JP2016203546A - Printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printer which has a simple structure and can perform double-sided printing with excellent accuracy.SOLUTION: A printer comprises a first cylinder 4 on which an image is formed by an image formation part and a second cylinder 5 adjacent to the first cylinder 4. The first cylinder 4 is provided with a surface transfer part 4F and a rear surface primary transfer part 4B. The second cylinder 5 is provided with a rear surface secondary transfer part 5B. Printing can be simultaneously performed on both surfaces of a paper sheet with conveyance of the paper sheet to the space between the first cylinder 4 and the second cylinder 5.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a printing machine, and more particularly to a duplex printing machine capable of printing on both sides of a sheet.

  There has been proposed a printing machine capable of printing on both front and back sides of a sheet conveyed from a paper feeding unit by a printing unit. For example, Patent Document 1 discloses such a printing machine. In the configuration of Patent Document 1, both sides of a sheet can be printed by one printing unit. That is, by disposing a transport cylinder around a pair of heads and a blanket cylinder, the sheet on which one side is printed is reversed, and the other side can be printed by the same printing unit.

JP 2014-205336 A

  However, in the configuration of Patent Document 1, when the front and back of the paper are reversed, the claw mechanism of the reversing cylinder grips the paper bottom of the sheet conveyed by the reversing double cylinder so that the top and bottom direction of the sheet is reversed. For this reason, there is a possibility that the registration accuracy of printing is deviated or the grip cannot be gripped depending on conditions, and there is room for improvement.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a printing machine capable of accurate double-sided printing with a simple configuration.

  In order to achieve the above object, the present invention includes a first cylinder 4 on which an image is formed by the image forming unit 3, and a second cylinder 5 adjacent to the first cylinder 4. In a printing machine that prints on a sheet by conveying a sheet between the first cylinder 4 and the second cylinder 5, the first cylinder 4 includes a front transfer unit 4F and a back primary transfer unit. 4B is provided, and the second cylinder 5 is provided with a secondary transfer portion 5B for the back surface, and a sheet is conveyed between the first cylinder 4 and the second cylinder 5. By doing so, it is possible to print on both sides of the sheet simultaneously.

  The image forming unit 3 is a digital image forming unit.

  The image forming unit 3 is capable of forming images of a plurality of colors.

  In the printing machine of the present invention, it is possible to provide a printing machine capable of accurate double-sided printing with a simple configuration without inverting the sheet.

1 is a schematic sectional side view of a printing press according to the present invention. It is a principal part enlarged view of the printing machine shown in FIG.

  Next, modes for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 shows an example of a printer capable of duplex printing according to the present invention. As shown in FIG. 1, the printing press according to the present embodiment is an ink jet type sheet-fed printing press. The printing machine includes a feeder unit and a sheet separator (not shown) from the paper stacking unit 1 and a sheet feeding unit for feeding sheets as printing sheets one by one by a feeder board 2 and the like, and a sheet from the sheet feeding unit. A printing unit for printing on a paper sheet and a paper discharge unit for discharging a sheet printed by the printing unit are provided. The specific configuration of each part constituting the printing press is not limited to that shown in the figure. A control unit (not shown) controls each drive of the printing machine.

  The printing unit mainly includes an inkjet head 3 that is an image forming unit, a first transfer cylinder 4 that is a first cylinder, and a second transfer cylinder 5 that is a second cylinder. The first transfer cylinder 4 is configured to have a diameter twice that of the second transfer cylinder 5 (double cylinder). The printed sheet is discharged from the second transfer cylinder 5. That is, an endless chain 8 is wound around a sprocket 6 provided on the front side (upstream side) in the sheet conveyance direction and a sprocket 7 provided on the rear side (downstream side) in the sheet conveyance direction. As a result of the rotation of the sprockets 6 and 7, the chain 8 circulates while being restricted by a chain guide (not shown). The chain 8 is provided with a plurality of chain grippers (not shown) so that the sheet received from the second transfer cylinder 5 can be discharged onto the discharge tray 9. Further, drying devices 10 and 10 are provided with the chain 8 interposed therebetween, and both sides of the sheet can be dried.

  The ink jet head 3 is formed to extend in the axial direction (the depth direction of the paper surface) of the first transfer cylinder 4 and can print over the paper surface width direction of the sheet. The inkjet head 3 is configured to be able to eject four colors of ink of black (BK), cyan (C), magenta (M), and yellow (Y). The inkjet head 3 is configured to be able to print different images one by one on a sheet according to an instruction from a control unit (not shown), and so-called variable printing is possible.

  As shown in FIG. 2, the first transfer cylinder 4 is provided with two gaps 4a that are long in the axial direction and opposed in the circumferential direction (at intervals of 180 degrees). Further, across the gap 4a, a front surface transfer portion 4F is provided on one circumferential surface, and a back surface primary transfer portion 4B is provided on the other circumferential surface. An image to be printed is formed on the front surface of the sheet, and an image to be printed on the back surface of the sheet is formed in the back surface primary transfer unit 4B.

  The second transfer cylinder 5 is provided with one gap 5a in the circumferential direction. The gap 5a is provided so as to face both the gaps 4a of the first transfer cylinder 4 when the first transfer cylinder 4 and the second transfer cylinder 5 rotate. The gap 5a is provided with a gripper 5c for gripping a sheet conveyed by the feeder board 2 with a nail base and a nail. The second transfer cylinder 5 is provided with a secondary transfer section 5B for the back surface over the entire circumference except for the gap 5a, and an image formed on the primary transfer section 4B for the back surface of the first transfer cylinder 4 is displayed. It is configured to be transcribed.

  The operation of the printer capable of duplex printing configured as described above will be described. When the controller drives a motor (not shown), each cylinder of the printing press starts to rotate. When each cylinder reaches a predetermined number of revolutions, the control unit controls the ink jet head 3, and the ink jet head 3 discharges ink when the back surface primary transfer portion 4 </ b> B of the first transfer cylinder 4 faces to perform the back surface primary transfer. A back image is formed on the portion 4B.

  The back side primary transfer part 4B to which the back side image has been transferred faces the back side secondary transfer part 5B of the second transfer cylinder 5 and transfers the image. At the same time, a surface image is formed by the inkjet head 3 on the surface transfer portion 4F of the first transfer cylinder 4. FIG. 1 shows this state.

  In the state shown in FIG. 1, the sheet is conveyed on the feeder board 2 and is held by the gripper 5 c of the second transfer cylinder 5 in accordance with an instruction from the control unit. In this state, the sheet is conveyed between the first transfer cylinder 4 and the second transfer cylinder 5, so that the front surface of the sheet is transferred by the front transfer unit 4F, and the back surface of the sheet is transferred to the back surface. Images are formed (printed) by the primary transfer portion 4B. After transporting the sheet (after printing), the back image is formed again on the primary transfer unit 4B for the back surface. Accordingly, the sheet is supplied every other rotation of the second transfer cylinder 5, and image transfer and printing are performed.

  The printed sheet is conveyed from the second transfer cylinder 5 to the chain gripper described above, dried by the drying devices 10 and 10, and then discharged to the discharge tray 9.

  By configuring in this way, unlike conventional techniques, duplex printing can be performed with a simple configuration. In particular, since there is no change in the orientation of the sheet accompanying reversal, the registration accuracy is increased without reversing the top-to-bottom direction, and a high-quality printed matter can be obtained without a gripping error.

  In addition, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the summary of this invention. For example, in the above-described embodiment, the first transfer cylinder 4 is formed as a double cylinder. However, the present invention is not limited to this, and the first transfer cylinder 4 may be a single cylinder having the same diameter as the second transfer cylinder 5. In this case, the front image and the back image are alternately formed on the circumferential surface of the first transfer cylinder 4 every round. In addition to the drying device 10, a fixing roller that contacts the sheet and fixes the ink may be provided.

  In the above-described embodiment, the ink jet printer is used. However, the present invention is not limited to this, and an electrophotographic printer, a gravure printer, a flexographic printer, or the like can be used as long as the printer can perform double-sided printing. There may be.

  The printer according to the present invention is extremely useful in a printer capable of duplex printing.

1: Paper stack 2: Feeder board 3: Ink jet head 4: 1st transfer cylinder 4B: Back surface primary transfer part 4F: Front transfer part 4a: Gap 5: 2nd transfer cylinder 5B: Back side secondary transfer part 5a : Gap 5c: Gripper 6: Sprocket 7: Sprocket 8: Chain 9: Discharge stand 10: Drying device

Claims (3)

  A first cylinder on which an image is formed by the image forming unit; and a second cylinder adjacent to the first cylinder, and a sheet of paper is interposed between the first cylinder and the second cylinder. In a printing machine that prints on a sheet by conveying, the first cylinder is provided with a front surface transfer section and a back surface primary transfer section, and the second cylinder has a back surface secondary transfer section. A printing machine is provided, wherein a sheet is transported between the first cylinder and the second cylinder so that printing can be performed on both sides of the sheet simultaneously.   The printing machine according to claim 1, wherein the image forming unit is a digital image forming unit. The printing machine according to claim 1 or 2, wherein the image forming unit is capable of forming images of a plurality of colors.

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