JP3789806B2 - Printing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a printing apparatus including a bridge roller.
[0002]
[Prior art]
  In a printing device such as an offset printing machine, after supplying dampening water to the printing plate by the water application roller, ink is supplied to the printing plate by the ink application roller, thereby supplying ink only to the image area of the printing plate. It is the composition to do.
[0003]
  In such a printing apparatus, the ink on the printing plate is transferred onto the printing roller when the printing roller comes into contact with the surface of the printing plate after the ink is supplied. For this reason, when printing is continuously performed, a phenomenon occurs in which the ink accumulates on the swim roller and the ink is emulsified. Such a phenomenon occurs particularly remarkably when a pattern having a small dot area ratio and a large number of non-image areas is printed. When the emulsified ink is accumulated on the swim roller, background stains occur in the non-image area, and the print quality deteriorates.
[0004]
  For this reason, a bridge roller that abuts both the swim roller and the ink form roller is provided, and the emulsified ink on the swim roller is mixed with the ink on the ink roller so that it is between the swim roller and the ink roller. A printing apparatus has also been proposed in which the ink is leveled and the emulsified body of the ink on the swim roller is properly maintained.
[0005]
[Problems to be solved by the invention]
  In such a printing apparatus, the bridge roller is kept in contact with both the water form roller and the ink form roller, or the bridge roller is not in contact with either the water form roller or the ink form roller. Since printing can only be performed in either state, the operator monitors the printing status, and when emulsified ink is accumulated on the swim roller, printing is stopped or the swim roller is washed. I was doing. For this reason, not only does the work become complicated, but if the monitoring of the printing state becomes insufficient, background smearing occurs in the non-image area, and the printing quality deteriorates.
[0006]
  The present invention has been made to solve the above-described problems, and an object thereof is to provide a printing apparatus capable of executing high-quality printing without requiring complicated work.
[0007]
[Means for Solving the Problems]
  According to the first aspect of the present invention, there is provided a dampening water supply device including a dampening roller that supplies dampening water to the printing plate by rotating in contact with the surface of the printing plate; An ink supply device provided with an ink form roller for supplying ink to the printing plate by rotating, a leveling position in contact with both the water form roller and the ink form roller, A bridge roller that can move between a position separated from the ink form roller and a moving mechanism that moves the bridge rollerAnd the moving mechanismA control unit that moves the bridge roller to the leveling position or the separation position by controllingThe control unit moves the bridge roller from the separation position to the leveling position when the limit number of prints experimentally obtained in advance from the halftone dot area ratio of the image to be printed is reached.It is characterized by that.
[0008]
  According to a second aspect of the present invention, in the first aspect of the present invention, the bridge roller rotates about the axis of the swim roller so that the gap between the leveling position and the separation position is obtained. Moving.
[0009]
  According to a third aspect of the present invention, in the invention of the second aspect, the bridge roller swings in a direction parallel to the axis.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
[0011]
  [Overall configuration of printing device]
[0012]
  First, the overall configuration of a printing apparatus to which the present invention is applied will be described. FIG. 1 is a schematic diagram of a printing apparatus to which the present invention is applied.
[0013]
  In this printing apparatus, an image is recorded on a printing plate on which the images held on the first and second plate cylinders 11 and 12 are not recorded, and then the ink supplied to the printing plate is first, Printing is performed by transferring to the printing paper held by the impression cylinder 15 via the second blanket cylinders 13 and 14.
[0014]
  This printing apparatus includes a first plate cylinder 11 that can move between a first printing position indicated by a solid line in FIG. 1 and an image recording position indicated by a two-dot chain line, and a second printing indicated by a solid line in FIG. And a second plate cylinder 12 movable between the position and the image recording position.
[0015]
  Around the first plate cylinder 11 moved to the first printing position, an ink supply device 20a for supplying black (K) ink to the printing plate and magenta (M) ink to the printing plate, for example. An ink supply device 20b for supplying water and dampening water supply devices 21a and 21b for supplying dampening water to the printing plate are arranged. Further, around the second printing cylinder 12 moved to the second printing position, an ink supply device 20c for supplying, for example, cyan (C) ink to the printing plate, and, for example, yellow (Y) to the printing plate. An ink supply device 20d for supplying the ink and dampening water supply devices 21c and 21d for supplying dampening water to the printing plate are disposed. Further, around the first plate cylinder 11 or the second plate cylinder 12 moved to the image recording position, a plate feeding unit 23, a plate discharging unit 24, an image recording device 25, and a development processing device 26 are arranged. Has been.
[0016]
  In addition, the printing apparatus includes a first blanket cylinder 13 provided so as to be in contact with the first plate cylinder 11 and a second blanket cylinder 14 provided so as to be able to contact the second plate cylinder 12. The first and second blanket cylinders 13 and 14 are provided with an impression cylinder 15 that can contact the first and second blanket cylinders 13 and 14 at different positions, and a supply for passing the printing paper supplied from the paper supply unit 27 to the impression cylinder 15. A paper cylinder 16, a paper discharge cylinder 17 around which a chain 19 for discharging printed printing paper received from the impression cylinder 15 to a paper discharge unit 28 is wound, and a blanket cleaning device 29 are provided.
[0017]
  The first and second plate cylinders 11 and 12 are respectively connected to a plate cylinder moving mechanism (not shown), and the first or second printing position and the image recording position described above are driven by driving the plate cylinder moving mechanism. Move back and forth between. Further, by driving a motor (not shown), the first plate cylinder 11 rotates in synchronization with the first blanket cylinder 13 at the first printing position, and the second plate cylinder 12 is rotated at the second printing position. The second blanket cylinder 14 is configured to rotate in synchronization. Further, a plate cylinder rotating mechanism (not shown) is provided in the vicinity of the image recording position, and both the first and second plate cylinders 11 and 12 are moved to the image recording position. It is comprised so that it may rotate by the drive of a rotation mechanism.
[0018]
  A plate feeding unit 23 and a plate discharging unit 24 are arranged around the first plate cylinder 11 or the second plate cylinder 12 moved to the image recording position.
[0019]
  In the plate supply unit 23, a supply cassette 63 that stores a long roll-shaped printing plate on which no image is recorded in a light-tight state, and a front end portion of the printing plate drawn out from the supply cassette 63 is a first plate. A guide member 64 and a guide roller 65 for guiding the surface of the cylinder 11 or the second plate cylinder 12 and a cutter 66 for cutting a long printing plate into a sheet-like printing plate are provided. ing. Further, the first and second plate cylinders 11 and 12 are provided with a pair of gripping claws (not shown) for holding the leading end portion and the trailing end portion of the printing plate supplied from the plate feeding portion 23. .
[0020]
  The plate discharging unit 24 discharges the printing plate peeled off by the action of the nail mechanism 73 for peeling off the printing plate held on the first plate cylinder 11 or the second plate cylinder 12 after the printing is completed. A conveyor mechanism 69 for conveying to the cassette 68 and a discharge cassette 68 are provided.
[0021]
  The leading end portion of the printing plate drawn out from the supply cassette 63 in the plate supply unit 23 is guided by the guide roller 65 and the guide member 64, and is held in one holding nail of the first plate cylinder 11 or the second plate cylinder 12. It is done. Then, the first plate cylinder 11 or the second plate cylinder 12 is rotated by driving the plate cylinder rotation mechanism 30, and the printing plate is wound around the outer periphery of the first plate cylinder 11 or the second plate cylinder 12. Then, the rear end portion of the printing plate cut by the cutter 66 is held by the other holding nail. In this state, the printing held on the outer periphery of the first plate cylinder 11 or the second plate cylinder 12 by the image recording device 25 while rotating the first plate cylinder 11 or the second plate cylinder 12 at a low speed. An image is recorded by irradiating the surface of the plate with a modulated laser beam.
[0022]
  The printing plate P mounted on the outer periphery of the first plate cylinder 11 has an image area 67a for printing with black ink by the image recording device 25 as shown in FIG. An image area 67b for printing with magenta ink is recorded. Further, the printing plate P mounted on the outer peripheral portion of the second plate cylinder 12 has an image area 67c for printing with cyan ink by the image recording device 25 as shown in FIG. An image area 67d for printing with yellow ink is recorded. The image area 67a and the image area 67b are recorded at positions where the image area 67a and the image area 67b are equally distributed (that is, 180 degrees apart from each other) when mounted on the outer periphery of the first plate cylinder 11. Similarly, the image area 67c and the image area 67d are recorded at positions where the image area 67c and the image area 67d are evenly distributed (ie, 180 degrees apart from each other) when mounted on the outer periphery of the second plate cylinder 12. The
[0023]
  Referring to FIG. 1 again, as described above, around the first plate cylinder 11 moved to the first printing position, the ink supply device 20a and the ink supply device 20b are also used for the second printing. Around the second plate cylinder 12 moved to the position, an ink supply device 20c and an ink supply device 20d are arranged. Each of these ink supply devices 20a, 20b, 20c and 20d (referred to collectively as “ink supply device 20”) has a plurality of ink rollers and ink fountains 72.
[0024]
  The ink rollers of the ink supply devices 20a and 20b are swung by the action of a cam (not shown). And by this rocking | fluctuation operation | movement, it is the ink supply apparatus 20a or 20b in arbitrary image areas of the two image areas 67a and 67b formed in the printing plate P hold | maintained at the outer peripheral part of the 1st plate cylinder 11. FIG. When the ink roller is brought into contact, ink can be supplied only to a necessary image area. Similarly, the ink rollers of the ink supply devices 20c and 20d also swing by the action of a cam (not shown). And by this rocking | fluctuation operation | movement, it is the ink supply apparatus 20c or 20d to arbitrary image area | regions of the two image area | regions 67c and 67d formed in the printing plate P hold | maintained at the outer peripheral part of the 2nd plate cylinder 12. FIG. When the ink roller is brought into contact, ink can be supplied only to a necessary image area.
[0025]
  Referring to FIG. 1 again, dampening water supply devices 21a, 21b, 21c and 21d (referred to collectively as “dampening water supply device 21”) are applied to the printing plate P by the ink supply device 20. Before supplying ink, dampening water is supplied to the printing plate P. Among these fountain solution devices 21, the fountain solution supply device 21a is in the image area 67a of the printing plate P, the fountain solution supply device 21b is in the image region 67b of the printing plate P, and the fountain solution supply device 21c is in the printing area. The dampening water supply device 21d supplies dampening water to the image area 67c of the printing plate P and the image area 67d of the printing plate P, respectively.
[0026]
  In addition, bridge rollers, which will be described later, are disposed between the dampening water supply devices 21a, 21b, 21c and 21d and the ink supply devices 20a, 20b, 20c and 20d.
[0027]
  A development processing device 26 is disposed below the first plate cylinder 11 or the second plate cylinder 12 that has moved to the image recording position. The development processing device 26 includes a development unit, a fixing unit, and a diaphragm unit, and is configured to be movable up and down between a standby position indicated by a two-dot chain line and a development processing position indicated by a solid line in FIG.
[0028]
  In the case where the printing plate P on which an image is recorded by the image recording device 25 is developed by the development processing device 26, the development is performed on the printing plate P that rotates together with the first plate cylinder 11 or the second plate cylinder. The contact portion, the fixing portion, and the aperture portion are sequentially brought into contact.
[0029]
  The first and second blanket cylinders 13 and 14 provided so as to be in contact with the first and second plate cylinders 11 and 12 have the same diameter as the first and second plate cylinders 11 and 12. A blanket for ink transfer is mounted on the outer periphery. The first and second blanket cylinders 13 and 14 can be brought into contact with and separated from the first and second plate cylinders 11 and 12 and the impression cylinder 15 by a cylinder insertion mechanism (not shown).
[0030]
  A blanket cleaning device 29 disposed between the first and second blanket cylinders 13 and 14 is a long cleaning unit that is attached to a path from a winding roll to a winding roll via a plurality of pressure rollers. The cleaning liquid is supplied to the cloth, and the surface of the first and second blanket cylinders 13 and 14 is brought into contact with the first and second blanket cylinders 13 and 14 by sliding them. Is to wash.
[0031]
  The impression cylinder 15 provided so as to be in contact with the first and second blanket cylinders 13 and 14 has diameters of the first and second plate cylinders 11 and 12 and the first and second blanket cylinders 13 and 14. It has a diameter of 1/2. The impression cylinder 15 has a gripper (not shown) for holding and transporting the leading edge of the printing paper.
[0032]
  In addition, the sheet feeding cylinder 16 disposed adjacent to the impression cylinder 15 has the same diameter as the impression cylinder 15. The sheet feeding cylinder 16 conveys the leading end of the printing paper supplied one by one from the sheet feeding unit 27 by the suction plate 74 that reciprocally moves, with a gripper not shown. The leading end of the printing paper held by the gripper is held by the gripper of the impression cylinder 15 when the printing paper is transferred from the paper supply cylinder 16 to the impression cylinder 15.
[0033]
  Further, the paper discharge cylinder 17 disposed adjacent to the impression cylinder 15 has the same diameter as the impression cylinder 15. The discharge cylinder 17 has a structure in which a pair of chains 19 are wound around both ends thereof, and grippers 41 described later are disposed on connecting members (not shown) that connect the pair of chains 19. . The leading edge of the printing paper held by the gripper of the pressure drum 15 is held by any gripper 41 of the paper discharge drum 17 when the printing paper is transferred from the pressure drum 15 to the paper discharge drum 17. Then, as the chain 19 moves, the printing paper is conveyed onto the paper discharge unit 28 and discharged.
[0034]
  The paper feed cylinder 16 is connected to a drive motor via a belt (not shown). The paper feed cylinder 16, the pressure drum 15, the paper discharge cylinder 17, and the first and second blanket cylinders 13 and 14 are connected to each other by gears attached to their ends. Further, the first blanket cylinder 13 and the first plate cylinder 11 moved to the first printing position, and the second blanket cylinder 14 and the second plate cylinder 12 moved to the second printing position are: They are connected by gears attached to the end portions. Accordingly, the drive cylinder (not shown) drives the feed cylinder 16, the impression cylinder 15, the discharge cylinder 17, the first and second blanket cylinders 13 and 14, and the first and second plate cylinders 11 and 12. , Rotate in sync with each other.
[0035]
  Next, plate making and printing operations by this printing apparatus will be described. FIG. 3 is a flowchart showing an outline of plate making and printing operations by this printing apparatus. The printing and plate making operations are for the case where multicolor printing is performed on printing paper with four colors of inks of yellow, magenta, cyan, and black.
[0036]
  First, a plate making process is performed in which an image is recorded on the printing plate P on the first and second plate cylinders 11 and 12 and development processing is performed (step S1). This plate making process is executed according to the process shown in the flowchart of FIG. 4 as a subroutine.
[0037]
  That is, first, the first plate cylinder 11 is moved to the image recording position indicated by the two-dot chain line in FIG. 1 (step S11).
[0038]
  Next, the printing plate P is supplied to the outer periphery of the first plate cylinder 11 (step S12). The supply of the printing plate P is executed by holding the leading portion of the printing plate P drawn from the supply cassette 63 and the rear end portion of the printing plate P cut by the cutter 66 with a pair of gripping claws (not shown).
[0039]
  Subsequently, an image is recorded on the printing plate P held on the outer periphery of the first plate cylinder 11 (step S13). This image recording is performed by rotating the first plate cylinder 11 at a low speed and irradiating a modulated laser beam onto the printing plate P held on the outer periphery of the first plate cylinder 11 from the image recording apparatus 25. Executed.
[0040]
  Next, the printing plate P on which the image is recorded is developed (step S14). This development processing is performed on the printing plate P that rotates with the first plate cylinder 11 after the development processing device 26 is raised from the standby position indicated by the two-dot chain line in FIG. 1 to the development processing position indicated by the solid line. This is executed by sequentially bringing the contact portion, the fixing portion and the aperture portion into contact with each other.
[0041]
  When the developing process is completed, the first plate cylinder 11 is moved to the first printing position indicated by the solid line in FIG. 1 (step S15).
[0042]
  Subsequently, a plate making process for the printing plate P held on the outer periphery of the second plate cylinder 12 is performed by the same operation as in steps S11 to 15 (steps S16 to S20). And if the plate making to the printing plate P hold | maintained on the outer periphery of the 1st, 2nd plate cylinders 11 and 12 is complete | finished, a plate making process will be complete | finished.
[0043]
  Referring to FIG. 3 again, when the plate making process is completed, a printing process for printing on printing paper using printing plates P on the first and second plate cylinders 11 and 12 is executed (step S2).
[0044]
  In this printing process, first, each fountain solution supply device 21 and each ink supply device 20 are only connected to the corresponding image areas of the printing plates P held on the first and second plate cylinders 11 and 12. Make contact. Accordingly, the dampening water and the ink are supplied from the corresponding dampening water supply devices 21 and the ink supply devices 20 to the respective image regions 67a, 67b, 67c, and 67d. The ink supplied to the printing plate P is transferred to corresponding areas of the first and second blanket cylinders 13 and 14.
[0045]
  Then, the printing paper is supplied to the paper feed cylinder 16. This printing paper is transferred from the paper feed cylinder 16 to the impression cylinder 15. When the impression cylinder 15 continues to rotate in this state, the impression cylinder 15 has a diameter that is ½ of the first and second plate cylinders 11 and 12 and the first and second blanket cylinders 13 and 14. Therefore, black and cyan inks are transferred to the printing paper held on the outer periphery of the impression cylinder 15 in the first rotation, and magenta and yellow inks are transferred in the second rotation.
[0046]
  In this way, the leading end portion of the printing paper on which printing of four colors has been completed is transferred from the impression cylinder 15 to the discharge cylinder 17. The printing paper on which the printing of the four colors has been completed is conveyed toward the paper discharge unit 28 by driving the pair of chains 19, and after the image is read by the imaging unit 40, the print paper is discharged onto the paper discharge unit 28. The
[0047]
  In this printing step, a leveling operation by a bridge roller described later is executed.
[0048]
  When the printing process is completed, the printing plate P used for printing is discharged (step S3). In order to discharge the printing plate P, the first plate cylinder 11 is first moved to an image recording position indicated by a two-dot chain line in FIG. Then, the first plate cylinder 11 is rotated counterclockwise, and the end portion of the printing plate P held on the first plate cylinder 11 is peeled off by the claw mechanism 73, and then the printing plate P is transferred to the conveyor mechanism. It is guided by 69 and discharged into the discharge cassette 68. Then, after returning the first plate cylinder 11 to the first printing position, the second plate cylinder 12 is moved from the second printing position to the image recording position, and the same operation as described above is executed. The printing plate P held on the second plate cylinder 12 is discharged into the discharge cassette 68.
[0049]
  When the discharge process of the printing plate P is completed, the first and second blanket cylinders 13 and 14 are cleaned by the blanket cylinder cleaning device 29 (step S4).
[0050]
  When the cleaning of the first and second blanket cylinders 13 and 14 is completed, it is confirmed whether or not another printing paper is to be printed (step S5). When other printing work is performed, the operations in steps 1 to 4 are repeated.
[0051]
  When the printing operation is completed, the ink is washed (step S6). This ink cleaning is performed by removing and cleaning ink adhering to the ink roller and the ink fountain 72 in each ink supply device 20 by an ink cleaning device (not shown) disposed in each ink supply device 20.
[0052]
  When the ink cleaning process is completed, all processes are completed.
[0053]
  [Configuration of Features of the Present Invention]
[0054]
  Next, the structure of the characteristic part of this invention is demonstrated.
[0055]
  First, the configuration of the above-described ink supply device 20d will be described. 5 and 6 are schematic side views of the ink supply device 20d. In the following description, the ink supply device 20d among the four ink supply devices 20a, 20b, 20c, and 20d will be described, but the other ink supply devices 20a, 20b, and 20c are equivalent to the ink supply device 20d. It has a configuration.
[0056]
  The ink supply device 20d has three ink deposits for supplying ink to the printing plate P by contacting the ink base roller 290 constituting the ink fountain 72 and the printing plate P mounted on the second plate cylinder 12. The ink on the ink base roller 290 is transferred to the ink kneading roller 296 and the three ink kneading rollers 294, 295, and 296 that knead the ink by the rollers 291, 292, and 293, and the swinging motion that reciprocates in the axial direction. An ink calling roller 297 and two ink transfer rollers 298 and 299. In this specification, when these rollers 290, 291, 292, 293, 294, 295, 296, 297, 298, and 299 are collectively referred to, they are simply referred to as “ink rollers”.
[0057]
  The ink supply device 20d including the ink roller and the ink fountain 72 is supported directly or indirectly by the pair of left and right side plates 315. The pair of left and right side plates 315 are configured to be swingable about a shaft 251 by driving a pair of left and right air cylinders (not shown).
[0058]
  Of the ink rollers described above, the ink form roller 291 is pivotally supported by a pair of left and right arms 302 that swing about a shaft 301. The arm 302 is urged by a pair of left and right springs 303 in a direction (counterclockwise in FIGS. 5 and 6) in which the ink form roller 291 contacts the second plate cylinder 12. Further, a pair of left and right contact members 306 that contact the release cam 304 is attached to the arm 302.
[0059]
  The ink form roller 292 is pivotally supported by a pair of left and right arms 308 that swing about a shaft 307. The arm 308 is urged by a pair of left and right springs 309 in a direction in which the ink form roller 292 contacts the second plate cylinder 12 (counterclockwise in FIGS. 5 and 6). Furthermore, a pair of left and right contact members 311 that contact the release cam 305 are attached to the arm 308.
[0060]
  Further, the ink form roller 293 is pivotally supported by a pair of left and right arms 312 that swing about a shaft 307. The arm 312 is urged by a pair of left and right springs 313 in a direction in which the ink form roller 293 contacts the first plate cylinder 11 (clockwise in FIGS. 5 and 6). Further, a pair of left and right contact members 314 that come into contact with the release cam 305 are attached to the arm 312.
[0061]
  In the ink supply device 20d, the ink stored in the ink fountain 72 is transferred from the ink base roller 290 to the ink kneading roller 296 by the ink calling roller 297, and the ink kneading rollers 294, 295, 296 and the ink transfer rollers 298, After being kneaded by 299, it is supplied to the ink form rollers 291, 292, and 293.
[0062]
  At this time, in the ink supply device 20d, the cam disposed on the side surface of the second plate cylinder 12 rotates the release cams 304 and 305 in the clockwise direction as the second plate cylinder 12 rotates. As a result, the arms 302, 308, 312 rotate from the position shown in FIG. 5 to the position shown in FIG. As the arms 302, 308, and 312 rotate, the ink form rollers 291, 292, and 293 are separated from the surface of the printing plate P mounted on the second plate cylinder 12. For this reason, by attaching a cam having an appropriate shape to the second plate cylinder 12, among the two image areas 67c and 67d formed on the printing plate P held on the outer peripheral portion of the second plate cylinder 12. The ink form rollers 291, 292, and 293 of the ink supply device 20 d come into contact with any desired image area, so that ink can be supplied only to the necessary image area.
[0063]
  Next, the configuration of the dampening water supply device 21d described above will be described. 7 and 8 are schematic side views showing the fountain solution supply device 21d together with the ink form roller 293 and the ink kneading roller 295 described above. In the following description, the dampening water supply device 21d among the four dampening water supply devices 21a, 21b, 21c, and 21d will be described, but the other dampening water supply devices 21a, 21b, and 21c are also inks. It has the same configuration as the supply device 21d.
[0064]
  The dampening water supply device 21d is configured such that a dampening roller 351 that supplies dampening water to the printing plate P by abutting against the printing plate P mounted on the second plate cylinder 12, and a part thereof is a water boat 352. The water source roller 353 is immersed in the dampening water stored therein, and the water intermediate roller 354 is configured to transfer the dampening water from the water source roller 353 to the swim roller 351.
[0065]
  The water source roller 353 is rotatably supported by the support plate 355. Further, the water intermediate roller 354 is rotatably supported by the support plate 356. A predetermined nip pressure is applied between the water source roller 353 and the water intermediate roller 354 by the adjusting screw 357. On the other hand, the swim roller 351 is supported by the support plate 358 so as to be rotatable about the shaft 364. A predetermined nip pressure is applied between the water-filling roller 351 and the water intermediate roller 354 by the air cylinder 359.
[0066]
  A support plate 362 is rotatably attached to a shaft 364 that is the rotation center of the swim roller 351. An air cylinder 365 is connected to the support plate 362. A bridge roller 361 is supported on the support plate 362 so as to be rotatable about a shaft 363. That is, the bridge roller 361 is supported by the support plate 362 that rotates around the shaft 364 in response to the driving of the air cylinder 365 so as to be rotatable around the shaft 364 that is the axis of the swim roller 351. become.
[0067]
  The bridge roller 361 moves between the separation position shown in FIG. 7 and the leveling position shown in FIG. 8 by driving the air cylinder 365. Here, the separation position is a position where the bridge roller 361 is in contact with the water application roller 351 but is separated from the ink application roller 293 of the ink supply device 20d. Further, the leveling position is a position where the bridge roller 361 contacts both the water application roller 351 and the ink application roller 293 of the ink supply device 20d.
[0068]
  The bridge roller 361 is configured to swing in a direction parallel to its axis by the action of a swing mechanism.
[0069]
  FIG. 9 is a schematic cross-sectional view showing the swing mechanism of the bridge roller 361.
[0070]
  As shown in this figure, a gear 372 is attached to one end of a shaft 364 in the swim roller 351. The gear 372 meshes with a gear 371 attached to one end of the shaft 363 in the bridge roller 361. For this reason, the shaft 364 and the shaft 363 rotate in synchronization. At this time, the swim roller 351 and the shaft 364 are fixed to each other. On the other hand, the bridge roller 361 and the shaft 363 are connected via a thrust bearing 376, and the bridge roller 361 is configured to be rotatable around the shaft 363. For this reason, the bridge roller 361 rotates independently of the shaft 363 due to the frictional force with the swim roller 351.
[0071]
  Further, both end portions of the bridge roller 361 are configured as inclined surfaces 375 that are parallel to each other, and the inclined surfaces 375 and the outer peripheral surfaces of a pair of bearings 373 that can rotate around pins 374 erected on the shaft 363. It is in contact. For this reason, when the shaft 363 rotates in synchronization with the shaft 363, the bridge roller 361 swings in a direction parallel to the axis.
[0072]
  By the swinging motion of the bridge roller 361, the ink on the water-filling roller 351 can be leveled in the axial direction of the water-sealing roller 351. That is, the bridge roller 351 has a function of a rider roller used in a normal printing apparatus.
[0073]
  FIG. 10 is a block diagram showing the main electrical configuration of the printing apparatus.
[0074]
  The printing apparatus includes a control unit 140 including a ROM 141 that stores an operation program necessary for controlling the apparatus, a RAM 142 that temporarily stores data and the like during control, and a CPU 143 that executes logical operations. This control unit 140 is connected to the ink supply device 20, the image recording device 25, the development processing device 26, the blanket cylinder cleaning device 29, the cylinder insertion mechanisms of the first and second blanket cylinders 13 and 14, and the like via the interface 144. Are connected to a drive circuit 145 for generating a drive signal such as a drive unit. The printing apparatus is controlled by the control unit 140 and executes a plate making operation and a printing operation, which will be described later.
[0075]
  Further, the RAM 142 in the control unit 140 stores a relationship between a limit print number and a halftone dot area ratio, which will be described later, and halftone dot area ratio data of an image to be actually printed. The controller 140 controls the operation of the bridge roller 361 by driving the air cylinder 365 and the like based on these data.
[0076]
  [Description of ink leveling operation]
[0077]
  Next, the ink leveling operation during printing by the printing apparatus including the ink supply device 20 and the fountain solution supply device 21 described above will be described. FIG. 11 is a flowchart showing the ink leveling operation executed in the printing process.
[0078]
  When printing is performed using the above-described printing apparatus, emulsification is previously performed on the swim roller 351 when printing is continuously performed based on the dot area ratio of the image to be printed. The limit number of prints (hereinafter referred to as “limit print number” in this specification) at which ink cannot be accumulated due to accumulation of ink is measured.
[0079]
  FIG. 12 is a graph showing the relationship between the limit printing number and the dot area ratio.
[0080]
  As shown in this figure, generally, the limit printing number decreases as the halftone dot area ratio decreases. This is presumably because the smaller the halftone dot area ratio, the smaller the amount of ink consumed, so that the emulsified ink tends to accumulate on the swim roller 351. For this reason, the relationship between the halftone dot area ratio of the image to be printed and the limit print number at that time is experimentally obtained. Prior to printing, the limit print sheet number m for printing the image is recognized from the halftone dot area ratio n of the image to be actually printed.
[0081]
  As the halftone dot area ratio n of an image to be actually printed, the average halftone dot area ratio of the entire image may be used as the total halftone dot area ratio. You may utilize the halftone dot area rate of the area | region with a low dot area rate as the whole halftone dot area rate.
[0082]
  Thereafter, printing is executed. This printing operation is executed as a subroutine of the printing process (step S2) shown in FIG.
[0083]
  In a state where the printing operation is being performed, the ink form rollers 291, 292, and 293 are in contact with the printing plate P as shown in FIGS. 5 and 7. Further, as shown in FIG. 7, the swim roller 351 is in contact with the printing plate P. Further, the bridge roller 361 is disposed at a separated position that is in contact with the swim roller 351 but is separated from the ink roller 293.
[0084]
  At the time of the printing operation, the number of prints that have been printed is integrated, and it is confirmed whether or not the integrated number of prints has reached the limit print number m recognized in advance (step S21). When the accumulated number of printed sheets reaches a limit number of printed sheets of about 1000 sheets, for example, an ink leveling operation is executed.
[0085]
  That is, the paper supply unit 27 shown in FIG. 1 is controlled to temporarily stop the supply of printing paper (step S22). Then, each ink form roller 291, 292, 293 is moved away from the printing plate P by raising each ink form roller 291, 292, 293 (step S 23). Further, by the action of the air cylinder 365, the bridge roller 361 is moved from the separation position shown in FIG. 7 to the leveling position where the bridge roller 361 shown in FIG. 8 is in contact with both the water application roller 351 and the ink application roller 293 ( Step S24).
[0086]
  In this state, the emulsified ink on the water application roller 351 is mixed with the ink on the ink application roller 293, whereby the ink is leveled between the water application roller 351 and the ink application roller 293. For this reason, the ink on the swim roller 351 is appropriate.
[0087]
  For example, when a time of about 2 seconds elapses after the bridge roller 361 moves to the leveling position (Step S25), the bridge roller 361 is separated from the leveling position shown in FIG. Move to position (step S26).
[0088]
  Then, each ink form roller 291, 292, 293 is moved down to move each ink form roller 291, 292, 293 to a position where it abuts against the printing plate P (step S 27), and the paper feed unit 27 causes the printing paper to be printed. Is resumed (step S28), and the printing operation is resumed.
[0089]
  In the above-described embodiment, when performing the ink leveling operation, only the ink form rollers 291, 292, and 293 are separated from the printing plate P, and the water application roller 351 is brought into contact with the printing plate P. It remains in the state. This is to prevent the printing plate P from drying during the ink leveling operation. However, if drying of the printing plate P does not cause a problem, the swim roller 351 may be separated from the printing plate P.
[0090]
  In the above-described embodiment, the ink leveling operation is performed after the printing operation is temporarily interrupted by temporarily stopping paper feeding. However, in the printing apparatus according to this embodiment, each ink supply device 20 is brought into contact only with the corresponding image area of the printing plate P held on the first and second plate cylinders 11 and 12. Accordingly, each of the image regions 67a, 67b, 67c, and 67d is configured to be supplied with ink from the corresponding ink supply device 20, so that each ink supply device 20 supplies ink to the printing plate P. By performing the above-described ink leveling operation when there is no ink, the ink leveling operation can be performed without stopping the printing operation.
[0091]
  Furthermore, in the above-described embodiment, a printing apparatus that receives image data and makes a printing plate and executes printing using the printing plate after plate making is used. The same applies to the case of using a normal printing apparatus for execution.
[0092]
【The invention's effect】
  According to the first aspect of the present invention, the bridge roller can be moved between the leveling position and the separation position, and the bridge roller can be leveled or separated by controlling the moving mechanism for moving the bridge roller. Since the control unit to be moved to is provided, a high-quality printed matter can be obtained without requiring complicated work.
[0093]
  In addition, the control unit moves the bridge roller from the separation position to the leveling position automatically when the limit print number obtained experimentally in advance from the halftone dot area ratio of the image to be printed is reached. The leveling operation can be executed, and a high-quality printed matter can be obtained without requiring complicated work.
[0094]
  According to the second aspect of the present invention, the bridge roller moves between the leveling position and the separation position by rotating around the axis of the swim roller, so that the bridge roller has a simple configuration. It is possible to accurately move between the smoothing position and the separation position.
[0095]
  According to the third aspect of the invention, since the bridge roller swings in a direction parallel to the axis of the bridge roller, the ink on the swim roller can be leveled in the axial direction by the swing operation of the bridge roller. It becomes possible.
[Brief description of the drawings]
FIG. 1 is a schematic side view of a printing apparatus to which the present invention is applied.
FIG. 2 is an explanatory diagram showing an arrangement of an image area 67 on a printing plate P.
FIG. 3 is a flowchart showing an outline of plate making and printing operations by the printing apparatus.
FIG. 4 is a flowchart showing a plate making process.
FIG. 5 is a schematic side view of an ink supply device 20d.
FIG. 6 is a schematic side view of an ink supply device 20d.
FIG. 7 is a schematic side view showing the dampening water supply device 21d together with the ink form roller 293 and the ink kneading roller 295 described above.
FIG. 8 is a schematic side view showing the dampening water supply device 21d together with the ink form roller 293 and the ink kneading roller 295 described above.
9 is a schematic cross-sectional view showing a swing mechanism of a bridge roller 361. FIG.
FIG. 10 is a block diagram illustrating a main electrical configuration of the printing apparatus.
FIG. 11 is a flowchart showing an ink leveling operation executed in a printing process.
FIG. 12 is a graph showing the relationship between the limit printing number and the dot area ratio.
[Explanation of symbols]
  11 First plate cylinder
  12 Second plate cylinder
  13 First blanket cylinder
  14 Second blanket cylinder
  15 impression cylinder
  16 Feed cylinder
  17 Discharge cylinder
  18 Sprocket
  19 chain
  20 Ink supply device
  21 Dampening water supply device
  23 Plate Supply Department
  24 Discarding part
  25 Image recording device
  26 Development processing equipment
  27 Feeder
  28 Paper discharge unit
  72 Inkwell
  290 Ink base roller
  291 Inking roller
  292 Inking roller
  293 Inking roller
  294 Ink kneading roller
  295 Ink kneading roller
  296 Ink kneading roller
  297 Ink call roller
  304 Release cam
  305 Release cam
  351 Swim Roller
  352 water boat
  353 Mizumoto Roller
  354 Water intermediate roller
  355 Support plate
  356 support plate
  357 Adjustment screw
  358 Support plate
  359 Air cylinder
  361 Bridge Roller
  362 Support plate
  363 axes
  364 axes
  365 Air cylinder
  371 gear
  372 gear
  373 Bearing
  374 pins
  375 inclined surface
  376 Thrust bearing

Claims (3)

A dampening water supply device comprising a dampening roller for supplying dampening water to the printing plate by rotating in contact with the surface of the printing plate;
An ink supply device having an ink form roller for supplying ink to the printing plate by rotating in contact with the surface of the printing plate;
A bridge roller that is movable between a leveling position that abuts both of the swim roller and the ink form roller, and a spaced position that abuts the swim roller and is spaced from the ink form roller;
A moving mechanism for moving the bridge roller ;
A control unit that moves the bridge roller to the leveling position or the separation position by controlling the moving mechanism ;
Equipped with a,
The controller is configured to move the bridge roller from the separation position to the leveling position when a limit printing number obtained experimentally in advance from a halftone dot area ratio of an image to be printed is reached. Printing device to do. The printing apparatus according to claim 1,
The bridge roller is a printing apparatus that moves between the leveling position and the separation position by rotating around the axis of the swim roller. The printing apparatus according to claim 2,
The bridge roller is a printing device that swings in a direction parallel to its axis.

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