JP2009269740A - Paper processing device and printer with paper processing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paper processing device capable of correcting the skew of paper and the generation of wrinkles without staining the paper with ink and the like, and being disposed in a small layout space, and a printer. <P>SOLUTION: The paper processing device comprises an air suction type belt carrying mechanism 41, a normally/reversely rotating roller mechanism 42, and a control portion 60. The belt carrying mechanism 41 can switch forward movement and backward movement, and the normally/reversely rotating roller mechanism 42 can switch normal rotation and the reverse rotation. The control portion 60 controls the drive of the belt carrying mechanism 41 and the normally/reversely rotating roller mechanism 42 to successively execute a bend forming step of forming the bend of a predetermined amount at a paper front end by making the paper abut on the normally/reversely rotating roller mechanism 42 in a stop state, a clipping step of clipping the front end of the paper by the normally/reversely rotating roller mechanism 42, a wrinkle smoothing step of carrying the paper in forward/backward traveling by the belt carrying mechanism 41 and applying tension in the carrying direction on the paper, and a releasing step of releasing the paper from the clipping state by reversely rotating the normally/reversely rotating roller mechanism 42 after the tension in the backward traveling is applied on the paper. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a sheet processing apparatus and a printing apparatus including the sheet processing apparatus, and in particular, a sheet processing apparatus that is disposed in a sheet conveyance path such as a printing apparatus and is suitable for use in reversing a sheet and correcting a sheet state. The present invention relates to a printing apparatus including the sheet processing apparatus.

  In a printing apparatus, skew or wrinkles may occur in the paper during the paper transfer process from the printing unit to the paper transport path, the paper transport process in the paper transport path, the paper transfer process from the paper transport path to the next process, etc. If the conveyance is continued in a state where skew and wrinkles are generated, the sheet itself is damaged or stained with ink or the like, and the process in the next process cannot be performed with high accuracy.

  In particular, in a duplex printing apparatus, in general, after printing the surface of a sheet by a first printing unit, the sheet is once discharged to a sheet conveyance path, and the sheet is reversed by the sheet conveyance path, and is then sent to a second printing unit. Since the paper is supplied and the back side of the paper is printed, if the skew or wrinkle of the paper is generated on the paper transport path, the back side of the paper is printed during printing in the second printing unit. In some cases, printing is inclined at an angle, a defective printing portion is generated, or ink stains are generated.

In order to prevent the generation of paper wrinkles in a printing apparatus or the like, there is a wrinkle generation preventing apparatus as shown in FIG. 5 (Patent Document 1). The wrinkle generation preventing device shown in FIG. 5 includes a vacuum suction type belt conveyance mechanism 101 and a roller mechanism (fixing device) 104 including a pair of upper and lower rollers 102 and 103 disposed at the end of the conveyance path of the belt conveyance mechanism 101. And a control unit 105. When the paper P is fed from the belt transport mechanism 101 to the roller mechanism 104, the belt transport mechanism 101 is controlled so that the paper P is tensioned in the transport direction immediately after the roller mechanism 104 sandwiches the leading end of the paper P. This prevents wrinkles from occurring.
Japanese Patent Laid-Open No. 06-101792

  The conventional paper processing apparatus (wrinkle generation preventing apparatus) shown in FIG. 5 can prevent the paper P from wrinkling, but cannot correct the skew of the paper. Further, since the paper P is configured to pass through the nip portion of the roller mechanism 104 from the belt transport mechanism 101, if this wrinkle prevention device is arranged in the transport path of the duplex printing apparatus, the surface is printed. The entire sheet P passes between the rollers 102 and 103, and at this time, the ink is transferred to the surface of one of the rollers 102 or 103, and the ink is transferred again from the transferred roller 102 or 103 to the next sheet. As a result, the paper is smeared with ink.

(Object of invention)
SUMMARY OF THE INVENTION An object of the present invention is to provide a paper processing apparatus that can prevent skewing and wrinkle of paper and prevent it from being soiled by retransfer of ink, and can be disposed in a small space. .

  In order to solve the above problems, a sheet processing apparatus according to the present invention includes an air suction type belt conveyance mechanism, a forward / reverse roller mechanism including a pair of rollers disposed in the vicinity of a conveyance path end of the belt conveyance mechanism, A control unit that controls driving of the belt conveyance mechanism and the forward / reverse rotation roller mechanism, and the belt conveyance mechanism moves forward to convey the paper toward the forward / reverse rotation roller mechanism, and moves the paper away from the forward / reverse rotation roller mechanism. The forward / reverse roller mechanism is switchable between a forward rotation for moving the sandwiched paper forward and a reverse rotation for moving backward, The control unit drives the belt conveyance mechanism forward to bring the front end of the paper into contact with the nip portion of the stopped forward / reverse rotation roller mechanism, and forms a predetermined amount of deflection at the front end of the paper. Bending forming process, stopping the belt conveyance mechanism, rotating the forward / reverse roller mechanism forward, clamping the front end of the paper, and applying a tension in the backward direction to the paper to stretch the wrinkles And after the tension in the reverse direction is applied to the paper, the forward / reverse roller mechanism is reversely rotated to release the paper from the nipping state. Control the drive.

  According to the above configuration, since the paper is processed and U-turned by using the forward and backward movements of the belt conveyance mechanism, the paper processing space can be kept small. In this small processing space, The generation of wrinkles can be prevented. In particular, the belt conveyance mechanism sucks one side of the paper to advance and reverse the paper, and the forward / reverse rotation roller mechanism holds only the front end of the paper, so the paper processing device of the present invention is incorporated in the double-sided printing device. When provided, the printing surface of the paper is not soiled. Further, when a transport path is provided between the first printing unit and the second printing unit as in the double-sided printing device, the paper processing device according to the present invention is provided on the transport path, so that the ink is used. It is possible to effectively prevent contamination.

  According to the present invention, in the paper processing apparatus, in the final opening step, the paper feeding speed in the backward direction by the forward / reverse roller mechanism can be set to be higher than the paper feeding speed in the backward direction by the belt transport mechanism.

  As the forward / reverse roller mechanism is used, the surface of the roller may be unevenly worn, and the holding pressure of the roller may be uneven in the roller width direction. In that case, if the paper is pulled strongly in the opening process, there is a possibility of re-slanting, but by setting the relative paper feed speed between the belt conveying mechanism and the forward / reverse roller mechanism as described above, Even if the nipping pressure of the rollers is not uniform, the roller can be released without being re-slanted, and skew correction accuracy can be maintained.

  The present invention may include a correction step of correcting the position in the width direction of the sheet by moving the forward / reverse rotation roller mechanism in the roller axial direction after the clamping step.

  According to the above configuration, in addition to correcting skew feeding and preventing wrinkles, the position in the width direction of the sheet can be easily corrected to the normal position with respect to the belt conveyance mechanism. In particular, in a double-sided printing apparatus, when printing in the second printing unit after paper processing, the width direction between the stencil sheet and the paper without moving the plate cylinder or the like of the second printing unit in the paper width direction. The positions can be matched, and the correction work is easy.

  Furthermore, in the paper processing apparatus including the correction step, the paper can be corrected to an appropriate position based on detecting one edge of the paper in the width direction by a sensor. That is, the position in the width direction of the paper can be corrected easily and accurately.

  The present invention also provides a printing apparatus provided with the above-described paper processing device in a printing paper conveyance path.

[First embodiment of the present invention]
1 to 4 show examples in which a paper processing apparatus according to the present invention is provided in a stencil duplex printing apparatus, and an embodiment of the present invention will be described based on these drawings.

(Overall configuration of stencil duplex printing device)
FIG. 1 is a schematic front view showing an internal mechanism of a stencil duplex printing apparatus. Between a paper feeding device 3 and a paper receiving device 4 arranged at a distance from each other, the first and The second printing units 11 and 12 are arranged, the timing roller 5 is arranged between the first printing unit 11 and the paper feeding device 3, and the both printing units 11 and 12 are substantially horizontal. A straight (planar) direct paper transport path 23 and a reverse paper transport path 21 provided downwardly below the direct paper transport path 23 are provided so as to be switchable. Further, a paper processing device 24 according to the present invention is provided.

(Configuration of printing units 11 and 12)
Each printing unit 11, 12 is composed of plate cylinders 11 a, 12 a on which pre-made stencil sheets are mounted, and pressing rollers 11 b, 12 b that face the lower ends of the plate cylinders 11 a, 12 a so as to be able to come into contact with each other from below. The sheet P is held between the image forming portions A1 and A2 formed by the contact portions between the plate cylinders 11a and 12a and the pressing rollers 11b and 12b, and the image of the stencil sheet of the plate cylinders 11a and 12a is transferred to the sheet P. It is configured to print (transfer) on the upper surface.

(Configuration of paper feeding device 3)
The sheet feeding device 3 includes a sheet feeding table 15 on which a large number of sheets P are stacked, a sheet feeding roller 16, and the like. Each is sent to the timing roller 5. The timing roller 5 rotates at an appropriate timing in synchronism with the driving of the first printing unit 11 and feeds the paper P to the image forming unit A1 of the first printing unit 11.

(Configuration of direct conveyance path 23)
The direct conveyance path 23 extends so as to connect the image forming unit A1 of the first printing unit 11 and the image forming unit A2 of the second printing unit 12 in a substantially planar shape (straight line). A portion of the path 23 on the first printing unit 11 side is constituted by an upper conveyance surface of the entrance-side belt conveyance mechanism 31 arranged as a path switching means, and a portion of the direct conveyance path 23 on the second printing unit 12 side is The upper side conveyance surface of the outlet side belt conveyance mechanism 32 is formed in a triangular shape in a side view. Each of the inlet side belt conveyance mechanism 31 and the outlet side belt conveyance mechanism 32 is an air suction type, and includes an air suction box, and the sheet P on the conveyance surface is sucked downward by the air suction box. Yes.

  The inlet side belt conveyance mechanism 31 used as the path switching means is composed of a pair of rotating wheels 31a and 31b, a conveying belt 31c wound between the rotating wheels 31a and 31b, and the air suction box. The other rotating wheel 31b is rotated with the rotating wheel 31a on the paper feeding device 3 side as a rotation fulcrum, whereby a horizontal straight line position K1 indicated by a solid line and a reverse position K2 inclined downward indicated by a dashed line, Can be switched between.

(Configuration of reverse conveyance path 21)
The reverse conveyance path 21 includes a conveyance surface of the inlet side belt conveyance mechanism 31, a conveyance surface 41 a of the air suction type belt conveyance mechanism 41 of the paper processing device 24, and a lower conveyance surface 32 b of the outlet side belt conveyance mechanism 32. It is composed of The sheet processing device 24 includes the air suction belt conveyance mechanism 41 and the forward / reverse roller mechanism 42. The belt conveyance mechanism 41 is linearly and obliquely downward so as to be continuous with the inlet side belt conveyance mechanism 31. The forward / reverse roller mechanism 42 is disposed in the vicinity of the lower end portion of the belt conveyance mechanism 41 and is composed of a pair of rollers 42a and 42b. A switching gate 37 that can be switched between a paper supply state and a paper discharge state is disposed at the upper end of the belt transport mechanism 41, and this switching gate 37 is rotatable about a rotation fulcrum 37a by a predetermined angle. By rotating upward, the paper feeding state is established in which the conveying surface of the inlet side belt conveying mechanism 31 and the conveying surface 41a of the belt conveying mechanism 41 are communicated, and by rotating downward, the belt is conveyed. A paper discharge state is established in which the conveyance surface 41a of the mechanism 41 and the lower conveyance surface 32b of the outlet side belt conveyance mechanism 32 communicate with each other.

(Detailed configuration of the paper processing device 24)
2 is an enlarged schematic front view of the sheet processing apparatus 24, FIG. 3 is a view taken along the line III of FIG. 2, and FIG. 4 is an operation explanatory view sequentially illustrating processing steps (processing methods) by the sheet processing apparatus 24. In FIG. 2, an air suction belt transport mechanism 41 includes a driving roller 51, a driven roller 50, a transport belt 52 with an air suction hole wound between the two rollers 50, 51, and a suction fan 53. A suction box 54. The drive roller 51 is linked to a drive motor 57 via a transmission mechanism 56 using a timing belt or the like and a forward / reverse switching mechanism (not shown). The belt conveyance mechanism 41 is driven in a forward drive for moving the paper P on the conveyance surface 41a in the forward direction D1 toward the forward / reverse roller mechanism 42 side, and in a reverse direction D2 away from the forward / reverse roller mechanism 42 side. It is possible to switch between the reverse drive and the reverse drive.

  The drive motor 57 is electrically connected to the control unit 60, and forward rotation, reverse rotation, stop, rotation speed, and the like are controlled by a command signal from the control unit 60. Further, the drive motor 57 or the transmission mechanism 56 is provided with an encoder 59 (or a rotational speed sensor) electrically connected to the control unit 60 to detect the rotational speed of the drive motor 57 and input it to the control unit 60. It is like that.

  Both rollers 42a, 42b of the forward / reverse roller mechanism 42 are rotatably supported by a box-shaped moving case 61, and the driving roller 42b is a transmission mechanism 63 using a timing belt or the like and a forward / reverse switching mechanism ( Via a roller driving motor 65 via a link (not shown). The driving state of the forward / reverse roller mechanism 42 includes a forward rotation direction R1 in which the paper P sandwiched in the nip portion moves in the forward direction D1, a reverse rotational direction R2 in which the paper P sandwiched in the nip portion moves in the backward direction D2, and Can be switched between.

  The drive motor 65 is electrically connected to the control unit 60, and forward rotation, reverse rotation, stop at a predetermined position, rotation speed, and the like are controlled by a command signal from the control unit 60. Further, the drive motor 65 or the transmission mechanism 63 is provided with an encoder 66 (or rotational speed sensor) electrically connected to the control unit 60, and detects the speed and stop angle (stop position) of the drive motor 65, The data is input to the control unit 60.

  A position detection sensor 67 for detecting one end edge in the width direction of the paper P is disposed between the front end portion of the belt transport mechanism 41 and the forward / reverse roller mechanism 42. The position detection sensor 67 is a transmissive optical sensor having a light emitting unit and a light receiving unit, and the light emitting unit and the light receiving unit are electrically connected to the control unit 60. Basically, the presence or absence of the paper P is detected and input to the control unit 60, but the boundary between the detection range of the paper P and the non-detection range of the paper P is identified as the paper edge.

  The moving case 61 is supported by a pair of guide rods 62 parallel to the roller axial direction of the rollers 42a and 42b so as to be movable in the roller axial direction (paper width direction).

  In FIG. 3, guide rods 62 and 62 that support the movable case 61 so as to be movable in the roller axis direction are installed between a pair of fixed walls 70 and 70 in the printing apparatus. A moving nut 71 having a female screw hole is fixed, and the moving nut 71 is screwed into a lead screw 72 arranged in parallel with the rod axis direction. The lead screw 72 is rotatably supported between the fixed walls 70, and one end of the lead screw 72 is linked to a stepping motor 75 via a transmission mechanism 73 having a timing belt or the like. The stepping motor motor 75 can be switched between forward and reverse. By rotating forward, the lead screw 72 is rotated to one side via the transmission mechanism 73, and the moving nut 71 is moved, for example, to the right by the screw feeding action. On the other hand, by reversely rotating the stepping motor motor 75, the lead screw 72 is rotated to the other side via the transmission mechanism 73, and the moving nut 71 is moved to the left by the screw feeding action.

  The stepping motor motor 75 is electrically connected to the control unit 60 and controlled to rotate in a predetermined rotation direction by a predetermined rotation amount in accordance with a command from the control unit 60. Further, the stepping motor 75 is provided with an encoder 76, and the encoder 76 is electrically connected to the control unit 60, detects the rotation amount and stop angle (stop position) of the stepping motor 75, etc. It can be input.

  The paper position detection sensor 67 is disposed at a position corresponding to one edge (for example, the left edge) Pa of the paper P located at an appropriate position on the belt conveyance mechanism 41.

(Control content of control unit 60)
The storage unit of the control unit 60 incorporates a program for sequentially executing the following steps with respect to driving control of the belt conveyance mechanism 41 and the forward / reverse rotation roller mechanism 42.

(1) Deflection forming step: As shown in FIGS. 4A and 4B, the sheet adsorbed on the conveyance surface 41a is maintained by keeping the forward / reverse rotation roller mechanism 42 stopped and driving the belt conveyance mechanism 41 forward. P is transported in the forward direction D1, the front end of the paper P is brought into contact with the nip portion of the forward / reverse roller mechanism 42, and after the contact, the belt transport mechanism 41 is further driven forward for a predetermined time. The forward movement is continued, and a predetermined amount of bending is formed at the front end of the paper P.

(2) Nipping process: As shown in FIG. 4C, the belt conveyance mechanism 41 is stopped, and the rollers 42a and 42b of the forward / reverse roller mechanism 42 are rotated in the forward rotation direction R1. Then, the rotation of the rollers 42a and 42b is stopped.

(3) Wrinkle stretching step: As shown in FIG. 4D, with the forward / reverse roller mechanism 42 stopped, the belt transport mechanism 41 is driven backward to transport the paper P in the reverse direction D2, A tension in the backward direction D2 is applied to the paper P, and the wrinkles of the paper P are stretched.

(4) Opening step: As shown in FIG. 4 (e), after the belt conveyance mechanism 41 is driven backward, the paper P is tensioned in the backward direction D2, and then the forward / reverse roller mechanism 42 is moved in the reverse rotational direction R2. By rotating the sheet P, the reversely moving sheet P is released from the forward / reverse roller mechanism 42. In this opening process, the speed (linear speed) at which the paper P is fed in the backward direction D2 by the forward / reverse roller mechanism 42 is equal to or higher than the speed (linear speed) at which the paper P is transported in the backward direction D2 by the belt transport mechanism 41. Be controlled.

  Between the bending process and the wrinkle stretching process, the following position adjustment process in the width direction of the paper P is performed as necessary.

  That is, in FIG. 3, it is determined whether or not the left edge Pa of the paper P is detected by the position detection sensor 67. If the left edge Pa is not detected, the paper is not positioned at an appropriate position. Judgment is made and the positions of the rollers 42a and 42b are adjusted in the roller axial direction. Specifically, when the position detection sensor 67 detects the sheet P itself, the stepping motor 75 is rotated forward, and the rollers 42 a and 42 b are moved by the screw feeding operation of the lead screw 72 and the moving nut 71. It moves to one side in the axial direction, for example, to the right in the paper width direction, and is corrected to an appropriate position. On the contrary, when the position detection sensor 67 does not detect the sheet P itself, the stepping motor 75 is rotated in the reverse direction, and the rollers 42a and 42b are moved in the sheet width direction by the screw feeding operation of the lead screw 72 and the moving nut 71. Move to the left of and correct it to the correct position.

(Work flow for duplex printing)
(1) In FIG. 1, when both the front and back sides of the sheet P are printed by the first and second printing units 11 and 12, the entrance side belt conveyance mechanism 31 is switched to the position K2 on the reverse sheet conveyance path 24 side. .

(2) The sheets P stacked on the sheet feeding table 15 of the sheet feeding device 3 are supplied one by one from the top to the timing roller 5 by the sheet feeding roller 16, and the timing roller 5 performs the first printing. The paper P is fed into the image forming unit A1 of the first printing unit 11 in accordance with the rotation angle (printing start position) of the plate cylinder 11a of the unit 11.

(2) In the first printing unit 11, the sheet P is sandwiched from above and below by the image forming unit A1, the sheet surface facing the upper side (the plate cylinder 11a side) is printed, and sent to the path switching inlet side belt conveyance mechanism 31. .

(3) When the paper P is fed into the entrance side belt transport mechanism 31, the switching gate 37 for the reverse transport path is in a paper supply state in which the entrance side is opened. Accordingly, the sheet P is supplied into the reverse conveyance path 21 through the switching gate 37 and is conveyed in the forward direction D1 while being sucked by air on the conveyance surface 41a of the belt conveyance mechanism 41 of the sheet processing device 24.

(4) In the paper processing device 24, the deflection forming process, the clamping process, the wrinkle stretching process, and the opening process described in FIGS. 4A, 4B, 4C, 4D, and 4E, or in addition thereto Then, the sheet width direction position correcting step is performed, and thereafter, the sheet is conveyed in the backward direction D2, guided by the switching gate 37 in the sheet discharge state, and supplied to the lower conveying surface 32b of the outlet side belt conveying mechanism 32.

(5) The paper P supplied to the lower transport surface 32b of the exit side belt transport mechanism 32 is supplied to the image forming unit A2 of the second printing unit 12 at a predetermined timing, and the back surface of the paper facing upward is provided. It is printed, sent to the discharge device 6, and discharged from the discharge device 6 to the paper receiving device 4 of FIG.

(Operation and effect of paper processing device)
Since the details of the control have already been described in detail in the description section of the control unit 60, there are many overlapping portions, but the effects of the sheet processing device 24 will be described again, including the description of the effects.

(1) As shown in FIG. 4A, the paper P supplied into the reverse conveyance path 21 is drawn in the forward direction D1 while being sucked into the conveyance surface 41a by the belt conveyance mechanism 41 that is driven forward. The front end of the sheet P comes into contact with the nip portion of the forward / reverse roller mechanism 42 that is conveyed and stopped.

(2) As shown in FIG. 4B, after the front end of the paper P comes into contact with the nip portion of the forward / reverse rotation roller mechanism 42, the front end of the paper P is further conveyed by transporting the paper P in the forward direction D1. A bend is formed in the part (a bend forming step). When the predetermined amount of bending is formed, the belt conveyance mechanism 41 is stopped. By this bending forming process, the front end of the paper P is aligned parallel to the roller axial direction along the nip portion between the rollers 42a and 42b, and the skew of the paper P is corrected.

(3) As shown in FIG. 4C, with the belt conveying mechanism 41 stopped, the rollers 42a and 42b of the forward / reverse roller mechanism 42 are rotated in the forward rotation direction R1, and the front end of the paper P is moved. After nipping by both rollers 42a and 42b, the rotation of each roller 42a and 42b is stopped (nipping process). In this clamping process, both rollers 42a and 42b clamp only the front end portion of the paper P, so that the roller 42a does not come into contact with the printed surface of the paper P, and the printing surface is not stained. .

(4) At the time of the sandwiching step, when the position of the sheet P in the sheet width direction is shifted from the appropriate position in FIG. 3, the roller shafts of both rollers 42 a and 42 b based on the detection signal from the position detection sensor 67. The position of the direction is adjusted, and the left edge Pa of the paper P is positioned on the position detection sensor 67.

  For example, when the paper P is detected by the position detection sensor 67 when the paper is sandwiched, the moving case 61 and the moving nut 61 and the moving nut 71 are rotated by rotating the stepping motor 75 in the forward direction. The rollers 42a and 42b are moved to the right in the roller axial direction. Then, when the position detection sensor 67 changes from the paper detection state to the paper non-detection state, the stepping motor 75 is stopped and the paper P is stopped at an appropriate position.

  On the other hand, when the sheet P is not detected by the position detection sensor 67 when the sheet is sandwiched, the moving case 61 and the moving nut 71 are rotated together with the moving nut 71 by rotating the stepping motor 75 in the reverse direction. The rollers 42a and 42b are moved to the left in the roller axial direction. Then, when the position detection sensor 67 changes from the paper non-detection state to the paper detection state, the stepping motor 75 is stopped and the paper P is stopped at an appropriate position.

  In this way, by correcting the lateral shift of the paper P and positioning it at an appropriate position, the width direction positions of the stencil sheet and the paper P of the second printing unit 12 in FIG. Can be printed at the exact position.

(5) After correcting the paper position, as shown in FIG. 4D, with the forward / reverse roller mechanism 42 stopped, the belt transport mechanism 41 is driven backward to transport the paper P in the reverse direction D2. Then, a tension in the backward direction D2 is applied to the paper P to stretch the wrinkles of the paper P (wrinkle stretching process).

(6) Following the wrinkle-stretching step, as shown in FIG. 4 (e), after the belt conveying mechanism 41 is driven backward, the paper P is tensioned in the backward direction D2, and then the forward / reverse roller mechanism 42 is rotated backward. By rotating in the direction R <b> 2, the reversely traveling paper P is released from the forward / reverse roller mechanism 42. In this opening step, the speed (linear speed) at which the paper P is fed in the reverse direction D2 by the forward / reverse roller mechanism 42 is set to be higher than the speed (linear speed) at which the paper P is conveyed in the reverse direction D2 by the belt conveyance mechanism 41. Therefore, even if the surfaces of the rollers 42a and 42b are non-uniform due to uneven wear or the like, it is possible to eliminate the extra load from the belt transport mechanism 41 in the reverse direction D2 and cause the skew again. The paper can be opened without any trouble.

(For multi-color printing)
In the case of performing multicolor (two colors) printing on the same surface of the paper, in FIG. 1, the entrance side belt conveyance mechanism 31 for path switching is held at the horizontal straight position K1 and the first printing unit 11 The paper P on which the surface is printed is supplied to the second printing unit 12 without being inverted, and the same surface is printed with other colors.

[Other Embodiments of the Invention]
(1) Although FIG. 1 is applied to a double-sided printing apparatus including two sets of printing units 11 and 12, the printing apparatus includes a single printing unit, prints the surface of the paper, and then reverses the front and back of the paper. It is also possible to provide the paper processing apparatus of the present invention in the paper transport path of the double-sided printing apparatus that prints the back side of the paper by the same printing unit.

(2) The printing apparatus of FIG. 1 includes a stencil printing type printing unit composed of a printing plate cylinder and a pressing roller as a printing unit, but the printing apparatus including an ink jet printing unit also includes the printing apparatus of the present invention. It is possible to provide a paper processing device.

(3) As the position detection sensor 67 for detecting the edge in the width direction of the paper P, a light reflection type optical sensor can be used in addition to a light transmission type optical sensor, and a CCD sensor is used. You can also

(4) The position detection sensor 67 for detecting the edge in the width direction of the paper P can be configured to be movable and adjustable in the roller axial direction in accordance with the size of the paper. It can also be arranged at intervals in the axial direction.

1 is a schematic front view showing an internal mechanism of a stencil duplex printing apparatus provided with a paper processing apparatus according to the present invention. FIG. 2 is an enlarged schematic front view of the sheet processing apparatus of FIG. 1. FIG. 3 is a view taken in the direction of arrow III in FIG. 2. FIG. 5 is an operation explanatory view sequentially illustrating processing steps (processing methods) by the sheet processing apparatus. It is a simplified front view of a conventional example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 21 Reverse conveyance path 24 Paper processing apparatus 41 Air suction type belt conveyance mechanism 42 Forward / reverse roller mechanism 42a, 42b Roller 60 Control part 67 Position detection sensor 71, 72, 75 Moving nut, lead screw, stepping motor (roller moving mechanism)

Claims (5)

An air suction belt transport mechanism;
A forward / reverse roller mechanism comprising a pair of rollers disposed near the end of the transport path of the belt transport mechanism;
A control unit for controlling the driving of the belt conveyance mechanism and the forward / reverse rotation roller mechanism,
The belt conveyance mechanism is switchable between a forward drive for conveying the paper toward the forward / reverse roller mechanism and a reverse drive for conveying the paper away from the forward / reverse roller mechanism,
The forward / reverse roller mechanism is switchable between a forward rotation for moving forward the sandwiched paper and a reverse rotation for moving backward,
The controller is
A deflection forming step of causing the front end portion of the sheet to contact the nip portion of the forward / reverse rotation roller mechanism in a stopped state by driving the belt conveyance mechanism forward, and forming a predetermined amount of deflection at the front end portion of the sheet;
A sandwiching step of stopping the belt transport mechanism, rotating the forward / reverse roller mechanism forward, and sandwiching the front end of the paper;
A wrinkle-stretching process that stops the forward / reverse roller mechanism, reversely drives the belt conveyance mechanism, and applies a tension in the reverse direction to the paper to stretch the wrinkles;
After the reverse tension is applied to the paper, the forward / reverse roller mechanism is reversely rotated to release the paper from the nipping state; and
A sheet processing apparatus that controls driving of the belt conveyance mechanism and the forward / reverse rotation roller mechanism so as to sequentially perform the steps. The sheet processing apparatus according to claim 1,
In the opening step, the sheet processing apparatus is configured such that the sheet feeding speed in the backward direction by the forward / reverse roller mechanism is set to be higher than the sheet conveying speed in the backward direction by the belt conveying mechanism. In the paper processing apparatus according to claim 1 or 2,
A paper processing apparatus including a correcting step of correcting the position in the width direction of the paper by moving the forward / reverse roller mechanism in the roller axial direction after the clamping step. The sheet processing apparatus according to claim 3.
In the correction step, the sheet processing apparatus corrects the sheet to an appropriate position based on detection of one edge of the sheet in the width direction by a position detection sensor.   5. A printing apparatus in which the paper processing apparatus according to claim 1 is disposed in a paper conveyance path for printing paper.

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