the meandering correction of the buffer mechanism unit 8 at the same time, more efficient meandering correction of the paper 5 is possible. Further, as a result of fine adjustment of the paper meander, the amount of paper meander can be reduced as a whole, and the amount of paper meander correction in the fixing mechanism can be reduced.

  As described above, according to the present invention, the sheet of the fixing mechanism section can be used even for special sheets in which meandering correction may be insufficient only by changing the nip pressure of the backup roller 10 due to the difference in the thickness of the left and right sheets. By adopting a configuration in which the meandering correction is also performed in the tension control mechanism for the paper 5 in the upstream portion of the conveyance, the meandering of the paper can be corrected.

  The rotation angle of the buffer control motor 27 is set within a range where the behavior of the paper 5 when the heat roller 7 and the backup roller 10 enter the nip portion is stable, and the operation angle is set in the microprocessor 34 that performs meandering correction control. Process with restrictions.

  Further, the control angle of the second buffer arm 30 immediately before the stop of printing is stored in a storage area (not shown) by the microprocessor 34, and the control is performed as the control angle of the second buffer arm 30 when the immediately preceding print is stopped at the next printing start. You may do it. As a result, it is possible to restore the tension on the sheet immediately before the stop of printing, and it is possible to quickly start up and reduce the load on the sheet without requiring fine adjustment of the tension on the sheet.

  In the above-described embodiment, the case where the buffer mechanism unit 8 is disposed between the conveyance tractor 6 (or the conveyance roller) and the fixing mechanism unit including the heat roller 7 and the backup roller 10 has been described, but the present invention is not limited thereto. A buffer mechanism is disposed between the first continuous paper transport mechanism having a transport tractor and transport rollers and the second continuous paper transport mechanism having the same transport tractor and transport rollers. It is also applicable to cases.

  In the embodiment, the rotation angle control of the buffer control motor 27 and the rotation angle control of the cam motor 33 are performed by one control unit (microprocessor 34), but the buffer control motor that performs the rotation angle control of the buffer control motor 27 is performed. It is also possible to separately provide a control unit and a cam motor control unit that controls the rotation angle of the cam motor.

  FIG. 7 is a schematic configuration diagram for explaining the configuration from the transport tractor to the heat roller of the printing apparatus according to the second embodiment of the present invention.

  In the present embodiment, as shown in the figure, the cam motor control unit and the buffer control motor control unit have microprocessors 34 ′ and 34 ″, respectively, and the detected values from the paper meander detector 13 are the respective microprocessors 34 ′ and 34 ″. 34 ". The microprocessors 34 'and 34 "perform the same arithmetic processing 35' and 35" as in the first embodiment, and independently drive and control the cam motor drive circuit 36 and the buffer control motor drive circuit 37, respectively.

  In this way, by providing the cam motor control unit and the buffer control motor control unit independently, the paper meandering correction processing in the buffer mechanism unit 8 and the fixing mechanism unit can be performed according to the respective characteristics. By carrying out individually, more agile and detailed paper meandering correction control becomes possible.

  In the present embodiment, the meandering amount storage means for storing the meandering amount of paper from the meandering sheet detecting unit, the meandering amount average value calculating means for calculating the meandering amount average value, and the meandering amount change rate from the meandering amount average value. Meandering amount change rate calculating means for calculating the meandering amount, driving amount calculating means for calculating the driving amount of the paper conveyance driving means based on the meandering amount change rate, and an offset for determining whether the position of the continuous paper is away from a predetermined position And a rotation angle control of the buffer control motor by the buffer control motor control unit in the buffer mechanism unit, and a rotation angle of the buffer control motor by the buffer control motor control unit in the buffer mechanism unit based on these calculation results. By adopting a configuration in which the control is performed in parallel, more appropriate paper meandering correction can be performed.

The effects according to the embodiment of the present invention are listed as follows.
(1) By providing a drive source that varies the tension applied to the paper on the rotation shaft of the buffer mechanism, fluctuations in paper tension in the buffer mechanism can be immediately applied to the paper.

(2) Fixing up to now by simultaneously performing paper meandering correction in which a part of the buffer mechanism part rotates and the tension applied to the paper by the buffer mechanism part is varied at the same time as the change in the pressing load of the fixing mechanism part roller. Stable paper meandering correction control is possible even for special papers that differ in paper thickness on the left and right, which may have become unstable due to changes in the pressing load of the mechanism roller.

(3) Stable paper meandering correction control immediately after resuming printing by storing the variable state of the tension applied to the paper in the buffer mechanism when the printing operation is stopped, and reproducing the state immediately before stopping when printing is resumed Is possible.

(4) By performing the paper meandering correction according to the present invention in the image forming apparatus, the operation reliability is high and stable printing quality can be obtained.

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Charging device 3 Developing machine 4 Transfer device 5 Continuous paper 6 Conveyance tractor (or conveyance roller)
7 Heat roller 8 Buffer mechanism 9 Cam shaft 10 Backup roller 11 Stacker 12 Toner image 13 Paper meander detector 14a Front cam 14b Rear cam 15 Arm member 15a First arm 15b Second arm 15c Support Shaft 15d Cam contact portion 16 Coil spring 17a Front frame 17b Rear frame 18 Bearing holder 19 Buffer drive shaft 20 First buffer arm 22 Buffer shaft 23 Buffer spring 24 Buffer position sensor 25 Buffer arm fixing screw 26 Pin 27 Buffer control motor 28 Bearing holder 29 Buffer position pin 30 Second buffer arm 31 Buffer shaft 32 Coupling 33 Cam motor 34 34 ', 34 "Microprocessor 35 Arithmetic processing 36 Cam motor drive circuit 37 Buffer control motor drive circuit 38 Buffer position motor 39 Buffer position gear 40 Heat roller drive motor X Paper transport direction.

Japanese Patent No. 3738983 Japanese Patent No. 4328043 JP 2007-186301 A JP 2008-230734 A

Claims (6)

A first paper transport mechanism unit and a second paper transport mechanism unit disposed on the continuous paper transport path from the upstream side to the downstream side in the paper transport direction;
A buffer mechanism section provided between the first sheet transport mechanism section and the second sheet transport mechanism section for applying tension to the continuous sheet to absorb a sheet transport speed difference between the sheet transport mechanism sections;
In the paper meandering correction apparatus provided with a paper meandering amount detection unit that is provided between the first paper transporting mechanism unit and the buffer mechanism unit on the upstream side in the paper transporting direction and detects the meandering amount of the continuous paper,
The buffer mechanism is
Frames disposed on both sides of the continuous sheet in the width direction in parallel with the sheet conveyance direction;
A buffer drive shaft rotatably supported between the frames;
A buffer control motor for rotationally driving the buffer drive shaft;
A buffer control motor control unit for controlling the rotation angle of the buffer control motor;
A first buffer arm having a base end fixed to one end of the buffer drive shaft;
A second buffer arm having a base end rotatably held on the other end side of the buffer drive shaft;
A buffer spring installed at both ends of the buffer drive shaft and elastically urging the first buffer arm and the second buffer arm in the rotational direction of the buffer drive shaft;
The free end side of the first buffer arm and the second buffer arm is installed so as to be movable in the vertical rotation direction of the buffer drive shaft, and the continuous paper is tensioned by the movement of the first buffer arm and the second buffer arm. A buffer shaft for providing
Based on the detection result from the paper meandering detection unit, the buffer control motor control unit controls the rotation angle of the buffer control motor to correct meandering of the continuous paper.
A meandering correction device for paper. The paper meandering correction apparatus according to claim 1,
An elongated hole is formed in each of the free end sides of the first buffer arm and the second buffer arm, and both ends of the buffer shaft are inserted into the elongated hole so as to be movable in the vertical rotation direction. Meander correction device. The paper meandering correction apparatus according to claim 1,
A storage unit for storing a state of tension applied to continuous paper by the buffer mechanism unit;
When resuming the conveyance of the continuous sheet after the conveyance of the continuous sheet is stopped, the buffer control motor is controlled based on the tension state stored in the storage unit immediately before the conveyance of the continuous sheet is stopped. A meandering correction device for paper. A paper transport mechanism for transporting continuous paper with the toner image transferred thereon;
A heat roller, a backup roller pressed to the heat roller side, and a roller pressing means for pressing the backup roller to the heat roller side, disposed on the downstream side of the paper conveyance mechanism unit in the paper conveyance direction; In the image forming apparatus provided with a fixing mechanism that fixes the toner image on the continuous paper while passing the continuous paper between the heat roller and the backup roller and sandwiching and conveying the continuous paper by rotation of both rollers.
The image forming apparatus according to claim 1, wherein the buffer mechanism section according to claim 1 is provided between the sheet transport mechanism section and the fixing mechanism section. The image forming apparatus according to claim 4.
The roller pressing means is
Frames disposed on both sides of the continuous paper in the width direction in parallel with the paper conveyance direction;
A camshaft that is rotatably supported between the frames and has a first cam and a second cam attached to both end portions;
A pressing force transmitting member interposed between one of the first cam and the rotation axis of the backup roller, and between the second cam and the other rotation axis of the backup roller;
A cam motor for rotationally driving the cam shaft;
A cam motor control unit for controlling the rotation angle of the cam motor;
Based on the detection result from the paper meander detection unit,
Rotation angle control of the cam motor by the cam motor control unit in the fixing mechanism unit;
An image forming apparatus, wherein the buffer mechanism motor is configured to perform the rotation angle control of the buffer control motor in parallel with the buffer mechanism motor. The image forming apparatus according to claim 5.
A meandering amount storage means for storing a meandering amount of paper from the meandering detection unit;
Meandering amount average value calculating means for calculating the meandering amount average value;
Meandering amount change rate calculating means for calculating a meandering amount change rate from the meandering amount average value;
A driving amount calculating means for calculating a driving amount of the paper conveyance driving means based on the meandering amount change rate;
An offset amount calculating means for determining whether the position of the continuous sheet is away from a predetermined position;
Based on these calculation results,
Rotation angle control of the cam motor by the cam motor control unit in the fixing mechanism unit;
An image forming apparatus, wherein the buffer mechanism motor is configured to perform the rotation angle control of the buffer control motor in parallel with the buffer mechanism motor.

Images