JP2005112569A - Double-side printing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a double-side printing device capable of effectively preventing occurrence of ink transfer stain. <P>SOLUTION: In this double-side printing device 1 having plate cylinders 2, 3 and press rollers 4, 5 provided by corresponding to the plate cylinders 2, 3 and performing a rear surface printing process in which rear surface image is printed on other face of a paper sheet P after performing a surface printing process in which surface image is printed on one surface of the paper sheet P, a paper refeeding means 9 for feeding a surface printed paper sheet into the rear surface printing process after storing the surface printed paper sheet after the surface printing process temporarily is provided, and storage time of the surface printed paper sheet by the paper refeeding means 9 can be controlled. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a printing apparatus, and more particularly to a duplex printing apparatus capable of printing on both sides of a sheet in one step.

  Conventionally, digital thermal stencil printing is known as a simple printing method. The stencil printing apparatus used for this stencil printing has a master in accordance with image information by bringing a thermal head in which fine heating elements are arranged in a line into contact with the master and conveying the master while energizing the heating elements in pulses. After the master is wound around the outer peripheral surface of a porous cylindrical plate cylinder, the outer surface of the plate cylinder is pressed by a pressing means such as a press roller through a sheet of paper, so that the ink is transferred from the master perforated portion. Is transmitted and transferred to a sheet of paper to obtain a printed image.

  In this stencil printing, in recent years, double-sided printing, in which printing is performed on both sides of a sheet, has been frequently performed for the purpose of reducing paper consumption and document storage space. This double-sided printing is a conventional method in which the paper stacked on the paper feeding unit is passed through the printing unit, printed on one side, then turned over, and again passed through the printing unit to print on the other side. However, there is a problem in that it is troublesome to set the paper once ejected to the paper feeding unit or to align the paper after single-sided printing. In addition, since the paper is passed through the printing unit twice, the net printing time is twice as long as that of single-sided printing, and it takes too much time.

  In order to solve the above-mentioned problems, a first plate cylinder and a first plate cylinder disposed opposite to the first plate cylinder via a paper conveyance path and provided so as to be capable of being pressed and separated from the first plate cylinder. A pressing unit; a second plate cylinder disposed on the downstream side of the first plate cylinder in the sheet conveying direction and facing the first plate cylinder via the sheet conveying path; and the sheet conveying path. A second pressing unit disposed opposite to the second plate cylinder and provided so as to be capable of being pressed and separated from the second plate cylinder, and presses the first plate cylinder and the first pressing unit. After that, for example, “Patent Document 1” discloses a stencil printing apparatus that performs double-sided printing by pressing a second plate cylinder and a second pressing unit.

  Further, a divided master-making master having a first image printed on one side of the paper and a second image printed on the other side of the paper is wound around the plate cylinder, and the paper is fed by the first press roller. After pressing the plate cylinder to print the first image on one side of the paper, the one-side printed paper is re-fed by the urging means, and the second press roller is used to feed the second image on the other side of the paper. A stencil printing apparatus that performs double-sided printing by printing an image is disclosed in, for example, “Patent Document 2”.

  By using the techniques disclosed in each of the above-mentioned patent documents, printing can be performed on both sides of the paper with a single sheet passing, and the printing work time can be reduced to about half compared to conventional double-sided printing. Is possible. Furthermore, during double-sided printing, when printing on one-side printed paper printed by the upstream printing unit, the unfixed ink transferred to the pressure roll is retransferred to the back side of the paper when printing is performed by the downstream printing unit. In order to prevent this problem, for example, “Patent Document 3” discloses a technique of providing minute irregularities on the outer peripheral surface of a pressure roll used in a downstream printing unit.

JP 2000-103768 A JP-A-9-95033 JP 2002-219849 A

  However, in the techniques disclosed in “Patent Document 1” and “Patent Document 2”, printing is performed on one side of the paper and then printing on the other side of the paper. When printing, the ink adhering to one side of the paper is transferred to the surface of the press roller, and when printing on one side of the next paper, it is transferred from the previous paper to the other side of this paper. There is a problem that the stained ink adheres and the back stain occurs.

  In order to solve this problem, a cleaning device having a cleaning roller that can be brought into contact with and separated from the press roller in the vicinity of the press roller is disposed, and cleaning is performed by bringing the cleaning roller into contact with the press roller. Yes. However, with this method, the cleaning roller itself is immediately soiled with ink, and the cleaning performance is significantly reduced. Therefore, it is necessary to frequently replace the cleaning roller with a new one, which greatly reduces the running cost. End up. In addition, when the cleaning performance is improved by using a dedicated cleaning liquid in combination, there is a problem that the liquid leakage or the liquid recovery mechanism is expensive to handle the liquid, and the waste liquid treatment and supply New problems such as an increase also occur.

  As another means for solving the above-described problems, it is conceivable to use a metal roller having sandpaper on the outer peripheral surface as the press roller, and to reduce ink adhesion to the outer peripheral surface of the press roller. In this case, there is no major problem as long as the press roller merely conveys the paper, but since the press roller needs to press the paper against the plate cylinder with a predetermined pressing force, the abrasive grains of the sand paper In addition to the problem of the durability of the press roller itself due to falling off, there is a problem that the paper and the master are damaged. It is also conceivable to use a press roller having metal protrusions on the outer periphery. In this case, the protrusions are likely to wear due to friction with the paper, and there is a problem in terms of cost, and the paper is strongly pinched and conveyed. In addition, there is a problem in the transportability of the paper, and there is a problem in terms of safety because the metal protrusion rotates.

  Therefore, it is conceivable to perform double-sided printing using the press roller disclosed in “Patent Document 3”, but even if this press roller is used, the ink adhering to the surface is gradually accumulated, and as the number of printed sheets increases. It is inevitable that dirt on the image surface becomes noticeable. This stain is particularly noticeable when the solid image area is large, or when the amount of ink transferred to the paper becomes excessive at high temperatures or low speeds.

  In addition, when a jam occurs in the paper transport unit and the press roller directly presses the plate cylinder without the paper intervening, a large amount of ink is transferred to the peripheral surface of the press roller, and the print image surface Will be re-transferred to. According to the experiment results of the present inventor, even if the spherical bodies having substantially the same shape as shown in FIG. Thus, it has been found that the effect of preventing ink transfer stains cannot be expected when the solid image is large, when the amount of ink transfer to the paper becomes excessive, or when a paper transport jam occurs.

  An object of the present invention is to provide a double-sided printing apparatus that solves the above-described problems and can effectively prevent the occurrence of ink transfer stains.

  The invention according to claim 1 includes a plate cylinder and a press roller provided corresponding to the plate cylinder that presses the sheet against the plate cylinder, and a surface on which a surface image is printed on one surface of the sheet In a double-sided printing apparatus that performs a backside printing step of printing a backside image on the other side of the paper after performing a printing step, after temporarily storing the surface-printed paper after the frontside printing step, the backside printing step It has a re-feeding means to send out, and the storage time of the surface printed paper by the re-feeding means is controllable.

  According to a second aspect of the present invention, in the double-sided printing apparatus according to the first aspect, the plate cylinder can be idled during the storage time, and the number of idling of the plate cylinder during the storage time can be set. It is characterized by that.

  The invention described in claim 3 is the double-sided printing apparatus according to claim 1 or 2, further comprising a cleaning device for cleaning a peripheral surface of the press roller used in the back surface printing step, and during the storage time. The peripheral surface of the press roller is cleaned by the cleaning device.

  According to a fourth aspect of the present invention, the double-sided printing apparatus according to the third aspect further comprises a counting means for counting the number of times of double-sided printing in which double-sided printing has been performed, and cleaning is performed when the number of double-sided printing reaches a predetermined value. It is performed.

  The invention according to claim 5 has a plate cylinder and a press roller provided corresponding to the plate cylinder that presses the sheet against the plate cylinder, and prints a surface image on one surface of the sheet. In a double-sided printing apparatus that performs a backside printing step of printing a backside image on the other side of the paper after performing a printing step, a cleaning device that further cleans the peripheral surface of the press roller used in the backside printing step; And a jam detection unit that detects a paper conveyance jam during the back side printing process, and cleaning is performed when the paper conveyance jam is detected by the jam detection unit.

  According to a sixth aspect of the present invention, in the double-sided printing apparatus according to the fifth aspect of the present invention, the double-sided printing apparatus further includes a counting unit that counts the number of times of double-sided printing in which double-sided printing has been performed. It is performed.

  The invention according to claim 7 has a plate cylinder and a press roller provided corresponding to the plate cylinder that presses the sheet against the plate cylinder, and a surface on which a surface image is printed on one surface of the sheet In a double-sided printing apparatus that performs a backside printing step of printing a backside image on the other side of the paper after performing a printing step, the plate making master is wound around the plate cylinder, and then used in the backside printing step A cleaning mode is provided in which the press roller is directly pressed by a press roller to clean the press roller.

  The invention according to claim 8 is the double-sided printing apparatus according to claim 7, further comprising jam detecting means for detecting a paper transport jam at the time of the back surface printing process, and the paper transport jam is detected by the jam detection means. In this case, the cleaning is performed in the cleaning mode.

  According to the present invention, the surface-printed paper is stored in the re-feeding means for a longer time than normal printing, thereby promoting the permeation and drying of the ink transferred to the paper. Since the transfer of ink to the press roller can be suppressed, even if the surface image has a solid image or when printing for applications that are extremely resistant to stains, there is little retransfer stain. Can be obtained.

  FIG. 1 shows a duplex printing apparatus employing the first embodiment of the present invention. In FIG. 1, a duplex printing apparatus 1 includes plate cylinders 2 and 3, press rollers 4 and 5, a paper feed tray 6, a paper feed roller 7, a registration roller pair 8, a refeed unit 9, a paper discharge tray 10, and the like. ing.

  The plate cylinder 2 is rotatably supported by an apparatus main body (not shown), and is driven to rotate by a plate cylinder driving unit 37 (see FIG. 3). The plate cylinder 2 has an openable / closable clamper 11 on its outer peripheral surface, and a plate-making master 12 made by a plate making apparatus 38 (see FIG. 3) is wound around the outer peripheral surface of the plate cylinder 2. A plate-making image corresponding to the surface image printed on the surface of the paper P is formed on the plate-making master 12. In the vicinity of the outer peripheral surface of the plate cylinder 2, a rotary encoder 44 (see FIG. 3) for detecting the rotation angle and the number of rotations of the plate cylinder 2 is provided.

  The plate cylinder 3 is also rotatably supported by an apparatus main body (not shown), and is driven to rotate in the reverse direction in synchronization with the plate cylinder 2 by the plate cylinder driving means 37. The plate cylinder 3 has an openable / closable clamper 13 on its outer peripheral surface, and a pre-made master 14 made by a plate making apparatus 39 (see FIG. 3) is wound around the outer peripheral surface of the plate cylinder 3. A plate-making image corresponding to the back surface image printed on the back surface of the paper P is formed on the plate-making master 14.

  A press roller 4 is disposed below the plate cylinder 2. The press roller 4 made of an elastic material having water repellency such as fluororesin is rotatably supported at both ends by an arm member (not shown), and the arm member (not shown) can be swung by a swinging means 40 (see FIG. 3). It is supported by. As a result, the press roller 4 is separated by a two-dot chain line in FIG. 1 where the circumferential surface is separated from the plate cylinder 2 by a solid line in FIG. It selectively occupies the indicated pressure contact position.

  A press roller 5 is disposed above the plate cylinder 3. Both ends of a press roller 5 made of the same material as the press roller 4 are also rotatably supported by an arm member (not shown). The arm member (not shown) is swingably supported by a swinging means 41 (see FIG. 3). ing. As a result, the press roller 5 is separated by a two-dot chain line in FIG. 1 where the peripheral surface is separated from the plate cylinder 3 by a solid line in FIG. It selectively occupies the indicated pressure contact position. A press roller driving means 42 (see FIG. 3) is connected to the press roller 5, and the press roller 5 is configured to be rotationally driven by the press roller driving means 42 only when it occupies the separated position.

  Two cleaning rollers 15 and 16 functioning as a cleaning device are rotatably supported on an arm member (not shown) that supports the press roller 5. The cleaning rollers 15 and 16 having a non-woven fabric or felt made of synthetic fiber or natural fiber on their peripheral surfaces are configured to be movable by a cleaning roller moving means 43 (see FIG. 3), and each peripheral surface is a press roller 5. 1 is separated from the peripheral surface of FIG. 1 by a solid line, and a press contact position indicated by a two-dot chain line in FIG. 1 where each peripheral surface is pressed against the peripheral surface of the press roller 5 is selectively occupied.

  A paper feed tray 6 is disposed on the right side of the plate cylinder 2. The paper feed tray 6 on which a large amount of paper P is stacked is supported by an elevating means 45 (see FIG. 3) so as to be movable up and down. When the upper limit position is occupied, a paper feed roller 7 disposed above the paper feed tray 7 is provided. On the other hand, the uppermost sheet P is configured to come into pressure contact with a predetermined pressure contact force. The paper feed roller 7 is rotationally driven by a paper feed roller driving means 46 (see FIG. 3), and separates and feeds the paper P on the paper feed tray 6 in cooperation with a separation member (not shown).

  A registration roller pair 8 is disposed on the left side of the paper feed tray 6 and the paper feed roller 7. The registration roller pair 8 including a driving roller and a driven roller arranged in pressure contact with the driving roller is separated by the paper feeding roller 7 by the rotation of the driving roller by the rotation driving force transmitted from the plate cylinder driving means 37. The fed paper P is fed between the plate cylinder 2 and the press roller 4 at a predetermined timing.

  Refeeding means 9 is disposed between the plate cylinders 2 and 3. The paper refeeding unit 9 includes a paper transport member 17, a paper front end stopper 18, a paper front end detection sensor 19, and the like.

  The sheet conveying member 17 disposed below the sheet conveying path 24 includes a driving roller 20 and a driven roller 21 made up of a plurality of finely divided rollers, an endless belt 22, a suction fan 23, and the like. Each drive roller 20 is fixed to the same spindle, and each driven roller 21 is arranged corresponding to each drive roller 20. Endless belts 22 having a plurality of holes are spanned between each driving roller 20 and each driven roller 21, and each driving roller 20 is belt driving means 47 (see FIG. 3). 1 is moved in the direction of the arrow in FIG. The suction fan 23 is actuated by a fan driving means 48 (see FIG. 3), and sucks the paper P onto the endless belt 22 by sucking air when the drive rollers 20 are driven to rotate and the endless belts 22 are moved. To do.

  The paper leading end stopper 18 disposed on the upper side of the paper transport path 24 opens the paper transport path 24 and the blocking position indicated by the solid line in FIG. 1 where the paper transport path 24 is blocked by the stopper moving means 49 (see FIG. 3). It selectively occupies the open position indicated by the two-dot chain line in FIG. The sheet leading edge detection sensor 19 detects the leading edge of the sheet P conveyed by the sheet conveying member 17 and outputs a signal. A signal from the paper leading edge detection sensor 19 is sent to the control means 36 described later.

  The paper discharge tray 10 is disposed at the end of the paper transport path 24 in order to stack paper P on which double-sided printing has been performed. The paper discharge tray 10 is provided with one end fence 35 with which the leading edge of the paper P abuts and a pair of side fences (not shown) that align the paper P in the width direction.

  FIG. 2 shows an operation panel of the duplex printing apparatus 1. In the figure, the operation panel 25 includes a plate making start key 26, a printing start key 27, a stop key 28, a numeric keypad 29, a display device 30 comprising a 7-segment LED, a display device 31 comprising an LCD, etc. A print mode setting key 32, a cleaning key 33, a cleaning mode setting key 34, and the like are provided.

  FIG. 3 shows a block diagram of the control means 36 used in the duplex printing apparatus 1. The control means 36 is a microcomputer having a CPU, ROM, RAM and the like inside, and based on the detection signals from the paper leading edge detection sensor 19 and the rotary encoder 44 and the operation signals from the operation panel 25, the plate cylinder driving means 37. , Plate making devices 38, 39, swinging means 40, 41, press roller driving means 42, cleaning roller moving means 43, elevating means 45, paper feed roller driving means 46, belt driving means 47, fan driving means 48, stopper moving means. 49, controls the operation of the plate ejection devices 50 and 51. The plate discharging device 50 is disposed in the vicinity of the outer peripheral surface of the plate cylinder 2, and the used master 12 is peeled off from the outer peripheral surface of the plate cylinder 2, and the plate discharging device 51 is disposed in the vicinity of the outer peripheral surface of the plate cylinder 3. The used master-making master 14 is peeled off from the outer peripheral surface of the plate cylinder 3.

Based on the above configuration, the operation of the duplex printing apparatus 1 will be described below.
When an original is set in an image reading device (not shown) and the plate making start key 26 is pressed by the operator, an original image is read in the image reading device (not shown) and the plate discharging devices 50 and 51 are operated to operate each of the plate discharging devices 50 and 51. Used masters 12 and 14 are peeled off from the outer peripheral surfaces of the plate cylinders 2 and 3. After the plate removal, the plate making apparatuses 38 and 39 are operated to make the plate making masters 12 and 14, respectively. The plate making masters 12 and 14 thus made are wound around the plate cylinders 2 and 3, respectively.

  After the winding operation is completed and the duplex printing apparatus 1 enters the print standby state, the printing operation is started when the operator presses the print start key 27 after setting various printing conditions. When the printing start key 27 is pressed, the plate cylinder driving means 37 is operated to rotate each of the plate cylinders 2 and 3 at a set speed, and the paper supply roller driving means 46 is operated to supply the paper supply roller 7. Is rotated, and one sheet of paper P positioned on the uppermost sheet feed tray 6 is fed. The fed paper P is temporarily stopped with the leading end in contact with the nip portion of the registration roller pair 8, and the registration roller pair 8 rotates at a predetermined timing synchronized with the rotation of the plate cylinder 2. 2 and the press roller 4.

  When the plate cylinder 2 is rotated to a predetermined angle and the plate-making image of the plate-making master 12 wound on the outer peripheral surface occupies a predetermined position corresponding to the press roller 4, the swinging means 40 is activated and the press roller 4. Occupies the press contact position, the paper P is pressed into contact with the master 12 and the surface image is transferred to one surface thereof. The sheet P having the surface image transferred thereon to become a surface-printed sheet is peeled off from the outer peripheral surface of the plate cylinder 2 by a peeling device (not shown) provided in the vicinity of the peripheral surface of the plate cylinder 2, and the paper transport member 17 from its leading end. Sent to.

  In the sheet conveying member 17, the belt driving unit 47 and the fan driving unit 48 are operated simultaneously with the operation of the plate cylinder driving unit 37, and the surface-printed paper P peeled off from the outer peripheral surface of the plate cylinder 2 is each endless belt. While being sucked by the upper surface of 22, it is conveyed to the left in FIG. At this time, the paper front end stopper 18 occupies the blocking position, and the paper P is temporarily stopped with the front end in contact with the paper front end stopper 18. At this time, the leading edge of the paper P is detected by the paper leading edge detection sensor 19, and the operation of the belt driving means 47 and the fan driving means 48 is stopped.

  When the plate cylinder 3 rotates to a predetermined angle and the plate-making image of the plate-making master 14 wound on the outer peripheral surface occupies a position slightly ahead of a predetermined position corresponding to the press roller 5, the paper front end stopper 18 is moved. The belt driving means 47 and the fan driving means 48 are operated while occupying the open position, and the temporarily stopped paper P is sent between the plate cylinder 3 and the press roller 5. Then, when the plate-making image of the plate-making master 14 occupies a predetermined position, the swinging means 41 is operated, and the press roller 5 occupies the press-contact position, whereby the paper P is pressed against the plate-making master 14 and the other side of the paper P The back image is transferred to

  The paper P on which the back image is transferred and becomes a printed paper is peeled off from the outer peripheral surface of the plate cylinder 3 by a peeling device (not shown) provided in the vicinity of the peripheral surface of the plate cylinder 3 and sent to the paper discharge tray 10. The printed paper P sent to the paper discharge tray 10 has its front end abutted against the end fence 35 and both sides thereof are aligned by a pair of side fences (not shown) and are stacked on the paper discharge tray 10 in an orderly manner. The When the set number of prints is consumed, each operating part is stopped and the printing operation is completed.

  During the printing operation described above, the press roller 5 contacts the image surface of the paper P on which surface printing has been performed, but since the ink transferred to the paper P is still in an undried state, the ink is transferred and the peripheral surface is It gets dirty. When the next paper P is pressed in this state, the ink transferred from the previous paper P is transferred again to the image surface of the next paper P, and the image surface is soiled. This problem is particularly noticeable when there is a solid image on the surface image.

  Therefore, when the surface image has a solid image, or when printing for applications that are extremely unfavorable to dirt, duplex printing is performed using the intermittent printing mode. In this intermittent printing mode, the storage time for storing the surface-printed paper P in the re-feeding means 9 is made longer than that in the normal printing described above, and the drying of the ink transferred onto the paper P is promoted. This example is shown below.

  After the duplex printing apparatus 1 enters the print standby state, the operator presses the intermittent print mode setting key 32. Then, a screen for setting the storage time is displayed on the display device 31, and the operator sets the storage time using the numeric keypad 29. In this example, after the surface-printed paper P is stored in the refeed unit 9, the plate cylinder 2 is idled, and the storage time is set by the number of idling times of the plate cylinder 2. The operator presses “3” of the numeric keypad 29, for example, and sets the number of idling of the plate cylinder 2 to 3 times.

  When the operator presses the print start key 27 after setting the storage time, the printing operation is performed in the same manner as described above. Then, the surface-printed paper P comes into contact with the paper front end stopper 18 and the operations of the belt driving means 47 and the fan driving means 48 are stopped, and the paper P is stored in the refeed means 9. When the paper P is stored, the control means 36 counts the number of idling of the plate cylinder 2 based on the signal from the rotary encoder 44. Then, the number of idling of the plate cylinder 2 ends three rotations, and after the plate cylinder 2 starts the fourth rotation, the plate cylinder 3 rotates to a predetermined angle, and the plate-making image of the plate-making master 14 corresponds to the press roller 5. If it occupies a position slightly before the predetermined position, the stored paper P is sent between the plate cylinder 3 and the press roller 5.

  The fed paper P is transferred from the outer surface of the plate cylinder 3 by a peeling device (not shown) to the paper discharge tray 10 after the back image is transferred to the other side by the press roller 5 occupying the pressure contact position. Sent. When the set number of prints is consumed, each operating part is stopped and the printing operation is completed.

  According to this configuration, the surface-printed paper P is stored in the refeeding means 9 for a longer time than in normal printing, thereby promoting the penetration and drying of the ink transferred to the paper P. Since the transfer of ink to the press roller 5 for performing the back surface printing process can be suppressed, it is possible to repeat the printing even when the front surface image has a solid image or when printing for applications in which the stain is extremely avoided. A good double-sided printed matter with less transfer stain can be obtained.

  During the storage time described above, the cleaning roller moving means 43 is operated to move the cleaning rollers 15 and 16 to the press contact position, and the press roller 5 occupying the separated position is rotationally driven by the press roller driving means 42. As a result, the ink transferred to the peripheral surface of the press roller 5 can be cleaned by the cleaning rollers 15 and 16, and a better double-sided printed matter free from retransfer stains can be obtained. In this case, the operator presses the print start key 27 after pressing the cleaning key 33 after setting the storage time.

  This cleaning is useless when the press roller 5 is clean, and useless cleaning only accelerates the wear of the cleaning rollers 15 and 16 and the press roller 5, so that the double-sided printing operation proceeds to some extent and the press roller. It is desirable to carry out based on the state where the ink has been transferred to the peripheral surface of No. 5. Therefore, a counting unit (not shown) that counts the number of double-sided printed sheets is provided as an internal counter inside the control unit 36, and cleaning is performed when the counting unit counts a certain number of sheets (for example, 1000 sheets). It is possible to effectively prevent the occurrence of re-transfer stain without performing unnecessary cleaning.

  Further, the ink transferred to the peripheral surface of the press roller 5 may be cleaned using a cleaning mode. In this case, after setting the storage time, the operator presses the cleaning mode setting key 34 and then presses the print start key 27.

  In the cleaning mode, the control means 36 operates the plate removal device 51 to peel the master plate 14 from the outer peripheral surface of the plate cylinder 3, and then operates the plate making device 39 to operate the plate making device 3 on the outer peripheral surface of the plate cylinder 3. Wrap a new master of platemaking. Thereafter, the control means 36 operates the plate cylinder driving means 37 to drive the plate cylinder 3 to rotate at a predetermined speed and to deactivate the paper feed roller 7, that is, the swing means without feeding the paper P. 41 is actuated to press the press roller 5 against the unmade master on the plate cylinder 3. As a result of this pressure contact, the ink transferred to the peripheral surface of the press roller 5 is transferred again to the plate making master, and the press roller 5 is cleaned. According to this cleaning mode, since the ink transferred to the peripheral surface of the press roller 5 is easily transferred to the master film, the press roller 5 is cleaned more easily, reliably and effectively than other methods. be able to.

  However, in this cleaning mode, since the master plate master 14 wound around the plate cylinder 3 is peeled off and then the master plate master is wound, if it is performed during printing, the master plate master is peeled off after the cleaning mode is executed. Thus, it becomes necessary to make the same master 14 as the previous version and wind it around the plate cylinder 3, which results in a significant cost increase. Therefore, it is desirable to execute the cleaning mode after the printing process is completed.

  In addition, a counting unit (not shown) for counting the number of double-sided printed sheets is provided as an internal counter in the control unit 36, and cleaning is performed after the printing process is completed after the counting unit has counted a certain number of sheets (for example, 10,000 sheets). By doing so, it is possible to effectively prevent the occurrence of retransfer stain without using a useless master.

  FIG. 4 shows a double-sided printing apparatus adopting the second embodiment of the present invention. This double-sided printing device 52 is different from the double-sided printing device 1 shown in the first embodiment only in that it has a paper detection sensor 53 as jam detection means, and the other configurations are the same. It is.

  The paper detection sensor 53 is disposed above the paper transport path 24 and upstream and downstream of the contact position between the plate cylinder 3 and the press roller 5 in the paper transport direction, and is located immediately below the paper transport path. This is detected when the sheet P passes through the sheet 24, and a signal is output to the control means 36. With this configuration, when one or both of the paper detection sensors 53 do not output a signal at a predetermined timing, it is detected that a jam has occurred on the surface-printed paper P sent by the paper transport member 17.

  In the second embodiment, when the jam of the paper P is detected by each paper detection sensor 53, the operation of the duplex roller 52 is stopped, and then the press roller 5 by the cleaning rollers 15 and 16 described above is stopped. Cleaning or cleaning of the press roller 5 in the cleaning mode is performed. This is because there is a high possibility that the press roller 5 is pressed against the peripheral surface of the plate cylinder 3 without the paper P because the paper P is jammed. With this configuration, it is possible to prevent image smearing from occurring on the surface-printed paper P due to the ink transferred from the plate cylinder 3 to the press roller 5 during the return operation after the jam processing.

  In the second embodiment described above, an arm member (not shown) that supports the press roller 5 or a swing means 41 is provided with a sensor (not shown) that detects whether the press roller 5 is swung to occupy the press contact position. When the jam of the paper P is detected by the paper detection sensor 53 and the press roller 5 is detected to occupy the press contact position by a sensor (not shown), the same cleaning as described above may be performed. As a result, the emergency stop of the double-sided printing device 52 when a jam occurs is faster than the swinging operation of the press roller 5 to the press contact position, and cleaning is performed even though the press roller 5 is not pressed against the plate cylinder 3. The occurrence of problems such as loss of printing time, wear of each of the cleaning rollers 15 and 16 and the press roller 5, and useless use of the pre-made master can be prevented.

  Also in the second embodiment, a counting means (not shown) for counting the number of printed sheets on both sides is provided as an internal counter inside the control means 36, and cleaning is performed after the printing process is finished after the counting means has counted a certain number of sheets. It is also possible to add a configuration. Thereby, the effect similar to the above can be obtained.

  In each of the above-described embodiments, two plate cylinders 2 and 3 and two press rollers 4 and 5 provided corresponding thereto are used, and the surface printing process is performed on the paper P by the plate cylinder 2 and the press roller 4. Although the double-sided printing apparatuses 1 and 52 for performing the back surface printing process on the paper P by the plate cylinder 3 and the press roller 5 after performing the above are shown, the double-sided printing apparatuses to which the present invention can be applied are not limited to these, for example, The present invention can also be applied to a double-sided printing apparatus disclosed in Japanese Patent No. 200635. This embodiment will be described below as a third embodiment.

  FIG. 5 shows a third embodiment of the present invention. In the figure, a double-sided printing apparatus 54 includes a printing unit 55, a plate making unit 56, a paper feeding unit 57, a plate discharging unit 58, a paper discharging unit 59, an image reading unit 60, an auxiliary tray 61, a refeeding unit 62, a switching member 63, and the like. have.

  The printing unit 55 disposed substantially at the center of the apparatus main body includes a plate cylinder 64 and a press roller 65. The plate cylinder 64 is rotatably supported by the apparatus main body, and is driven to rotate by a plate cylinder driving means (not shown). The plate cylinder 64 has an openable / closable clamper 66 on the outer peripheral surface thereof, and a divided master plate master 67 made by the plate making unit 56 is wound on the outer peripheral surface of the plate cylinder 64. In the divided master-making master 67, a plate-making image corresponding to the front image and a plate-making image corresponding to the back image are formed, and an unmade portion is formed between the plate-making images. On the plate cylinder 64, the divided plate-making master 67 has a plate-making image corresponding to the front image in the front surface area shown in FIG. 5, a plate-making image corresponding to the back image in the same back surface area, and a non-plate making portion in the intermediate area. Each is wound to correspond. A rotary encoder (not shown) that detects the rotation angle and the number of rotations of the plate cylinder 64 is provided in the vicinity of the outer peripheral surface of the plate cylinder 64.

  A press roller 65 is disposed below the plate cylinder 64. The press roller 65 made of an elastic material having water repellency such as fluororesin is rotatably supported at both ends by an arm member (not shown), and the arm member (not shown) is supported by a swing means (not shown) so as to be swingable. Yes. The press roller 65 selectively occupies the separation position shown in FIG. 5 where the peripheral surface is separated from the plate cylinder 64 and the press contact position where the peripheral surface is in pressure contact with the divided plate-making master 67 on the plate cylinder 64. A press roller driving means (not shown) is connected to the press roller 65, and the press roller 65 is configured to be rotationally driven by the press roller driving means when occupied in the separated position. In the vicinity of the peripheral surface of the press roller 65, a cleaning roller 70 that functions as a cleaning device that performs cleaning by contacting the peripheral surface of the press roller 65 is disposed. The cleaning roller 70 is rotationally driven by a driving unit (not shown).

  Near the right side of the press roller 65, a refeed guide member 68 for transporting the surface-printed paper P sent from the refeed unit 62 along the peripheral surface of the press roller 65 is disposed. A re-feeding registration roller 69 is disposed below the press roller 65 to feed the paper P stored on the auxiliary tray 61 in contact with the peripheral surface of the press roller 65. A refeed conveyance unit 71 having an auxiliary tray 61 on the upper surface is disposed on the lower left side of the press roller 65, and a refeed positioning member 72 is provided integrally therewith. A sheet receiving plate 73 that is movable along the upper surface of the auxiliary tray 61 is disposed above the refeed conveyance unit 71. The auxiliary tray 61, the refeed guide member 68, the refeed registration roller 69, the refeed positioning member 72, the refeed conveyance unit 71, and the sheet receiving plate 73 constitute a refeed unit 62.

  On the left side of the contact position between the plate cylinder 64 and the press roller 65 and on the transport path of the paper P, a switching member 63 is disposed. The switching member 63 is rotatably supported at the downstream end of the sheet conveying direction by the apparatus main body, and is moved by a moving means (not shown). The first position shown by the solid line and the second dotted line shown in FIG. 2 positions are selectively occupied. The paper P that has passed between the plate cylinder 64 and the press roller 65 is guided to the paper discharge unit 59 when the switching member 63 occupies the first position, and the switching member 63 occupies the second position. Is guided to the auxiliary tray 61.

  A plate making section 56 is disposed on the upper right side of the printing section 55. The plate making unit 56 has a known configuration including a master holding member, a platen roller, a thermal head, a cutting unit, a master stock unit, a tension roller pair, a reversing roller pair, and the like. .

  A sheet feeding unit 57 is disposed below the plate making unit 56. The paper feed unit 57 has a known configuration including a paper feed tray 74, a paper feed roller 75, a separation roller 76, a separation pad 77, a registration roller pair 78, and the like.

  The plate discharging unit 58 disposed on the upper left side of the printing unit 55 also has a well-known configuration including an upper plate discharging member, a lower plate discharging member, a plate discharging box, a compression plate, and the like. Is peeled off from the outer peripheral surface of the plate and discarded inside the plate removal box.

  A paper discharge unit 59 is disposed below the plate discharge unit 58. The paper discharge unit 59 includes a peeling claw, a paper discharge conveyance unit 79, a paper discharge tray 80, and the like. The paper discharge conveyance unit 79 includes a driving roller, a driven roller, an endless belt, a suction fan, and the like, and conveys the printed paper P on the upper surface of the endless belt in the direction of the arrow in FIG. The paper discharge tray 80 has one end fence 81 and a pair of side fences 82, and the printed paper P is stacked on the upper surface thereof.

  An image reading unit 60 is disposed on the upper part of the apparatus main body. The image reading unit 60 includes a contact glass on which a document is placed, a pressure plate provided so as to be able to contact and separate from the contact glass, a reflection mirror and a fluorescent lamp that scan and read a document image, a lens that focuses the scanned image, An image sensor or the like that processes the focused image is included.

Based on the above-described configuration, the operation of the duplex printing apparatus 54 will be described below. The double-sided printing device 54 is also provided with the operation panel 25 described above.
When a manuscript is set in the image reading unit 60 and the plate making start key 26 is pressed by the operator, the image reading unit 60 performs a reading operation of the manuscript image and the plate discharging unit 58 is operated to start from the outer peripheral surface of the plate cylinder 64. The used divided plate-making master 67 is peeled off. After the plate removal, the plate making unit 56 operates to make a new divided plate making master 67, which is wound around the plate cylinder 64.

  After the winding operation is completed and the duplex printing apparatus 1 enters the print standby state, when the print start key 27 is pressed by the operator after setting various printing conditions, the plate cylinder 64 is driven to rotate at a set speed. The sheet feeding roller 75 and the separation roller 76 are operated to feed one sheet P located on the uppermost position on the sheet feeding tray 74. The fed paper P is temporarily stopped by the registration roller pair 78 and then sent between the plate cylinder 64 and the press roller 65 at a predetermined timing.

  When the plate cylinder 64 is rotated to a predetermined angle and the surface area occupies a predetermined position corresponding to the press roller 65, the press roller 65 occupies the press contact position, whereby the paper P is divided into the master plate 67 on the plate cylinder 64. And a surface image is transferred to one surface thereof. The sheet P that has become the surface-printed sheet is peeled off from the outer peripheral surface of the plate cylinder 64 and is then sent to the refeed conveyance unit 71 by the switching member 63 occupying the second position. At this time, the front end of the paper P is received by the paper receiving plate 73 and is placed on the auxiliary tray 61 from the rear end side. The paper P on the auxiliary tray 61 is conveyed in the direction of the arrow in FIG. 5 by the refeed conveyance unit 71, and is temporarily stopped in a state where the leading end is in contact with the refeed positioning member 72.

  The plate cylinder 64 continues to rotate while the first sheet P is being guided on the auxiliary tray 61, and the second sheet is fed from the sheet feeding unit 57 at the same timing as the first sheet P. P is fed. Similarly to the first sheet P, the fed second sheet P is re-transferred by the switching member 63 occupying the second position after the surface image is transferred to one surface thereof by the press roller 65. It is sent to the paper feeding / conveying unit 71.

  After the second sheet P is fed from the sheet feeding section 57, the sheet re-feeding registration roller 69 operates at a timing slightly earlier than the back surface area of the plate cylinder 64 reaches the position corresponding to the press roller 65. Then, the first sheet P stored on the auxiliary tray 61 is pressed against the peripheral surface of the press roller 65. The first sheet P that is pressed against the peripheral surface of the press roller 65 is conveyed toward the contact portion with the plate cylinder 64 by the rotational force of the press roller 65 that is pressed against the plate cylinder 64 and is driven to rotate. The back image is transferred to the other side by being pressed against the divided master-making master 67.

  The first sheet P, which has been printed on both sides with the back side image transferred, is guided to the sheet discharge transport unit 79 by the switching member 63 occupying the first position, and is discharged onto the sheet discharge tray 80. Is done. Thereafter, the above operation is repeated until the set number of printed sheets is consumed. When the set number of printed sheets is reached, the operation of each part is stopped and the printing operation is completed.

  During the printing operation described above, the press roller 65 contacts the image surface of the paper P when the surface-printed paper P is pressed from the auxiliary tray 61 by the re-feeding registration roller 69. Since the ink transferred to P is in an undried state, the ink is transferred and the peripheral surface becomes dirty. Therefore, the intermittent printing mode described above is used.

  When the intermittent print mode setting key 32 is pressed, a screen for setting the storage time is displayed on the display device 31, and the operator sets the storage time using the numeric keypad 29. Also in this example, the plate cylinder 64 is idled after the surface-printed paper P is stored in the refeeding means 62, and the storage time is set by the number of idling of the plate cylinder 64. For example, the operator presses “3” of the numeric keypad 29 and sets the number of idling of the plate cylinder 64 to 3 times.

  When the operator presses the print start key 27 after setting the storage time, the printing operation is performed in the same manner as described above. When the surface-printed paper P is stored on the auxiliary tray 61, the paper feeding from the paper feeding unit 57 is stopped and the plate cylinder 64 is idled. Based on a signal from a rotary encoder (not shown), when the number of idlings of the plate cylinder 64 finishes three rotations and starts the fourth rotation, and the surface area occupies a position slightly ahead of a predetermined position corresponding to the press roller 65, A second sheet P is fed from the sheet feeding unit 57 toward the contact portion between the plate cylinder 64 and the press roller 65. The second sheet P has a surface image transferred to one surface thereof by a press roller 65, and then is sent to a refeed conveyance unit 71 by a switching member 63. After the second sheet P is fed, the re-feeding registration roller 69 operates at the same timing as described above, and the first sheet P on the auxiliary tray 61 is pressed against the peripheral surface of the press roller 65, The back image is transferred to the other side. The first sheet P, which has been printed on both sides, is guided to the sheet discharge conveyance unit 79 by the switching member 63 and is discharged and stacked on the sheet discharge tray 80. Thereafter, the above operation is repeated until the set number of printed sheets is consumed. When the set number of printed sheets is reached, the operation of each part is stopped and the printing operation is completed.

  Also according to the third embodiment, the surface-printed paper P is stored in the re-feeding means 62 for a longer time than normal printing, thereby promoting the permeation and drying of the ink transferred to the paper P. Since the transfer of ink from the paper P to the press roller 64 can be suppressed, the same effects as those of the first embodiment can be obtained.

  In the above-described intermittent printing mode, when the cleaning key 33 is pressed by the operator after the storage time is set, the press roller 65 and the cleaning roller 70 are rotationally driven during the storage time, and the press roller 65 is cleaned. Thereby, it is possible to obtain a better double-sided printed material free from retransfer stains.

  Further, in the intermittent printing mode described above, when the cleaning mode setting key 34 is pressed by the operator after setting the storage time, the plate discharging unit 58 is activated and the divided plate-making master 67 is peeled off from the outer peripheral surface of the plate cylinder 64. After that, the plate making unit 56 is operated to wind a new master plate that is not yet made on the outer peripheral surface of the plate cylinder 64. Thereafter, the plate cylinder 64 is rotated in a state where the paper feeding unit 57 is inactivated. The press roller 65 is pressed against the roller, and the press roller 65 is cleaned. As a result, the press roller 65 can be easily and reliably cleaned, and a better double-sided printed product free from retransfer stains can be obtained.

  In the third embodiment, it is also possible to add a structure for providing a counting means (not shown) for counting the number of double-sided printed sheets and performing cleaning after the printing process after the counting means counts a certain number of sheets. . Thereby, the effect similar to the above can be obtained.

  FIG. 6 shows a duplex printing apparatus employing the fourth embodiment of the present invention. This double-sided printing device 83 is different from the double-sided printing device 54 shown in the third embodiment only in that it has a paper detection sensor 84 as jam detection means, and the other configurations are the same. It is.

  The paper detection sensor 84 is disposed in the vicinity of the peripheral surface of the press roller 65, in the vicinity of the refeed guide member 68, and in the paper discharge conveyance unit 79. When P is guided to the switching member 63 occupying the first position via the peripheral surface of the press roller 65 and reaches the paper discharge conveyance unit 79, it detects this and outputs a signal respectively. With this configuration, when one or both of the paper detection sensors 84 do not output a signal at a predetermined timing, it is detected that a jam has occurred in the front surface printed paper P that has been re-fed by the re-feeding means 62. The

  In the fourth embodiment, when the jam of the paper P is detected by each paper detection sensor 84, the operation of the duplex printing device 83 is stopped, and then the press roller 65 is cleaned by the cleaning roller 70 described above, or The press roller 65 is cleaned in the cleaning mode. This is because, as in the second embodiment, the paper P is jammed in the re-feeding means 62, so that the press roller 65 may be pressed against the peripheral surface of the plate cylinder 64 without passing through the paper P. This is because the nature is high. With this configuration, it is possible to prevent image smear from occurring on the surface-printed paper P due to the ink transferred from the plate cylinder 64 to the press roller 65 during the return operation after the jam processing.

  In the fourth embodiment, as in the second embodiment, the press roller 65 occupies the pressure contact position on the arm member (not shown) that supports the press roller 65 or the swinging means (not shown) that swings the press roller 65. A sensor (not shown) for detecting whether or not a jam occurs in the paper P is detected by each paper detection sensor 84 and when the press roller 65 is detected to occupy the press contact position by a sensor (not shown), the same cleaning as described above. It is good also as composition which performs. Further, in the fourth embodiment, it is possible to add a configuration in which a counting unit (not shown) that counts the number of double-sided printings is provided and cleaning is performed after the printing process ends after the counting unit counts a certain number of sheets. .

  In each of the above-described embodiments and modifications, the press roller 5 and the press roller 65 are made of an elastic material having water repellency such as a fluororesin, but the press roller 5 and the press roller 65 are as shown in FIG. In addition, a material having an uneven surface such as a resin sheet 87 in which a glass bead 86 is bonded to the peripheral surface of the elastic body 85 may be used. As a result, the amount of ink transferred from the surface-printed paper P can be reduced, and a better double-sided printed product can be obtained.

1 is a schematic front view of a main part of a double-sided printing apparatus that employs a first embodiment of the present invention. It is the schematic of the operation panel used for the 1st Embodiment of this invention. It is a block diagram of the control means used for the 1st Embodiment of this invention. It is a schematic front view of the principal part of the double-sided printing apparatus which employ | adopted the 2nd Embodiment of this invention. It is a schematic front view of the double-sided printing apparatus which employ | adopted the 3rd Embodiment of this invention. It is a schematic front view of the double-sided printing apparatus which employ | adopted the 4th Embodiment of this invention. It is the elements on larger scale of the press roller main part used for the modification of the 1st thru | or 4th embodiment of this invention.

Explanation of symbols

1, 52, 64, 83 Double-sided printing device 2, 3, 64 Plate cylinder 4, 5, 65 Press roller 9, 62 Refeed means 15, 16, 70 Cleaning device (cleaning roller)
53, 84 Jam detection means (paper detection sensor)
P paper

Claims (8)

A plate cylinder and a press roller provided corresponding to the plate cylinder for pressing the sheet against the plate cylinder, and the sheet after performing a surface printing step of printing a surface image on one surface of the sheet In a double-sided printing apparatus that performs a backside printing process for printing a backside image on the other side of
It has a paper refeeding means for temporarily storing the surface printed paper after the front surface printing process and then sending it to the back surface printing process, and the storage time of the surface printed paper by the refeeding means is controllable. A double-sided printing apparatus characterized by that. The double-sided printing apparatus according to claim 1,
The duplex printing apparatus, wherein the plate cylinder can be idled during the storage time, and the number of idle rotations of the plate cylinder during the storage time can be set. The double-sided printing apparatus according to claim 1 or 2,
A double-sided printing apparatus, comprising: a cleaning device that cleans a peripheral surface of the press roller used in the back surface printing step, and cleaning the peripheral surface of the press roller by the cleaning device during the storage time. The double-sided printing apparatus according to claim 3.
A double-sided printing apparatus, comprising: a counting unit that counts the number of times of double-sided printing in which double-sided printing has been performed, and cleaning is performed when the number of double-sided printing reaches a predetermined value. A plate cylinder and a press roller provided corresponding to the plate cylinder for pressing the sheet against the plate cylinder, and the sheet after performing a surface printing step of printing a surface image on one surface of the sheet In a double-sided printing apparatus that performs a backside printing process for printing a backside image on the other side of
A cleaning device for cleaning a peripheral surface of the press roller used in the back surface printing process; and jam detecting means for detecting a paper transport jam during the back surface printing process, and the paper transport jam is detected by the jam detecting means. A double-sided printing apparatus, in which cleaning is performed when it is performed. The double-sided printing apparatus according to claim 5, wherein
A double-sided printing apparatus, comprising: a counting unit that counts the number of times of double-sided printing in which double-sided printing has been performed, and cleaning is performed when the number of double-sided printing reaches a predetermined value. A plate cylinder, and a press roller provided in correspondence with the plate cylinder for pressing the sheet against the plate cylinder, and after performing a surface printing process for printing a surface image on one surface of the sheet In a double-sided printing apparatus that performs a backside printing process of printing a backside image on the other side of
It has a cleaning mode for winding the plate making master around the plate cylinder and then cleaning the press roller by directly pressing the plate making master with the press roller used in the back surface printing step. Double-sided printing device. The double-sided printing apparatus according to claim 7,
A double-sided printing apparatus, comprising: a jam detection unit that detects a paper conveyance jam during the reverse side printing step, and cleaning is performed in the cleaning mode when a paper conveyance jam is detected by the jam detection unit.

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