Sheet Processing Device

Abstract

To propose a sheet processing device with a simpler and more compact configuration than a conventional one.SOLUTION: A sheet processing device includes: a processing part capable of processing one face of a sheet S1; a printing cylinder 33 that conveys the sheet S1 while gripping and holding the sheet S1 with the first gripping claw devices 33A to 33C; a standby part 52 for waiting the sheet S1; a transfer cylinder 36 in contact with the printing cylinder 33 that receives the sheet S1 from the printing cylinder 33 by a third gripper device and delivers the sheet S1 to the sheet delivery 4 or delivers to the standby section 52; and a return cylinder 40 that transfers from a rear end to the printing cylinder 33 again, which the rear end of the sheet S1 which is waiting in the standby section 52 is held in its grip by the second gripping claw device 40A, so that one side processed by the processing section is in contact with the printing cylinder 33.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention is suitably applied to a sheet processing apparatus having, for example, a reversing mechanism. [Background technology]

[0002] Conventionally, there is a sheet-fed rotary press with a reversing mechanism that has a sheet reversing mechanism for printing the front side of a sheet and then reversing it to print the back side (for example, see Patent Document 1). This sheet-fed rotary press with a reversing mechanism has a reversing unit that can reverse a sheet between adjacent printing units, and is capable of single-sided printing and double-sided printing.

[0003] In the sheet-fed rotary printing press with a reversing mechanism of Patent Document 1, the reversing unit consists of a transfer cylinder (figure number 17 in Figure 4 of Patent Document 1) and an impression cylinder (figure number 16 in Figure 4 of Patent Document 1), and when performing double-sided printing, the transfer cylinder grasps the leading end of the sheet while it is being transported, and the transport direction of the sheet can be changed and the sheet can be transported. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 03-080108 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the sheet-fed rotary printing press with a reversing mechanism of Patent Document 1 has separate configurations for printing the front and back sides, and has a problem in that the device as a whole is large in size due to its long, linear configuration.

[0006] The present invention has been made to solve such problems, and aims to propose a sheet processing apparatus having a simpler and smaller structure than the conventional ones. [Means for solving the problem]

[0007] In order to solve the above problems, the sheet processing apparatus according to the present invention includes a first cylinder having a first gripper device for gripping one end of a sheet and transporting the sheet, a processing section for processing one side of the sheet being transported by the first cylinder, and a discharge section for discharging the processed sheet. The sheet processing apparatus includes a waiting section that receives the processed sheet from one end thereof and keeps the sheet waiting, a distribution mechanism that selectively distributes the sheet from the first cylinder to either the discharge device or the waiting section, and an inversion section that has a second gripping device that grips the other end of the sheet waiting in the waiting section and passes the other end of the sheet to the first gripping device of the first cylinder so that the one surface of the sheet contacts the first cylinder.

[0008] In the present invention, the sheet processing apparatus may further include a first adjustment unit that adjusts a position of the other end of the sheet in the standby section.

[0009] The sheet processing apparatus of the present invention may further comprise a second adjustment device that adjusts a position of a side edge in a width direction of the sheet before the sheet is gripped by the second gripper device.

[0010] The present invention may be directed to a sheet processing device, wherein the waiting section includes a belt for transporting a sheet, and the first adjustment means is a stopper that abuts against the one end of the sheet and is freely movable in the transport direction of the sheet.

[0011] In the sheet processing device of the present invention, the waiting section may include a pair of rollers for clamping a sheet and a motor for rotating the pair of rollers, and the first adjustment means may include a control unit for controlling the motor based on the size of the sheet.

[0012] In the sheet processing device of the present invention, there is provided a second cylinder that faces the first cylinder, has a third gripper device that receives the sheet from the first cylinder, and transports the sheet, and a front reversing cylinder that faces the second cylinder, has a fourth gripper device that receives the sheet from the second cylinder, and transports the sheet, wherein the sorting mechanism is provided on the second cylinder, and the belt receives the sheet being transported by the front reversing cylinder.

[0013] The sheet processing apparatus of the present invention may further include a guide member that lifts the other end of the sheet in the standby section and delivers the sheet to the second gripper device of the reversing section. Effect of the Invention

[0014] According to the invention of claim 1, by using a waiting section for waiting the sheet and a transport section for transporting the sheet from the first cylinder to the waiting section, the number of cylinders used can be reduced, and the first cylinder can be used again to process the sheet in an inverted state, thereby simplifying the configuration and realizing a sheet processing device with a simpler and smaller configuration than conventional ones.

[0015] According to the invention of claim 2, by adjusting the position of the sheet in the waiting section by the first adjustment means, even if the sheet size changes, the sheet can be reliably reversed in accordance with the sheet size.

[0016] Furthermore, according to the invention of claim 3, it is possible to perform register adjustment in the width direction when processing the other side of the inverted sheet.

[0017] According to the invention of claim 4, the waiting section transports the sheet using a belt, and the position of the sheet in the waiting section can be adjusted by a stopper provided so as to be movable in the sheet transport direction.

[0018] Furthermore, according to the invention of claim 5, by adjusting the position of the sheet in the waiting section by controlling a motor that rotates a pair of rollers that clamp the sheet instead of using a stopper, the sheet can be reliably inverted to match the sheet size even if the sheet size changes.

[0019] Furthermore, according to the invention of claim 6, the conveyance of the sheet from the second cylinder to the standby section is performed by the front reversing cylinder and the belt, and the belt also serves as the standby section, so that the configuration can be simplified.

[0020] Furthermore, according to the invention of claim 7, by lifting the end of the sheet in the waiting section via the guide roller, the sheet can be reliably delivered to the second gripper device in the reversing section. [Brief description of the drawings]

[0021] [Figure 1] 1 is a side view showing the overall configuration of a digital printing apparatus according to a first embodiment. [Diagram 2] FIG. 4 is an enlarged side view showing the vicinity of the return cylinder and the guide roller. [Diagram 3] FIG. 2 is a side view showing a sheet conveying process (1). [Figure 4] FIG. 11 is a side view showing a sheet conveying step (2). [Diagram 5] FIG. 11 is a side view showing a sheet conveying step (3). [Figure 6] FIG. 11 is a side view showing a sheet conveying step (4). [Figure 7] FIG. 11 is a side view showing a sheet conveying step (5). [Figure 8] FIG. 11 is a side view showing a sheet conveying step (6). [Figure 9] FIG. 11 is a side view showing a sheet conveying step (7). [Figure 10] FIG. 11 is a side view showing the overall configuration of a digital printing device according to a second embodiment. [Figure 11] FIG. 4 is a side view showing the configuration of an upper guide and a lower guide. [Figure 12] FIG. 2 is a side view showing a sheet conveying process (1). [Figure 13] FIG. 11 is a side view showing a sheet conveying step (2). [Figure 14] FIG. 11 is a side view showing a sheet conveying step (3). [Figure 15] FIG. 11 is a side view showing a sheet conveying step (4). [Figure 16] FIG. 11 is a side view showing a sheet conveying step (5). [Figure 17] FIG. 11 is a side view showing a sheet conveying step (6). [Figure 18] FIG. 11 is a side view showing a sheet conveying step (7). [Figure 19] FIG. 11 is a block diagram for explaining another embodiment of the waiting unit. [Figure 20] FIG. 11 is a side view showing an upper guide and a lower guide mechanism in another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Next, an embodiment of the present invention will be described with reference to the drawings.

[0023] (1) First embodiment In FIG. 1, reference numeral 1 denotes a digital printing apparatus serving as a sheet processing apparatus, which is made up of a sheet feeder 2, a digital printing unit 3, and a sheet delivery 4 serving as a discharge device.

[0024] The sheet feeder 2 of the digital printing device 1 adsorbs a single sheet S1 on the top row of sheets 22 stacked on a stacking plate 21 using a sheet sucker 23 as a sheet supplying device, and then moves the sheet S1 to the feeder board FB and places it there, thereby sequentially supplying the sheets S1 one by one to the digital printing unit 3.

[0025] The sheet sucker 23 is connected to a negative pressure source not shown, and transports the sheet S1 of the sheet stack 22 to the feeder board FB by adsorbing the sheet S1 through the first suction 23A and the second suction 23B, moving the sheet S1 horizontally, and then releasing the suction.

[0026] Here, when a single-sided printing mode in which only the front side of the sheet S1 is selected, the sheet feeder 2 performs continuous paper feeding by continuously adsorbing the sheet S1 at certain time intervals using the sheet sucker 23 and transporting it to the feeder board FB in accordance with instructions from a control unit consisting of a CPU (Central Processing Unit) not shown.

[0027] On the other hand, when a double-sided printing mode is selected in which the sheet S1 is printed not only on the front side but also on the back side, the sheet feeder 2, in accordance with instructions from the control unit (not shown), intermittently adsorbs the sheet S1 using the sheet sucker 23 at time intervals such that the sheets are spaced apart from one another compared to the case of continuous feeding, and transports them to the feeder board FB, thereby performing intermittent feeding.

[0028] In this manner, the digital printing device 1 is configured so that the sheets S1 can be fed continuously from the sheet feeder 2 to the digital printing unit 3 one by one, or the sheets S1 can be fed intermittently.

[0029] The sheet S1 conveyed to the feeder board FB has its conveying position aligned in the top, bottom, left and right directions by a registration device (not shown) at the leading edge FB1 of the feeder board.

[0030] The digital printing unit 3 of the digital printing device 1 includes a swing device 31 that receives the sheet S1 supplied from the feeder board FB with a claw portion (not shown), and a supply cylinder 32 that grips one end of the sheet S1 supplied by the swing device 31 with a gripping claw device 32A and then passes it on to the printing cylinder 33, which serves as the first cylinder.

[0031] The digital printing unit 3 is provided with a triple-cylinder printing cylinder 33 which grips one end of the sheet S1 supplied from the supply cylinder 32 using one of three first gripper devices 33A, 33B or 33C on the printing cylinder 33 and rotates while adsorbing the entire surface of the sheet S1, an inkjet nozzle section 34 as a four-color processing section arranged downstream of the supply cylinder 32 in the transport direction and facing the printing cylinder 33, and a transfer cylinder 36 as a second cylinder arranged downstream of the inkjet nozzle section 34 in the transport direction and facing the printing cylinder 33.

[0032] Here, while the supply cylinder 32 has one gripper device 32A and is large enough to transport one sheet S1 on its peripheral surface, the printing cylinder 33 is a triple cylinder having three first gripper devices 33A, 33B, and 33C arranged at regular angular intervals and a peripheral surface having a circumference equivalent to that of three of the largest sheets S1 anticipated to be connected together.

[0033] In addition, the printing cylinder 33 has a plurality of suction holes (not shown) formed at predetermined intervals over its entire surface, and is structured to transport the sheet S1 while holding it by suction from the inside through the plurality of suction holes.

[0034] The printing cylinder 33 grips the sheets S1, which are supplied one by one by the gripper device 32A of the supply cylinder 32, in sequence with the first gripper devices 33A, 33B, and 33C of the printing cylinder 33, and sequentially transports the sheets S1 to the inkjet nozzle section 34 by rotating in the direction of the arrow (counterclockwise).

[0035] The inkjet nozzle section 34 comprises an inkjet nozzle head 34A for black, an inkjet nozzle head 34B for cyan, an inkjet nozzle head 34C for magenta, and an inkjet nozzle head 34D for yellow, which are arranged in sequence downstream in the transport direction, and performs a digital printing process on sheet S1 by ejecting and spraying fine droplets of ink onto the outer peripheral surface of sheet S1 which is transported while being fully adhered to the peripheral surface of printing cylinder 33.

[0036] In order to maintain a predetermined level of print quality, the gap between the inkjet nozzle heads 34A-34D corresponding to each color of the inkjet nozzle section 34 and the sheet S1 adsorbed to the entire circumferential surface of the printing cylinder 33 needs to be set to an extremely small minimum gap. Therefore, by adsorbing the entire sheet S1 to its circumferential surface, the printing cylinder 33 can maintain the gap between the inkjet nozzle heads 34A-34D and the sheet S1 adsorbed to the printing cylinder 33 at an extremely small minimum gap.

[0037] In the digital printing unit 3, a transfer cylinder 36 serving as a distribution mechanism is arranged downstream of the printing cylinder 33 in the conveying direction, in contact with the printing cylinder 33, a delivery belt DB for transporting the sheet S1 to the sheet delivery 4 is arranged downstream of the transfer cylinder 36 in the conveying direction, and a front reversal cylinder 39 is arranged downstream of the transfer cylinder 36 in the conveying direction, in contact with the transfer cylinder 36.

[0038] Therefore, when single-sided printing mode is selected, the transfer cylinder 36 in the digital printing unit 3 grips the sheet S1, which is gripped by one of the first gripper devices 33A to 33C of the printing cylinder 33 and is entirely adsorbed to the peripheral surface of the printing cylinder 33, with the third gripper device 36A of the transfer cylinder 36, and then places the sheet S1 on a conveyor-like delivery belt DB, thereby sequentially discharging the sheet S1 via the delivery belt DB to the downstream sheet delivery 4.

[0039] The sheet delivery 4 stacks the sheet S1 conveyed via the delivery belt DB on a stacking plate 41, and discharges the sheet S1 after digital printing.

[0040] When a double-sided printing mode in which the back side of sheet S1 is to be printed is selected, the digital printing unit 3 digitally prints the front side of sheet S1 using the printing cylinder 33 and the inkjet nozzle section 34, and then, instead of transferring sheet S1 to the delivery belt DB using the third gripper device 36A of the transfer cylinder 36, transfers one end of the sheet S1 from the third gripper device 36A of the transfer cylinder 36 to the fourth gripper device 39A of the front reversal cylinder 39.

[0041] The front reversing cylinder 39 grips one end of the sheet S1 from the transfer cylinder 36 using a fourth gripper device 39A, and then passes the sheet S1 to a belt 64 arranged downstream in the conveying direction of the front reversing cylinder 39. Note that in the digital printing unit 3, a return cylinder 40 is arranged downstream in the conveying direction of the transfer cylinder 36 in a state of abutting against the printing cylinder 33. The return cylinder 40 constitutes part of the "reversing section" as defined in the present invention.

[0042] Next, a description will be given of the structure of the belt 64. One end of the belt 64 contacts the front reversing cylinder 39, and the other end forms the standby section 52, and is wound around the driving rollers 62 and 68 disposed at both ends and the driven roller 63 disposed near the driving roller 62, and is configured to place the sheet S1 transported from the front reversing cylinder 39 on the belt.

[0043] A thin guide cover 61 is provided on the belt 64 so as to face the placement surface on which the sheet S1 is to be placed, and is spaced slightly apart from the belt 64 and substantially parallel to the belt 64. This allows the belt 64 to convey the sheet S1 while suppressing fluttering of the sheet S1 conveyed on the belt 64 via the driving rollers 62 and 68.

[0044] Further, the belt 64 has a stopper 67 attached near the drive roller 68, which stops the sheet S1 being conveyed by the belt 64 by abutting against it. Therefore, the sheet S1 being conveyed by the belt 64 eventually abuts against the stopper 67 and waits in the waiting section 52, but since the drive rollers 62 and 68 are still rotating at this time, the sheet S1 is configured to continue to press one end (front end) of the sheet S1 against the stopper 67 while sliding on the belt 64, and as a result, the top-bottom register of the sheet S1 is adjusted.

[0045] At this time, the left-right register of the sheet S1 is adjusted by a side gauge device 67A as a second adjustment means provided between the stopper 67 and an upper guide 66A (described later). Although not shown in detail, the side gauge device 67A includes a pair of rollers that selectively pinch one side edge of the sheet S1, and a side stopper located on the side of the sheet S1. The pair of rollers rotate about a rotation axis extending in a direction parallel to the conveying direction of the sheet S1, and are configured to move toward and away from each other. In more detail, the pair of rollers move away from each other just before the sheet S1 arrives, and when the sheet S1 enters between the rollers, the pair of rollers pinch the sheet S1 and rotate so that the sheet S1 advances toward the side stopper. The side contact defines the position of the side edge of the sheet S1. When the side edge of the sheet S1 is moved laterally by the pair of rollers, the side contact adjusts the left-right registration of the sheet S1.

[0046] In the belt 64, when the transport of the sheet S1 is restrained by the stopper 67, a guide roller 65 is disposed at a position corresponding to the rear end, which is the other end of the sheet S1, and the other end of the sheet S1 is positioned between the upper drive roller 65A and the lower driven roller 65B of the guide roller 65. Incidentally, through holes are formed in the guide cover 61 at portions corresponding to the upper drive roller 65A and the lower driven roller 65B. Therefore, the sheet S1 can be conveyed while being sandwiched together with the belt 61 by the upper drive roller 65A and the lower driven roller 65B.

[0047] In addition, a stopper 67 is attached to the belt 64 so as to be freely movable along the belt 64 depending on the length of the sheet S1 in the sheet conveying direction. That is, the belt 64 is configured such that the longer the sheet S1, the closer the stopper 67 is to the drive roller 68, whereas the shorter the sheet S1, the closer the stopper 67 is to the return cylinder 40. The standby position of the sheet S1 can be adjusted via the stopper 67.

[0048] The belt 64 is configured such that when the other end of the sheet S1 is positioned between the upper drive roller 65A and the lower driven roller 65B of the guide roller 65, the lower driven roller 65B can move freely upward.

[0049] As a result, with the upper drive roller 65A and the lower driven roller 65B of the belt 64 clamping the other end of the sheet S1, the entire guide roller 65 is lifted above the loading surface of the belt 64, and the other end of the sheet S1 is moved away from the loading surface of the belt 64.

[0050] In practice, the belt 64 is configured so that the lower driven roller 65B of the guide roller 65 moves upward to lift the rear end of the sheet S1 and pinches the rear end of the sheet S1 with the upper drive roller 65A in accordance with the gripping change timing at which the second gripper device 40A of the return cylinder 40 grips the other end of the sheet S1, and the upper drive roller 65A rotates to transport the sheet S1 toward the second gripper device 40A of the return cylinder 40. At this time, the upper drive roller 65A may start rotating when it pinches the sheet S1 with the lower driven roller 65B from a stopped state, or may be configured to rotate constantly.

[0051] As a result, as shown in Figure 2, in order to guide the rear end of sheet S1, which is sandwiched between the upper drive roller 65A and the lower driven roller 65B, to the return cylinder 40, the belt 64 inserts the rear end of sheet S1 between upper guide 66A and lower guide 66B, which serve as guide members, so that the rear end of sheet S1 is guided to the second gripper device 40A of the return cylinder 40 and is gripped by the second gripper device 40A.

[0052] The return cylinder 40 rotates clockwise in the direction of the arrow while holding the sheet S1, the trailing end of which is gripped by the second gripper device 40A, and passes the sheet S1, in an inverted state from the front side to the back side, to the printing cylinder 33 via the return cylinder 40.

[0053] In other words, the digital printing unit 3 can use a return cylinder 40 arranged so that the surface that has been digitally printed by the printing cylinder 33 is in contact with the printing cylinder 33, thereby allowing the inverted sheet S1 gripped by the second gripper device 40A to be transferred again from its rear end to the printing cylinder 33.

[0054] In practice, in the digital printing unit 3, when the second gripper device 40A of the return cylinder 40 faces any of the first gripper devices 33A to 33C of the printing cylinder 33, the sheet S1 can be transferred from the return cylinder 40 to the printing cylinder 33, thereby transporting the sheet S1 in an inverted state from the return cylinder 40 to the printing cylinder 33.

[0055] Thus, the digital printing unit 3 transports the sheet S1, which has been gripped by the first gripper device 33A of the printing cylinder 33, back to the inkjet nozzle section 34 while adsorbing it entirely with its peripheral surface, and after performing digital printing processing on the back side of the sheet S1, passes it on to the delivery belt DB via the transfer cylinder 36, thereby completing the double-sided printing process.

[0056] Incidentally, in the belt 64, the belt device 60 is formed by the drive rollers 62, 68, the driven roller 63 and the belt 64, and the conveying section 51 is formed by the conveying belt portion in the range from the drive roller 62 to just before the guide roller 65 and the front reversal cylinder 39, out of the entire range of the belt 64 from the drive roller 62 to the drive roller 68.

[0057] In addition, of the entire range of the belt 64 from the drive roller 62 to the drive roller 68, the conveying belt portion from the guide roller 65 to the drive roller 68 forms a waiting section 52 for temporarily waiting the sheet S1 so that the sheet S1 can be transferred from the return cylinder 40 to the printing cylinder 33.

[0058] Here, the belt 64 only logically defines the conveying section 51 and the waiting section 52, and is not necessarily limited to this. For example, it is also possible to logically define the conveying section 51 so as not to include the front inversion cylinder 39. The “reversing portion” in the present invention is composed of the guide roller 65 and the return cylinder 40 .

[0059] In the above configuration, when the double-sided printing mode is selected in the digital printing unit 3, as shown in FIG. 3, the leading end of the sheet S1 gripped by the gripper device 32A of the supply cylinder 32 is re-griped by, for example, the first gripper device 33A of the printing cylinder 33.

[0060] As shown in FIG. 4, in the digital printing unit 3, the printing cylinder 33 rotates counterclockwise, and the sheet S1 held by the first gripper device 33A is transferred to the third gripper device 36A of the transfer cylinder 36.

[0061] 5, in the digital printing unit 3, when the third gripper device 36A of the transfer cylinder 36 and the fourth gripper device 39A of the front reversing cylinder 39 face each other, the sheet S1 is transferred from the transfer cylinder 36 to the front reversing cylinder 39. At the same time, in the digital printing unit 3, a new sheet S1 next intermittently fed by the supply cylinder 32 is held by the first gripper device 33C of the printing cylinder 33.

[0062] 6, in the digital printing unit 3, the sheet S1 held by the fourth gripper device 39A of the front reversing cylinder 39 is placed on the belt 64. At the same time, the digital printing unit 3 conveys the next sheet S1, which was previously held by the first gripper device 33C of the printing cylinder 33, while adsorbing the sheet to the circumferential surface of the printing cylinder 33.

[0063] As shown in FIG. 7, in the digital printing unit 3, the sheet S1 placed on the belt 64 is transported to the waiting section 52 by the belt 64, the leading end of the sheet S1 is abutted by a stopper 67, and the register is adjusted by operating the horizontal needle device 67A.

[0064] As shown in Figure 8, in the digital printing unit 3, in accordance with the timing of the gripping change when the second gripper device 40A of the return cylinder 40 arrives, the lower driven roller 65B rises and lifts the rear end of the sheet S1, which is engaged via the stopper 67 of the waiting section 52, above the conveying belt 64 and clamps it between the upper drive roller 65A, and the upper drive roller 65A of the guide roller 65 rotates to transport the sheet S1 toward the second gripper device 40A of the return cylinder 40.

[0065] As a result, in the digital printing unit 3, the rear end of the sheet S1 is gripped from the guide roller 65 to the second gripper device 40A of the return cylinder 40, and then the sheet S1 is transferred from the second gripper device 40A of the return cylinder 40 to the first gripper device 33C of the printing cylinder 33.

[0066] In this case, as shown in Figure 9, in the digital printing unit 3, the printing cylinder 33 transports the sheet S1, which is already inverted to its back side when it is handed over from the return cylinder 40 to the printing cylinder 33, so that the back side of the sheet S1 transported again by the printing cylinder 33 that printed the front side can be digitally printed by the inkjet nozzle section 34.

[0067] According to the above configuration, in the digital printing unit 3 of the digital printing device 1, the surface of the sheet transported by the printing cylinder 33 is digitally printed by the inkjet nozzle section 34, and then the sheet S1 is transferred to the belt 64 via the transfer cylinder 36 and the front reversal cylinder 39, and the sheet S1 is transported via the belt 64 to the conveying section 51 and the waiting section 52. At the same time, the end (front end) of the sheet S1 is abutted against the stopper 67 of the waiting section 52, and the waiting position of the sheet S1 is adjusted, i.e., the register is adjusted, by operating the horizontal needle device 67A.

[0068] In the digital printing unit 3, when the second gripper device 40A of the return cylinder 40 approaches the rear end of the sheet S1, the lower driven roller 65B rises to lift the rear end of the sheet S1 above the conveying belt 64 and clamps it between the upper drive roller, and the upper drive roller 65A of the guide roller 65 rotates to transport the sheet S1 toward the second gripper device 40A of the return cylinder 40.

[0069] As a result, the digital printing unit 3 can guide the rear end of the sheet S1 to the second gripper device 40A of the return cylinder 40 via the guide roller 65, upper guide 66A and lower guide 66B, so that it is securely gripped by the second gripper device 40A of the return cylinder 40, and the sheet S1 can be transferred from the second gripper device 40A of the return cylinder 40 to the first gripper devices 33A to 33C of the printing cylinder 33, so that the sheet S1 can be transported again to the printing cylinder 33 while maintaining its register adjustment state.

[0070] Thus, the digital printing unit 3 can perform digital printing processing on the back side of the sheet S1 after the register adjustment has been performed via the printing cylinder 33 and the inkjet nozzle section 34, thereby preventing misalignment between the printing results on the front side and the back side, and improving the printing quality on both the front and back sides of the sheet S1.

[0071] Furthermore, the digital printing unit 3 can reuse the printing cylinder 33 and inkjet nozzle section 34 that have performed digital printing processing on the front side of sheet S1 to also perform digital printing processing on the back side of sheet S1.Since the printing cylinder 33 and inkjet nozzle section 34 can be used for digital printing processing on both the front and back sides, double-sided printing of sheet S1 can be performed with high precision without increasing the size of the entire device.

[0072] (2) Second embodiment In FIG. 10, in which the same reference numerals are used for parts corresponding to those in FIG. 1, reference numeral 100 denotes a digital printing apparatus serving as a sheet processing apparatus, and is made up of a sheet feeder 2, a digital printing unit 3, and a sheet delivery 4 serving as a discharge device.

[0073] The sheet feeder 2 of the digital printing device 100 adsorbs a single sheet S1 on the top row of sheets 22 stacked on a stacking plate 21 using a sheet sucker 23 as a sheet supplying device, and then moves the sheet S1 to the feeder board FB and places it there, thereby sequentially supplying the sheets S1 one by one to the digital printing unit 3.

[0074] The sheet sucker 23 is connected to a negative pressure source not shown, and transports the sheet S1 of the sheet stack 22 to the feeder board FB by adsorbing the sheet S1 through the first suction 23A and the second suction 23B, moving the sheet S1 horizontally, and then releasing the suction.

[0075] Here, when a single-sided printing mode in which only the front side of the sheet S1 is selected, the sheet feeder 2 performs continuous paper feeding by continuously adsorbing the sheet S1 using the sheet sucker 23 at predetermined time intervals and transporting it to the feeder board FB in accordance with instructions from a control unit consisting of a CPU (Central Processing Unit) not shown.

[0076] On the other hand, when a double-sided printing mode is selected in which printing is performed on both the front and back sides of sheet S1, sheet feeder 2 performs intermittent feeding by intermittently adsorbing sheets S1 at time intervals of every other sheet in accordance with instructions from the control unit (not shown) and transporting them to feeder board FB.

[0077] As a result, the digital printing apparatus 100 is configured so that the sheets S1 can be continuously fed one by one from the sheet feeder 2 to the digital printing unit 3, or the sheets S1 can be intermittently fed.

[0078] The sheet S1 conveyed to the feeder board FB has its conveying position aligned in the top, bottom, left and right directions by a registration device (not shown) at the leading edge FB1 of the feeder board.

[0079] The digital printing unit 3 of the digital printing device 100 includes a swing device 31 that receives the sheet S1 supplied from the feeder board FB with a claw portion (not shown), and a supply cylinder 32 that grips one end of the sheet S1 supplied by the swing device 31 with a gripping claw device 32A and then passes it on to the printing cylinder 33, which serves as the first cylinder.

[0080] The digital printing unit 3 is provided with a triple-cylinder printing cylinder 33 which grips one end of the sheet S1 supplied from the supply cylinder 32 using one of three first gripper devices 33A, 33B or 33C on the printing cylinder 33 and rotates while adsorbing the entire surface of the sheet S1, an inkjet nozzle section 34 as a four-color processing section arranged downstream of the supply cylinder 32 in the transport direction and facing the printing cylinder 33, and a transfer cylinder 36 as a second cylinder arranged downstream of the inkjet nozzle section 34 in the transport direction and facing the printing cylinder 33.

[0081] Here, while the supply cylinder 32 has one gripper device 32A and is large enough to transport one sheet S1 on its peripheral surface, the printing cylinder 33 is a triple cylinder having three first gripper devices 33A, 33B, and 33C arranged at regular angular intervals and a peripheral surface having a circumference equivalent to that of three of the largest sheets S1 anticipated to be connected together.

[0082] In addition, the printing cylinder 33 has a plurality of suction holes (not shown) formed at predetermined intervals over its entire surface, and is structured to transport the sheet S1 while holding it by suction from the inside through the plurality of suction holes.

[0083] The printing cylinder 33 grips the sheets S1, which are supplied one by one by the gripper device 32A of the supply cylinder 32, in sequence with the first gripper devices 33A, 33B, and 33C of the printing cylinder 33, and sequentially transports the sheets S1 to the inkjet nozzle section 34 by rotating in the direction of the arrow (counterclockwise).

[0084] The inkjet nozzle section 34 comprises an inkjet nozzle head 34A for black, an inkjet nozzle head 34B for cyan, an inkjet nozzle head 34C for magenta, and an inkjet nozzle head 34D for yellow, which are arranged in sequence downstream in the transport direction, and performs a digital printing process on sheet S1 by ejecting and spraying fine droplets of ink onto the outer peripheral surface of sheet S1 which is transported while being fully adhered to the peripheral surface of printing cylinder 33.

[0085] In order to maintain a predetermined level of print quality, the gap between the inkjet nozzle heads 34A-34D corresponding to each color of the inkjet nozzle section 34 and the sheet S1 adsorbed to the entire circumferential surface of the printing cylinder 33 needs to be set to an extremely small minimum gap. Therefore, by adsorbing the entire sheet S1 to its circumferential surface, the printing cylinder 33 can maintain the gap between the inkjet nozzle heads 34A-34D and the sheet S1 adsorbed to the printing cylinder 33 at an extremely small minimum gap.

[0086] In the digital printing unit 3, a transfer cylinder 36 serving as a distribution mechanism in contact with the printing cylinder 33 is arranged downstream in the conveying direction from the printing cylinder 33, and an auxiliary cylinder 36B in contact with the transfer cylinder 36 is arranged downstream in the conveying direction from the transfer cylinder 36.

[0087] Between the transfer cylinder 36 and the auxiliary cylinder 36B, there are provided upper guide 71 and lower guide 72 made of thin plates formed in a horizontal straight line to guide and transport the sheet S1 transported by the transfer cylinder 36 to the sheet delivery 4. In the digital printing unit 3, a return cylinder 40 is disposed downstream of the transfer cylinder 36 in the transport direction so as to abut against the printing cylinder 33.

[0088] As shown in FIG. 11, upper guide 71 and lower guide 72 provided between transfer drum 36 and auxiliary drum 36B are attached in an integrated state to upper guide 84 and lower guide 85 which are curved in a semicircular shape from their middle. Sheet S1 is discharged to sheet delivery 4 via upper guide 71 and lower guide 72, while sheet S1 is transported from upper guide 71 and lower guide 72 to transport section 151 via upper guide 84 and lower guide 85.

[0089] The digital printing unit 3 is provided with nip rollers 73A and 73B and nip rollers 74A and 74B for conveying sheet S1 from the transfer cylinder 36 to the sheet delivery 4 while the sheet S1 passing between the upper guide 71 and the lower guide 72 is sandwiched therebetween. Here, the nip rollers 73B and 74B provided on the lower side are driven to rotate counterclockwise by a motor (not shown), and the nip rollers 73A and 74A in contact with the nip rollers 73B and 74B are rotated accordingly.

[0090] Incidentally, the upper guide 71 and the lower guide 72 have through holes formed at locations corresponding to the pairs of nip rollers 73A and 73B, 74A and 74B, so that the sheet S1 can be transported while being clamped by the nip rollers 73A and 73B, 74A and 74B without interference between the pairs of nip rollers 73A and 73B, 74A and 74B and the upper guide 71 and the lower guide 72.

[0091] The upper guide 84 and the lower guide 85 are made of thin plates that are curved into a semicircular shape and then extend in an almost straight line, and are provided with nip rollers 75A and 75B, nip rollers 76A and 76B, nip rollers 77A and 77B, nip rollers 78A and 78B, and guide rollers 65 (upper drive roller 65A and lower driven roller 65B) for transporting sheet S1 from the transfer drum 36 while the sheet S1 passing between the upper guide 84 and the lower guide 85 is sandwiched therebetween.

[0092] Here, nip rollers 75B, 76B, 77B, and 78B provided on the lower side and upper drive roller 65A are driven to rotate clockwise via a motor (not shown), while nip rollers 75B, 76B, 77B, and 78B, nip rollers 75A, 76A, 77A, and 78A in contact with upper drive roller 65A, and lower driven roller 65B are driven to rotate.

[0093] Meanwhile, in the upper guide 84 and the lower guide 85, like the upper guide 71 and the lower guide 72, through holes are formed at locations corresponding to the pairs of nip rollers 75A and 75B, 76A and 76B, 77A and 77B, 78A and 78B, and the guide roller 65 (upper driving roller 65A and lower driven roller 65B).

[0094] This allows the sheet S1 to be transported while being clamped by the pairs of nip rollers 75A and 75B, 76A and 76B, 77A and 77B, 78A and 78B, and guide roller 65 (upper drive roller 65A and lower driven roller 65B) without interference between the upper guide 84 and the lower guide 85.

[0095] The upper guide 84 and the lower guide 85 extend to the vicinity of the driving roller 80 of the driving rollers 80, 81 of the belt 87, and the upper guide 84 and the lower guide 85 are mounted in a slightly downward inclined state from the nip rollers 78A, 78B toward the belt 87.

[0096] The belt 87 is wound around drive rollers 80 and 81 arranged along the extension line of the upper guide 84 and the lower guide 85, and a driven roller 82 arranged in the vicinity of the drive roller 80, and the sheet S1 transported via the upper guide 84 and the lower guide 85 is placed on top of the belt 87.

[0097] A thin guide cover 86 is provided on the belt 87 so as to face a placement surface on which the sheet S1 is to be placed, and is disposed substantially parallel to the belt 87 at a small distance from the belt 87. This allows the belt 87 to suppress flapping of the sheet S1 transported on the belt 87 via the drive rollers 80 and 81 by the guide cover 86.

[0098] The belt 87 is provided with a stopper 67 for holding the sheet S1 in place by abutting one end of the sheet S1 conveyed by the belt 87. As a result, the belt 87 rotates via the drive rollers 80 and 81, causing the conveyed sheet S1 to abut against the stopper 67 and wait in a waiting section 152 on the belt 87, but since the drive rollers 80 and 81 continue to rotate at this time, one end (front end) of the sheet S1 continues to be pressed against the stopper 67 while sliding on the belt 87, and as a result, the top-bottom register of the sheet S1 is adjusted.

[0099] At this time, the left-right register of the sheet S1 is adjusted by a horizontal needle device 67A provided between the stopper 67 and the upper drive roller 65A.

[0100] On the belt 87, a guide roller 65 is disposed at a position corresponding to the rear end of the sheet S1 when the transport of the sheet S1 is suppressed by the stopper 67, and the rear end of the sheet S1 is positioned between the upper drive roller 65A and the lower driven roller 65B of the guide roller 65.

[0101] In addition, the stopper 67 is attached to the belt 87 so as to be freely movable along the belt 87 depending on the length of the sheet S1 in the sheet conveying direction. That is, the belt 87 is configured such that the longer the sheet S1 is, the closer the stopper 67 is attached to the drive roller 81, whereas the shorter the sheet S1 is, the closer the stopper 67 is attached to the drive roller 80, and the standby position of the sheet S1 can be adjusted via the stopper 67.

[0102] In this case, although the upper guide 84 and the lower guide 85 are extended close to the drive roller 80 and are separate from the belt 87, the gap between the two is extremely small, and when the front end (one end) of the sheet S1 abuts against the stopper 67, the rear end (the other end) of the sheet S1 is positioned between the upper drive roller 65A and the lower driven roller 65B of the guide roller 65.

[0103] The belt 87 is configured so that when the other end of the sheet S1 is positioned between the upper drive roller 65A and the lower driven roller 65B of the guide roller 65, the lower driven roller 65B can move freely upward.

[0104] As a result, in the belt 87, with the upper drive roller 65A and the lower driven roller 65B clamping the other end of the sheet S1, the lower driven roller 65B is lifted above the loading surface of the belt 64, and the other end of the sheet S1 is moved away from the loading surface of the belt 87.

[0105] In practice, the belt 87 is configured so that the lower driven roller 65B of the guide roller 65 moves upward to lift the rear end of the sheet S1 and pinches the rear end of the sheet S1 with the upper drive roller 65A in accordance with the gripping change timing at which the second gripper device 40A of the return cylinder 40 grips the other end of the sheet S1, and the upper drive roller 65A rotates to transport the sheet S1 toward the second gripper device 40A of the return cylinder 40. At this time, the upper drive roller 65A may start rotating from a stopped state when it pinches the sheet S1 with the lower driven roller 65B, or may be configured to rotate constantly.

[0106] As a result, the belt 87 transports the rear end of the sheet S1, which is sandwiched between the upper drive roller 65A and the lower driven roller 65B, toward the return cylinder 40, and the rear end of the sheet S1 is gripped by the second gripper device 40A of the return cylinder 40.

[0107] The return cylinder 40 rotates clockwise in the direction of the arrow while holding the sheet S1, the trailing end of which is gripped by the second gripper device 40A, and passes the sheet S1, in an inverted state from the front side to the back side, to the printing cylinder 33 via the return cylinder 40.

[0108] In other words, the digital printing unit 3 can use a return cylinder 40 arranged so that the surface that has been digitally printed by the printing cylinder 33 is in contact with the printing cylinder 33, thereby allowing the inverted sheet S1 gripped by the second gripper device 40A to be transferred again from its rear end to the printing cylinder 33.

[0109] The return cylinder 40 is located between the guide roller 65 and the printing cylinder 33, and an arc-shaped guide cover 40B is provided along the circumferential surface of the return cylinder 40 at a position slightly away from the circumferential surface of the return cylinder 40. This prevents the sheet S1 being transported from the return cylinder 40 to the printing cylinder 33 from flapping away from the circumferential surface of the return cylinder 40 by the guide cover 40B.

[0110] In other words, in the digital printing unit 3, when the second gripper device 40A of the return cylinder 40 faces any of the first gripper devices 33A to 33C of the printing cylinder 33, the sheet S1 can be transferred from the return cylinder 40 to the printing cylinder 33, thereby transporting the sheet S1 in an inverted state from the return cylinder 40 to the printing cylinder 33.

[0111] Thus, the digital printing unit 3 transports the sheet S1, which has been gripped by the first gripper device 33A of the printing cylinder 33, back to the inkjet nozzle section 34 while adsorbing it entirely with its peripheral surface, and after performing digital printing processing on the back side of the sheet S1, passes it on to the delivery belt DB via the transfer cylinder 36, thereby completing the double-sided printing process.

[0112] Incidentally, the range of the upper guide 84 and the lower guide 85 is logically defined as a conveying section 151 for conveying the sheet S1, and the range of the belt 87 is logically defined as a waiting section 152 for temporarily waiting the sheet S1 so that the sheet S1 can be handed over from the return cylinder 40 to the printing cylinder 33, but this is not necessarily limited to this. The “reversing portion” in the present invention is composed of the guide roller 65 and the return cylinder 40 .

[0113] In the digital printing unit 3, how the destination of the sheet S1 is allocated between when the sheet S1 is transported from the transfer cylinder 36 to the sheet delivery 4 via the upper guide 71 and the lower guide 72 and when the sheet S1 is transported from the transfer cylinder 36 to the transport section 151 via the upper guide 84 and the lower guide 85 will be explained.

[0114] As shown in Figure 11, when sheet S1 gripped by gripper device 36A of transfer cylinder 36 is transported to conveying section 151 via upper guide 84 and lower guide 85, in the digital printing unit 3, the timing of releasing sheet S1 by gripper device 36A is advanced so that the leading end of sheet S1 is naturally guided to upper guide 84 and lower guide 85 by its own weight, and sheet S1 is transported to conveying section 151.

[0115] On the other hand, when the sheet S1 gripped by the gripper device 36A of the transfer cylinder 36 is transported to the sheet delivery 4 via the upper guide 71 and the lower guide 72, in the digital printing unit 3, the timing at which the gripper device 36A releases the sheet S1 is delayed as much as possible, so that the front end of the sheet S1 does not droop due to its own weight and is not guided to the upper guide 84 and the lower guide 85, but rather the front end is guided to the upper guide 71 and the lower guide 72, and the sheet S1 is transported to the sheet delivery 4.

[0116] In the above configuration, when the double-sided printing mode is selected in the digital printing unit 3, as shown in Figure 12, the leading end of the sheet S1 gripped by the gripper device 32A of the supply cylinder 32 is re-grip by, for example, the first gripper device 33A of the printing cylinder 33.

[0117] As shown in FIG. 13, in the digital printing unit 3, the sheet S1 held by the first gripper device 33A is transferred to the third gripper device 36A of the transfer cylinder 36 by the rotation of the printing cylinder 33.

[0118] Then, in the digital printing unit 3, as shown in FIG. 14, the sheet S1 is released from the third gripper device 36A of the transfer cylinder 36 at a predetermined timing, and the sheet S1 is transported to nip rollers 75A and 75B, 76A and 76B, 77A and 77B, 78A and 78B, and guide roller 65 in the transport section 151 via upper guide 84 and lower guide 85, as shown in FIG. 15.

[0119] As shown in FIG. 16, in the digital printing unit 3, the sheet S1 is conveyed from the conveying section 151 to the standby section 152 via nip rollers 77A and 77B, 78A and 78B, and a guide roller 65.

[0120] As shown in FIG. 17, in the digital printing unit 3, the sheet S1 placed on the belt 87 in the waiting section 152 is transported by the belt 87, the leading end of the sheet S1 is abutted by the stopper 67, and the register is adjusted by operating the horizontal needle device 67A.

[0121] As shown in Figure 18, in the digital printing unit 3, in accordance with the timing of the gripping change when the second gripper device 40A of the return cylinder 40 arrives, the lower driven roller 65B rises and lifts the rear end of the sheet S1, which is engaged via the stopper 67 of the waiting section 152, above the belt 87 and clamps it between the upper drive roller 5A, and the upper drive roller 65A of the guide roller 65 rotates to transport the sheet S1 toward the second gripper device 40A of the return cylinder 40.

[0122] As a result, in the digital printing unit 3, the rear end of the sheet S1 is gripped from the guide roller 65 to the second gripper device 40A of the return cylinder 40, and then the sheet S1 is transferred from the second gripper device 40A of the return cylinder 40 to the first gripper device 33C of the printing cylinder 33.

[0123] In this case, in the digital printing unit 3, the printing cylinder 33 transports the sheet S1, which is already inverted to its back side when it is handed over from the return cylinder 40 to the printing cylinder 33, so that the back side of the sheet S1 transported again by the printing cylinder 33 that printed the front side can be digitally printed by the inkjet nozzle section 34.

[0124] According to the above configuration, in the digital printing unit 3 of the digital printing device 1, the surface of the sheet S1 transported by the printing cylinder 33 is digitally printed by the inkjet nozzle section 34, and then the sheet S1 is transferred to the transport section 151 via the transfer cylinder 36, and the end (front end) of the sheet S1 is abutted against the stopper 67 of the waiting section 152. The horizontal needle device 67A is then operated to adjust the waiting position of the sheet S1, i.e., to perform a register adjustment.

[0125] In this digital printing unit 3, when the second gripper device 40A of the return cylinder 40 approaches the rear end of the sheet S1, the lower driven roller 65B rises and lifts the rear end of the sheet S1 above the conveying belt 64 to pinch it between the upper drive roller 65A, and the upper drive roller 65A of the guide roller 65 rotates to transport the sheet S1 toward the second gripper device 40A of the return cylinder 40.

[0126] This enables the digital printing unit 3 to reliably grip the rear end of the sheet S1 against the second gripper device 40A of the return cylinder 40, and transfer the sheet S1 from the second gripper device 40A of the return cylinder 40 to the first gripper devices 33A to 33C of the printing cylinder 33, so that the sheet S1 can be transported again to the printing cylinder 33 while maintaining its register adjustment state.

[0127] Thus, the digital printing unit 3 can perform digital printing processing on the back side of the sheet S1 after the register adjustment has been performed via the printing cylinder 33 and the inkjet nozzle section 34, thereby preventing misalignment between the printing results on the front side and the back side, and improving the printing quality on both the front and back sides of the sheet S1.

[0128] Furthermore, the digital printing unit 3 can reuse the printing cylinder 33 and inkjet nozzle section 34 that have performed digital printing processing on the front side of sheet S1 to also perform digital printing processing on the back side of sheet S1.Since the printing cylinder 33 and inkjet nozzle section 34 can be used for digital printing processing on both the front and back sides, double-sided printing of sheet S1 can be performed with high precision without increasing the size of the entire device.

[0129] In addition, the digital printing unit 3 is mounted with the upper guide 84 and lower guide 85 of the conveying section 151 tilted slightly downward from the nip rollers 78A, 78B toward the belt 87, and the surface of the belt 87 on which the sheets are placed is similarly tilted.

[0130] As a result, even if the sheet S1 placed on the belt 87 slips due to the rotation of the belt 87 and cannot be transported, the sheet S1 will naturally be transported toward the stopper 67 due to its own weight, thereby preventing the sheet S1 from losing its vertical registration.

[0131] (3) Other embodiments In the first and second embodiments described above, the first cylinder is a three-fold cylinder. Although the above description has been given with respect to a case where the printing cylinder 33 is used, the present invention is not limited to this. A printing cylinder having a double cylinder size, a six-times cylinder size, or the like may be used.

[0132] Furthermore, in the above-described first embodiment, a case has been described in which the conveying section 51 integrated with the waiting section 52 is used as the conveying section, but the present invention is not limited to this, and a conveying section separate from the waiting section 52 may also be used.

[0133] Furthermore, in the above-described first and second embodiments, a case has been described in which a transfer cylinder 36 having a single-times cylinder size is used as the second cylinder, but the present invention is not limited to this, and a transfer cylinder having a double-times cylinder size, a triple-times cylinder size, etc. may be used.

[0134] Furthermore, in the above-mentioned first and second embodiments, a case has been described in which a return cylinder 40 having a size of 1x is used as the reversing section, but the present invention is not limited to this, and it is also possible to use a reversing swing device having a configuration similar to that of the swing device 31 and which swings from the waiting section 52, 152 toward the printing cylinder 33.

[0135] Furthermore, in the above-mentioned first and second embodiments, a case has been described in which a movably attached stopper 67 is used as the first adjustment means, but the present invention is not limited to this, and if the size of the seat S1 is fixed, a stopper 67 fixed at a predetermined position may be used.

[0136] Furthermore, in the above-mentioned first and second embodiments, the belts 64, 87 and the stopper 67 that can be freely attached are used as the adjustment means. However, the present invention is not limited to this, and the transport of the sheet S1 may be stopped and the waiting position may be adjusted using a configuration such as that described in paragraphs "0138" to "0143" below.

[0137] Instead of using the belts 64, 87 and the stopper 67, a pair of nip rollers that sandwich and transport the sheet S1 is provided at the position of the guide roller 65 in the first and second embodiments. The nip rollers are rotatable and axially movable.

[0138] In this case, the digital printing device 1 (sheet processing device) is equipped with a sheet size detection sensor 91 consisting of a photoelectric sensor or the like that detects the length of the sheet S1 in the transport direction, a sheet side end position detection sensor 92 consisting of a photoelectric sensor or the like that detects the position of one side end of the sheet S1, and an encoder 93 that can detect the phase of the drive unit of the sheet processing device, as shown in the block diagram of Figure 19.

[0139] The sheet processing device includes a motor 94 as a first adjustment means for rotating the nip roller, an adjustment mechanism 95 as a second adjustment means for adjusting the axial position of the nip roller, and a control unit 96 as a first adjustment means and second adjustment means for controlling the motor 94 and the adjustment mechanism 95 based on a sheet size detection sensor 91, a sheet side end position detection sensor 92, and an encoder 93, as shown in the block diagram of Figure 19.

[0140] The position adjustment of sheet S1 in standby section 52, 152, which is performed using these configurations, will be described below. Sheet S1 transported to the nip rollers is transported to standby section 52, 152 by the rotation of the nip rollers. Here, control section 96 rotates motor 94 according to information on the length of sheet S1 from sheet size detection sensor 91 until the sheet S1 is transported an appropriate amount to standby section 52, 152, and then stops the motor 94 to adjust the top-bottom register position.

[0141] Next, the control unit 96 operates the adjustment mechanism 95 according to the information on the widthwise position of the sheet S1 from the sheet side end position detection sensor 92 so that the sheet S1 is positioned at the correct widthwise registration position.

[0142] Next, the control unit 96 reverses the rotation of the motor 94 at the timing when the other end of the sheet S1, which has been aligned in the top-to-bottom and width directions based on the signal from the encoder 93, is gripped by the second gripper device 40A of the return drum 40, thereby reversely rotating the nip roller and gripping the other end of the sheet S1 into the second gripper device 40A.

[0143] Furthermore, in the above-mentioned second embodiment, the case where the sheet S1 is conveyed from the transfer cylinder 36 to the sheet delivery 4 via the upper guide 71 and the lower guide 72 and the case where the sheet S1 is conveyed from the transfer cylinder 36 to the belt conveying section 150 via the upper guide 84 and the lower guide 85 is switched by adjusting the release timing of the sheet S1 by the gripper device 36A of the transfer cylinder 36. However, the present invention is not limited to this, and as shown in Fig. 20 (A) and (B), a switching unit 101 as a plate-shaped sorting mechanism provided at the branch point between the upper guide 71 and the lower guide 72 and the upper guide 84 and the lower guide 85 may be switched to the upper guide 71 and the lower guide 72 side or the upper guide 84 and the lower guide 85 side, and the release timing of the sheet S1 by the gripper device 36A may be controlled and the switching of the plate-shaped switching unit 101 may be used in combination to increase reliability.

[0144] Furthermore, in the first and second embodiments described above, the sheet processing device is described as being applied to a digital printing device, but the present invention is not limited to this, and may also be applied to an offset printing device, an inspection device, a foil transfer device, an embossing device, etc.

[0145] Furthermore, in the first and second embodiments described above, in the inversion section 51 and waiting section 52, 152, the sheet is transported by a belt, and a guide cover provided along the belt is used to prevent the sheet S1 from flapping or floating off the belt. However, the present invention is not limited to this configuration. A configuration may also be used in which suction holes are provided on the belt surface and negative pressure is generated on the surface of the belt that does not come into contact with the sheet, thereby sucking the sheet S1 instead of using a guide cover, thereby preventing the sheet S1 from flapping or floating off the belt while being transported. [Explanation of symbols]

[0146] 1, 100...digital printing device, 2...sheet S1 feeder, 3...digital printing unit, 4...sheet delivery, 21...loading plate, 22, 42...loaded sheets, 23...sheet sucker, 31...swing device, 32...supply cylinder, 33...printing cylinder, 36...transfer cylinder, 39...front inversion cylinder, 40...return cylinder, FB...feeder board, DB...delivery belt, S1...sheet, 51, 151...conveying section, 52, 152...waiting section, 65...guide roller, 67...stopper, 62, 68, 80, 81...drive roller, 63, 82...driven roller, 64, 87...belt, 61...guide cover, 71, 84...upper guide, 72, 85...lower guide, 73-78...nip roller.

Claims

1. A first cylinder having a first gripping claw device for gripping one end of a sheet supplied from a sheet feeder through at least a supply cylinder, and for conveying the sheet by gripping one end of the sheet; a processing section for performing processing on one side of the sheet being conveyed by the first cylinder; a discharge device for discharging the treated sheet; In a sheet processing apparatus comprising: a waiting section that receives the processed sheet from the one end portion and keeps the sheet waiting; a distribution mechanism that selectively distributes the sheet from the first cylinder to either the discharge device or the standby section; a turnover unit provided on a return cylinder arranged upstream of the supply cylinder in the rotation direction of the first cylinder and downstream of the sorting mechanism in the rotation direction of the first cylinder, the turnover unit having a second gripper device for gripping the other end of the sheet, and transferring the other end of the sheet to the first gripper device of the first cylinder so that the one surface of the sheet contacts the first cylinder; A sheet processing apparatus comprising:

2. 2. The sheet processing apparatus according to claim 1, further comprising a first adjustment unit that adjusts a position of the other end of the sheet in the standby portion.

3. 3. The sheet processing apparatus according to claim 2, further comprising a second adjusting means for adjusting a position of a side edge in a width direction of the sheet before the sheet is gripped by the second gripper device.

4. the waiting section includes a belt for conveying a sheet, 4. The sheet processing apparatus according to claim 3, wherein the first adjustment means is a stopper that is provided so as to be movable in the sheet transport direction and against which the one end of the sheet abuts.

5. the standby section includes a pair of rollers that sandwich a sheet and a motor that rotates the pair of rollers, The first adjustment means includes a control unit that controls the motor based on the size of the sheet.

4. The sheet processing apparatus according to claim 3,

6. a second cylinder that faces the first cylinder and has a third gripper device that receives the sheet from the first cylinder and transports the sheet; a front inversion cylinder that faces the second cylinder, has a fourth gripper device that receives a sheet from the second cylinder, and transports the sheet; The sorting mechanism is provided on the second cylinder, The belt receives the sheet being conveyed by the front inversion cylinder.

5. The sheet processing apparatus according to claim 4,

7. 7. The sheet processing apparatus according to claim 1, further comprising a guide member which lifts the other end of the sheet in the waiting section and delivers the sheet to the second gripper device of the reversing section.

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